Update: Added Ts runtime

shcat_c/parser/Makefile

@@ -6,7 +6,7 @@
 #    By: maiboyer <maiboyer@student.42.fr>          +#+  +:+       +#+         #
 #                                                 +#+#+#+#+#+   +#+            #
 #    Created: 2023/11/03 13:20:01 by maiboyer          #+#    #+#              #
-#    Updated: 2024/04/28 17:23:03 by maiboyer         ###   ########.fr        #
+#    Updated: 2024/04/28 17:48:04 by maiboyer         ###   ########.fr        #
 #                                                                              #
 # **************************************************************************** #
 
@@ -71,8 +71,8 @@ fclean: clean
 	rm -f $(BUILD_DIR)/$(NAME)
 
 re:
-	$(MAKE) --no-print-directory fclean
+	@$(MAKE) --no-print-directory fclean
-	$(MAKE) --no-print-directory all
+	@$(MAKE) --no-print-directory all
 
 generate_filelist:
 	@/usr/bin/env zsh -c "tree -iFf --noreport $(SRC_DIR) | rg '^$(SRC_DIR)/(.*)\.c\$$' --replace '\$$1' | sort -u" > ./source_files.list

shcat_c/parser/src/array.h

@@ -0,0 +1,290 @@
+#ifndef TREE_SITTER_ARRAY_H_
+#define TREE_SITTER_ARRAY_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+
+
+#include <assert.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+
+#ifdef _MSC_VER
+#pragma warning(disable : 4101)
+#elif defined(__GNUC__) || defined(__clang__)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wunused-variable"
+#endif
+
+#define Array(T)       \
+  struct {             \
+    T *contents;       \
+    uint32_t size;     \
+    uint32_t capacity; \
+  }
+
+/// Initialize an array.
+#define array_init(self) \
+  ((self)->size = 0, (self)->capacity = 0, (self)->contents = NULL)
+
+/// Create an empty array.
+#define array_new() \
+  { NULL, 0, 0 }
+
+/// Get a pointer to the element at a given `index` in the array.
+#define array_get(self, _index) \
+  (assert((uint32_t)(_index) < (self)->size), &(self)->contents[_index])
+
+/// Get a pointer to the first element in the array.
+#define array_front(self) array_get(self, 0)
+
+/// Get a pointer to the last element in the array.
+#define array_back(self) array_get(self, (self)->size - 1)
+
+/// Clear the array, setting its size to zero. Note that this does not free any
+/// memory allocated for the array's contents.
+#define array_clear(self) ((self)->size = 0)
+
+/// Reserve `new_capacity` elements of space in the array. If `new_capacity` is
+/// less than the array's current capacity, this function has no effect.
+#define array_reserve(self, new_capacity) \
+  _array__reserve((Array *)(self), array_elem_size(self), new_capacity)
+
+/// Free any memory allocated for this array. Note that this does not free any
+/// memory allocated for the array's contents.
+#define array_delete(self) _array__delete((Array *)(self))
+
+/// Push a new `element` onto the end of the array.
+#define array_push(self, element)                            \
+  (_array__grow((Array *)(self), 1, array_elem_size(self)), \
+   (self)->contents[(self)->size++] = (element))
+
+/// Increase the array's size by `count` elements.
+/// New elements are zero-initialized.
+#define array_grow_by(self, count) \
+  do { \
+    if ((count) == 0) break; \
+    _array__grow((Array *)(self), count, array_elem_size(self)); \
+    memset((self)->contents + (self)->size, 0, (count) * array_elem_size(self)); \
+    (self)->size += (count); \
+  } while (0)
+
+/// Append all elements from one array to the end of another.
+#define array_push_all(self, other)                                       \
+  array_extend((self), (other)->size, (other)->contents)
+
+/// Append `count` elements to the end of the array, reading their values from the
+/// `contents` pointer.
+#define array_extend(self, count, contents)                    \
+  _array__splice(                                               \
+    (Array *)(self), array_elem_size(self), (self)->size, \
+    0, count,  contents                                        \
+  )
+
+/// Remove `old_count` elements from the array starting at the given `index`. At
+/// the same index, insert `new_count` new elements, reading their values from the
+/// `new_contents` pointer.
+#define array_splice(self, _index, old_count, new_count, new_contents)  \
+  _array__splice(                                                       \
+    (Array *)(self), array_elem_size(self), _index,                \
+    old_count, new_count, new_contents                                 \
+  )
+
+/// Insert one `element` into the array at the given `index`.
+#define array_insert(self, _index, element) \
+  _array__splice((Array *)(self), array_elem_size(self), _index, 0, 1, &(element))
+
+/// Remove one element from the array at the given `index`.
+#define array_erase(self, _index) \
+  _array__erase((Array *)(self), array_elem_size(self), _index)
+
+/// Pop the last element off the array, returning the element by value.
+#define array_pop(self) ((self)->contents[--(self)->size])
+
+/// Assign the contents of one array to another, reallocating if necessary.
+#define array_assign(self, other) \
+  _array__assign((Array *)(self), (const Array *)(other), array_elem_size(self))
+
+/// Swap one array with another
+#define array_swap(self, other) \
+  _array__swap((Array *)(self), (Array *)(other))
+
+/// Get the size of the array contents
+#define array_elem_size(self) (sizeof *(self)->contents)
+
+/// Search a sorted array for a given `needle` value, using the given `compare`
+/// callback to determine the order.
+///
+/// If an existing element is found to be equal to `needle`, then the `index`
+/// out-parameter is set to the existing value's index, and the `exists`
+/// out-parameter is set to true. Otherwise, `index` is set to an index where
+/// `needle` should be inserted in order to preserve the sorting, and `exists`
+/// is set to false.
+#define array_search_sorted_with(self, compare, needle, _index, _exists) \
+  _array__search_sorted(self, 0, compare, , needle, _index, _exists)
+
+/// Search a sorted array for a given `needle` value, using integer comparisons
+/// of a given struct field (specified with a leading dot) to determine the order.
+///
+/// See also `array_search_sorted_with`.
+#define array_search_sorted_by(self, field, needle, _index, _exists) \
+  _array__search_sorted(self, 0, _compare_int, field, needle, _index, _exists)
+
+/// Insert a given `value` into a sorted array, using the given `compare`
+/// callback to determine the order.
+#define array_insert_sorted_with(self, compare, value) \
+  do { \
+    unsigned _index, _exists; \
+    array_search_sorted_with(self, compare, &(value), &_index, &_exists); \
+    if (!_exists) array_insert(self, _index, value); \
+  } while (0)
+
+/// Insert a given `value` into a sorted array, using integer comparisons of
+/// a given struct field (specified with a leading dot) to determine the order.
+///
+/// See also `array_search_sorted_by`.
+#define array_insert_sorted_by(self, field, value) \
+  do { \
+    unsigned _index, _exists; \
+    array_search_sorted_by(self, field, (value) field, &_index, &_exists); \
+    if (!_exists) array_insert(self, _index, value); \
+  } while (0)
+
+// Private
+
+typedef Array(void) Array;
+
+/// This is not what you're looking for, see `array_delete`.
+static inline void _array__delete(Array *self) {
+  if (self->contents) {
+    free(self->contents);
+    self->contents = NULL;
+    self->size = 0;
+    self->capacity = 0;
+  }
+}
+
+/// This is not what you're looking for, see `array_erase`.
+static inline void _array__erase(Array *self, size_t element_size,
+                                uint32_t index) {
+  assert(index < self->size);
+  char *contents = (char *)self->contents;
+  memmove(contents + index * element_size, contents + (index + 1) * element_size,
+          (self->size - index - 1) * element_size);
+  self->size--;
+}
+
+/// This is not what you're looking for, see `array_reserve`.
+static inline void _array__reserve(Array *self, size_t element_size, uint32_t new_capacity) {
+  if (new_capacity > self->capacity) {
+    if (self->contents) {
+      self->contents = realloc(self->contents, new_capacity * element_size);
+    } else {
+      self->contents = malloc(new_capacity * element_size);
+    }
+    self->capacity = new_capacity;
+  }
+}
+
+/// This is not what you're looking for, see `array_assign`.
+static inline void _array__assign(Array *self, const Array *other, size_t element_size) {
+  _array__reserve(self, element_size, other->size);
+  self->size = other->size;
+  memcpy(self->contents, other->contents, self->size * element_size);
+}
+
+/// This is not what you're looking for, see `array_swap`.
+static inline void _array__swap(Array *self, Array *other) {
+  Array swap = *other;
+  *other = *self;
+  *self = swap;
+}
+
+/// This is not what you're looking for, see `array_push` or `array_grow_by`.
+static inline void _array__grow(Array *self, uint32_t count, size_t element_size) {
+  uint32_t new_size = self->size + count;
+  if (new_size > self->capacity) {
+    uint32_t new_capacity = self->capacity * 2;
+    if (new_capacity < 8) new_capacity = 8;
+    if (new_capacity < new_size) new_capacity = new_size;
+    _array__reserve(self, element_size, new_capacity);
+  }
+}
+
+/// This is not what you're looking for, see `array_splice`.
+static inline void _array__splice(Array *self, size_t element_size,
+                                 uint32_t index, uint32_t old_count,
+                                 uint32_t new_count, const void *elements) {
+  uint32_t new_size = self->size + new_count - old_count;
+  uint32_t old_end = index + old_count;
+  uint32_t new_end = index + new_count;
+  assert(old_end <= self->size);
+
+  _array__reserve(self, element_size, new_size);
+
+  char *contents = (char *)self->contents;
+  if (self->size > old_end) {
+    memmove(
+      contents + new_end * element_size,
+      contents + old_end * element_size,
+      (self->size - old_end) * element_size
+    );
+  }
+  if (new_count > 0) {
+    if (elements) {
+      memcpy(
+        (contents + index * element_size),
+        elements,
+        new_count * element_size
+      );
+    } else {
+      memset(
+        (contents + index * element_size),
+        0,
+        new_count * element_size
+      );
+    }
+  }
+  self->size += new_count - old_count;
+}
+
+/// A binary search routine, based on Rust's `std::slice::binary_search_by`.
+/// This is not what you're looking for, see `array_search_sorted_with` or `array_search_sorted_by`.
+#define _array__search_sorted(self, start, compare, suffix, needle, _index, _exists) \
+  do { \
+    *(_index) = start; \
+    *(_exists) = false; \
+    uint32_t size = (self)->size - *(_index); \
+    if (size == 0) break; \
+    int comparison; \
+    while (size > 1) { \
+      uint32_t half_size = size / 2; \
+      uint32_t mid_index = *(_index) + half_size; \
+      comparison = compare(&((self)->contents[mid_index] suffix), (needle)); \
+      if (comparison <= 0) *(_index) = mid_index; \
+      size -= half_size; \
+    } \
+    comparison = compare(&((self)->contents[*(_index)] suffix), (needle)); \
+    if (comparison == 0) *(_exists) = true; \
+    else if (comparison < 0) *(_index) += 1; \
+  } while (0)
+
+/// Helper macro for the `_sorted_by` routines below. This takes the left (existing)
+/// parameter by reference in order to work with the generic sorting function above.
+#define _compare_int(a, b) ((int)*(a) - (int)(b))
+
+#ifdef _MSC_VER
+#pragma warning(default : 4101)
+#elif defined(__GNUC__) || defined(__clang__)
+#pragma GCC diagnostic pop
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif  // TREE_SITTER_ARRAY_H_

shcat_c/parser/src/error_costs.h

@@ -0,0 +1,11 @@
+#ifndef TREE_SITTER_ERROR_COSTS_H_
+#define TREE_SITTER_ERROR_COSTS_H_
+
+#define ERROR_STATE 0
+#define ERROR_COST_PER_RECOVERY 500
+#define ERROR_COST_PER_MISSING_TREE 110
+#define ERROR_COST_PER_SKIPPED_TREE 100
+#define ERROR_COST_PER_SKIPPED_LINE 30
+#define ERROR_COST_PER_SKIPPED_CHAR 1
+
+#endif

shcat_c/parser/src/host.h

@@ -0,0 +1,21 @@
+
+// Determine endian and pointer size based on known defines.
+// TS_BIG_ENDIAN and TS_PTR_SIZE can be set as -D compiler arguments
+// to override this.
+
+#if !defined(TS_BIG_ENDIAN)
+#if (defined(__BYTE_ORDER__) && __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__) \
+  || (defined( __APPLE_CC__) && (defined(__ppc__) || defined(__ppc64__)))
+#define TS_BIG_ENDIAN 1
+#else
+#define TS_BIG_ENDIAN 0
+#endif
+#endif
+
+#if !defined(TS_PTR_SIZE)
+#if UINTPTR_MAX == 0xFFFFFFFF
+#define TS_PTR_SIZE 32
+#else
+#define TS_PTR_SIZE 64
+#endif
+#endif

shcat_c/parser/src/language.c

@@ -0,0 +1,214 @@
+#include "./language.h"
+#include "tree_sitter/api.h"
+#include <string.h>
+
+const TSLanguage *ts_language_copy(const TSLanguage *self) {
+  return self;
+}
+
+void ts_language_delete(const TSLanguage *self) {
+}
+
+uint32_t ts_language_symbol_count(const TSLanguage *self) {
+  return self->symbol_count + self->alias_count;
+}
+
+uint32_t ts_language_state_count(const TSLanguage *self) {
+  return self->state_count;
+}
+
+uint32_t ts_language_version(const TSLanguage *self) {
+  return self->version;
+}
+
+uint32_t ts_language_field_count(const TSLanguage *self) {
+  return self->field_count;
+}
+
+void ts_language_table_entry(
+  const TSLanguage *self,
+  TSStateId state,
+  TSSymbol symbol,
+  TableEntry *result
+) {
+  if (symbol == ts_builtin_sym_error || symbol == ts_builtin_sym_error_repeat) {
+    result->action_count = 0;
+    result->is_reusable = false;
+    result->actions = NULL;
+  } else {
+    assert(symbol < self->token_count);
+    uint32_t action_index = ts_language_lookup(self, state, symbol);
+    const TSParseActionEntry *entry = &self->parse_actions[action_index];
+    result->action_count = entry->entry.count;
+    result->is_reusable = entry->entry.reusable;
+    result->actions = (const TSParseAction *)(entry + 1);
+  }
+}
+
+TSSymbolMetadata ts_language_symbol_metadata(
+  const TSLanguage *self,
+  TSSymbol symbol
+) {
+  if (symbol == ts_builtin_sym_error)  {
+    return (TSSymbolMetadata) {.visible = true, .named = true};
+  } else if (symbol == ts_builtin_sym_error_repeat) {
+    return (TSSymbolMetadata) {.visible = false, .named = false};
+  } else {
+    return self->symbol_metadata[symbol];
+  }
+}
+
+TSSymbol ts_language_public_symbol(
+  const TSLanguage *self,
+  TSSymbol symbol
+) {
+  if (symbol == ts_builtin_sym_error) return symbol;
+  return self->public_symbol_map[symbol];
+}
+
+TSStateId ts_language_next_state(
+  const TSLanguage *self,
+  TSStateId state,
+  TSSymbol symbol
+) {
+  if (symbol == ts_builtin_sym_error || symbol == ts_builtin_sym_error_repeat) {
+    return 0;
+  } else if (symbol < self->token_count) {
+    uint32_t count;
+    const TSParseAction *actions = ts_language_actions(self, state, symbol, &count);
+    if (count > 0) {
+      TSParseAction action = actions[count - 1];
+      if (action.type == TSParseActionTypeShift) {
+        return action.shift.extra ? state : action.shift.state;
+      }
+    }
+    return 0;
+  } else {
+    return ts_language_lookup(self, state, symbol);
+  }
+}
+
+const char *ts_language_symbol_name(
+  const TSLanguage *self,
+  TSSymbol symbol
+) {
+  if (symbol == ts_builtin_sym_error) {
+    return "ERROR";
+  } else if (symbol == ts_builtin_sym_error_repeat) {
+    return "_ERROR";
+  } else if (symbol < ts_language_symbol_count(self)) {
+    return self->symbol_names[symbol];
+  } else {
+    return NULL;
+  }
+}
+
+TSSymbol ts_language_symbol_for_name(
+  const TSLanguage *self,
+  const char *string,
+  uint32_t length,
+  bool is_named
+) {
+  if (!strncmp(string, "ERROR", length)) return ts_builtin_sym_error;
+  uint16_t count = (uint16_t)ts_language_symbol_count(self);
+  for (TSSymbol i = 0; i < count; i++) {
+    TSSymbolMetadata metadata = ts_language_symbol_metadata(self, i);
+    if ((!metadata.visible && !metadata.supertype) || metadata.named != is_named) continue;
+    const char *symbol_name = self->symbol_names[i];
+    if (!strncmp(symbol_name, string, length) && !symbol_name[length]) {
+      return self->public_symbol_map[i];
+    }
+  }
+  return 0;
+}
+
+TSSymbolType ts_language_symbol_type(
+  const TSLanguage *self,
+  TSSymbol symbol
+) {
+  TSSymbolMetadata metadata = ts_language_symbol_metadata(self, symbol);
+  if (metadata.named && metadata.visible) {
+    return TSSymbolTypeRegular;
+  } else if (metadata.visible) {
+    return TSSymbolTypeAnonymous;
+  } else {
+    return TSSymbolTypeAuxiliary;
+  }
+}
+
+const char *ts_language_field_name_for_id(
+  const TSLanguage *self,
+  TSFieldId id
+) {
+  uint32_t count = ts_language_field_count(self);
+  if (count && id <= count) {
+    return self->field_names[id];
+  } else {
+    return NULL;
+  }
+}
+
+TSFieldId ts_language_field_id_for_name(
+  const TSLanguage *self,
+  const char *name,
+  uint32_t name_length
+) {
+  uint16_t count = (uint16_t)ts_language_field_count(self);
+  for (TSSymbol i = 1; i < count + 1; i++) {
+    switch (strncmp(name, self->field_names[i], name_length)) {
+      case 0:
+        if (self->field_names[i][name_length] == 0) return i;
+        break;
+      case -1:
+        return 0;
+      default:
+        break;
+    }
+  }
+  return 0;
+}
+
+TSLookaheadIterator *ts_lookahead_iterator_new(const TSLanguage *self, TSStateId state) {
+  if (state >= self->state_count) return NULL;
+  LookaheadIterator *iterator = malloc(sizeof(LookaheadIterator));
+  *iterator = ts_language_lookaheads(self, state);
+  return (TSLookaheadIterator *)iterator;
+}
+
+void ts_lookahead_iterator_delete(TSLookaheadIterator *self) {
+  free(self);
+}
+
+bool ts_lookahead_iterator_reset_state(TSLookaheadIterator * self, TSStateId state) {
+  LookaheadIterator *iterator = (LookaheadIterator *)self;
+  if (state >= iterator->language->state_count) return false;
+  *iterator = ts_language_lookaheads(iterator->language, state);
+  return true;
+}
+
+const TSLanguage *ts_lookahead_iterator_language(const TSLookaheadIterator *self) {
+  const LookaheadIterator *iterator = (const LookaheadIterator *)self;
+  return iterator->language;
+}
+
+bool ts_lookahead_iterator_reset(TSLookaheadIterator *self, const TSLanguage *language, TSStateId state) {
+  if (state >= language->state_count) return false;
+  LookaheadIterator *iterator = (LookaheadIterator *)self;
+  *iterator = ts_language_lookaheads(language, state);
+  return true;
+}
+
+bool ts_lookahead_iterator_next(TSLookaheadIterator *self) {
+  LookaheadIterator *iterator = (LookaheadIterator *)self;
+  return ts_lookahead_iterator__next(iterator);
+}
+
+TSSymbol ts_lookahead_iterator_current_symbol(const TSLookaheadIterator *self) {
+  const LookaheadIterator *iterator = (const LookaheadIterator *)self;
+  return iterator->symbol;
+}
+
+const char *ts_lookahead_iterator_current_symbol_name(const TSLookaheadIterator *self) {
+  const LookaheadIterator *iterator = (const LookaheadIterator *)self;
+  return ts_language_symbol_name(iterator->language, iterator->symbol);
+}

shcat_c/parser/src/language.h

@@ -0,0 +1,299 @@
+#ifndef TREE_SITTER_LANGUAGE_H_
+#define TREE_SITTER_LANGUAGE_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include "./subtree.h"
+#include "./parser.h"
+
+#define ts_builtin_sym_error_repeat (ts_builtin_sym_error - 1)
+
+#define LANGUAGE_VERSION_WITH_PRIMARY_STATES 14
+#define LANGUAGE_VERSION_USABLE_VIA_WASM 13
+
+typedef struct {
+  const TSParseAction *actions;
+  uint32_t action_count;
+  bool is_reusable;
+} TableEntry;
+
+typedef struct {
+  const TSLanguage *language;
+  const uint16_t *data;
+  const uint16_t *group_end;
+  TSStateId state;
+  uint16_t table_value;
+  uint16_t section_index;
+  uint16_t group_count;
+  bool is_small_state;
+
+  const TSParseAction *actions;
+  TSSymbol symbol;
+  TSStateId next_state;
+  uint16_t action_count;
+} LookaheadIterator;
+
+void ts_language_table_entry(const TSLanguage *, TSStateId, TSSymbol, TableEntry *);
+
+TSSymbolMetadata ts_language_symbol_metadata(const TSLanguage *, TSSymbol);
+
+TSSymbol ts_language_public_symbol(const TSLanguage *, TSSymbol);
+
+TSStateId ts_language_next_state(const TSLanguage *self, TSStateId state, TSSymbol symbol);
+
+static inline bool ts_language_is_symbol_external(const TSLanguage *self, TSSymbol symbol) {
+  return 0 < symbol && symbol < self->external_token_count + 1;
+}
+
+static inline const TSParseAction *ts_language_actions(
+  const TSLanguage *self,
+  TSStateId state,
+  TSSymbol symbol,
+  uint32_t *count
+) {
+  TableEntry entry;
+  ts_language_table_entry(self, state, symbol, &entry);
+  *count = entry.action_count;
+  return entry.actions;
+}
+
+static inline bool ts_language_has_reduce_action(
+  const TSLanguage *self,
+  TSStateId state,
+  TSSymbol symbol
+) {
+  TableEntry entry;
+  ts_language_table_entry(self, state, symbol, &entry);
+  return entry.action_count > 0 && entry.actions[0].type == TSParseActionTypeReduce;
+}
+
+// Lookup the table value for a given symbol and state.
+//
+// For non-terminal symbols, the table value represents a successor state.
+// For terminal symbols, it represents an index in the actions table.
+// For 'large' parse states, this is a direct lookup. For 'small' parse
+// states, this requires searching through the symbol groups to find
+// the given symbol.
+static inline uint16_t ts_language_lookup(
+  const TSLanguage *self,
+  TSStateId state,
+  TSSymbol symbol
+) {
+  if (state >= self->large_state_count) {
+    uint32_t index = self->small_parse_table_map[state - self->large_state_count];
+    const uint16_t *data = &self->small_parse_table[index];
+    uint16_t group_count = *(data++);
+    for (unsigned i = 0; i < group_count; i++) {
+      uint16_t section_value = *(data++);
+      uint16_t symbol_count = *(data++);
+      for (unsigned j = 0; j < symbol_count; j++) {
+        if (*(data++) == symbol) return section_value;
+      }
+    }
+    return 0;
+  } else {
+    return self->parse_table[state * self->symbol_count + symbol];
+  }
+}
+
+static inline bool ts_language_has_actions(
+  const TSLanguage *self,
+  TSStateId state,
+  TSSymbol symbol
+) {
+  return ts_language_lookup(self, state, symbol) != 0;
+}
+
+// Iterate over all of the symbols that are valid in the given state.
+//
+// For 'large' parse states, this just requires iterating through
+// all possible symbols and checking the parse table for each one.
+// For 'small' parse states, this exploits the structure of the
+// table to only visit the valid symbols.
+static inline LookaheadIterator ts_language_lookaheads(
+  const TSLanguage *self,
+  TSStateId state
+) {
+  bool is_small_state = state >= self->large_state_count;
+  const uint16_t *data;
+  const uint16_t *group_end = NULL;
+  uint16_t group_count = 0;
+  if (is_small_state) {
+    uint32_t index = self->small_parse_table_map[state - self->large_state_count];
+    data = &self->small_parse_table[index];
+    group_end = data + 1;
+    group_count = *data;
+  } else {
+    data = &self->parse_table[state * self->symbol_count] - 1;
+  }
+  return (LookaheadIterator) {
+    .language = self,
+    .data = data,
+    .group_end = group_end,
+    .group_count = group_count,
+    .is_small_state = is_small_state,
+    .symbol = UINT16_MAX,
+    .next_state = 0,
+  };
+}
+
+static inline bool ts_lookahead_iterator__next(LookaheadIterator *self) {
+  // For small parse states, valid symbols are listed explicitly,
+  // grouped by their value. There's no need to look up the actions
+  // again until moving to the next group.
+  if (self->is_small_state) {
+    self->data++;
+    if (self->data == self->group_end) {
+      if (self->group_count == 0) return false;
+      self->group_count--;
+      self->table_value = *(self->data++);
+      unsigned symbol_count = *(self->data++);
+      self->group_end = self->data + symbol_count;
+      self->symbol = *self->data;
+    } else {
+      self->symbol = *self->data;
+      return true;
+    }
+  }
+
+  // For large parse states, iterate through every symbol until one
+  // is found that has valid actions.
+  else {
+    do {
+      self->data++;
+      self->symbol++;
+      if (self->symbol >= self->language->symbol_count) return false;
+      self->table_value = *self->data;
+    } while (!self->table_value);
+  }
+
+  // Depending on if the symbols is terminal or non-terminal, the table value either
+  // represents a list of actions or a successor state.
+  if (self->symbol < self->language->token_count) {
+    const TSParseActionEntry *entry = &self->language->parse_actions[self->table_value];
+    self->action_count = entry->entry.count;
+    self->actions = (const TSParseAction *)(entry + 1);
+    self->next_state = 0;
+  } else {
+    self->action_count = 0;
+    self->next_state = self->table_value;
+  }
+  return true;
+}
+
+// Whether the state is a "primary state". If this returns false, it indicates that there exists
+// another state that behaves identically to this one with respect to query analysis.
+static inline bool ts_language_state_is_primary(
+  const TSLanguage *self,
+  TSStateId state
+) {
+  if (self->version >= LANGUAGE_VERSION_WITH_PRIMARY_STATES) {
+    return state == self->primary_state_ids[state];
+  } else {
+    return true;
+  }
+}
+
+static inline const bool *ts_language_enabled_external_tokens(
+  const TSLanguage *self,
+  unsigned external_scanner_state
+) {
+  if (external_scanner_state == 0) {
+    return NULL;
+  } else {
+    return self->external_scanner.states + self->external_token_count * external_scanner_state;
+  }
+}
+
+static inline const TSSymbol *ts_language_alias_sequence(
+  const TSLanguage *self,
+  uint32_t production_id
+) {
+  return production_id ?
+    &self->alias_sequences[production_id * self->max_alias_sequence_length] :
+    NULL;
+}
+
+static inline TSSymbol ts_language_alias_at(
+  const TSLanguage *self,
+  uint32_t production_id,
+  uint32_t child_index
+) {
+  return production_id ?
+    self->alias_sequences[production_id * self->max_alias_sequence_length + child_index] :
+    0;
+}
+
+static inline void ts_language_field_map(
+  const TSLanguage *self,
+  uint32_t production_id,
+  const TSFieldMapEntry **start,
+  const TSFieldMapEntry **end
+) {
+  if (self->field_count == 0) {
+    *start = NULL;
+    *end = NULL;
+    return;
+  }
+
+  TSFieldMapSlice slice = self->field_map_slices[production_id];
+  *start = &self->field_map_entries[slice.index];
+  *end = &self->field_map_entries[slice.index] + slice.length;
+}
+
+static inline void ts_language_aliases_for_symbol(
+  const TSLanguage *self,
+  TSSymbol original_symbol,
+  const TSSymbol **start,
+  const TSSymbol **end
+) {
+  *start = &self->public_symbol_map[original_symbol];
+  *end = *start + 1;
+
+  unsigned idx = 0;
+  for (;;) {
+    TSSymbol symbol = self->alias_map[idx++];
+    if (symbol == 0 || symbol > original_symbol) break;
+    uint16_t count = self->alias_map[idx++];
+    if (symbol == original_symbol) {
+      *start = &self->alias_map[idx];
+      *end = &self->alias_map[idx + count];
+      break;
+    }
+    idx += count;
+  }
+}
+
+static inline void ts_language_write_symbol_as_dot_string(
+  const TSLanguage *self,
+  FILE *f,
+  TSSymbol symbol
+) {
+  const char *name = ts_language_symbol_name(self, symbol);
+  for (const char *chr = name; *chr; chr++) {
+    switch (*chr) {
+      case '"':
+      case '\\':
+        fputc('\\', f);
+        fputc(*chr, f);
+        break;
+      case '\n':
+        fputs("\\n", f);
+        break;
+      case '\t':
+        fputs("\\t", f);
+        break;
+      default:
+        fputc(*chr, f);
+        break;
+    }
+  }
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif  // TREE_SITTER_LANGUAGE_H_

shcat_c/parser/src/length.h

@@ -0,0 +1,52 @@
+#ifndef TREE_SITTER_LENGTH_H_
+#define TREE_SITTER_LENGTH_H_
+
+#include <stdlib.h>
+#include <stdbool.h>
+#include "./point.h"
+#include "tree_sitter/api.h"
+
+typedef struct {
+  uint32_t bytes;
+  TSPoint extent;
+} Length;
+
+static const Length LENGTH_UNDEFINED = {0, {0, 1}};
+static const Length LENGTH_MAX = {UINT32_MAX, {UINT32_MAX, UINT32_MAX}};
+
+static inline bool length_is_undefined(Length length) {
+  return length.bytes == 0 && length.extent.column != 0;
+}
+
+static inline Length length_min(Length len1, Length len2) {
+  return (len1.bytes < len2.bytes) ? len1 : len2;
+}
+
+static inline Length length_add(Length len1, Length len2) {
+  Length result;
+  result.bytes = len1.bytes + len2.bytes;
+  result.extent = point_add(len1.extent, len2.extent);
+  return result;
+}
+
+static inline Length length_sub(Length len1, Length len2) {
+  Length result;
+  result.bytes = len1.bytes - len2.bytes;
+  result.extent = point_sub(len1.extent, len2.extent);
+  return result;
+}
+
+static inline Length length_zero(void) {
+  Length result = {0, {0, 0}};
+  return result;
+}
+
+static inline Length length_saturating_sub(Length len1, Length len2) {
+  if (len1.bytes > len2.bytes) {
+    return length_sub(len1, len2);
+  } else {
+    return length_zero();
+  }
+}
+
+#endif

shcat_c/parser/src/lexer.c

@@ -0,0 +1,455 @@
+#include "./lexer.h"
+#include "./length.h"
+#include "./subtree.h"
+#include <stdint.h>
+#include <stdio.h>
+
+#define LOG(message, character)                                                \
+	if (self->logger.log)                                                      \
+	{                                                                          \
+		snprintf(self->debug_buffer, TREE_SITTER_SERIALIZATION_BUFFER_SIZE,    \
+				 32 <= character && character < 127 ? message                  \
+					 " character:'%c'"                                         \
+													: message " character:%d", \
+				 character);                                                   \
+		self->logger.log(self->logger.payload, TSLogTypeLex,                   \
+						 self->debug_buffer);                                  \
+	}
+
+static const int32_t BYTE_ORDER_MARK = 0xFEFF;
+
+static const TSRange DEFAULT_RANGE = {.start_point =
+										  {
+											  .row = 0,
+											  .column = 0,
+										  },
+									  .end_point =
+										  {
+											  .row = UINT32_MAX,
+											  .column = UINT32_MAX,
+										  },
+									  .start_byte = 0,
+									  .end_byte = UINT32_MAX};
+
+// Check if the lexer has reached EOF. This state is stored
+// by setting the lexer's `current_included_range_index` such that
+// it has consumed all of its available ranges.
+static bool ts_lexer__eof(const TSLexer *_self)
+{
+	Lexer *self = (Lexer *)_self;
+	return self->current_included_range_index == self->included_range_count;
+}
+
+// Clear the currently stored chunk of source code, because the lexer's
+// position has changed.
+static void ts_lexer__clear_chunk(Lexer *self)
+{
+	self->chunk = NULL;
+	self->chunk_size = 0;
+	self->chunk_start = 0;
+}
+
+// Call the lexer's input callback to obtain a new chunk of source code
+// for the current position.
+static void ts_lexer__get_chunk(Lexer *self)
+{
+	self->chunk_start = self->current_position.bytes;
+	self->chunk =
+		self->input.read(self->input.payload, self->current_position.bytes,
+						 self->current_position.extent, &self->chunk_size);
+	if (!self->chunk_size)
+	{
+		self->current_included_range_index = self->included_range_count;
+		self->chunk = NULL;
+	}
+}
+
+typedef uint32_t (*UnicodeDecodeFunction)(const uint8_t *chunk, uint32_t size,
+										  int32_t *lookahead);
+
+uint32_t my_decode(const uint8_t *chunk, uint32_t size, int32_t *lookahead)
+{
+	*((uint32_t *)lookahead) = *chunk;
+	return (1);
+}
+
+#define TS_DECODE_ERROR -1
+
+// Decode the next unicode character in the current chunk of source code.
+// This assumes that the lexer has already retrieved a chunk of source
+// code that spans the current position.
+static void ts_lexer__get_lookahead(Lexer *self)
+{
+	uint32_t position_in_chunk =
+		self->current_position.bytes - self->chunk_start;
+	uint32_t size = self->chunk_size - position_in_chunk;
+
+	if (size == 0)
+	{
+		self->lookahead_size = 1;
+		self->data.lookahead = '\0';
+		return;
+	}
+
+	const uint8_t *chunk = (const uint8_t *)self->chunk + position_in_chunk;
+	UnicodeDecodeFunction decode = my_decode;
+
+	self->lookahead_size = decode(chunk, size, &self->data.lookahead);
+
+	// If this chunk ended in the middle of a multi-byte character,
+	// try again with a fresh chunk.
+	if (self->data.lookahead == TS_DECODE_ERROR && size < 4)
+	{
+		ts_lexer__get_chunk(self);
+		chunk = (const uint8_t *)self->chunk;
+		size = self->chunk_size;
+		self->lookahead_size = decode(chunk, size, &self->data.lookahead);
+	}
+
+	if (self->data.lookahead == TS_DECODE_ERROR)
+	{
+		self->lookahead_size = 1;
+	}
+}
+
+static void ts_lexer_goto(Lexer *self, Length position)
+{
+	self->current_position = position;
+
+	// Move to the first valid position at or after the given position.
+	bool found_included_range = false;
+	for (unsigned i = 0; i < self->included_range_count; i++)
+	{
+		TSRange *included_range = &self->included_ranges[i];
+		if (included_range->end_byte > self->current_position.bytes &&
+			included_range->end_byte > included_range->start_byte)
+		{
+			if (included_range->start_byte >= self->current_position.bytes)
+			{
+				self->current_position = (Length){
+					.bytes = included_range->start_byte,
+					.extent = included_range->start_point,
+				};
+			}
+
+			self->current_included_range_index = i;
+			found_included_range = true;
+			break;
+		}
+	}
+
+	if (found_included_range)
+	{
+		// If the current position is outside of the current chunk of text,
+		// then clear out the current chunk of text.
+		if (self->chunk && (self->current_position.bytes < self->chunk_start ||
+							self->current_position.bytes >=
+								self->chunk_start + self->chunk_size))
+		{
+			ts_lexer__clear_chunk(self);
+		}
+
+		self->lookahead_size = 0;
+		self->data.lookahead = '\0';
+	}
+
+	// If the given position is beyond any of included ranges, move to the EOF
+	// state - past the end of the included ranges.
+	else
+	{
+		self->current_included_range_index = self->included_range_count;
+		TSRange *last_included_range =
+			&self->included_ranges[self->included_range_count - 1];
+		self->current_position = (Length){
+			.bytes = last_included_range->end_byte,
+			.extent = last_included_range->end_point,
+		};
+		ts_lexer__clear_chunk(self);
+		self->lookahead_size = 1;
+		self->data.lookahead = '\0';
+	}
+}
+
+// Intended to be called only from functions that control logging.
+static void ts_lexer__do_advance(Lexer *self, bool skip)
+{
+	if (self->lookahead_size)
+	{
+		self->current_position.bytes += self->lookahead_size;
+		if (self->data.lookahead == '\n')
+		{
+			self->current_position.extent.row++;
+			self->current_position.extent.column = 0;
+		}
+		else
+		{
+			self->current_position.extent.column += self->lookahead_size;
+		}
+	}
+
+	const TSRange *current_range =
+		&self->included_ranges[self->current_included_range_index];
+	while (self->current_position.bytes >= current_range->end_byte ||
+		   current_range->end_byte == current_range->start_byte)
+	{
+		if (self->current_included_range_index < self->included_range_count)
+		{
+			self->current_included_range_index++;
+		}
+		if (self->current_included_range_index < self->included_range_count)
+		{
+			current_range++;
+			self->current_position = (Length){
+				current_range->start_byte,
+				current_range->start_point,
+			};
+		}
+		else
+		{
+			current_range = NULL;
+			break;
+		}
+	}
+
+	if (skip)
+		self->token_start_position = self->current_position;
+
+	if (current_range)
+	{
+		if (self->current_position.bytes < self->chunk_start ||
+			self->current_position.bytes >=
+				self->chunk_start + self->chunk_size)
+		{
+			ts_lexer__get_chunk(self);
+		}
+		ts_lexer__get_lookahead(self);
+	}
+	else
+	{
+		ts_lexer__clear_chunk(self);
+		self->data.lookahead = '\0';
+		self->lookahead_size = 1;
+	}
+}
+
+// Advance to the next character in the source code, retrieving a new
+// chunk of source code if needed.
+static void ts_lexer__advance(TSLexer *_self, bool skip)
+{
+	Lexer *self = (Lexer *)_self;
+	if (!self->chunk)
+		return;
+	ts_lexer__do_advance(self, skip);
+}
+
+// Mark that a token match has completed. This can be called multiple
+// times if a longer match is found later.
+static void ts_lexer__mark_end(TSLexer *_self)
+{
+	Lexer *self = (Lexer *)_self;
+	if (!ts_lexer__eof(&self->data))
+	{
+		// If the lexer is right at the beginning of included range,
+		// then the token should be considered to end at the *end* of the
+		// previous included range, rather than here.
+		TSRange *current_included_range =
+			&self->included_ranges[self->current_included_range_index];
+		if (self->current_included_range_index > 0 &&
+			self->current_position.bytes == current_included_range->start_byte)
+		{
+			TSRange *previous_included_range = current_included_range - 1;
+			self->token_end_position = (Length){
+				previous_included_range->end_byte,
+				previous_included_range->end_point,
+			};
+			return;
+		}
+	}
+	self->token_end_position = self->current_position;
+}
+
+static uint32_t ts_lexer__get_column(TSLexer *_self)
+{
+	Lexer *self = (Lexer *)_self;
+
+	uint32_t goal_byte = self->current_position.bytes;
+
+	self->did_get_column = true;
+	self->current_position.bytes -= self->current_position.extent.column;
+	self->current_position.extent.column = 0;
+
+	if (self->current_position.bytes < self->chunk_start)
+	{
+		ts_lexer__get_chunk(self);
+	}
+
+	uint32_t result = 0;
+	if (!ts_lexer__eof(_self))
+	{
+		ts_lexer__get_lookahead(self);
+		while (self->current_position.bytes < goal_byte && self->chunk)
+		{
+			result++;
+			ts_lexer__do_advance(self, false);
+			if (ts_lexer__eof(_self))
+				break;
+		}
+	}
+
+	return result;
+}
+
+// Is the lexer at a boundary between two disjoint included ranges of
+// source code? This is exposed as an API because some languages' external
+// scanners need to perform custom actions at these boundaries.
+static bool ts_lexer__is_at_included_range_start(const TSLexer *_self)
+{
+	const Lexer *self = (const Lexer *)_self;
+	if (self->current_included_range_index < self->included_range_count)
+	{
+		TSRange *current_range =
+			&self->included_ranges[self->current_included_range_index];
+		return self->current_position.bytes == current_range->start_byte;
+	}
+	else
+	{
+		return false;
+	}
+}
+
+void ts_lexer_init(Lexer *self)
+{
+	*self = (Lexer){
+		.data =
+			{
+				// The lexer's methods are stored as struct fields so that
+				// generated
+				// parsers can call them without needing to be linked against
+				// this
+				// library.
+				.advance = ts_lexer__advance,
+				.mark_end = ts_lexer__mark_end,
+				.get_column = ts_lexer__get_column,
+				.is_at_included_range_start =
+					ts_lexer__is_at_included_range_start,
+				.eof = ts_lexer__eof,
+				.lookahead = 0,
+				.result_symbol = 0,
+			},
+		.chunk = NULL,
+		.chunk_size = 0,
+		.chunk_start = 0,
+		.current_position = {0, {0, 0}},
+		.logger = {.payload = NULL, .log = NULL},
+		.included_ranges = NULL,
+		.included_range_count = 0,
+		.current_included_range_index = 0,
+	};
+	ts_lexer_set_included_ranges(self, NULL, 0);
+}
+
+void ts_lexer_delete(Lexer *self)
+{
+	free(self->included_ranges);
+}
+
+void ts_lexer_set_input(Lexer *self, TSInput input)
+{
+	self->input = input;
+	ts_lexer__clear_chunk(self);
+	ts_lexer_goto(self, self->current_position);
+}
+
+// Move the lexer to the given position. This doesn't do any work
+// if the parser is already at the given position.
+void ts_lexer_reset(Lexer *self, Length position)
+{
+	if (position.bytes != self->current_position.bytes)
+	{
+		ts_lexer_goto(self, position);
+	}
+}
+
+void ts_lexer_start(Lexer *self)
+{
+	self->token_start_position = self->current_position;
+	self->token_end_position = LENGTH_UNDEFINED;
+	self->data.result_symbol = 0;
+	self->did_get_column = false;
+	if (!ts_lexer__eof(&self->data))
+	{
+		if (!self->chunk_size)
+			ts_lexer__get_chunk(self);
+		if (!self->lookahead_size)
+			ts_lexer__get_lookahead(self);
+		if (self->current_position.bytes == 0 &&
+			self->data.lookahead == BYTE_ORDER_MARK)
+			ts_lexer__advance(&self->data, true);
+	}
+}
+
+void ts_lexer_finish(Lexer *self, uint32_t *lookahead_end_byte)
+{
+	if (length_is_undefined(self->token_end_position))
+	{
+		ts_lexer__mark_end(&self->data);
+	}
+
+	// If the token ended at an included range boundary, then its end position
+	// will have been reset to the end of the preceding range. Reset the start
+	// position to match.
+	if (self->token_end_position.bytes < self->token_start_position.bytes)
+	{
+		self->token_start_position = self->token_end_position;
+	}
+
+	uint32_t current_lookahead_end_byte = self->current_position.bytes + 1;
+
+	// In order to determine that a byte sequence is invalid UTF8 or UTF16,
+	// the character decoding algorithm may have looked at the following byte.
+	// Therefore, the next byte *after* the current (invalid) character
+	// affects the interpretation of the current character.
+	if (self->data.lookahead == TS_DECODE_ERROR)
+	{
+		current_lookahead_end_byte++;
+	}
+
+	if (current_lookahead_end_byte > *lookahead_end_byte)
+	{
+		*lookahead_end_byte = current_lookahead_end_byte;
+	}
+}
+
+void ts_lexer_advance_to_end(Lexer *self)
+{
+	while (self->chunk)
+	{
+		ts_lexer__advance(&self->data, false);
+	}
+}
+
+void ts_lexer_mark_end(Lexer *self)
+{
+	ts_lexer__mark_end(&self->data);
+}
+
+bool ts_lexer_set_included_ranges(Lexer *self, const TSRange *ranges,
+								  uint32_t count)
+{
+	ranges = &DEFAULT_RANGE;
+	count = 1;
+	size_t size = count * sizeof(TSRange);
+	self->included_ranges = realloc(self->included_ranges, size);
+	memcpy(self->included_ranges, ranges, size);
+	self->included_range_count = count;
+	ts_lexer_goto(self, self->current_position);
+	return true;
+}
+
+TSRange *ts_lexer_included_ranges(const Lexer *self, uint32_t *count)
+{
+	*count = self->included_range_count;
+	return self->included_ranges;
+}
+
+#undef LOG

shcat_c/parser/src/lexer.h

@@ -0,0 +1,49 @@
+#ifndef TREE_SITTER_LEXER_H_
+#define TREE_SITTER_LEXER_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include "./length.h"
+#include "./subtree.h"
+#include "tree_sitter/api.h"
+#include "./parser.h"
+
+typedef struct {
+  TSLexer data;
+  Length current_position;
+  Length token_start_position;
+  Length token_end_position;
+
+  TSRange *included_ranges;
+  const char *chunk;
+  TSInput input;
+  TSLogger logger;
+
+  uint32_t included_range_count;
+  uint32_t current_included_range_index;
+  uint32_t chunk_start;
+  uint32_t chunk_size;
+  uint32_t lookahead_size;
+  bool did_get_column;
+
+  char debug_buffer[TREE_SITTER_SERIALIZATION_BUFFER_SIZE];
+} Lexer;
+
+void ts_lexer_init(Lexer *);
+void ts_lexer_delete(Lexer *);
+void ts_lexer_set_input(Lexer *, TSInput);
+void ts_lexer_reset(Lexer *, Length);
+void ts_lexer_start(Lexer *);
+void ts_lexer_finish(Lexer *, uint32_t *);
+void ts_lexer_advance_to_end(Lexer *);
+void ts_lexer_mark_end(Lexer *);
+bool ts_lexer_set_included_ranges(Lexer *self, const TSRange *ranges, uint32_t count);
+TSRange *ts_lexer_included_ranges(const Lexer *self, uint32_t *count);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif  // TREE_SITTER_LEXER_H_

shcat_c/parser/src/node.c

@@ -0,0 +1,774 @@
+#include <stdbool.h>
+#include "./subtree.h"
+#include "./tree.h"
+#include "./language.h"
+
+typedef struct {
+  Subtree parent;
+  const TSTree *tree;
+  Length position;
+  uint32_t child_index;
+  uint32_t structural_child_index;
+  const TSSymbol *alias_sequence;
+} NodeChildIterator;
+
+// TSNode - constructors
+
+TSNode ts_node_new(
+  const TSTree *tree,
+  const Subtree *subtree,
+  Length position,
+  TSSymbol alias
+) {
+  return (TSNode) {
+    {position.bytes, position.extent.row, position.extent.column, alias},
+    subtree,
+    tree,
+  };
+}
+
+static inline TSNode ts_node__null(void) {
+  return ts_node_new(NULL, NULL, length_zero(), 0);
+}
+
+// TSNode - accessors
+
+uint32_t ts_node_start_byte(TSNode self) {
+  return self.context[0];
+}
+
+TSPoint ts_node_start_point(TSNode self) {
+  return (TSPoint) {self.context[1], self.context[2]};
+}
+
+static inline uint32_t ts_node__alias(const TSNode *self) {
+  return self->context[3];
+}
+
+static inline Subtree ts_node__subtree(TSNode self) {
+  return *(const Subtree *)self.id;
+}
+
+// NodeChildIterator
+
+static inline NodeChildIterator ts_node_iterate_children(const TSNode *node) {
+  Subtree subtree = ts_node__subtree(*node);
+  if (ts_subtree_child_count(subtree) == 0) {
+    return (NodeChildIterator) {NULL_SUBTREE, node->tree, length_zero(), 0, 0, NULL};
+  }
+  const TSSymbol *alias_sequence = ts_language_alias_sequence(
+    node->tree->language,
+    subtree.ptr->production_id
+  );
+  return (NodeChildIterator) {
+    .tree = node->tree,
+    .parent = subtree,
+    .position = {ts_node_start_byte(*node), ts_node_start_point(*node)},
+    .child_index = 0,
+    .structural_child_index = 0,
+    .alias_sequence = alias_sequence,
+  };
+}
+
+static inline bool ts_node_child_iterator_done(NodeChildIterator *self) {
+  return self->child_index == self->parent.ptr->child_count;
+}
+
+static inline bool ts_node_child_iterator_next(
+  NodeChildIterator *self,
+  TSNode *result
+) {
+  if (!self->parent.ptr || ts_node_child_iterator_done(self)) return false;
+  const Subtree *child = &ts_subtree_children(self->parent)[self->child_index];
+  TSSymbol alias_symbol = 0;
+  if (!ts_subtree_extra(*child)) {
+    if (self->alias_sequence) {
+      alias_symbol = self->alias_sequence[self->structural_child_index];
+    }
+    self->structural_child_index++;
+  }
+  if (self->child_index > 0) {
+    self->position = length_add(self->position, ts_subtree_padding(*child));
+  }
+  *result = ts_node_new(
+    self->tree,
+    child,
+    self->position,
+    alias_symbol
+  );
+  self->position = length_add(self->position, ts_subtree_size(*child));
+  self->child_index++;
+  return true;
+}
+
+// TSNode - private
+
+static inline bool ts_node__is_relevant(TSNode self, bool include_anonymous) {
+  Subtree tree = ts_node__subtree(self);
+  if (include_anonymous) {
+    return ts_subtree_visible(tree) || ts_node__alias(&self);
+  } else {
+    TSSymbol alias = ts_node__alias(&self);
+    if (alias) {
+      return ts_language_symbol_metadata(self.tree->language, alias).named;
+    } else {
+      return ts_subtree_visible(tree) && ts_subtree_named(tree);
+    }
+  }
+}
+
+static inline uint32_t ts_node__relevant_child_count(
+  TSNode self,
+  bool include_anonymous
+) {
+  Subtree tree = ts_node__subtree(self);
+  if (ts_subtree_child_count(tree) > 0) {
+    if (include_anonymous) {
+      return tree.ptr->visible_child_count;
+    } else {
+      return tree.ptr->named_child_count;
+    }
+  } else {
+    return 0;
+  }
+}
+
+static inline TSNode ts_node__child(
+  TSNode self,
+  uint32_t child_index,
+  bool include_anonymous
+) {
+  TSNode result = self;
+  bool did_descend = true;
+
+  while (did_descend) {
+    did_descend = false;
+
+    TSNode child;
+    uint32_t index = 0;
+    NodeChildIterator iterator = ts_node_iterate_children(&result);
+    while (ts_node_child_iterator_next(&iterator, &child)) {
+      if (ts_node__is_relevant(child, include_anonymous)) {
+        if (index == child_index) {
+          return child;
+        }
+        index++;
+      } else {
+        uint32_t grandchild_index = child_index - index;
+        uint32_t grandchild_count = ts_node__relevant_child_count(child, include_anonymous);
+        if (grandchild_index < grandchild_count) {
+          did_descend = true;
+          result = child;
+          child_index = grandchild_index;
+          break;
+        }
+        index += grandchild_count;
+      }
+    }
+  }
+
+  return ts_node__null();
+}
+
+static bool ts_subtree_has_trailing_empty_descendant(
+  Subtree self,
+  Subtree other
+) {
+  for (unsigned i = ts_subtree_child_count(self) - 1; i + 1 > 0; i--) {
+    Subtree child = ts_subtree_children(self)[i];
+    if (ts_subtree_total_bytes(child) > 0) break;
+    if (child.ptr == other.ptr || ts_subtree_has_trailing_empty_descendant(child, other)) {
+      return true;
+    }
+  }
+  return false;
+}
+
+static inline TSNode ts_node__prev_sibling(TSNode self, bool include_anonymous) {
+  Subtree self_subtree = ts_node__subtree(self);
+  bool self_is_empty = ts_subtree_total_bytes(self_subtree) == 0;
+  uint32_t target_end_byte = ts_node_end_byte(self);
+
+  TSNode node = ts_node_parent(self);
+  TSNode earlier_node = ts_node__null();
+  bool earlier_node_is_relevant = false;
+
+  while (!ts_node_is_null(node)) {
+    TSNode earlier_child = ts_node__null();
+    bool earlier_child_is_relevant = false;
+    bool found_child_containing_target = false;
+
+    TSNode child;
+    NodeChildIterator iterator = ts_node_iterate_children(&node);
+    while (ts_node_child_iterator_next(&iterator, &child)) {
+      if (child.id == self.id) break;
+      if (iterator.position.bytes > target_end_byte) {
+        found_child_containing_target = true;
+        break;
+      }
+
+      if (iterator.position.bytes == target_end_byte &&
+          (!self_is_empty ||
+           ts_subtree_has_trailing_empty_descendant(ts_node__subtree(child), self_subtree))) {
+        found_child_containing_target = true;
+        break;
+      }
+
+      if (ts_node__is_relevant(child, include_anonymous)) {
+        earlier_child = child;
+        earlier_child_is_relevant = true;
+      } else if (ts_node__relevant_child_count(child, include_anonymous) > 0) {
+        earlier_child = child;
+        earlier_child_is_relevant = false;
+      }
+    }
+
+    if (found_child_containing_target) {
+      if (!ts_node_is_null(earlier_child)) {
+        earlier_node = earlier_child;
+        earlier_node_is_relevant = earlier_child_is_relevant;
+      }
+      node = child;
+    } else if (earlier_child_is_relevant) {
+      return earlier_child;
+    } else if (!ts_node_is_null(earlier_child)) {
+      node = earlier_child;
+    } else if (earlier_node_is_relevant) {
+      return earlier_node;
+    } else {
+      node = earlier_node;
+      earlier_node = ts_node__null();
+      earlier_node_is_relevant = false;
+    }
+  }
+
+  return ts_node__null();
+}
+
+static inline TSNode ts_node__next_sibling(TSNode self, bool include_anonymous) {
+  uint32_t target_end_byte = ts_node_end_byte(self);
+
+  TSNode node = ts_node_parent(self);
+  TSNode later_node = ts_node__null();
+  bool later_node_is_relevant = false;
+
+  while (!ts_node_is_null(node)) {
+    TSNode later_child = ts_node__null();
+    bool later_child_is_relevant = false;
+    TSNode child_containing_target = ts_node__null();
+
+    TSNode child;
+    NodeChildIterator iterator = ts_node_iterate_children(&node);
+    while (ts_node_child_iterator_next(&iterator, &child)) {
+      if (iterator.position.bytes < target_end_byte) continue;
+      if (ts_node_start_byte(child) <= ts_node_start_byte(self)) {
+        if (ts_node__subtree(child).ptr != ts_node__subtree(self).ptr) {
+          child_containing_target = child;
+        }
+      } else if (ts_node__is_relevant(child, include_anonymous)) {
+        later_child = child;
+        later_child_is_relevant = true;
+        break;
+      } else if (ts_node__relevant_child_count(child, include_anonymous) > 0) {
+        later_child = child;
+        later_child_is_relevant = false;
+        break;
+      }
+    }
+
+    if (!ts_node_is_null(child_containing_target)) {
+      if (!ts_node_is_null(later_child)) {
+        later_node = later_child;
+        later_node_is_relevant = later_child_is_relevant;
+      }
+      node = child_containing_target;
+    } else if (later_child_is_relevant) {
+      return later_child;
+    } else if (!ts_node_is_null(later_child)) {
+      node = later_child;
+    } else if (later_node_is_relevant) {
+      return later_node;
+    } else {
+      node = later_node;
+    }
+  }
+
+  return ts_node__null();
+}
+
+static inline TSNode ts_node__first_child_for_byte(
+  TSNode self,
+  uint32_t goal,
+  bool include_anonymous
+) {
+  TSNode node = self;
+  bool did_descend = true;
+
+  while (did_descend) {
+    did_descend = false;
+
+    TSNode child;
+    NodeChildIterator iterator = ts_node_iterate_children(&node);
+    while (ts_node_child_iterator_next(&iterator, &child)) {
+      if (ts_node_end_byte(child) > goal) {
+        if (ts_node__is_relevant(child, include_anonymous)) {
+          return child;
+        } else if (ts_node_child_count(child) > 0) {
+          did_descend = true;
+          node = child;
+          break;
+        }
+      }
+    }
+  }
+
+  return ts_node__null();
+}
+
+static inline TSNode ts_node__descendant_for_byte_range(
+  TSNode self,
+  uint32_t range_start,
+  uint32_t range_end,
+  bool include_anonymous
+) {
+  TSNode node = self;
+  TSNode last_visible_node = self;
+
+  bool did_descend = true;
+  while (did_descend) {
+    did_descend = false;
+
+    TSNode child;
+    NodeChildIterator iterator = ts_node_iterate_children(&node);
+    while (ts_node_child_iterator_next(&iterator, &child)) {
+      uint32_t node_end = iterator.position.bytes;
+
+      // The end of this node must extend far enough forward to touch
+      // the end of the range and exceed the start of the range.
+      if (node_end < range_end) continue;
+      if (node_end <= range_start) continue;
+
+      // The start of this node must extend far enough backward to
+      // touch the start of the range.
+      if (range_start < ts_node_start_byte(child)) break;
+
+      node = child;
+      if (ts_node__is_relevant(node, include_anonymous)) {
+        last_visible_node = node;
+      }
+      did_descend = true;
+      break;
+    }
+  }
+
+  return last_visible_node;
+}
+
+static inline TSNode ts_node__descendant_for_point_range(
+  TSNode self,
+  TSPoint range_start,
+  TSPoint range_end,
+  bool include_anonymous
+) {
+  TSNode node = self;
+  TSNode last_visible_node = self;
+
+  bool did_descend = true;
+  while (did_descend) {
+    did_descend = false;
+
+    TSNode child;
+    NodeChildIterator iterator = ts_node_iterate_children(&node);
+    while (ts_node_child_iterator_next(&iterator, &child)) {
+      TSPoint node_end = iterator.position.extent;
+
+      // The end of this node must extend far enough forward to touch
+      // the end of the range and exceed the start of the range.
+      if (point_lt(node_end, range_end)) continue;
+      if (point_lte(node_end, range_start)) continue;
+
+      // The start of this node must extend far enough backward to
+      // touch the start of the range.
+      if (point_lt(range_start, ts_node_start_point(child))) break;
+
+      node = child;
+      if (ts_node__is_relevant(node, include_anonymous)) {
+        last_visible_node = node;
+      }
+      did_descend = true;
+      break;
+    }
+  }
+
+  return last_visible_node;
+}
+
+// TSNode - public
+
+uint32_t ts_node_end_byte(TSNode self) {
+  return ts_node_start_byte(self) + ts_subtree_size(ts_node__subtree(self)).bytes;
+}
+
+TSPoint ts_node_end_point(TSNode self) {
+  return point_add(ts_node_start_point(self), ts_subtree_size(ts_node__subtree(self)).extent);
+}
+
+TSSymbol ts_node_symbol(TSNode self) {
+  TSSymbol symbol = ts_node__alias(&self);
+  if (!symbol) symbol = ts_subtree_symbol(ts_node__subtree(self));
+  return ts_language_public_symbol(self.tree->language, symbol);
+}
+
+const char *ts_node_type(TSNode self) {
+  TSSymbol symbol = ts_node__alias(&self);
+  if (!symbol) symbol = ts_subtree_symbol(ts_node__subtree(self));
+  return ts_language_symbol_name(self.tree->language, symbol);
+}
+
+const TSLanguage *ts_node_language(TSNode self) {
+  return self.tree->language;
+}
+
+TSSymbol ts_node_grammar_symbol(TSNode self) {
+  return ts_subtree_symbol(ts_node__subtree(self));
+}
+
+const char *ts_node_grammar_type(TSNode self) {
+  TSSymbol symbol = ts_subtree_symbol(ts_node__subtree(self));
+  return ts_language_symbol_name(self.tree->language, symbol);
+}
+
+char *ts_node_string(TSNode self) {
+  TSSymbol alias_symbol = ts_node__alias(&self);
+  return ts_subtree_string(
+    ts_node__subtree(self),
+    alias_symbol,
+    ts_language_symbol_metadata(self.tree->language, alias_symbol).visible,
+    self.tree->language,
+    false
+  );
+}
+
+bool ts_node_eq(TSNode self, TSNode other) {
+  return self.tree == other.tree && self.id == other.id;
+}
+
+bool ts_node_is_null(TSNode self) {
+  return self.id == 0;
+}
+
+bool ts_node_is_extra(TSNode self) {
+  return ts_subtree_extra(ts_node__subtree(self));
+}
+
+bool ts_node_is_named(TSNode self) {
+  TSSymbol alias = ts_node__alias(&self);
+  return alias
+    ? ts_language_symbol_metadata(self.tree->language, alias).named
+    : ts_subtree_named(ts_node__subtree(self));
+}
+
+bool ts_node_is_missing(TSNode self) {
+  return ts_subtree_missing(ts_node__subtree(self));
+}
+
+bool ts_node_has_changes(TSNode self) {
+  return ts_subtree_has_changes(ts_node__subtree(self));
+}
+
+bool ts_node_has_error(TSNode self) {
+  return ts_subtree_error_cost(ts_node__subtree(self)) > 0;
+}
+
+bool ts_node_is_error(TSNode self) {
+  TSSymbol symbol = ts_node_symbol(self);
+  return symbol == ts_builtin_sym_error;
+}
+
+uint32_t ts_node_descendant_count(TSNode self) {
+  return ts_subtree_visible_descendant_count(ts_node__subtree(self)) + 1;
+}
+
+TSStateId ts_node_parse_state(TSNode self) {
+  return ts_subtree_parse_state(ts_node__subtree(self));
+}
+
+TSStateId ts_node_next_parse_state(TSNode self) {
+  const TSLanguage *language = self.tree->language;
+  uint16_t state = ts_node_parse_state(self);
+  if (state == TS_TREE_STATE_NONE) {
+    return TS_TREE_STATE_NONE;
+  }
+  uint16_t symbol = ts_node_grammar_symbol(self);
+  return ts_language_next_state(language, state, symbol);
+}
+
+TSNode ts_node_parent(TSNode self) {
+  TSNode node = ts_tree_root_node(self.tree);
+  uint32_t end_byte = ts_node_end_byte(self);
+  if (node.id == self.id) return ts_node__null();
+
+  TSNode last_visible_node = node;
+  bool did_descend = true;
+  while (did_descend) {
+    did_descend = false;
+
+    TSNode child;
+    NodeChildIterator iterator = ts_node_iterate_children(&node);
+    while (ts_node_child_iterator_next(&iterator, &child)) {
+      if (
+        ts_node_start_byte(child) > ts_node_start_byte(self) ||
+        child.id == self.id
+      ) break;
+      if (iterator.position.bytes >= end_byte && ts_node_child_count(child) > 0) {
+        node = child;
+        if (ts_node__is_relevant(child, true)) {
+          last_visible_node = node;
+        }
+        did_descend = true;
+        break;
+      }
+    }
+  }
+
+  return last_visible_node;
+}
+
+TSNode ts_node_child(TSNode self, uint32_t child_index) {
+  return ts_node__child(self, child_index, true);
+}
+
+TSNode ts_node_named_child(TSNode self, uint32_t child_index) {
+  return ts_node__child(self, child_index, false);
+}
+
+TSNode ts_node_child_by_field_id(TSNode self, TSFieldId field_id) {
+recur:
+  if (!field_id || ts_node_child_count(self) == 0) return ts_node__null();
+
+  const TSFieldMapEntry *field_map, *field_map_end;
+  ts_language_field_map(
+    self.tree->language,
+    ts_node__subtree(self).ptr->production_id,
+    &field_map,
+    &field_map_end
+  );
+  if (field_map == field_map_end) return ts_node__null();
+
+  // The field mappings are sorted by their field id. Scan all
+  // the mappings to find the ones for the given field id.
+  while (field_map->field_id < field_id) {
+    field_map++;
+    if (field_map == field_map_end) return ts_node__null();
+  }
+  while (field_map_end[-1].field_id > field_id) {
+    field_map_end--;
+    if (field_map == field_map_end) return ts_node__null();
+  }
+
+  TSNode child;
+  NodeChildIterator iterator = ts_node_iterate_children(&self);
+  while (ts_node_child_iterator_next(&iterator, &child)) {
+    if (!ts_subtree_extra(ts_node__subtree(child))) {
+      uint32_t index = iterator.structural_child_index - 1;
+      if (index < field_map->child_index) continue;
+
+      // Hidden nodes' fields are "inherited" by their visible parent.
+      if (field_map->inherited) {
+
+        // If this is the *last* possible child node for this field,
+        // then perform a tail call to avoid recursion.
+        if (field_map + 1 == field_map_end) {
+          self = child;
+          goto recur;
+        }
+
+        // Otherwise, descend into this child, but if it doesn't contain
+        // the field, continue searching subsequent children.
+        else {
+          TSNode result = ts_node_child_by_field_id(child, field_id);
+          if (result.id) return result;
+          field_map++;
+          if (field_map == field_map_end) return ts_node__null();
+        }
+      }
+
+      else if (ts_node__is_relevant(child, true)) {
+        return child;
+      }
+
+      // If the field refers to a hidden node with visible children,
+      // return the first visible child.
+      else if (ts_node_child_count(child) > 0 ) {
+        return ts_node_child(child, 0);
+      }
+
+      // Otherwise, continue searching subsequent children.
+      else {
+        field_map++;
+        if (field_map == field_map_end) return ts_node__null();
+      }
+    }
+  }
+
+  return ts_node__null();
+}
+
+static inline const char *ts_node__field_name_from_language(TSNode self, uint32_t structural_child_index) {
+    const TSFieldMapEntry *field_map, *field_map_end;
+    ts_language_field_map(
+      self.tree->language,
+      ts_node__subtree(self).ptr->production_id,
+      &field_map,
+      &field_map_end
+    );
+    for (; field_map != field_map_end; field_map++) {
+      if (!field_map->inherited && field_map->child_index == structural_child_index) {
+        return self.tree->language->field_names[field_map->field_id];
+      }
+    }
+    return NULL;
+}
+
+const char *ts_node_field_name_for_child(TSNode self, uint32_t child_index) {
+  TSNode result = self;
+  bool did_descend = true;
+  const char *inherited_field_name = NULL;
+
+  while (did_descend) {
+    did_descend = false;
+
+    TSNode child;
+    uint32_t index = 0;
+    NodeChildIterator iterator = ts_node_iterate_children(&result);
+    while (ts_node_child_iterator_next(&iterator, &child)) {
+      if (ts_node__is_relevant(child, true)) {
+        if (index == child_index) {
+          const char *field_name = ts_node__field_name_from_language(result, iterator.structural_child_index - 1);
+          if (field_name) return field_name;
+          return inherited_field_name;
+        }
+        index++;
+      } else {
+        uint32_t grandchild_index = child_index - index;
+        uint32_t grandchild_count = ts_node__relevant_child_count(child, true);
+        if (grandchild_index < grandchild_count) {
+          const char *field_name = ts_node__field_name_from_language(result, iterator.structural_child_index - 1);
+          if (field_name) inherited_field_name = field_name;
+
+          did_descend = true;
+          result = child;
+          child_index = grandchild_index;
+          break;
+        }
+        index += grandchild_count;
+      }
+    }
+  }
+
+  return NULL;
+}
+
+TSNode ts_node_child_by_field_name(
+  TSNode self,
+  const char *name,
+  uint32_t name_length
+) {
+  TSFieldId field_id = ts_language_field_id_for_name(
+    self.tree->language,
+    name,
+    name_length
+  );
+  return ts_node_child_by_field_id(self, field_id);
+}
+
+uint32_t ts_node_child_count(TSNode self) {
+  Subtree tree = ts_node__subtree(self);
+  if (ts_subtree_child_count(tree) > 0) {
+    return tree.ptr->visible_child_count;
+  } else {
+    return 0;
+  }
+}
+
+uint32_t ts_node_named_child_count(TSNode self) {
+  Subtree tree = ts_node__subtree(self);
+  if (ts_subtree_child_count(tree) > 0) {
+    return tree.ptr->named_child_count;
+  } else {
+    return 0;
+  }
+}
+
+TSNode ts_node_next_sibling(TSNode self) {
+  return ts_node__next_sibling(self, true);
+}
+
+TSNode ts_node_next_named_sibling(TSNode self) {
+  return ts_node__next_sibling(self, false);
+}
+
+TSNode ts_node_prev_sibling(TSNode self) {
+  return ts_node__prev_sibling(self, true);
+}
+
+TSNode ts_node_prev_named_sibling(TSNode self) {
+  return ts_node__prev_sibling(self, false);
+}
+
+TSNode ts_node_first_child_for_byte(TSNode self, uint32_t byte) {
+  return ts_node__first_child_for_byte(self, byte, true);
+}
+
+TSNode ts_node_first_named_child_for_byte(TSNode self, uint32_t byte) {
+  return ts_node__first_child_for_byte(self, byte, false);
+}
+
+TSNode ts_node_descendant_for_byte_range(
+  TSNode self,
+  uint32_t start,
+  uint32_t end
+) {
+  return ts_node__descendant_for_byte_range(self, start, end, true);
+}
+
+TSNode ts_node_named_descendant_for_byte_range(
+  TSNode self,
+  uint32_t start,
+  uint32_t end
+) {
+  return ts_node__descendant_for_byte_range(self, start, end, false);
+}
+
+TSNode ts_node_descendant_for_point_range(
+  TSNode self,
+  TSPoint start,
+  TSPoint end
+) {
+  return ts_node__descendant_for_point_range(self, start, end, true);
+}
+
+TSNode ts_node_named_descendant_for_point_range(
+  TSNode self,
+  TSPoint start,
+  TSPoint end
+) {
+  return ts_node__descendant_for_point_range(self, start, end, false);
+}
+
+void ts_node_edit(TSNode *self, const TSInputEdit *edit) {
+  uint32_t start_byte = ts_node_start_byte(*self);
+  TSPoint start_point = ts_node_start_point(*self);
+
+  if (start_byte >= edit->old_end_byte) {
+    start_byte = edit->new_end_byte + (start_byte - edit->old_end_byte);
+    start_point = point_add(edit->new_end_point, point_sub(start_point, edit->old_end_point));
+  } else if (start_byte > edit->start_byte) {
+    start_byte = edit->new_end_byte;
+    start_point = edit->new_end_point;
+  }
+
+  self->context[0] = start_byte;
+  self->context[1] = start_point.row;
+  self->context[2] = start_point.column;
+}

shcat_c/parser/src/parser.h

@@ -0,0 +1,265 @@
+#ifndef TREE_SITTER_PARSER_H_
+#define TREE_SITTER_PARSER_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+#define ts_builtin_sym_error ((TSSymbol)-1)
+#define ts_builtin_sym_end 0
+#define TREE_SITTER_SERIALIZATION_BUFFER_SIZE 1024
+
+#ifndef TREE_SITTER_API_H_
+typedef uint16_t TSStateId;
+typedef uint16_t TSSymbol;
+typedef uint16_t TSFieldId;
+typedef struct TSLanguage TSLanguage;
+#endif
+
+typedef struct {
+  TSFieldId field_id;
+  uint8_t child_index;
+  bool inherited;
+} TSFieldMapEntry;
+
+typedef struct {
+  uint16_t index;
+  uint16_t length;
+} TSFieldMapSlice;
+
+typedef struct {
+  bool visible;
+  bool named;
+  bool supertype;
+} TSSymbolMetadata;
+
+typedef struct TSLexer TSLexer;
+
+struct TSLexer {
+  int32_t lookahead;
+  TSSymbol result_symbol;
+  void (*advance)(TSLexer *, bool);
+  void (*mark_end)(TSLexer *);
+  uint32_t (*get_column)(TSLexer *);
+  bool (*is_at_included_range_start)(const TSLexer *);
+  bool (*eof)(const TSLexer *);
+};
+
+typedef enum {
+  TSParseActionTypeShift,
+  TSParseActionTypeReduce,
+  TSParseActionTypeAccept,
+  TSParseActionTypeRecover,
+} TSParseActionType;
+
+typedef union {
+  struct {
+    uint8_t type;
+    TSStateId state;
+    bool extra;
+    bool repetition;
+  } shift;
+  struct {
+    uint8_t type;
+    uint8_t child_count;
+    TSSymbol symbol;
+    int16_t dynamic_precedence;
+    uint16_t production_id;
+  } reduce;
+  uint8_t type;
+} TSParseAction;
+
+typedef struct {
+  uint16_t lex_state;
+  uint16_t external_lex_state;
+} TSLexMode;
+
+typedef union {
+  TSParseAction action;
+  struct {
+    uint8_t count;
+    bool reusable;
+  } entry;
+} TSParseActionEntry;
+
+typedef struct {
+  int32_t start;
+  int32_t end;
+} TSCharacterRange;
+
+struct TSLanguage {
+  uint32_t version;
+  uint32_t symbol_count;
+  uint32_t alias_count;
+  uint32_t token_count;
+  uint32_t external_token_count;
+  uint32_t state_count;
+  uint32_t large_state_count;
+  uint32_t production_id_count;
+  uint32_t field_count;
+  uint16_t max_alias_sequence_length;
+  const uint16_t *parse_table;
+  const uint16_t *small_parse_table;
+  const uint32_t *small_parse_table_map;
+  const TSParseActionEntry *parse_actions;
+  const char * const *symbol_names;
+  const char * const *field_names;
+  const TSFieldMapSlice *field_map_slices;
+  const TSFieldMapEntry *field_map_entries;
+  const TSSymbolMetadata *symbol_metadata;
+  const TSSymbol *public_symbol_map;
+  const uint16_t *alias_map;
+  const TSSymbol *alias_sequences;
+  const TSLexMode *lex_modes;
+  bool (*lex_fn)(TSLexer *, TSStateId);
+  bool (*keyword_lex_fn)(TSLexer *, TSStateId);
+  TSSymbol keyword_capture_token;
+  struct {
+    const bool *states;
+    const TSSymbol *symbol_map;
+    void *(*create)(void);
+    void (*destroy)(void *);
+    bool (*scan)(void *, TSLexer *, const bool *symbol_whitelist);
+    unsigned (*serialize)(void *, char *);
+    void (*deserialize)(void *, const char *, unsigned);
+  } external_scanner;
+  const TSStateId *primary_state_ids;
+};
+
+static inline bool set_contains(TSCharacterRange *ranges, uint32_t len, int32_t lookahead) {
+  uint32_t index = 0;
+  uint32_t size = len - index;
+  while (size > 1) {
+    uint32_t half_size = size / 2;
+    uint32_t mid_index = index + half_size;
+    TSCharacterRange *range = &ranges[mid_index];
+    if (lookahead >= range->start && lookahead <= range->end) {
+      return true;
+    } else if (lookahead > range->end) {
+      index = mid_index;
+    }
+    size -= half_size;
+  }
+  TSCharacterRange *range = &ranges[index];
+  return (lookahead >= range->start && lookahead <= range->end);
+}
+
+/*
+ *  Lexer Macros
+ */
+
+#ifdef _MSC_VER
+#define UNUSED __pragma(warning(suppress : 4101))
+#else
+#define UNUSED __attribute__((unused))
+#endif
+
+#define START_LEXER()           \
+  bool result = false;          \
+  bool skip = false;            \
+  UNUSED                        \
+  bool eof = false;             \
+  int32_t lookahead;            \
+  goto start;                   \
+  next_state:                   \
+  lexer->advance(lexer, skip);  \
+  start:                        \
+  skip = false;                 \
+  lookahead = lexer->lookahead;
+
+#define ADVANCE(state_value) \
+  {                          \
+    state = state_value;     \
+    goto next_state;         \
+  }
+
+#define ADVANCE_MAP(...)                                              \
+  {                                                                   \
+    static const uint16_t map[] = { __VA_ARGS__ };                    \
+    for (uint32_t i = 0; i < sizeof(map) / sizeof(map[0]); i += 2) {  \
+      if (map[i] == lookahead) {                                      \
+        state = map[i + 1];                                           \
+        goto next_state;                                              \
+      }                                                               \
+    }                                                                 \
+  }
+
+#define SKIP(state_value) \
+  {                       \
+    skip = true;          \
+    state = state_value;  \
+    goto next_state;      \
+  }
+
+#define ACCEPT_TOKEN(symbol_value)     \
+  result = true;                       \
+  lexer->result_symbol = symbol_value; \
+  lexer->mark_end(lexer);
+
+#define END_STATE() return result;
+
+/*
+ *  Parse Table Macros
+ */
+
+#define SMALL_STATE(id) ((id) - LARGE_STATE_COUNT)
+
+#define STATE(id) id
+
+#define ACTIONS(id) id
+
+#define SHIFT(state_value)            \
+  {{                                  \
+    .shift = {                        \
+      .type = TSParseActionTypeShift, \
+      .state = (state_value)          \
+    }                                 \
+  }}
+
+#define SHIFT_REPEAT(state_value)     \
+  {{                                  \
+    .shift = {                        \
+      .type = TSParseActionTypeShift, \
+      .state = (state_value),         \
+      .repetition = true              \
+    }                                 \
+  }}
+
+#define SHIFT_EXTRA()                 \
+  {{                                  \
+    .shift = {                        \
+      .type = TSParseActionTypeShift, \
+      .extra = true                   \
+    }                                 \
+  }}
+
+#define REDUCE(symbol_name, children, precedence, prod_id) \
+  {{                                                       \
+    .reduce = {                                            \
+      .type = TSParseActionTypeReduce,                     \
+      .symbol = symbol_name,                               \
+      .child_count = children,                             \
+      .dynamic_precedence = precedence,                    \
+      .production_id = prod_id                             \
+    },                                                     \
+  }}
+
+#define RECOVER()                    \
+  {{                                 \
+    .type = TSParseActionTypeRecover \
+  }}
+
+#define ACCEPT_INPUT()              \
+  {{                                \
+    .type = TSParseActionTypeAccept \
+  }}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif  // TREE_SITTER_PARSER_H_

shcat_c/parser/src/point.h

@@ -0,0 +1,62 @@
+#ifndef TREE_SITTER_POINT_H_
+#define TREE_SITTER_POINT_H_
+
+#include "tree_sitter/api.h"
+
+#define POINT_ZERO ((TSPoint) {0, 0})
+#define POINT_MAX ((TSPoint) {UINT32_MAX, UINT32_MAX})
+
+static inline TSPoint point__new(unsigned row, unsigned column) {
+  TSPoint result = {row, column};
+  return result;
+}
+
+static inline TSPoint point_add(TSPoint a, TSPoint b) {
+  if (b.row > 0)
+    return point__new(a.row + b.row, b.column);
+  else
+    return point__new(a.row, a.column + b.column);
+}
+
+static inline TSPoint point_sub(TSPoint a, TSPoint b) {
+  if (a.row > b.row)
+    return point__new(a.row - b.row, a.column);
+  else
+    return point__new(0, a.column - b.column);
+}
+
+static inline bool point_lte(TSPoint a, TSPoint b) {
+  return (a.row < b.row) || (a.row == b.row && a.column <= b.column);
+}
+
+static inline bool point_lt(TSPoint a, TSPoint b) {
+  return (a.row < b.row) || (a.row == b.row && a.column < b.column);
+}
+
+static inline bool point_gt(TSPoint a, TSPoint b) {
+  return (a.row > b.row) || (a.row == b.row && a.column > b.column);
+}
+
+static inline bool point_gte(TSPoint a, TSPoint b) {
+  return (a.row > b.row) || (a.row == b.row && a.column >= b.column);
+}
+
+static inline bool point_eq(TSPoint a, TSPoint b) {
+  return a.row == b.row && a.column == b.column;
+}
+
+static inline TSPoint point_min(TSPoint a, TSPoint b) {
+  if (a.row < b.row || (a.row == b.row && a.column < b.column))
+    return a;
+  else
+    return b;
+}
+
+static inline TSPoint point_max(TSPoint a, TSPoint b) {
+  if (a.row > b.row || (a.row == b.row && a.column > b.column))
+    return a;
+  else
+    return b;
+}
+
+#endif

shcat_c/parser/src/reduce_action.h

@@ -0,0 +1,34 @@
+#ifndef TREE_SITTER_REDUCE_ACTION_H_
+#define TREE_SITTER_REDUCE_ACTION_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include "./array.h"
+#include "tree_sitter/api.h"
+
+typedef struct {
+  uint32_t count;
+  TSSymbol symbol;
+  int dynamic_precedence;
+  unsigned short production_id;
+} ReduceAction;
+
+typedef Array(ReduceAction) ReduceActionSet;
+
+static inline void ts_reduce_action_set_add(ReduceActionSet *self,
+                                            ReduceAction new_action) {
+  for (uint32_t i = 0; i < self->size; i++) {
+    ReduceAction action = self->contents[i];
+    if (action.symbol == new_action.symbol && action.count == new_action.count)
+      return;
+  }
+  array_push(self, new_action);
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif  // TREE_SITTER_REDUCE_ACTION_H_

shcat_c/parser/src/reusable_node.h

@@ -0,0 +1,95 @@
+#include "./subtree.h"
+
+typedef struct {
+  Subtree tree;
+  uint32_t child_index;
+  uint32_t byte_offset;
+} StackEntry;
+
+typedef struct {
+  Array(StackEntry) stack;
+  Subtree last_external_token;
+} ReusableNode;
+
+static inline ReusableNode reusable_node_new(void) {
+  return (ReusableNode) {array_new(), NULL_SUBTREE};
+}
+
+static inline void reusable_node_clear(ReusableNode *self) {
+  array_clear(&self->stack);
+  self->last_external_token = NULL_SUBTREE;
+}
+
+static inline Subtree reusable_node_tree(ReusableNode *self) {
+  return self->stack.size > 0
+    ? self->stack.contents[self->stack.size - 1].tree
+    : NULL_SUBTREE;
+}
+
+static inline uint32_t reusable_node_byte_offset(ReusableNode *self) {
+  return self->stack.size > 0
+    ? self->stack.contents[self->stack.size - 1].byte_offset
+    : UINT32_MAX;
+}
+
+static inline void reusable_node_delete(ReusableNode *self) {
+  array_delete(&self->stack);
+}
+
+static inline void reusable_node_advance(ReusableNode *self) {
+  StackEntry last_entry = *array_back(&self->stack);
+  uint32_t byte_offset = last_entry.byte_offset + ts_subtree_total_bytes(last_entry.tree);
+  if (ts_subtree_has_external_tokens(last_entry.tree)) {
+    self->last_external_token = ts_subtree_last_external_token(last_entry.tree);
+  }
+
+  Subtree tree;
+  uint32_t next_index;
+  do {
+    StackEntry popped_entry = array_pop(&self->stack);
+    next_index = popped_entry.child_index + 1;
+    if (self->stack.size == 0) return;
+    tree = array_back(&self->stack)->tree;
+  } while (ts_subtree_child_count(tree) <= next_index);
+
+  array_push(&self->stack, ((StackEntry) {
+    .tree = ts_subtree_children(tree)[next_index],
+    .child_index = next_index,
+    .byte_offset = byte_offset,
+  }));
+}
+
+static inline bool reusable_node_descend(ReusableNode *self) {
+  StackEntry last_entry = *array_back(&self->stack);
+  if (ts_subtree_child_count(last_entry.tree) > 0) {
+    array_push(&self->stack, ((StackEntry) {
+      .tree = ts_subtree_children(last_entry.tree)[0],
+      .child_index = 0,
+      .byte_offset = last_entry.byte_offset,
+    }));
+    return true;
+  } else {
+    return false;
+  }
+}
+
+static inline void reusable_node_advance_past_leaf(ReusableNode *self) {
+  while (reusable_node_descend(self)) {}
+  reusable_node_advance(self);
+}
+
+static inline void reusable_node_reset(ReusableNode *self, Subtree tree) {
+  reusable_node_clear(self);
+  array_push(&self->stack, ((StackEntry) {
+    .tree = tree,
+    .child_index = 0,
+    .byte_offset = 0,
+  }));
+
+  // Never reuse the root node, because it has a non-standard internal structure
+  // due to transformations that are applied when it is accepted: adding the EOF
+  // child and any extra children.
+  if (!reusable_node_descend(self)) {
+    reusable_node_clear(self);
+  }
+}

shcat_c/parser/src/stack.c

@@ -0,0 +1,899 @@
+
+#include "./language.h"
+#include "./subtree.h"
+#include "./array.h"
+#include "./stack.h"
+#include "./length.h"
+#include <assert.h>
+#include <inttypes.h>
+#include <stdio.h>
+
+#define MAX_LINK_COUNT 8
+#define MAX_NODE_POOL_SIZE 50
+#define MAX_ITERATOR_COUNT 64
+
+#if defined _WIN32 && !defined __GNUC__
+#define forceinline __forceinline
+#else
+#define forceinline static inline __attribute__((always_inline))
+#endif
+
+typedef struct StackNode StackNode;
+
+typedef struct {
+  StackNode *node;
+  Subtree subtree;
+  bool is_pending;
+} StackLink;
+
+struct StackNode {
+  TSStateId state;
+  Length position;
+  StackLink links[MAX_LINK_COUNT];
+  short unsigned int link_count;
+  uint32_t ref_count;
+  unsigned error_cost;
+  unsigned node_count;
+  int dynamic_precedence;
+};
+
+typedef struct {
+  StackNode *node;
+  SubtreeArray subtrees;
+  uint32_t subtree_count;
+  bool is_pending;
+} StackIterator;
+
+typedef Array(StackNode *) StackNodeArray;
+
+typedef enum {
+  StackStatusActive,
+  StackStatusPaused,
+  StackStatusHalted,
+} StackStatus;
+
+typedef struct {
+  StackNode *node;
+  StackSummary *summary;
+  unsigned node_count_at_last_error;
+  Subtree last_external_token;
+  Subtree lookahead_when_paused;
+  StackStatus status;
+} StackHead;
+
+struct Stack {
+  Array(StackHead) heads;
+  StackSliceArray slices;
+  Array(StackIterator) iterators;
+  StackNodeArray node_pool;
+  StackNode *base_node;
+  SubtreePool *subtree_pool;
+};
+
+typedef unsigned StackAction;
+enum {
+  StackActionNone,
+  StackActionStop = 1,
+  StackActionPop = 2,
+};
+
+typedef StackAction (*StackCallback)(void *, const StackIterator *);
+
+static void stack_node_retain(StackNode *self) {
+  if (!self)
+    return;
+  assert(self->ref_count > 0);
+  self->ref_count++;
+  assert(self->ref_count != 0);
+}
+
+static void stack_node_release(
+  StackNode *self,
+  StackNodeArray *pool,
+  SubtreePool *subtree_pool
+) {
+recur:
+  assert(self->ref_count != 0);
+  self->ref_count--;
+  if (self->ref_count > 0) return;
+
+  StackNode *first_predecessor = NULL;
+  if (self->link_count > 0) {
+    for (unsigned i = self->link_count - 1; i > 0; i--) {
+      StackLink link = self->links[i];
+      if (link.subtree.ptr) ts_subtree_release(subtree_pool, link.subtree);
+      stack_node_release(link.node, pool, subtree_pool);
+    }
+    StackLink link = self->links[0];
+    if (link.subtree.ptr) ts_subtree_release(subtree_pool, link.subtree);
+    first_predecessor = self->links[0].node;
+  }
+
+  if (pool->size < MAX_NODE_POOL_SIZE) {
+    array_push(pool, self);
+  } else {
+    free(self);
+  }
+
+  if (first_predecessor) {
+    self = first_predecessor;
+    goto recur;
+  }
+}
+
+/// Get the number of nodes in the subtree, for the purpose of measuring
+/// how much progress has been made by a given version of the stack.
+static uint32_t stack__subtree_node_count(Subtree subtree) {
+  uint32_t count = ts_subtree_visible_descendant_count(subtree);
+  if (ts_subtree_visible(subtree)) count++;
+
+  // Count intermediate error nodes even though they are not visible,
+  // because a stack version's node count is used to check whether it
+  // has made any progress since the last time it encountered an error.
+  if (ts_subtree_symbol(subtree) == ts_builtin_sym_error_repeat) count++;
+
+  return count;
+}
+
+static StackNode *stack_node_new(
+  StackNode *previous_node,
+  Subtree subtree,
+  bool is_pending,
+  TSStateId state,
+  StackNodeArray *pool
+) {
+  StackNode *node = pool->size > 0
+    ? array_pop(pool)
+    : malloc(sizeof(StackNode));
+  *node = (StackNode) {
+    .ref_count = 1,
+    .link_count = 0,
+    .state = state
+  };
+
+  if (previous_node) {
+    node->link_count = 1;
+    node->links[0] = (StackLink) {
+      .node = previous_node,
+      .subtree = subtree,
+      .is_pending = is_pending,
+    };
+
+    node->position = previous_node->position;
+    node->error_cost = previous_node->error_cost;
+    node->dynamic_precedence = previous_node->dynamic_precedence;
+    node->node_count = previous_node->node_count;
+
+    if (subtree.ptr) {
+      node->error_cost += ts_subtree_error_cost(subtree);
+      node->position = length_add(node->position, ts_subtree_total_size(subtree));
+      node->node_count += stack__subtree_node_count(subtree);
+      node->dynamic_precedence += ts_subtree_dynamic_precedence(subtree);
+    }
+  } else {
+    node->position = length_zero();
+    node->error_cost = 0;
+  }
+
+  return node;
+}
+
+static bool stack__subtree_is_equivalent(Subtree left, Subtree right) {
+  if (left.ptr == right.ptr) return true;
+  if (!left.ptr || !right.ptr) return false;
+
+  // Symbols must match
+  if (ts_subtree_symbol(left) != ts_subtree_symbol(right)) return false;
+
+  // If both have errors, don't bother keeping both.
+  if (ts_subtree_error_cost(left) > 0 && ts_subtree_error_cost(right) > 0) return true;
+
+  return (
+    ts_subtree_padding(left).bytes == ts_subtree_padding(right).bytes &&
+    ts_subtree_size(left).bytes == ts_subtree_size(right).bytes &&
+    ts_subtree_child_count(left) == ts_subtree_child_count(right) &&
+    ts_subtree_extra(left) == ts_subtree_extra(right) &&
+    ts_subtree_external_scanner_state_eq(left, right)
+  );
+}
+
+static void stack_node_add_link(
+  StackNode *self,
+  StackLink link,
+  SubtreePool *subtree_pool
+) {
+  if (link.node == self) return;
+
+  for (int i = 0; i < self->link_count; i++) {
+    StackLink *existing_link = &self->links[i];
+    if (stack__subtree_is_equivalent(existing_link->subtree, link.subtree)) {
+      // In general, we preserve ambiguities until they are removed from the stack
+      // during a pop operation where multiple paths lead to the same node. But in
+      // the special case where two links directly connect the same pair of nodes,
+      // we can safely remove the ambiguity ahead of time without changing behavior.
+      if (existing_link->node == link.node) {
+        if (
+          ts_subtree_dynamic_precedence(link.subtree) >
+          ts_subtree_dynamic_precedence(existing_link->subtree)
+        ) {
+          ts_subtree_retain(link.subtree);
+          ts_subtree_release(subtree_pool, existing_link->subtree);
+          existing_link->subtree = link.subtree;
+          self->dynamic_precedence =
+            link.node->dynamic_precedence + ts_subtree_dynamic_precedence(link.subtree);
+        }
+        return;
+      }
+
+      // If the previous nodes are mergeable, merge them recursively.
+      if (
+        existing_link->node->state == link.node->state &&
+        existing_link->node->position.bytes == link.node->position.bytes &&
+        existing_link->node->error_cost == link.node->error_cost
+      ) {
+        for (int j = 0; j < link.node->link_count; j++) {
+          stack_node_add_link(existing_link->node, link.node->links[j], subtree_pool);
+        }
+        int32_t dynamic_precedence = link.node->dynamic_precedence;
+        if (link.subtree.ptr) {
+          dynamic_precedence += ts_subtree_dynamic_precedence(link.subtree);
+        }
+        if (dynamic_precedence > self->dynamic_precedence) {
+          self->dynamic_precedence = dynamic_precedence;
+        }
+        return;
+      }
+    }
+  }
+
+  if (self->link_count == MAX_LINK_COUNT) return;
+
+  stack_node_retain(link.node);
+  unsigned node_count = link.node->node_count;
+  int dynamic_precedence = link.node->dynamic_precedence;
+  self->links[self->link_count++] = link;
+
+  if (link.subtree.ptr) {
+    ts_subtree_retain(link.subtree);
+    node_count += stack__subtree_node_count(link.subtree);
+    dynamic_precedence += ts_subtree_dynamic_precedence(link.subtree);
+  }
+
+  if (node_count > self->node_count) self->node_count = node_count;
+  if (dynamic_precedence > self->dynamic_precedence) self->dynamic_precedence = dynamic_precedence;
+}
+
+static void stack_head_delete(
+  StackHead *self,
+  StackNodeArray *pool,
+  SubtreePool *subtree_pool
+) {
+  if (self->node) {
+    if (self->last_external_token.ptr) {
+      ts_subtree_release(subtree_pool, self->last_external_token);
+    }
+    if (self->lookahead_when_paused.ptr) {
+      ts_subtree_release(subtree_pool, self->lookahead_when_paused);
+    }
+    if (self->summary) {
+      array_delete(self->summary);
+      free(self->summary);
+    }
+    stack_node_release(self->node, pool, subtree_pool);
+  }
+}
+
+static StackVersion ts_stack__add_version(
+  Stack *self,
+  StackVersion original_version,
+  StackNode *node
+) {
+  StackHead head = {
+    .node = node,
+    .node_count_at_last_error = self->heads.contents[original_version].node_count_at_last_error,
+    .last_external_token = self->heads.contents[original_version].last_external_token,
+    .status = StackStatusActive,
+    .lookahead_when_paused = NULL_SUBTREE,
+  };
+  array_push(&self->heads, head);
+  stack_node_retain(node);
+  if (head.last_external_token.ptr) ts_subtree_retain(head.last_external_token);
+  return (StackVersion)(self->heads.size - 1);
+}
+
+static void ts_stack__add_slice(
+  Stack *self,
+  StackVersion original_version,
+  StackNode *node,
+  SubtreeArray *subtrees
+) {
+  for (uint32_t i = self->slices.size - 1; i + 1 > 0; i--) {
+    StackVersion version = self->slices.contents[i].version;
+    if (self->heads.contents[version].node == node) {
+      StackSlice slice = {*subtrees, version};
+      array_insert(&self->slices, i + 1, slice);
+      return;
+    }
+  }
+
+  StackVersion version = ts_stack__add_version(self, original_version, node);
+  StackSlice slice = { *subtrees, version };
+  array_push(&self->slices, slice);
+}
+
+static StackSliceArray stack__iter(
+  Stack *self,
+  StackVersion version,
+  StackCallback callback,
+  void *payload,
+  int goal_subtree_count
+) {
+  array_clear(&self->slices);
+  array_clear(&self->iterators);
+
+  StackHead *head = array_get(&self->heads, version);
+  StackIterator new_iterator = {
+    .node = head->node,
+    .subtrees = array_new(),
+    .subtree_count = 0,
+    .is_pending = true,
+  };
+
+  bool include_subtrees = false;
+  if (goal_subtree_count >= 0) {
+    include_subtrees = true;
+    array_reserve(&new_iterator.subtrees, (uint32_t)ts_subtree_alloc_size(goal_subtree_count) / sizeof(Subtree));
+  }
+
+  array_push(&self->iterators, new_iterator);
+
+  while (self->iterators.size > 0) {
+    for (uint32_t i = 0, size = self->iterators.size; i < size; i++) {
+      StackIterator *iterator = &self->iterators.contents[i];
+      StackNode *node = iterator->node;
+
+      StackAction action = callback(payload, iterator);
+      bool should_pop = action & StackActionPop;
+      bool should_stop = action & StackActionStop || node->link_count == 0;
+
+      if (should_pop) {
+        SubtreeArray subtrees = iterator->subtrees;
+        if (!should_stop) {
+          ts_subtree_array_copy(subtrees, &subtrees);
+        }
+        ts_subtree_array_reverse(&subtrees);
+        ts_stack__add_slice(
+          self,
+          version,
+          node,
+          &subtrees
+        );
+      }
+
+      if (should_stop) {
+        if (!should_pop) {
+          ts_subtree_array_delete(self->subtree_pool, &iterator->subtrees);
+        }
+        array_erase(&self->iterators, i);
+        i--, size--;
+        continue;
+      }
+
+      for (uint32_t j = 1; j <= node->link_count; j++) {
+        StackIterator *next_iterator;
+        StackLink link;
+        if (j == node->link_count) {
+          link = node->links[0];
+          next_iterator = &self->iterators.contents[i];
+        } else {
+          if (self->iterators.size >= MAX_ITERATOR_COUNT) continue;
+          link = node->links[j];
+          StackIterator current_iterator = self->iterators.contents[i];
+          array_push(&self->iterators, current_iterator);
+          next_iterator = array_back(&self->iterators);
+          ts_subtree_array_copy(next_iterator->subtrees, &next_iterator->subtrees);
+        }
+
+        next_iterator->node = link.node;
+        if (link.subtree.ptr) {
+          if (include_subtrees) {
+            array_push(&next_iterator->subtrees, link.subtree);
+            ts_subtree_retain(link.subtree);
+          }
+
+          if (!ts_subtree_extra(link.subtree)) {
+            next_iterator->subtree_count++;
+            if (!link.is_pending) {
+              next_iterator->is_pending = false;
+            }
+          }
+        } else {
+          next_iterator->subtree_count++;
+          next_iterator->is_pending = false;
+        }
+      }
+    }
+  }
+
+  return self->slices;
+}
+
+Stack *ts_stack_new(SubtreePool *subtree_pool) {
+  Stack *self = calloc(1, sizeof(Stack));
+
+  array_init(&self->heads);
+  array_init(&self->slices);
+  array_init(&self->iterators);
+  array_init(&self->node_pool);
+  array_reserve(&self->heads, 4);
+  array_reserve(&self->slices, 4);
+  array_reserve(&self->iterators, 4);
+  array_reserve(&self->node_pool, MAX_NODE_POOL_SIZE);
+
+  self->subtree_pool = subtree_pool;
+  self->base_node = stack_node_new(NULL, NULL_SUBTREE, false, 1, &self->node_pool);
+  ts_stack_clear(self);
+
+  return self;
+}
+
+void ts_stack_delete(Stack *self) {
+  if (self->slices.contents)
+    array_delete(&self->slices);
+  if (self->iterators.contents)
+    array_delete(&self->iterators);
+  stack_node_release(self->base_node, &self->node_pool, self->subtree_pool);
+  for (uint32_t i = 0; i < self->heads.size; i++) {
+    stack_head_delete(&self->heads.contents[i], &self->node_pool, self->subtree_pool);
+  }
+  array_clear(&self->heads);
+  if (self->node_pool.contents) {
+    for (uint32_t i = 0; i < self->node_pool.size; i++)
+      free(self->node_pool.contents[i]);
+    array_delete(&self->node_pool);
+  }
+  array_delete(&self->heads);
+  free(self);
+}
+
+uint32_t ts_stack_version_count(const Stack *self) {
+  return self->heads.size;
+}
+
+TSStateId ts_stack_state(const Stack *self, StackVersion version) {
+  return array_get(&self->heads, version)->node->state;
+}
+
+Length ts_stack_position(const Stack *self, StackVersion version) {
+  return array_get(&self->heads, version)->node->position;
+}
+
+Subtree ts_stack_last_external_token(const Stack *self, StackVersion version) {
+  return array_get(&self->heads, version)->last_external_token;
+}
+
+void ts_stack_set_last_external_token(Stack *self, StackVersion version, Subtree token) {
+  StackHead *head = array_get(&self->heads, version);
+  if (token.ptr) ts_subtree_retain(token);
+  if (head->last_external_token.ptr) ts_subtree_release(self->subtree_pool, head->last_external_token);
+  head->last_external_token = token;
+}
+
+unsigned ts_stack_error_cost(const Stack *self, StackVersion version) {
+  StackHead *head = array_get(&self->heads, version);
+  unsigned result = head->node->error_cost;
+  if (
+    head->status == StackStatusPaused ||
+    (head->node->state == ERROR_STATE && !head->node->links[0].subtree.ptr)) {
+    result += ERROR_COST_PER_RECOVERY;
+  }
+  return result;
+}
+
+unsigned ts_stack_node_count_since_error(const Stack *self, StackVersion version) {
+  StackHead *head = array_get(&self->heads, version);
+  if (head->node->node_count < head->node_count_at_last_error) {
+    head->node_count_at_last_error = head->node->node_count;
+  }
+  return head->node->node_count - head->node_count_at_last_error;
+}
+
+void ts_stack_push(
+  Stack *self,
+  StackVersion version,
+  Subtree subtree,
+  bool pending,
+  TSStateId state
+) {
+  StackHead *head = array_get(&self->heads, version);
+  StackNode *new_node = stack_node_new(head->node, subtree, pending, state, &self->node_pool);
+  if (!subtree.ptr) head->node_count_at_last_error = new_node->node_count;
+  head->node = new_node;
+}
+
+forceinline StackAction pop_count_callback(void *payload, const StackIterator *iterator) {
+  unsigned *goal_subtree_count = payload;
+  if (iterator->subtree_count == *goal_subtree_count) {
+    return StackActionPop | StackActionStop;
+  } else {
+    return StackActionNone;
+  }
+}
+
+StackSliceArray ts_stack_pop_count(Stack *self, StackVersion version, uint32_t count) {
+  return stack__iter(self, version, pop_count_callback, &count, (int)count);
+}
+
+forceinline StackAction pop_pending_callback(void *payload, const StackIterator *iterator) {
+  (void)payload;
+  if (iterator->subtree_count >= 1) {
+    if (iterator->is_pending) {
+      return StackActionPop | StackActionStop;
+    } else {
+      return StackActionStop;
+    }
+  } else {
+    return StackActionNone;
+  }
+}
+
+StackSliceArray ts_stack_pop_pending(Stack *self, StackVersion version) {
+  StackSliceArray pop = stack__iter(self, version, pop_pending_callback, NULL, 0);
+  if (pop.size > 0) {
+    ts_stack_renumber_version(self, pop.contents[0].version, version);
+    pop.contents[0].version = version;
+  }
+  return pop;
+}
+
+forceinline StackAction pop_error_callback(void *payload, const StackIterator *iterator) {
+  if (iterator->subtrees.size > 0) {
+    bool *found_error = payload;
+    if (!*found_error && ts_subtree_is_error(iterator->subtrees.contents[0])) {
+      *found_error = true;
+      return StackActionPop | StackActionStop;
+    } else {
+      return StackActionStop;
+    }
+  } else {
+    return StackActionNone;
+  }
+}
+
+SubtreeArray ts_stack_pop_error(Stack *self, StackVersion version) {
+  StackNode *node = array_get(&self->heads, version)->node;
+  for (unsigned i = 0; i < node->link_count; i++) {
+    if (node->links[i].subtree.ptr && ts_subtree_is_error(node->links[i].subtree)) {
+      bool found_error = false;
+      StackSliceArray pop = stack__iter(self, version, pop_error_callback, &found_error, 1);
+      if (pop.size > 0) {
+        assert(pop.size == 1);
+        ts_stack_renumber_version(self, pop.contents[0].version, version);
+        return pop.contents[0].subtrees;
+      }
+      break;
+    }
+  }
+  return (SubtreeArray) {.size = 0};
+}
+
+forceinline StackAction pop_all_callback(void *payload, const StackIterator *iterator) {
+  (void)payload;
+  return iterator->node->link_count == 0 ? StackActionPop : StackActionNone;
+}
+
+StackSliceArray ts_stack_pop_all(Stack *self, StackVersion version) {
+  return stack__iter(self, version, pop_all_callback, NULL, 0);
+}
+
+typedef struct {
+  StackSummary *summary;
+  unsigned max_depth;
+} SummarizeStackSession;
+
+forceinline StackAction summarize_stack_callback(void *payload, const StackIterator *iterator) {
+  SummarizeStackSession *session = payload;
+  TSStateId state = iterator->node->state;
+  unsigned depth = iterator->subtree_count;
+  if (depth > session->max_depth) return StackActionStop;
+  for (unsigned i = session->summary->size - 1; i + 1 > 0; i--) {
+    StackSummaryEntry entry = session->summary->contents[i];
+    if (entry.depth < depth) break;
+    if (entry.depth == depth && entry.state == state) return StackActionNone;
+  }
+  array_push(session->summary, ((StackSummaryEntry) {
+    .position = iterator->node->position,
+    .depth = depth,
+    .state = state,
+  }));
+  return StackActionNone;
+}
+
+void ts_stack_record_summary(Stack *self, StackVersion version, unsigned max_depth) {
+  SummarizeStackSession session = {
+    .summary = malloc(sizeof(StackSummary)),
+    .max_depth = max_depth
+  };
+  array_init(session.summary);
+  stack__iter(self, version, summarize_stack_callback, &session, -1);
+  StackHead *head = &self->heads.contents[version];
+  if (head->summary) {
+    array_delete(head->summary);
+    free(head->summary);
+  }
+  head->summary = session.summary;
+}
+
+StackSummary *ts_stack_get_summary(Stack *self, StackVersion version) {
+  return array_get(&self->heads, version)->summary;
+}
+
+int ts_stack_dynamic_precedence(Stack *self, StackVersion version) {
+  return array_get(&self->heads, version)->node->dynamic_precedence;
+}
+
+bool ts_stack_has_advanced_since_error(const Stack *self, StackVersion version) {
+  const StackHead *head = array_get(&self->heads, version);
+  const StackNode *node = head->node;
+  if (node->error_cost == 0) return true;
+  while (node) {
+    if (node->link_count > 0) {
+      Subtree subtree = node->links[0].subtree;
+      if (subtree.ptr) {
+        if (ts_subtree_total_bytes(subtree) > 0) {
+          return true;
+        } else if (
+          node->node_count > head->node_count_at_last_error &&
+          ts_subtree_error_cost(subtree) == 0
+        ) {
+          node = node->links[0].node;
+          continue;
+        }
+      }
+    }
+    break;
+  }
+  return false;
+}
+
+void ts_stack_remove_version(Stack *self, StackVersion version) {
+  stack_head_delete(array_get(&self->heads, version), &self->node_pool, self->subtree_pool);
+  array_erase(&self->heads, version);
+}
+
+void ts_stack_renumber_version(Stack *self, StackVersion v1, StackVersion v2) {
+  if (v1 == v2) return;
+  assert(v2 < v1);
+  assert((uint32_t)v1 < self->heads.size);
+  StackHead *source_head = &self->heads.contents[v1];
+  StackHead *target_head = &self->heads.contents[v2];
+  if (target_head->summary && !source_head->summary) {
+    source_head->summary = target_head->summary;
+    target_head->summary = NULL;
+  }
+  stack_head_delete(target_head, &self->node_pool, self->subtree_pool);
+  *target_head = *source_head;
+  array_erase(&self->heads, v1);
+}
+
+void ts_stack_swap_versions(Stack *self, StackVersion v1, StackVersion v2) {
+  StackHead temporary_head = self->heads.contents[v1];
+  self->heads.contents[v1] = self->heads.contents[v2];
+  self->heads.contents[v2] = temporary_head;
+}
+
+StackVersion ts_stack_copy_version(Stack *self, StackVersion version) {
+  assert(version < self->heads.size);
+  array_push(&self->heads, self->heads.contents[version]);
+  StackHead *head = array_back(&self->heads);
+  stack_node_retain(head->node);
+  if (head->last_external_token.ptr) ts_subtree_retain(head->last_external_token);
+  head->summary = NULL;
+  return self->heads.size - 1;
+}
+
+bool ts_stack_merge(Stack *self, StackVersion version1, StackVersion version2) {
+  if (!ts_stack_can_merge(self, version1, version2)) return false;
+  StackHead *head1 = &self->heads.contents[version1];
+  StackHead *head2 = &self->heads.contents[version2];
+  for (uint32_t i = 0; i < head2->node->link_count; i++) {
+    stack_node_add_link(head1->node, head2->node->links[i], self->subtree_pool);
+  }
+  if (head1->node->state == ERROR_STATE) {
+    head1->node_count_at_last_error = head1->node->node_count;
+  }
+  ts_stack_remove_version(self, version2);
+  return true;
+}
+
+bool ts_stack_can_merge(Stack *self, StackVersion version1, StackVersion version2) {
+  StackHead *head1 = &self->heads.contents[version1];
+  StackHead *head2 = &self->heads.contents[version2];
+  return
+    head1->status == StackStatusActive &&
+    head2->status == StackStatusActive &&
+    head1->node->state == head2->node->state &&
+    head1->node->position.bytes == head2->node->position.bytes &&
+    head1->node->error_cost == head2->node->error_cost &&
+    ts_subtree_external_scanner_state_eq(head1->last_external_token, head2->last_external_token);
+}
+
+void ts_stack_halt(Stack *self, StackVersion version) {
+  array_get(&self->heads, version)->status = StackStatusHalted;
+}
+
+void ts_stack_pause(Stack *self, StackVersion version, Subtree lookahead) {
+  StackHead *head = array_get(&self->heads, version);
+  head->status = StackStatusPaused;
+  head->lookahead_when_paused = lookahead;
+  head->node_count_at_last_error = head->node->node_count;
+}
+
+bool ts_stack_is_active(const Stack *self, StackVersion version) {
+  return array_get(&self->heads, version)->status == StackStatusActive;
+}
+
+bool ts_stack_is_halted(const Stack *self, StackVersion version) {
+  return array_get(&self->heads, version)->status == StackStatusHalted;
+}
+
+bool ts_stack_is_paused(const Stack *self, StackVersion version) {
+  return array_get(&self->heads, version)->status == StackStatusPaused;
+}
+
+Subtree ts_stack_resume(Stack *self, StackVersion version) {
+  StackHead *head = array_get(&self->heads, version);
+  assert(head->status == StackStatusPaused);
+  Subtree result = head->lookahead_when_paused;
+  head->status = StackStatusActive;
+  head->lookahead_when_paused = NULL_SUBTREE;
+  return result;
+}
+
+void ts_stack_clear(Stack *self) {
+  stack_node_retain(self->base_node);
+  for (uint32_t i = 0; i < self->heads.size; i++) {
+    stack_head_delete(&self->heads.contents[i], &self->node_pool, self->subtree_pool);
+  }
+  array_clear(&self->heads);
+  array_push(&self->heads, ((StackHead) {
+    .node = self->base_node,
+    .status = StackStatusActive,
+    .last_external_token = NULL_SUBTREE,
+    .lookahead_when_paused = NULL_SUBTREE,
+  }));
+}
+
+bool ts_stack_print_dot_graph(Stack *self, const TSLanguage *language, FILE *f) {
+  array_reserve(&self->iterators, 32);
+  if (!f) f = stderr;
+
+  fprintf(f, "digraph stack {\n");
+  fprintf(f, "rankdir=\"RL\";\n");
+  fprintf(f, "edge [arrowhead=none]\n");
+
+  Array(StackNode *) visited_nodes = array_new();
+
+  array_clear(&self->iterators);
+  for (uint32_t i = 0; i < self->heads.size; i++) {
+    StackHead *head = &self->heads.contents[i];
+    if (head->status == StackStatusHalted) continue;
+
+    fprintf(f, "node_head_%u [shape=none, label=\"\"]\n", i);
+    fprintf(f, "node_head_%u -> node_%p [", i, (void *)head->node);
+
+    if (head->status == StackStatusPaused) {
+      fprintf(f, "color=red ");
+    }
+    fprintf(f,
+      "label=%u, fontcolor=blue, weight=10000, labeltooltip=\"node_count: %u\nerror_cost: %u",
+      i,
+      ts_stack_node_count_since_error(self, i),
+      ts_stack_error_cost(self, i)
+    );
+
+    if (head->summary) {
+      fprintf(f, "\nsummary:");
+      for (uint32_t j = 0; j < head->summary->size; j++) fprintf(f, " %u", head->summary->contents[j].state);
+    }
+
+    if (head->last_external_token.ptr) {
+      const ExternalScannerState *state = &head->last_external_token.ptr->external_scanner_state;
+      const char *data = ts_external_scanner_state_data(state);
+      fprintf(f, "\nexternal_scanner_state:");
+      for (uint32_t j = 0; j < state->length; j++) fprintf(f, " %2X", data[j]);
+    }
+
+    fprintf(f, "\"]\n");
+    array_push(&self->iterators, ((StackIterator) {
+      .node = head->node
+    }));
+  }
+
+  bool all_iterators_done = false;
+  while (!all_iterators_done) {
+    all_iterators_done = true;
+
+    for (uint32_t i = 0; i < self->iterators.size; i++) {
+      StackIterator iterator = self->iterators.contents[i];
+      StackNode *node = iterator.node;
+
+      for (uint32_t j = 0; j < visited_nodes.size; j++) {
+        if (visited_nodes.contents[j] == node) {
+          node = NULL;
+          break;
+        }
+      }
+
+      if (!node) continue;
+      all_iterators_done = false;
+
+      fprintf(f, "node_%p [", (void *)node);
+      if (node->state == ERROR_STATE) {
+        fprintf(f, "label=\"?\"");
+      } else if (
+        node->link_count == 1 &&
+        node->links[0].subtree.ptr &&
+        ts_subtree_extra(node->links[0].subtree)
+      ) {
+        fprintf(f, "shape=point margin=0 label=\"\"");
+      } else {
+        fprintf(f, "label=\"%d\"", node->state);
+      }
+
+      fprintf(
+        f,
+        " tooltip=\"position: %u,%u\nnode_count:%u\nerror_cost: %u\ndynamic_precedence: %d\"];\n",
+        node->position.extent.row + 1,
+        node->position.extent.column,
+        node->node_count,
+        node->error_cost,
+        node->dynamic_precedence
+      );
+
+      for (int j = 0; j < node->link_count; j++) {
+        StackLink link = node->links[j];
+        fprintf(f, "node_%p -> node_%p [", (void *)node, (void *)link.node);
+        if (link.is_pending) fprintf(f, "style=dashed ");
+        if (link.subtree.ptr && ts_subtree_extra(link.subtree)) fprintf(f, "fontcolor=gray ");
+
+        if (!link.subtree.ptr) {
+          fprintf(f, "color=red");
+        } else {
+          fprintf(f, "label=\"");
+          bool quoted = ts_subtree_visible(link.subtree) && !ts_subtree_named(link.subtree);
+          if (quoted) fprintf(f, "'");
+          ts_language_write_symbol_as_dot_string(language, f, ts_subtree_symbol(link.subtree));
+          if (quoted) fprintf(f, "'");
+          fprintf(f, "\"");
+          fprintf(
+            f,
+            "labeltooltip=\"error_cost: %u\ndynamic_precedence: %" PRId32 "\"",
+            ts_subtree_error_cost(link.subtree),
+            ts_subtree_dynamic_precedence(link.subtree)
+          );
+        }
+
+        fprintf(f, "];\n");
+
+        StackIterator *next_iterator;
+        if (j == 0) {
+          next_iterator = &self->iterators.contents[i];
+        } else {
+          array_push(&self->iterators, iterator);
+          next_iterator = array_back(&self->iterators);
+        }
+        next_iterator->node = link.node;
+      }
+
+      array_push(&visited_nodes, node);
+    }
+  }
+
+  fprintf(f, "}\n");
+
+  array_delete(&visited_nodes);
+  return true;
+}
+
+#undef forceinline

shcat_c/parser/src/stack.h

@@ -0,0 +1,133 @@
+#ifndef TREE_SITTER_PARSE_STACK_H_
+#define TREE_SITTER_PARSE_STACK_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include "./array.h"
+#include "./subtree.h"
+#include "./error_costs.h"
+#include <stdio.h>
+
+typedef struct Stack Stack;
+
+typedef unsigned StackVersion;
+#define STACK_VERSION_NONE ((StackVersion)-1)
+
+typedef struct {
+  SubtreeArray subtrees;
+  StackVersion version;
+} StackSlice;
+typedef Array(StackSlice) StackSliceArray;
+
+typedef struct {
+  Length position;
+  unsigned depth;
+  TSStateId state;
+} StackSummaryEntry;
+typedef Array(StackSummaryEntry) StackSummary;
+
+// Create a stack.
+Stack *ts_stack_new(SubtreePool *);
+
+// Release the memory reserved for a given stack.
+void ts_stack_delete(Stack *);
+
+// Get the stack's current number of versions.
+uint32_t ts_stack_version_count(const Stack *);
+
+// Get the state at the top of the given version of the stack. If the stack is
+// empty, this returns the initial state, 0.
+TSStateId ts_stack_state(const Stack *, StackVersion);
+
+// Get the last external token associated with a given version of the stack.
+Subtree ts_stack_last_external_token(const Stack *, StackVersion);
+
+// Set the last external token associated with a given version of the stack.
+void ts_stack_set_last_external_token(Stack *, StackVersion, Subtree );
+
+// Get the position of the given version of the stack within the document.
+Length ts_stack_position(const Stack *, StackVersion);
+
+// Push a tree and state onto the given version of the stack.
+//
+// This transfers ownership of the tree to the Stack. Callers that
+// need to retain ownership of the tree for their own purposes should
+// first retain the tree.
+void ts_stack_push(Stack *, StackVersion, Subtree , bool, TSStateId);
+
+// Pop the given number of entries from the given version of the stack. This
+// operation can increase the number of stack versions by revealing multiple
+// versions which had previously been merged. It returns an array that
+// specifies the index of each revealed version and the trees that were
+// removed from that version.
+StackSliceArray ts_stack_pop_count(Stack *, StackVersion, uint32_t count);
+
+// Remove an error at the top of the given version of the stack.
+SubtreeArray ts_stack_pop_error(Stack *, StackVersion);
+
+// Remove any pending trees from the top of the given version of the stack.
+StackSliceArray ts_stack_pop_pending(Stack *, StackVersion);
+
+// Remove any all trees from the given version of the stack.
+StackSliceArray ts_stack_pop_all(Stack *, StackVersion);
+
+// Get the maximum number of tree nodes reachable from this version of the stack
+// since the last error was detected.
+unsigned ts_stack_node_count_since_error(const Stack *, StackVersion);
+
+int ts_stack_dynamic_precedence(Stack *, StackVersion);
+
+bool ts_stack_has_advanced_since_error(const Stack *, StackVersion);
+
+// Compute a summary of all the parse states near the top of the given
+// version of the stack and store the summary for later retrieval.
+void ts_stack_record_summary(Stack *, StackVersion, unsigned max_depth);
+
+// Retrieve a summary of all the parse states near the top of the
+// given version of the stack.
+StackSummary *ts_stack_get_summary(Stack *, StackVersion);
+
+// Get the total cost of all errors on the given version of the stack.
+unsigned ts_stack_error_cost(const Stack *, StackVersion version);
+
+// Merge the given two stack versions if possible, returning true
+// if they were successfully merged and false otherwise.
+bool ts_stack_merge(Stack *, StackVersion, StackVersion);
+
+// Determine whether the given two stack versions can be merged.
+bool ts_stack_can_merge(Stack *, StackVersion, StackVersion);
+
+Subtree ts_stack_resume(Stack *, StackVersion);
+
+void ts_stack_pause(Stack *, StackVersion, Subtree);
+
+void ts_stack_halt(Stack *, StackVersion);
+
+bool ts_stack_is_active(const Stack *, StackVersion);
+
+bool ts_stack_is_paused(const Stack *, StackVersion);
+
+bool ts_stack_is_halted(const Stack *, StackVersion);
+
+void ts_stack_renumber_version(Stack *, StackVersion, StackVersion);
+
+void ts_stack_swap_versions(Stack *, StackVersion, StackVersion);
+
+StackVersion ts_stack_copy_version(Stack *, StackVersion);
+
+// Remove the given version from the stack.
+void ts_stack_remove_version(Stack *, StackVersion);
+
+void ts_stack_clear(Stack *);
+
+bool ts_stack_print_dot_graph(Stack *, const TSLanguage *, FILE *);
+
+typedef void (*StackIterateCallback)(void *, TSStateId, uint32_t);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif  // TREE_SITTER_PARSE_STACK_H_

shcat_c/parser/src/subtree.h

@@ -0,0 +1,382 @@
+#ifndef TREE_SITTER_SUBTREE_H_
+#define TREE_SITTER_SUBTREE_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <limits.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include "./length.h"
+#include "./array.h"
+#include "./error_costs.h"
+#include "./host.h"
+#include "tree_sitter/api.h"
+#include "./parser.h"
+
+#define TS_TREE_STATE_NONE USHRT_MAX
+#define NULL_SUBTREE ((Subtree) {.ptr = NULL})
+
+// The serialized state of an external scanner.
+//
+// Every time an external token subtree is created after a call to an
+// external scanner, the scanner's `serialize` function is called to
+// retrieve a serialized copy of its state. The bytes are then copied
+// onto the subtree itself so that the scanner's state can later be
+// restored using its `deserialize` function.
+//
+// Small byte arrays are stored inline, and long ones are allocated
+// separately on the heap.
+typedef struct {
+  union {
+    char *long_data;
+    char short_data[24];
+  };
+  uint32_t length;
+} ExternalScannerState;
+
+// A compact representation of a subtree.
+//
+// This representation is used for small leaf nodes that are not
+// errors, and were not created by an external scanner.
+//
+// The idea behind the layout of this struct is that the `is_inline`
+// bit will fall exactly into the same location as the least significant
+// bit of the pointer in `Subtree` or `MutableSubtree`, respectively.
+// Because of alignment, for any valid pointer this will be 0, giving
+// us the opportunity to make use of this bit to signify whether to use
+// the pointer or the inline struct.
+typedef struct SubtreeInlineData SubtreeInlineData;
+
+#define SUBTREE_BITS    \
+  bool visible : 1;     \
+  bool named : 1;       \
+  bool extra : 1;       \
+  bool has_changes : 1; \
+  bool is_missing : 1;  \
+  bool is_keyword : 1;
+
+#define SUBTREE_SIZE           \
+  uint8_t padding_columns;     \
+  uint8_t padding_rows : 4;    \
+  uint8_t lookahead_bytes : 4; \
+  uint8_t padding_bytes;       \
+  uint8_t size_bytes;
+
+#if TS_BIG_ENDIAN
+#if TS_PTR_SIZE == 32
+
+struct SubtreeInlineData {
+  uint16_t parse_state;
+  uint8_t symbol;
+  SUBTREE_BITS
+  bool unused : 1;
+  bool is_inline : 1;
+  SUBTREE_SIZE
+};
+
+#else
+
+struct SubtreeInlineData {
+  SUBTREE_SIZE
+  uint16_t parse_state;
+  uint8_t symbol;
+  SUBTREE_BITS
+  bool unused : 1;
+  bool is_inline : 1;
+};
+
+#endif
+#else
+
+struct SubtreeInlineData {
+  bool is_inline : 1;
+  SUBTREE_BITS
+  uint8_t symbol;
+  uint16_t parse_state;
+  SUBTREE_SIZE
+};
+
+#endif
+
+#undef SUBTREE_BITS
+#undef SUBTREE_SIZE
+
+// A heap-allocated representation of a subtree.
+//
+// This representation is used for parent nodes, external tokens,
+// errors, and other leaf nodes whose data is too large to fit into
+// the inline representation.
+typedef struct {
+  volatile uint32_t ref_count;
+  Length padding;
+  Length size;
+  uint32_t lookahead_bytes;
+  uint32_t error_cost;
+  uint32_t child_count;
+  TSSymbol symbol;
+  TSStateId parse_state;
+
+  bool visible : 1;
+  bool named : 1;
+  bool extra : 1;
+  bool fragile_left : 1;
+  bool fragile_right : 1;
+  bool has_changes : 1;
+  bool has_external_tokens : 1;
+  bool has_external_scanner_state_change : 1;
+  bool depends_on_column: 1;
+  bool is_missing : 1;
+  bool is_keyword : 1;
+
+  union {
+    // Non-terminal subtrees (`child_count > 0`)
+    struct {
+      uint32_t visible_child_count;
+      uint32_t named_child_count;
+      uint32_t visible_descendant_count;
+      int32_t dynamic_precedence;
+      uint16_t repeat_depth;
+      uint16_t production_id;
+      struct {
+        TSSymbol symbol;
+        TSStateId parse_state;
+      } first_leaf;
+    };
+
+    // External terminal subtrees (`child_count == 0 && has_external_tokens`)
+    ExternalScannerState external_scanner_state;
+
+    // Error terminal subtrees (`child_count == 0 && symbol == ts_builtin_sym_error`)
+    int32_t lookahead_char;
+  };
+} SubtreeHeapData;
+
+// The fundamental building block of a syntax tree.
+typedef union {
+  SubtreeInlineData data;
+  const SubtreeHeapData *ptr;
+} Subtree;
+
+// Like Subtree, but mutable.
+typedef union {
+  SubtreeInlineData data;
+  SubtreeHeapData *ptr;
+} MutableSubtree;
+
+typedef Array(Subtree) SubtreeArray;
+typedef Array(MutableSubtree) MutableSubtreeArray;
+
+typedef struct {
+  MutableSubtreeArray free_trees;
+  MutableSubtreeArray tree_stack;
+} SubtreePool;
+
+void ts_external_scanner_state_init(ExternalScannerState *, const char *, unsigned);
+const char *ts_external_scanner_state_data(const ExternalScannerState *);
+bool ts_external_scanner_state_eq(const ExternalScannerState *self, const char *, unsigned);
+void ts_external_scanner_state_delete(ExternalScannerState *self);
+
+void ts_subtree_array_copy(SubtreeArray, SubtreeArray *);
+void ts_subtree_array_clear(SubtreePool *, SubtreeArray *);
+void ts_subtree_array_delete(SubtreePool *, SubtreeArray *);
+void ts_subtree_array_remove_trailing_extras(SubtreeArray *, SubtreeArray *);
+void ts_subtree_array_reverse(SubtreeArray *);
+
+SubtreePool ts_subtree_pool_new(uint32_t capacity);
+void ts_subtree_pool_delete(SubtreePool *);
+
+Subtree ts_subtree_new_leaf(
+  SubtreePool *, TSSymbol, Length, Length, uint32_t,
+  TSStateId, bool, bool, bool, const TSLanguage *
+);
+Subtree ts_subtree_new_error(
+  SubtreePool *, int32_t, Length, Length, uint32_t, TSStateId, const TSLanguage *
+);
+MutableSubtree ts_subtree_new_node(TSSymbol, SubtreeArray *, unsigned, const TSLanguage *);
+Subtree ts_subtree_new_error_node(SubtreeArray *, bool, const TSLanguage *);
+Subtree ts_subtree_new_missing_leaf(SubtreePool *, TSSymbol, Length, uint32_t, const TSLanguage *);
+MutableSubtree ts_subtree_make_mut(SubtreePool *, Subtree);
+void ts_subtree_retain(Subtree);
+void ts_subtree_release(SubtreePool *, Subtree);
+int ts_subtree_compare(Subtree, Subtree, SubtreePool *);
+void ts_subtree_set_symbol(MutableSubtree *, TSSymbol, const TSLanguage *);
+void ts_subtree_summarize(MutableSubtree, const Subtree *, uint32_t, const TSLanguage *);
+void ts_subtree_summarize_children(MutableSubtree, const TSLanguage *);
+void ts_subtree_balance(Subtree, SubtreePool *, const TSLanguage *);
+Subtree ts_subtree_edit(Subtree, const TSInputEdit *edit, SubtreePool *);
+char *ts_subtree_string(Subtree, TSSymbol, bool, const TSLanguage *, bool include_all);
+void ts_subtree_print_dot_graph(Subtree, const TSLanguage *, FILE *);
+Subtree ts_subtree_last_external_token(Subtree);
+const ExternalScannerState *ts_subtree_external_scanner_state(Subtree self);
+bool ts_subtree_external_scanner_state_eq(Subtree, Subtree);
+
+#define SUBTREE_GET(self, name) ((self).data.is_inline ? (self).data.name : (self).ptr->name)
+
+static inline TSSymbol ts_subtree_symbol(Subtree self) { return SUBTREE_GET(self, symbol); }
+static inline bool ts_subtree_visible(Subtree self) { return SUBTREE_GET(self, visible); }
+static inline bool ts_subtree_named(Subtree self) { return SUBTREE_GET(self, named); }
+static inline bool ts_subtree_extra(Subtree self) { return SUBTREE_GET(self, extra); }
+static inline bool ts_subtree_has_changes(Subtree self) { return SUBTREE_GET(self, has_changes); }
+static inline bool ts_subtree_missing(Subtree self) { return SUBTREE_GET(self, is_missing); }
+static inline bool ts_subtree_is_keyword(Subtree self) { return SUBTREE_GET(self, is_keyword); }
+static inline TSStateId ts_subtree_parse_state(Subtree self) { return SUBTREE_GET(self, parse_state); }
+static inline uint32_t ts_subtree_lookahead_bytes(Subtree self) { return SUBTREE_GET(self, lookahead_bytes); }
+
+#undef SUBTREE_GET
+
+// Get the size needed to store a heap-allocated subtree with the given
+// number of children.
+static inline size_t ts_subtree_alloc_size(uint32_t child_count) {
+  return child_count * sizeof(Subtree) + sizeof(SubtreeHeapData);
+}
+
+// Get a subtree's children, which are allocated immediately before the
+// tree's own heap data.
+#define ts_subtree_children(self) \
+  ((self).data.is_inline ? NULL : (Subtree *)((self).ptr) - (self).ptr->child_count)
+
+static inline void ts_subtree_set_extra(MutableSubtree *self, bool is_extra) {
+  if (self->data.is_inline) {
+    self->data.extra = is_extra;
+  } else {
+    self->ptr->extra = is_extra;
+  }
+}
+
+static inline TSSymbol ts_subtree_leaf_symbol(Subtree self) {
+  if (self.data.is_inline) return self.data.symbol;
+  if (self.ptr->child_count == 0) return self.ptr->symbol;
+  return self.ptr->first_leaf.symbol;
+}
+
+static inline TSStateId ts_subtree_leaf_parse_state(Subtree self) {
+  if (self.data.is_inline) return self.data.parse_state;
+  if (self.ptr->child_count == 0) return self.ptr->parse_state;
+  return self.ptr->first_leaf.parse_state;
+}
+
+static inline Length ts_subtree_padding(Subtree self) {
+  if (self.data.is_inline) {
+    Length result = {self.data.padding_bytes, {self.data.padding_rows, self.data.padding_columns}};
+    return result;
+  } else {
+    return self.ptr->padding;
+  }
+}
+
+static inline Length ts_subtree_size(Subtree self) {
+  if (self.data.is_inline) {
+    Length result = {self.data.size_bytes, {0, self.data.size_bytes}};
+    return result;
+  } else {
+    return self.ptr->size;
+  }
+}
+
+static inline Length ts_subtree_total_size(Subtree self) {
+  return length_add(ts_subtree_padding(self), ts_subtree_size(self));
+}
+
+static inline uint32_t ts_subtree_total_bytes(Subtree self) {
+  return ts_subtree_total_size(self).bytes;
+}
+
+static inline uint32_t ts_subtree_child_count(Subtree self) {
+  return self.data.is_inline ? 0 : self.ptr->child_count;
+}
+
+static inline uint32_t ts_subtree_repeat_depth(Subtree self) {
+  return self.data.is_inline ? 0 : self.ptr->repeat_depth;
+}
+
+static inline uint32_t ts_subtree_is_repetition(Subtree self) {
+  return self.data.is_inline
+    ? 0
+    : !self.ptr->named && !self.ptr->visible && self.ptr->child_count != 0;
+}
+
+static inline uint32_t ts_subtree_visible_descendant_count(Subtree self) {
+  return (self.data.is_inline || self.ptr->child_count == 0)
+    ? 0
+    : self.ptr->visible_descendant_count;
+}
+
+static inline uint32_t ts_subtree_visible_child_count(Subtree self) {
+  if (ts_subtree_child_count(self) > 0) {
+    return self.ptr->visible_child_count;
+  } else {
+    return 0;
+  }
+}
+
+static inline uint32_t ts_subtree_error_cost(Subtree self) {
+  if (ts_subtree_missing(self)) {
+    return ERROR_COST_PER_MISSING_TREE + ERROR_COST_PER_RECOVERY;
+  } else {
+    return self.data.is_inline ? 0 : self.ptr->error_cost;
+  }
+}
+
+static inline int32_t ts_subtree_dynamic_precedence(Subtree self) {
+  return (self.data.is_inline || self.ptr->child_count == 0) ? 0 : self.ptr->dynamic_precedence;
+}
+
+static inline uint16_t ts_subtree_production_id(Subtree self) {
+  if (ts_subtree_child_count(self) > 0) {
+    return self.ptr->production_id;
+  } else {
+    return 0;
+  }
+}
+
+static inline bool ts_subtree_fragile_left(Subtree self) {
+  return self.data.is_inline ? false : self.ptr->fragile_left;
+}
+
+static inline bool ts_subtree_fragile_right(Subtree self) {
+  return self.data.is_inline ? false : self.ptr->fragile_right;
+}
+
+static inline bool ts_subtree_has_external_tokens(Subtree self) {
+  return self.data.is_inline ? false : self.ptr->has_external_tokens;
+}
+
+static inline bool ts_subtree_has_external_scanner_state_change(Subtree self) {
+  return self.data.is_inline ? false : self.ptr->has_external_scanner_state_change;
+}
+
+static inline bool ts_subtree_depends_on_column(Subtree self) {
+  return self.data.is_inline ? false : self.ptr->depends_on_column;
+}
+
+static inline bool ts_subtree_is_fragile(Subtree self) {
+  return self.data.is_inline ? false : (self.ptr->fragile_left || self.ptr->fragile_right);
+}
+
+static inline bool ts_subtree_is_error(Subtree self) {
+  return ts_subtree_symbol(self) == ts_builtin_sym_error;
+}
+
+static inline bool ts_subtree_is_eof(Subtree self) {
+  return ts_subtree_symbol(self) == ts_builtin_sym_end;
+}
+
+static inline Subtree ts_subtree_from_mut(MutableSubtree self) {
+  Subtree result;
+  result.data = self.data;
+  return result;
+}
+
+static inline MutableSubtree ts_subtree_to_mut_unsafe(Subtree self) {
+  MutableSubtree result;
+  result.data = self.data;
+  return result;
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif  // TREE_SITTER_SUBTREE_H_

shcat_c/parser/src/tree.c

@@ -0,0 +1,140 @@
+#define _POSIX_C_SOURCE 200112L
+
+#include "tree_sitter/api.h"
+#include "./array.h"
+
+#include "./length.h"
+#include "./subtree.h"
+#include "./tree_cursor.h"
+#include "./tree.h"
+
+TSTree *ts_tree_new(
+  Subtree root, const TSLanguage *language,
+  const TSRange *included_ranges, unsigned included_range_count
+) {
+  TSTree *result = malloc(sizeof(TSTree));
+  result->root = root;
+  result->language = ts_language_copy(language);
+  result->included_ranges = calloc(included_range_count, sizeof(TSRange));
+  memcpy(result->included_ranges, included_ranges, included_range_count * sizeof(TSRange));
+  result->included_range_count = included_range_count;
+  return result;
+}
+
+TSTree *ts_tree_copy(const TSTree *self) {
+  ts_subtree_retain(self->root);
+  return ts_tree_new(self->root, self->language, self->included_ranges, self->included_range_count);
+}
+
+void ts_tree_delete(TSTree *self) {
+  if (!self) return;
+
+  SubtreePool pool = ts_subtree_pool_new(0);
+  ts_subtree_release(&pool, self->root);
+  ts_subtree_pool_delete(&pool);
+  ts_language_delete(self->language);
+  free(self->included_ranges);
+  free(self);
+}
+
+TSNode ts_tree_root_node(const TSTree *self) {
+  return ts_node_new(self, &self->root, ts_subtree_padding(self->root), 0);
+}
+
+TSNode ts_tree_root_node_with_offset(
+  const TSTree *self,
+  uint32_t offset_bytes,
+  TSPoint offset_extent
+) {
+  Length offset = {offset_bytes, offset_extent};
+  return ts_node_new(self, &self->root, length_add(offset, ts_subtree_padding(self->root)), 0);
+}
+
+const TSLanguage *ts_tree_language(const TSTree *self) {
+  return self->language;
+}
+
+void ts_tree_edit(TSTree *self, const TSInputEdit *edit) {
+  for (unsigned i = 0; i < self->included_range_count; i++) {
+    TSRange *range = &self->included_ranges[i];
+    if (range->end_byte >= edit->old_end_byte) {
+      if (range->end_byte != UINT32_MAX) {
+        range->end_byte = edit->new_end_byte + (range->end_byte - edit->old_end_byte);
+        range->end_point = point_add(
+          edit->new_end_point,
+          point_sub(range->end_point, edit->old_end_point)
+        );
+        if (range->end_byte < edit->new_end_byte) {
+          range->end_byte = UINT32_MAX;
+          range->end_point = POINT_MAX;
+        }
+      }
+    } else if (range->end_byte > edit->start_byte) {
+      range->end_byte = edit->start_byte;
+      range->end_point = edit->start_point;
+    }
+    if (range->start_byte >= edit->old_end_byte) {
+      range->start_byte = edit->new_end_byte + (range->start_byte - edit->old_end_byte);
+      range->start_point = point_add(
+        edit->new_end_point,
+        point_sub(range->start_point, edit->old_end_point)
+      );
+      if (range->start_byte < edit->new_end_byte) {
+        range->start_byte = UINT32_MAX;
+        range->start_point = POINT_MAX;
+      }
+    } else if (range->start_byte > edit->start_byte) {
+      range->start_byte = edit->start_byte;
+      range->start_point = edit->start_point;
+    }
+  }
+
+  SubtreePool pool = ts_subtree_pool_new(0);
+  self->root = ts_subtree_edit(self->root, edit, &pool);
+  ts_subtree_pool_delete(&pool);
+}
+
+TSRange *ts_tree_included_ranges(const TSTree *self, uint32_t *length) {
+  *length = self->included_range_count;
+  TSRange *ranges = calloc(self->included_range_count, sizeof(TSRange));
+  memcpy(ranges, self->included_ranges, self->included_range_count * sizeof(TSRange));
+  return ranges;
+}
+
+#ifdef _WIN32
+
+#include <io.h>
+#include <windows.h>
+
+int _ts_dup(HANDLE handle) {
+  HANDLE dup_handle;
+  if (!DuplicateHandle(
+    GetCurrentProcess(), handle,
+    GetCurrentProcess(), &dup_handle,
+    0, FALSE, DUPLICATE_SAME_ACCESS
+  )) return -1;
+
+  return _open_osfhandle((intptr_t)dup_handle, 0);
+}
+
+void ts_tree_print_dot_graph(const TSTree *self, int fd) {
+  FILE *file = _fdopen(_ts_dup((HANDLE)_get_osfhandle(fd)), "a");
+  ts_subtree_print_dot_graph(self->root, self->language, file);
+  fclose(file);
+}
+
+#else
+
+#include <unistd.h>
+
+int _ts_dup(int file_descriptor) {
+  return dup(file_descriptor);
+}
+
+void ts_tree_print_dot_graph(const TSTree *self, int file_descriptor) {
+  FILE *file = fdopen(_ts_dup(file_descriptor), "a");
+  ts_subtree_print_dot_graph(self->root, self->language, file);
+  fclose(file);
+}
+
+#endif

shcat_c/parser/src/tree.h

@@ -0,0 +1,31 @@
+#ifndef TREE_SITTER_TREE_H_
+#define TREE_SITTER_TREE_H_
+
+#include "./subtree.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef struct {
+  const Subtree *child;
+  const Subtree *parent;
+  Length position;
+  TSSymbol alias_symbol;
+} ParentCacheEntry;
+
+struct TSTree {
+  Subtree root;
+  const TSLanguage *language;
+  TSRange *included_ranges;
+  unsigned included_range_count;
+};
+
+TSTree *ts_tree_new(Subtree root, const TSLanguage *language, const TSRange *, unsigned);
+TSNode ts_node_new(const TSTree *, const Subtree *, Length, TSSymbol);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif  // TREE_SITTER_TREE_H_

shcat_c/parser/src/tree_cursor.c

@@ -0,0 +1,714 @@
+#include "tree_sitter/api.h"
+
+#include "./tree_cursor.h"
+#include "./language.h"
+#include "./tree.h"
+
+typedef struct {
+  Subtree parent;
+  const TSTree *tree;
+  Length position;
+  uint32_t child_index;
+  uint32_t structural_child_index;
+  uint32_t descendant_index;
+  const TSSymbol *alias_sequence;
+} CursorChildIterator;
+
+// CursorChildIterator
+
+static inline bool ts_tree_cursor_is_entry_visible(const TreeCursor *self, uint32_t index) {
+  TreeCursorEntry *entry = &self->stack.contents[index];
+  if (index == 0 || ts_subtree_visible(*entry->subtree)) {
+    return true;
+  } else if (!ts_subtree_extra(*entry->subtree)) {
+    TreeCursorEntry *parent_entry = &self->stack.contents[index - 1];
+    return ts_language_alias_at(
+      self->tree->language,
+      parent_entry->subtree->ptr->production_id,
+      entry->structural_child_index
+    );
+  } else {
+    return false;
+  }
+}
+
+static inline CursorChildIterator ts_tree_cursor_iterate_children(const TreeCursor *self) {
+  TreeCursorEntry *last_entry = array_back(&self->stack);
+  if (ts_subtree_child_count(*last_entry->subtree) == 0) {
+    return (CursorChildIterator) {NULL_SUBTREE, self->tree, length_zero(), 0, 0, 0, NULL};
+  }
+  const TSSymbol *alias_sequence = ts_language_alias_sequence(
+    self->tree->language,
+    last_entry->subtree->ptr->production_id
+  );
+
+  uint32_t descendant_index = last_entry->descendant_index;
+  if (ts_tree_cursor_is_entry_visible(self, self->stack.size - 1)) {
+    descendant_index += 1;
+  }
+
+  return (CursorChildIterator) {
+    .tree = self->tree,
+    .parent = *last_entry->subtree,
+    .position = last_entry->position,
+    .child_index = 0,
+    .structural_child_index = 0,
+    .descendant_index = descendant_index,
+    .alias_sequence = alias_sequence,
+  };
+}
+
+static inline bool ts_tree_cursor_child_iterator_next(
+  CursorChildIterator *self,
+  TreeCursorEntry *result,
+  bool *visible
+) {
+  if (!self->parent.ptr || self->child_index == self->parent.ptr->child_count) return false;
+  const Subtree *child = &ts_subtree_children(self->parent)[self->child_index];
+  *result = (TreeCursorEntry) {
+    .subtree = child,
+    .position = self->position,
+    .child_index = self->child_index,
+    .structural_child_index = self->structural_child_index,
+    .descendant_index = self->descendant_index,
+  };
+  *visible = ts_subtree_visible(*child);
+  bool extra = ts_subtree_extra(*child);
+  if (!extra) {
+    if (self->alias_sequence) {
+      *visible |= self->alias_sequence[self->structural_child_index];
+    }
+    self->structural_child_index++;
+  }
+
+  self->descendant_index += ts_subtree_visible_descendant_count(*child);
+  if (*visible) {
+    self->descendant_index += 1;
+  }
+
+  self->position = length_add(self->position, ts_subtree_size(*child));
+  self->child_index++;
+
+  if (self->child_index < self->parent.ptr->child_count) {
+    Subtree next_child = ts_subtree_children(self->parent)[self->child_index];
+    self->position = length_add(self->position, ts_subtree_padding(next_child));
+  }
+
+  return true;
+}
+
+// Return a position that, when `b` is added to it, yields `a`. This
+// can only be computed if `b` has zero rows. Otherwise, this function
+// returns `LENGTH_UNDEFINED`, and the caller needs to recompute
+// the position some other way.
+static inline Length length_backtrack(Length a, Length b) {
+  if (length_is_undefined(a) || b.extent.row != 0) {
+    return LENGTH_UNDEFINED;
+  }
+
+  Length result;
+  result.bytes = a.bytes - b.bytes;
+  result.extent.row = a.extent.row;
+  result.extent.column = a.extent.column - b.extent.column;
+  return result;
+}
+
+static inline bool ts_tree_cursor_child_iterator_previous(
+  CursorChildIterator *self,
+  TreeCursorEntry *result,
+  bool *visible
+) {
+  // this is mostly a reverse `ts_tree_cursor_child_iterator_next` taking into
+  // account unsigned underflow
+  if (!self->parent.ptr || (int8_t)self->child_index == -1) return false;
+  const Subtree *child = &ts_subtree_children(self->parent)[self->child_index];
+  *result = (TreeCursorEntry) {
+    .subtree = child,
+    .position = self->position,
+    .child_index = self->child_index,
+    .structural_child_index = self->structural_child_index,
+  };
+  *visible = ts_subtree_visible(*child);
+  bool extra = ts_subtree_extra(*child);
+  if (!extra && self->alias_sequence) {
+    *visible |= self->alias_sequence[self->structural_child_index];
+    self->structural_child_index--;
+  }
+
+  self->position = length_backtrack(self->position, ts_subtree_padding(*child));
+  self->child_index--;
+
+  // unsigned can underflow so compare it to child_count
+  if (self->child_index < self->parent.ptr->child_count) {
+    Subtree previous_child = ts_subtree_children(self->parent)[self->child_index];
+    Length size = ts_subtree_size(previous_child);
+    self->position = length_backtrack(self->position, size);
+  }
+
+  return true;
+}
+
+// TSTreeCursor - lifecycle
+
+TSTreeCursor ts_tree_cursor_new(TSNode node) {
+  TSTreeCursor self = {NULL, NULL, {0, 0, 0}};
+  ts_tree_cursor_init((TreeCursor *)&self, node);
+  return self;
+}
+
+void ts_tree_cursor_reset(TSTreeCursor *_self, TSNode node) {
+  ts_tree_cursor_init((TreeCursor *)_self, node);
+}
+
+void ts_tree_cursor_init(TreeCursor *self, TSNode node) {
+  self->tree = node.tree;
+  self->root_alias_symbol = node.context[3];
+  array_clear(&self->stack);
+  array_push(&self->stack, ((TreeCursorEntry) {
+    .subtree = (const Subtree *)node.id,
+    .position = {
+      ts_node_start_byte(node),
+      ts_node_start_point(node)
+    },
+    .child_index = 0,
+    .structural_child_index = 0,
+    .descendant_index = 0,
+  }));
+}
+
+void ts_tree_cursor_delete(TSTreeCursor *_self) {
+  TreeCursor *self = (TreeCursor *)_self;
+  array_delete(&self->stack);
+}
+
+// TSTreeCursor - walking the tree
+
+TreeCursorStep ts_tree_cursor_goto_first_child_internal(TSTreeCursor *_self) {
+  TreeCursor *self = (TreeCursor *)_self;
+  bool visible;
+  TreeCursorEntry entry;
+  CursorChildIterator iterator = ts_tree_cursor_iterate_children(self);
+  while (ts_tree_cursor_child_iterator_next(&iterator, &entry, &visible)) {
+    if (visible) {
+      array_push(&self->stack, entry);
+      return TreeCursorStepVisible;
+    }
+    if (ts_subtree_visible_child_count(*entry.subtree) > 0) {
+      array_push(&self->stack, entry);
+      return TreeCursorStepHidden;
+    }
+  }
+  return TreeCursorStepNone;
+}
+
+bool ts_tree_cursor_goto_first_child(TSTreeCursor *self) {
+  for (;;) {
+    switch (ts_tree_cursor_goto_first_child_internal(self)) {
+      case TreeCursorStepHidden:
+        continue;
+      case TreeCursorStepVisible:
+        return true;
+      default:
+        return false;
+    }
+  }
+  return false;
+}
+
+TreeCursorStep ts_tree_cursor_goto_last_child_internal(TSTreeCursor *_self) {
+  TreeCursor *self = (TreeCursor *)_self;
+  bool visible;
+  TreeCursorEntry entry;
+  CursorChildIterator iterator = ts_tree_cursor_iterate_children(self);
+  if (!iterator.parent.ptr || iterator.parent.ptr->child_count == 0) return TreeCursorStepNone;
+
+  TreeCursorEntry last_entry = {0};
+  TreeCursorStep last_step = TreeCursorStepNone;
+  while (ts_tree_cursor_child_iterator_next(&iterator, &entry, &visible)) {
+    if (visible) {
+      last_entry = entry;
+      last_step = TreeCursorStepVisible;
+    }
+    else if (ts_subtree_visible_child_count(*entry.subtree) > 0) {
+      last_entry = entry;
+      last_step = TreeCursorStepHidden;
+    }
+  }
+  if (last_entry.subtree) {
+    array_push(&self->stack, last_entry);
+    return last_step;
+  }
+
+  return TreeCursorStepNone;
+}
+
+bool ts_tree_cursor_goto_last_child(TSTreeCursor *self) {
+  for (;;) {
+    switch (ts_tree_cursor_goto_last_child_internal(self)) {
+      case TreeCursorStepHidden:
+        continue;
+      case TreeCursorStepVisible:
+        return true;
+      default:
+        return false;
+    }
+  }
+  return false;
+}
+
+static inline int64_t ts_tree_cursor_goto_first_child_for_byte_and_point(
+  TSTreeCursor *_self,
+  uint32_t goal_byte,
+  TSPoint goal_point
+) {
+  TreeCursor *self = (TreeCursor *)_self;
+  uint32_t initial_size = self->stack.size;
+  uint32_t visible_child_index = 0;
+
+  bool did_descend;
+  do {
+    did_descend = false;
+
+    bool visible;
+    TreeCursorEntry entry;
+    CursorChildIterator iterator = ts_tree_cursor_iterate_children(self);
+    while (ts_tree_cursor_child_iterator_next(&iterator, &entry, &visible)) {
+      Length entry_end = length_add(entry.position, ts_subtree_size(*entry.subtree));
+      bool at_goal = entry_end.bytes >= goal_byte && point_gte(entry_end.extent, goal_point);
+      uint32_t visible_child_count = ts_subtree_visible_child_count(*entry.subtree);
+      if (at_goal) {
+        if (visible) {
+          array_push(&self->stack, entry);
+          return visible_child_index;
+        }
+        if (visible_child_count > 0) {
+          array_push(&self->stack, entry);
+          did_descend = true;
+          break;
+        }
+      } else if (visible) {
+        visible_child_index++;
+      } else {
+        visible_child_index += visible_child_count;
+      }
+    }
+  } while (did_descend);
+
+  self->stack.size = initial_size;
+  return -1;
+}
+
+int64_t ts_tree_cursor_goto_first_child_for_byte(TSTreeCursor *self, uint32_t goal_byte) {
+  return ts_tree_cursor_goto_first_child_for_byte_and_point(self, goal_byte, POINT_ZERO);
+}
+
+int64_t ts_tree_cursor_goto_first_child_for_point(TSTreeCursor *self, TSPoint goal_point) {
+  return ts_tree_cursor_goto_first_child_for_byte_and_point(self, 0, goal_point);
+}
+
+TreeCursorStep ts_tree_cursor_goto_sibling_internal(
+    TSTreeCursor *_self,
+    bool (*advance)(CursorChildIterator *, TreeCursorEntry *, bool *)) {
+  TreeCursor *self = (TreeCursor *)_self;
+  uint32_t initial_size = self->stack.size;
+
+  while (self->stack.size > 1) {
+    TreeCursorEntry entry = array_pop(&self->stack);
+    CursorChildIterator iterator = ts_tree_cursor_iterate_children(self);
+    iterator.child_index = entry.child_index;
+    iterator.structural_child_index = entry.structural_child_index;
+    iterator.position = entry.position;
+    iterator.descendant_index = entry.descendant_index;
+
+    bool visible = false;
+    advance(&iterator, &entry, &visible);
+    if (visible && self->stack.size + 1 < initial_size) break;
+
+    while (advance(&iterator, &entry, &visible)) {
+      if (visible) {
+        array_push(&self->stack, entry);
+        return TreeCursorStepVisible;
+      }
+
+      if (ts_subtree_visible_child_count(*entry.subtree)) {
+        array_push(&self->stack, entry);
+        return TreeCursorStepHidden;
+      }
+    }
+  }
+
+  self->stack.size = initial_size;
+  return TreeCursorStepNone;
+}
+
+TreeCursorStep ts_tree_cursor_goto_next_sibling_internal(TSTreeCursor *_self) {
+  return ts_tree_cursor_goto_sibling_internal(_self, ts_tree_cursor_child_iterator_next);
+}
+
+bool ts_tree_cursor_goto_next_sibling(TSTreeCursor *self) {
+  switch (ts_tree_cursor_goto_next_sibling_internal(self)) {
+    case TreeCursorStepHidden:
+      ts_tree_cursor_goto_first_child(self);
+      return true;
+    case TreeCursorStepVisible:
+      return true;
+    default:
+      return false;
+  }
+}
+
+TreeCursorStep ts_tree_cursor_goto_previous_sibling_internal(TSTreeCursor *_self) {
+  // since subtracting across row loses column information, we may have to
+  // restore it
+  TreeCursor *self = (TreeCursor *)_self;
+
+  // for that, save current position before traversing
+  TreeCursorStep step = ts_tree_cursor_goto_sibling_internal(
+      _self, ts_tree_cursor_child_iterator_previous);
+  if (step == TreeCursorStepNone)
+    return step;
+
+  // if length is already valid, there's no need to recompute it
+  if (!length_is_undefined(array_back(&self->stack)->position))
+    return step;
+
+  // restore position from the parent node
+  const TreeCursorEntry *parent = &self->stack.contents[self->stack.size - 2];
+  Length position = parent->position;
+  uint32_t child_index = array_back(&self->stack)->child_index;
+  const Subtree *children = ts_subtree_children((*(parent->subtree)));
+
+  if (child_index > 0) {
+    // skip first child padding since its position should match the position of the parent
+    position = length_add(position, ts_subtree_size(children[0]));
+    for (uint32_t i = 1; i < child_index; ++i) {
+      position = length_add(position, ts_subtree_total_size(children[i]));
+    }
+    position = length_add(position, ts_subtree_padding(children[child_index]));
+  }
+
+  array_back(&self->stack)->position = position;
+
+  return step;
+}
+
+bool ts_tree_cursor_goto_previous_sibling(TSTreeCursor *self) {
+  switch (ts_tree_cursor_goto_previous_sibling_internal(self)) {
+    case TreeCursorStepHidden:
+      ts_tree_cursor_goto_last_child(self);
+      return true;
+    case TreeCursorStepVisible:
+      return true;
+    default:
+      return false;
+  }
+}
+
+bool ts_tree_cursor_goto_parent(TSTreeCursor *_self) {
+  TreeCursor *self = (TreeCursor *)_self;
+  for (unsigned i = self->stack.size - 2; i + 1 > 0; i--) {
+    if (ts_tree_cursor_is_entry_visible(self, i)) {
+      self->stack.size = i + 1;
+      return true;
+    }
+  }
+  return false;
+}
+
+void ts_tree_cursor_goto_descendant(
+  TSTreeCursor *_self,
+  uint32_t goal_descendant_index
+) {
+  TreeCursor *self = (TreeCursor *)_self;
+
+  // Ascend to the lowest ancestor that contains the goal node.
+  for (;;) {
+    uint32_t i = self->stack.size - 1;
+    TreeCursorEntry *entry = &self->stack.contents[i];
+    uint32_t next_descendant_index =
+      entry->descendant_index +
+      (ts_tree_cursor_is_entry_visible(self, i) ? 1 : 0) +
+      ts_subtree_visible_descendant_count(*entry->subtree);
+    if (
+      (entry->descendant_index <= goal_descendant_index) &&
+      (next_descendant_index > goal_descendant_index)
+    ) {
+      break;
+    } else if (self->stack.size <= 1) {
+      return;
+    } else {
+      self->stack.size--;
+    }
+  }
+
+  // Descend to the goal node.
+  bool did_descend = true;
+  do {
+    did_descend = false;
+    bool visible;
+    TreeCursorEntry entry;
+    CursorChildIterator iterator = ts_tree_cursor_iterate_children(self);
+    if (iterator.descendant_index > goal_descendant_index) {
+      return;
+    }
+
+    while (ts_tree_cursor_child_iterator_next(&iterator, &entry, &visible)) {
+      if (iterator.descendant_index > goal_descendant_index) {
+        array_push(&self->stack, entry);
+        if (visible && entry.descendant_index == goal_descendant_index) {
+          return;
+        } else {
+          did_descend = true;
+          break;
+        }
+      }
+    }
+  } while (did_descend);
+}
+
+uint32_t ts_tree_cursor_current_descendant_index(const TSTreeCursor *_self) {
+  const TreeCursor *self = (const TreeCursor *)_self;
+  TreeCursorEntry *last_entry = array_back(&self->stack);
+  return last_entry->descendant_index;
+}
+
+TSNode ts_tree_cursor_current_node(const TSTreeCursor *_self) {
+  const TreeCursor *self = (const TreeCursor *)_self;
+  TreeCursorEntry *last_entry = array_back(&self->stack);
+  TSSymbol alias_symbol = self->root_alias_symbol;
+  if (self->stack.size > 1 && !ts_subtree_extra(*last_entry->subtree)) {
+    TreeCursorEntry *parent_entry = &self->stack.contents[self->stack.size - 2];
+    alias_symbol = ts_language_alias_at(
+      self->tree->language,
+      parent_entry->subtree->ptr->production_id,
+      last_entry->structural_child_index
+    );
+  }
+  return ts_node_new(
+    self->tree,
+    last_entry->subtree,
+    last_entry->position,
+    alias_symbol
+  );
+}
+
+// Private - Get various facts about the current node that are needed
+// when executing tree queries.
+void ts_tree_cursor_current_status(
+  const TSTreeCursor *_self,
+  TSFieldId *field_id,
+  bool *has_later_siblings,
+  bool *has_later_named_siblings,
+  bool *can_have_later_siblings_with_this_field,
+  TSSymbol *supertypes,
+  unsigned *supertype_count
+) {
+  const TreeCursor *self = (const TreeCursor *)_self;
+  unsigned max_supertypes = *supertype_count;
+  *field_id = 0;
+  *supertype_count = 0;
+  *has_later_siblings = false;
+  *has_later_named_siblings = false;
+  *can_have_later_siblings_with_this_field = false;
+
+  // Walk up the tree, visiting the current node and its invisible ancestors,
+  // because fields can refer to nodes through invisible *wrapper* nodes,
+  for (unsigned i = self->stack.size - 1; i > 0; i--) {
+    TreeCursorEntry *entry = &self->stack.contents[i];
+    TreeCursorEntry *parent_entry = &self->stack.contents[i - 1];
+
+    const TSSymbol *alias_sequence = ts_language_alias_sequence(
+      self->tree->language,
+      parent_entry->subtree->ptr->production_id
+    );
+
+    #define subtree_symbol(subtree, structural_child_index) \
+      ((                                                    \
+        !ts_subtree_extra(subtree) &&                       \
+        alias_sequence &&                                   \
+        alias_sequence[structural_child_index]              \
+      ) ?                                                   \
+        alias_sequence[structural_child_index] :            \
+        ts_subtree_symbol(subtree))
+
+    // Stop walking up when a visible ancestor is found.
+    TSSymbol entry_symbol = subtree_symbol(
+      *entry->subtree,
+      entry->structural_child_index
+    );
+    TSSymbolMetadata entry_metadata = ts_language_symbol_metadata(
+      self->tree->language,
+      entry_symbol
+    );
+    if (i != self->stack.size - 1 && entry_metadata.visible) break;
+
+    // Record any supertypes
+    if (entry_metadata.supertype && *supertype_count < max_supertypes) {
+      supertypes[*supertype_count] = entry_symbol;
+      (*supertype_count)++;
+    }
+
+    // Determine if the current node has later siblings.
+    if (!*has_later_siblings) {
+      unsigned sibling_count = parent_entry->subtree->ptr->child_count;
+      unsigned structural_child_index = entry->structural_child_index;
+      if (!ts_subtree_extra(*entry->subtree)) structural_child_index++;
+      for (unsigned j = entry->child_index + 1; j < sibling_count; j++) {
+        Subtree sibling = ts_subtree_children(*parent_entry->subtree)[j];
+        TSSymbolMetadata sibling_metadata = ts_language_symbol_metadata(
+          self->tree->language,
+          subtree_symbol(sibling, structural_child_index)
+        );
+        if (sibling_metadata.visible) {
+          *has_later_siblings = true;
+          if (*has_later_named_siblings) break;
+          if (sibling_metadata.named) {
+            *has_later_named_siblings = true;
+            break;
+          }
+        } else if (ts_subtree_visible_child_count(sibling) > 0) {
+          *has_later_siblings = true;
+          if (*has_later_named_siblings) break;
+          if (sibling.ptr->named_child_count > 0) {
+            *has_later_named_siblings = true;
+            break;
+          }
+        }
+        if (!ts_subtree_extra(sibling)) structural_child_index++;
+      }
+    }
+
+    #undef subtree_symbol
+
+    if (!ts_subtree_extra(*entry->subtree)) {
+      const TSFieldMapEntry *field_map, *field_map_end;
+      ts_language_field_map(
+        self->tree->language,
+        parent_entry->subtree->ptr->production_id,
+        &field_map, &field_map_end
+      );
+
+      // Look for a field name associated with the current node.
+      if (!*field_id) {
+        for (const TSFieldMapEntry *map = field_map; map < field_map_end; map++) {
+          if (!map->inherited && map->child_index == entry->structural_child_index) {
+            *field_id = map->field_id;
+            break;
+          }
+        }
+      }
+
+      // Determine if the current node can have later siblings with the same field name.
+      if (*field_id) {
+        for (const TSFieldMapEntry *map = field_map; map < field_map_end; map++) {
+          if (
+            map->field_id == *field_id &&
+            map->child_index > entry->structural_child_index
+          ) {
+            *can_have_later_siblings_with_this_field = true;
+            break;
+          }
+        }
+      }
+    }
+  }
+}
+
+uint32_t ts_tree_cursor_current_depth(const TSTreeCursor *_self) {
+  const TreeCursor *self = (const TreeCursor *)_self;
+  uint32_t depth = 0;
+  for (unsigned i = 1; i < self->stack.size; i++) {
+    if (ts_tree_cursor_is_entry_visible(self, i)) {
+      depth++;
+    }
+  }
+  return depth;
+}
+
+TSNode ts_tree_cursor_parent_node(const TSTreeCursor *_self) {
+  const TreeCursor *self = (const TreeCursor *)_self;
+  for (int i = (int)self->stack.size - 2; i >= 0; i--) {
+    TreeCursorEntry *entry = &self->stack.contents[i];
+    bool is_visible = true;
+    TSSymbol alias_symbol = 0;
+    if (i > 0) {
+      TreeCursorEntry *parent_entry = &self->stack.contents[i - 1];
+      alias_symbol = ts_language_alias_at(
+        self->tree->language,
+        parent_entry->subtree->ptr->production_id,
+        entry->structural_child_index
+      );
+      is_visible = (alias_symbol != 0) || ts_subtree_visible(*entry->subtree);
+    }
+    if (is_visible) {
+      return ts_node_new(
+        self->tree,
+        entry->subtree,
+        entry->position,
+        alias_symbol
+      );
+    }
+  }
+  return ts_node_new(NULL, NULL, length_zero(), 0);
+}
+
+TSFieldId ts_tree_cursor_current_field_id(const TSTreeCursor *_self) {
+  const TreeCursor *self = (const TreeCursor *)_self;
+
+  // Walk up the tree, visiting the current node and its invisible ancestors.
+  for (unsigned i = self->stack.size - 1; i > 0; i--) {
+    TreeCursorEntry *entry = &self->stack.contents[i];
+    TreeCursorEntry *parent_entry = &self->stack.contents[i - 1];
+
+    // Stop walking up when another visible node is found.
+    if (
+      i != self->stack.size - 1 &&
+      ts_tree_cursor_is_entry_visible(self, i)
+    ) break;
+
+    if (ts_subtree_extra(*entry->subtree)) break;
+
+    const TSFieldMapEntry *field_map, *field_map_end;
+    ts_language_field_map(
+      self->tree->language,
+      parent_entry->subtree->ptr->production_id,
+      &field_map, &field_map_end
+    );
+    for (const TSFieldMapEntry *map = field_map; map < field_map_end; map++) {
+      if (!map->inherited && map->child_index == entry->structural_child_index) {
+        return map->field_id;
+      }
+    }
+  }
+  return 0;
+}
+
+const char *ts_tree_cursor_current_field_name(const TSTreeCursor *_self) {
+  TSFieldId id = ts_tree_cursor_current_field_id(_self);
+  if (id) {
+    const TreeCursor *self = (const TreeCursor *)_self;
+    return self->tree->language->field_names[id];
+  } else {
+    return NULL;
+  }
+}
+
+TSTreeCursor ts_tree_cursor_copy(const TSTreeCursor *_cursor) {
+  const TreeCursor *cursor = (const TreeCursor *)_cursor;
+  TSTreeCursor res = {NULL, NULL, {0, 0}};
+  TreeCursor *copy = (TreeCursor *)&res;
+  copy->tree = cursor->tree;
+  copy->root_alias_symbol = cursor->root_alias_symbol;
+  array_init(&copy->stack);
+  array_push_all(&copy->stack, &cursor->stack);
+  return res;
+}
+
+void ts_tree_cursor_reset_to(TSTreeCursor *_dst, const TSTreeCursor *_src) {
+  const TreeCursor *cursor = (const TreeCursor *)_src;
+  TreeCursor *copy = (TreeCursor *)_dst;
+  copy->tree = cursor->tree;
+  copy->root_alias_symbol = cursor->root_alias_symbol;
+  array_clear(&copy->stack);
+  array_push_all(&copy->stack, &cursor->stack);
+}

shcat_c/parser/src/tree_cursor.h

@@ -0,0 +1,48 @@
+#ifndef TREE_SITTER_TREE_CURSOR_H_
+#define TREE_SITTER_TREE_CURSOR_H_
+
+#include "./subtree.h"
+
+typedef struct {
+  const Subtree *subtree;
+  Length position;
+  uint32_t child_index;
+  uint32_t structural_child_index;
+  uint32_t descendant_index;
+} TreeCursorEntry;
+
+typedef struct {
+  const TSTree *tree;
+  Array(TreeCursorEntry) stack;
+  TSSymbol root_alias_symbol;
+} TreeCursor;
+
+typedef enum {
+  TreeCursorStepNone,
+  TreeCursorStepHidden,
+  TreeCursorStepVisible,
+} TreeCursorStep;
+
+void ts_tree_cursor_init(TreeCursor *, TSNode);
+void ts_tree_cursor_current_status(
+  const TSTreeCursor *,
+  TSFieldId *,
+  bool *,
+  bool *,
+  bool *,
+  TSSymbol *,
+  unsigned *
+);
+
+TreeCursorStep ts_tree_cursor_goto_first_child_internal(TSTreeCursor *);
+TreeCursorStep ts_tree_cursor_goto_next_sibling_internal(TSTreeCursor *);
+
+static inline Subtree ts_tree_cursor_current_subtree(const TSTreeCursor *_self) {
+  const TreeCursor *self = (const TreeCursor *)_self;
+  TreeCursorEntry *last_entry = array_back(&self->stack);
+  return *last_entry->subtree;
+}
+
+TSNode ts_tree_cursor_parent_node(const TSTreeCursor *);
+
+#endif  // TREE_SITTER_TREE_CURSOR_H_