Added tree-sitter vendor library

1 files changed, 1039 insertions, 0 deletions

diff --git a/vendor/tree-sitter/lib/src/subtree.c b/vendor/tree-sitter/lib/src/subtree.c
new file mode 100644
index 0000000..51bc2ef
--- /dev/null
+++ b/vendor/tree-sitter/lib/src/subtree.c
@@ -0,0 +1,1039 @@
+#include <assert.h>
+#include <ctype.h>
+#include <limits.h>
+#include <stdbool.h>
+#include <string.h>
+#include <stdio.h>
+#include "./alloc.h"
+#include "./atomic.h"
+#include "./subtree.h"
+#include "./length.h"
+#include "./language.h"
+#include "./error_costs.h"
+#include <stddef.h>
+
+typedef struct {
+  Length start;
+  Length old_end;
+  Length new_end;
+} Edit;
+
+#define TS_MAX_INLINE_TREE_LENGTH UINT8_MAX
+#define TS_MAX_TREE_POOL_SIZE 32
+
+// ExternalScannerState
+
+void ts_external_scanner_state_init(ExternalScannerState *self, const char *data, unsigned length) {
+  self->length = length;
+  if (length > sizeof(self->short_data)) {
+    self->long_data = ts_malloc(length);
+    memcpy(self->long_data, data, length);
+  } else {
+    memcpy(self->short_data, data, length);
+  }
+}
+
+ExternalScannerState ts_external_scanner_state_copy(const ExternalScannerState *self) {
+  ExternalScannerState result = *self;
+  if (self->length > sizeof(self->short_data)) {
+    result.long_data = ts_malloc(self->length);
+    memcpy(result.long_data, self->long_data, self->length);
+  }
+  return result;
+}
+
+void ts_external_scanner_state_delete(ExternalScannerState *self) {
+  if (self->length > sizeof(self->short_data)) {
+    ts_free(self->long_data);
+  }
+}
+
+const char *ts_external_scanner_state_data(const ExternalScannerState *self) {
+  if (self->length > sizeof(self->short_data)) {
+    return self->long_data;
+  } else {
+    return self->short_data;
+  }
+}
+
+bool ts_external_scanner_state_eq(const ExternalScannerState *self, const char *buffer, unsigned length) {
+  return
+    self->length == length &&
+    memcmp(ts_external_scanner_state_data(self), buffer, length) == 0;
+}
+
+// SubtreeArray
+
+void ts_subtree_array_copy(SubtreeArray self, SubtreeArray *dest) {
+  dest->size = self.size;
+  dest->capacity = self.capacity;
+  dest->contents = self.contents;
+  if (self.capacity > 0) {
+    dest->contents = ts_calloc(self.capacity, sizeof(Subtree));
+    memcpy(dest->contents, self.contents, self.size * sizeof(Subtree));
+    for (uint32_t i = 0; i < self.size; i++) {
+      ts_subtree_retain(dest->contents[i]);
+    }
+  }
+}
+
+void ts_subtree_array_clear(SubtreePool *pool, SubtreeArray *self) {
+  for (uint32_t i = 0; i < self->size; i++) {
+    ts_subtree_release(pool, self->contents[i]);
+  }
+  array_clear(self);
+}
+
+void ts_subtree_array_delete(SubtreePool *pool, SubtreeArray *self) {
+  ts_subtree_array_clear(pool, self);
+  array_delete(self);
+}
+
+void ts_subtree_array_remove_trailing_extras(
+  SubtreeArray *self,
+  SubtreeArray *destination
+) {
+  array_clear(destination);
+  while (self->size > 0) {
+    Subtree last = self->contents[self->size - 1];
+    if (ts_subtree_extra(last)) {
+      self->size--;
+      array_push(destination, last);
+    } else {
+      break;
+    }
+  }
+  ts_subtree_array_reverse(destination);
+}
+
+void ts_subtree_array_reverse(SubtreeArray *self) {
+  for (uint32_t i = 0, limit = self->size / 2; i < limit; i++) {
+    size_t reverse_index = self->size - 1 - i;
+    Subtree swap = self->contents[i];
+    self->contents[i] = self->contents[reverse_index];
+    self->contents[reverse_index] = swap;
+  }
+}
+
+// SubtreePool
+
+SubtreePool ts_subtree_pool_new(uint32_t capacity) {
+  SubtreePool self = {array_new(), array_new()};
+  array_reserve(&self.free_trees, capacity);
+  return self;
+}
+
+void ts_subtree_pool_delete(SubtreePool *self) {
+  if (self->free_trees.contents) {
+    for (unsigned i = 0; i < self->free_trees.size; i++) {
+      ts_free(self->free_trees.contents[i].ptr);
+    }
+    array_delete(&self->free_trees);
+  }
+  if (self->tree_stack.contents) array_delete(&self->tree_stack);
+}
+
+static SubtreeHeapData *ts_subtree_pool_allocate(SubtreePool *self) {
+  if (self->free_trees.size > 0) {
+    return array_pop(&self->free_trees).ptr;
+  } else {
+    return ts_malloc(sizeof(SubtreeHeapData));
+  }
+}
+
+static void ts_subtree_pool_free(SubtreePool *self, SubtreeHeapData *tree) {
+  if (self->free_trees.capacity > 0 && self->free_trees.size + 1 <= TS_MAX_TREE_POOL_SIZE) {
+    array_push(&self->free_trees, (MutableSubtree) {.ptr = tree});
+  } else {
+    ts_free(tree);
+  }
+}
+
+// Subtree
+
+static inline bool ts_subtree_can_inline(Length padding, Length size, uint32_t lookahead_bytes) {
+  return
+    padding.bytes < TS_MAX_INLINE_TREE_LENGTH &&
+    padding.extent.row < 16 &&
+    padding.extent.column < TS_MAX_INLINE_TREE_LENGTH &&
+    size.extent.row == 0 &&
+    size.extent.column < TS_MAX_INLINE_TREE_LENGTH &&
+    lookahead_bytes < 16;
+}
+
+Subtree ts_subtree_new_leaf(
+  SubtreePool *pool, TSSymbol symbol, Length padding, Length size,
+  uint32_t lookahead_bytes, TSStateId parse_state,
+  bool has_external_tokens, bool depends_on_column,
+  bool is_keyword, const TSLanguage *language
+) {
+  TSSymbolMetadata metadata = ts_language_symbol_metadata(language, symbol);
+  bool extra = symbol == ts_builtin_sym_end;
+
+  bool is_inline = (
+    symbol <= UINT8_MAX &&
+    !has_external_tokens &&
+    ts_subtree_can_inline(padding, size, lookahead_bytes)
+  );
+
+  if (is_inline) {
+    return (Subtree) {{
+      .parse_state = parse_state,
+      .symbol = symbol,
+      .padding_bytes = padding.bytes,
+      .padding_rows = padding.extent.row,
+      .padding_columns = padding.extent.column,
+      .size_bytes = size.bytes,
+      .lookahead_bytes = lookahead_bytes,
+      .visible = metadata.visible,
+      .named = metadata.named,
+      .extra = extra,
+      .has_changes = false,
+      .is_missing = false,
+      .is_keyword = is_keyword,
+      .is_inline = true,
+    }};
+  } else {
+    SubtreeHeapData *data = ts_subtree_pool_allocate(pool);
+    *data = (SubtreeHeapData) {
+      .ref_count = 1,
+      .padding = padding,
+      .size = size,
+      .lookahead_bytes = lookahead_bytes,
+      .error_cost = 0,
+      .child_count = 0,
+      .symbol = symbol,
+      .parse_state = parse_state,
+      .visible = metadata.visible,
+      .named = metadata.named,
+      .extra = extra,
+      .fragile_left = false,
+      .fragile_right = false,
+      .has_changes = false,
+      .has_external_tokens = has_external_tokens,
+      .has_external_scanner_state_change = false,
+      .depends_on_column = depends_on_column,
+      .is_missing = false,
+      .is_keyword = is_keyword,
+      {{.first_leaf = {.symbol = 0, .parse_state = 0}}}
+    };
+    return (Subtree) {.ptr = data};
+  }
+}
+
+void ts_subtree_set_symbol(
+  MutableSubtree *self,
+  TSSymbol symbol,
+  const TSLanguage *language
+) {
+  TSSymbolMetadata metadata = ts_language_symbol_metadata(language, symbol);
+  if (self->data.is_inline) {
+    assert(symbol < UINT8_MAX);
+    self->data.symbol = symbol;
+    self->data.named = metadata.named;
+    self->data.visible = metadata.visible;
+  } else {
+    self->ptr->symbol = symbol;
+    self->ptr->named = metadata.named;
+    self->ptr->visible = metadata.visible;
+  }
+}
+
+Subtree ts_subtree_new_error(
+  SubtreePool *pool, int32_t lookahead_char, Length padding, Length size,
+  uint32_t bytes_scanned, TSStateId parse_state, const TSLanguage *language
+) {
+  Subtree result = ts_subtree_new_leaf(
+    pool, ts_builtin_sym_error, padding, size, bytes_scanned,
+    parse_state, false, false, false, language
+  );
+  SubtreeHeapData *data = (SubtreeHeapData *)result.ptr;
+  data->fragile_left = true;
+  data->fragile_right = true;
+  data->lookahead_char = lookahead_char;
+  return result;
+}
+
+// Clone a subtree.
+MutableSubtree ts_subtree_clone(Subtree self) {
+  size_t alloc_size = ts_subtree_alloc_size(self.ptr->child_count);
+  Subtree *new_children = ts_malloc(alloc_size);
+  Subtree *old_children = ts_subtree_children(self);
+  memcpy(new_children, old_children, alloc_size);
+  SubtreeHeapData *result = (SubtreeHeapData *)&new_children[self.ptr->child_count];
+  if (self.ptr->child_count > 0) {
+    for (uint32_t i = 0; i < self.ptr->child_count; i++) {
+      ts_subtree_retain(new_children[i]);
+    }
+  } else if (self.ptr->has_external_tokens) {
+    result->external_scanner_state = ts_external_scanner_state_copy(
+      &self.ptr->external_scanner_state
+    );
+  }
+  result->ref_count = 1;
+  return (MutableSubtree) {.ptr = result};
+}
+
+// Get mutable version of a subtree.
+//
+// This takes ownership of the subtree. If the subtree has only one owner,
+// this will directly convert it into a mutable version. Otherwise, it will
+// perform a copy.
+MutableSubtree ts_subtree_make_mut(SubtreePool *pool, Subtree self) {
+  if (self.data.is_inline) return (MutableSubtree) {self.data};
+  if (self.ptr->ref_count == 1) return ts_subtree_to_mut_unsafe(self);
+  MutableSubtree result = ts_subtree_clone(self);
+  ts_subtree_release(pool, self);
+  return result;
+}
+
+static void ts_subtree__compress(
+  MutableSubtree self,
+  unsigned count,
+  const TSLanguage *language,
+  MutableSubtreeArray *stack
+) {
+  unsigned initial_stack_size = stack->size;
+
+  MutableSubtree tree = self;
+  TSSymbol symbol = tree.ptr->symbol;
+  for (unsigned i = 0; i < count; i++) {
+    if (tree.ptr->ref_count > 1 || tree.ptr->child_count < 2) break;
+
+    MutableSubtree child = ts_subtree_to_mut_unsafe(ts_subtree_children(tree)[0]);
+    if (
+      child.data.is_inline ||
+      child.ptr->child_count < 2 ||
+      child.ptr->ref_count > 1 ||
+      child.ptr->symbol != symbol
+    ) break;
+
+    MutableSubtree grandchild = ts_subtree_to_mut_unsafe(ts_subtree_children(child)[0]);
+    if (
+      grandchild.data.is_inline ||
+      grandchild.ptr->child_count < 2 ||
+      grandchild.ptr->ref_count > 1 ||
+      grandchild.ptr->symbol != symbol
+    ) break;
+
+    ts_subtree_children(tree)[0] = ts_subtree_from_mut(grandchild);
+    ts_subtree_children(child)[0] = ts_subtree_children(grandchild)[grandchild.ptr->child_count - 1];
+    ts_subtree_children(grandchild)[grandchild.ptr->child_count - 1] = ts_subtree_from_mut(child);
+    array_push(stack, tree);
+    tree = grandchild;
+  }
+
+  while (stack->size > initial_stack_size) {
+    tree = array_pop(stack);
+    MutableSubtree child = ts_subtree_to_mut_unsafe(ts_subtree_children(tree)[0]);
+    MutableSubtree grandchild = ts_subtree_to_mut_unsafe(ts_subtree_children(child)[child.ptr->child_count - 1]);
+    ts_subtree_summarize_children(grandchild, language);
+    ts_subtree_summarize_children(child, language);
+    ts_subtree_summarize_children(tree, language);
+  }
+}
+
+void ts_subtree_balance(Subtree self, SubtreePool *pool, const TSLanguage *language) {
+  array_clear(&pool->tree_stack);
+
+  if (ts_subtree_child_count(self) > 0 && self.ptr->ref_count == 1) {
+    array_push(&pool->tree_stack, ts_subtree_to_mut_unsafe(self));
+  }
+
+  while (pool->tree_stack.size > 0) {
+    MutableSubtree tree = array_pop(&pool->tree_stack);
+
+    if (tree.ptr->repeat_depth > 0) {
+      Subtree child1 = ts_subtree_children(tree)[0];
+      Subtree child2 = ts_subtree_children(tree)[tree.ptr->child_count - 1];
+      long repeat_delta = (long)ts_subtree_repeat_depth(child1) - (long)ts_subtree_repeat_depth(child2);
+      if (repeat_delta > 0) {
+        unsigned n = (unsigned)repeat_delta;
+        for (unsigned i = n / 2; i > 0; i /= 2) {
+          ts_subtree__compress(tree, i, language, &pool->tree_stack);
+          n -= i;
+        }
+      }
+    }
+
+    for (uint32_t i = 0; i < tree.ptr->child_count; i++) {
+      Subtree child = ts_subtree_children(tree)[i];
+      if (ts_subtree_child_count(child) > 0 && child.ptr->ref_count == 1) {
+        array_push(&pool->tree_stack, ts_subtree_to_mut_unsafe(child));
+      }
+    }
+  }
+}
+
+// Assign all of the node's properties that depend on its children.
+void ts_subtree_summarize_children(
+  MutableSubtree self,
+  const TSLanguage *language
+) {
+  assert(!self.data.is_inline);
+
+  self.ptr->named_child_count = 0;
+  self.ptr->visible_child_count = 0;
+  self.ptr->error_cost = 0;
+  self.ptr->repeat_depth = 0;
+  self.ptr->visible_descendant_count = 0;
+  self.ptr->has_external_tokens = false;
+  self.ptr->depends_on_column = false;
+  self.ptr->has_external_scanner_state_change = false;
+  self.ptr->dynamic_precedence = 0;
+
+  uint32_t structural_index = 0;
+  const TSSymbol *alias_sequence = ts_language_alias_sequence(language, self.ptr->production_id);
+  uint32_t lookahead_end_byte = 0;
+
+  const Subtree *children = ts_subtree_children(self);
+  for (uint32_t i = 0; i < self.ptr->child_count; i++) {
+    Subtree child = children[i];
+
+    if (
+      self.ptr->size.extent.row == 0 &&
+      ts_subtree_depends_on_column(child)
+    ) {
+      self.ptr->depends_on_column = true;
+    }
+
+    if (ts_subtree_has_external_scanner_state_change(child)) {
+      self.ptr->has_external_scanner_state_change = true;
+    }
+
+    if (i == 0) {
+      self.ptr->padding = ts_subtree_padding(child);
+      self.ptr->size = ts_subtree_size(child);
+    } else {
+      self.ptr->size = length_add(self.ptr->size, ts_subtree_total_size(child));
+    }
+
+    uint32_t child_lookahead_end_byte =
+      self.ptr->padding.bytes +
+      self.ptr->size.bytes +
+      ts_subtree_lookahead_bytes(child);
+    if (child_lookahead_end_byte > lookahead_end_byte) {
+      lookahead_end_byte = child_lookahead_end_byte;
+    }
+
+    if (ts_subtree_symbol(child) != ts_builtin_sym_error_repeat) {
+      self.ptr->error_cost += ts_subtree_error_cost(child);
+    }
+
+    uint32_t grandchild_count = ts_subtree_child_count(child);
+    if (
+      self.ptr->symbol == ts_builtin_sym_error ||
+      self.ptr->symbol == ts_builtin_sym_error_repeat
+    ) {
+      if (!ts_subtree_extra(child) && !(ts_subtree_is_error(child) && grandchild_count == 0)) {
+        if (ts_subtree_visible(child)) {
+          self.ptr->error_cost += ERROR_COST_PER_SKIPPED_TREE;
+        } else if (grandchild_count > 0) {
+          self.ptr->error_cost += ERROR_COST_PER_SKIPPED_TREE * child.ptr->visible_child_count;
+        }
+      }
+    }
+
+    self.ptr->dynamic_precedence += ts_subtree_dynamic_precedence(child);
+    self.ptr->visible_descendant_count += ts_subtree_visible_descendant_count(child);
+
+    if (alias_sequence && alias_sequence[structural_index] != 0 && !ts_subtree_extra(child)) {
+      self.ptr->visible_descendant_count++;
+      self.ptr->visible_child_count++;
+      if (ts_language_symbol_metadata(language, alias_sequence[structural_index]).named) {
+        self.ptr->named_child_count++;
+      }
+    } else if (ts_subtree_visible(child)) {
+      self.ptr->visible_descendant_count++;
+      self.ptr->visible_child_count++;
+      if (ts_subtree_named(child)) self.ptr->named_child_count++;
+    } else if (grandchild_count > 0) {
+      self.ptr->visible_child_count += child.ptr->visible_child_count;
+      self.ptr->named_child_count += child.ptr->named_child_count;
+    }
+
+    if (ts_subtree_has_external_tokens(child)) self.ptr->has_external_tokens = true;
+
+    if (ts_subtree_is_error(child)) {
+      self.ptr->fragile_left = self.ptr->fragile_right = true;
+      self.ptr->parse_state = TS_TREE_STATE_NONE;
+    }
+
+    if (!ts_subtree_extra(child)) structural_index++;
+  }
+
+  self.ptr->lookahead_bytes = lookahead_end_byte - self.ptr->size.bytes - self.ptr->padding.bytes;
+
+  if (
+    self.ptr->symbol == ts_builtin_sym_error ||
+    self.ptr->symbol == ts_builtin_sym_error_repeat
+  ) {
+    self.ptr->error_cost +=
+      ERROR_COST_PER_RECOVERY +
+      ERROR_COST_PER_SKIPPED_CHAR * self.ptr->size.bytes +
+      ERROR_COST_PER_SKIPPED_LINE * self.ptr->size.extent.row;
+  }
+
+  if (self.ptr->child_count > 0) {
+    Subtree first_child = children[0];
+    Subtree last_child = children[self.ptr->child_count - 1];
+
+    self.ptr->first_leaf.symbol = ts_subtree_leaf_symbol(first_child);
+    self.ptr->first_leaf.parse_state = ts_subtree_leaf_parse_state(first_child);
+
+    if (ts_subtree_fragile_left(first_child)) self.ptr->fragile_left = true;
+    if (ts_subtree_fragile_right(last_child)) self.ptr->fragile_right = true;
+
+    if (
+      self.ptr->child_count >= 2 &&
+      !self.ptr->visible &&
+      !self.ptr->named &&
+      ts_subtree_symbol(first_child) == self.ptr->symbol
+    ) {
+      if (ts_subtree_repeat_depth(first_child) > ts_subtree_repeat_depth(last_child)) {
+        self.ptr->repeat_depth = ts_subtree_repeat_depth(first_child) + 1;
+      } else {
+        self.ptr->repeat_depth = ts_subtree_repeat_depth(last_child) + 1;
+      }
+    }
+  }
+}
+
+// Create a new parent node with the given children.
+//
+// This takes ownership of the children array.
+MutableSubtree ts_subtree_new_node(
+  TSSymbol symbol,
+  SubtreeArray *children,
+  unsigned production_id,
+  const TSLanguage *language
+) {
+  TSSymbolMetadata metadata = ts_language_symbol_metadata(language, symbol);
+  bool fragile = symbol == ts_builtin_sym_error || symbol == ts_builtin_sym_error_repeat;
+
+  // Allocate the node's data at the end of the array of children.
+  size_t new_byte_size = ts_subtree_alloc_size(children->size);
+  if (children->capacity * sizeof(Subtree) < new_byte_size) {
+    children->contents = ts_realloc(children->contents, new_byte_size);
+    children->capacity = (uint32_t)(new_byte_size / sizeof(Subtree));
+  }
+  SubtreeHeapData *data = (SubtreeHeapData *)&children->contents[children->size];
+
+  *data = (SubtreeHeapData) {
+    .ref_count = 1,
+    .symbol = symbol,
+    .child_count = children->size,
+    .visible = metadata.visible,
+    .named = metadata.named,
+    .has_changes = false,
+    .has_external_scanner_state_change = false,
+    .fragile_left = fragile,
+    .fragile_right = fragile,
+    .is_keyword = false,
+    {{
+      .visible_descendant_count = 0,
+      .production_id = production_id,
+      .first_leaf = {.symbol = 0, .parse_state = 0},
+    }}
+  };
+  MutableSubtree result = {.ptr = data};
+  ts_subtree_summarize_children(result, language);
+  return result;
+}
+
+// Create a new error node containing the given children.
+//
+// This node is treated as 'extra'. Its children are prevented from having
+// having any effect on the parse state.
+Subtree ts_subtree_new_error_node(
+  SubtreeArray *children,
+  bool extra,
+  const TSLanguage *language
+) {
+  MutableSubtree result = ts_subtree_new_node(
+    ts_builtin_sym_error, children, 0, language
+  );
+  result.ptr->extra = extra;
+  return ts_subtree_from_mut(result);
+}
+
+// Create a new 'missing leaf' node.
+//
+// This node is treated as 'extra'. Its children are prevented from having
+// having any effect on the parse state.
+Subtree ts_subtree_new_missing_leaf(
+  SubtreePool *pool,
+  TSSymbol symbol,
+  Length padding,
+  uint32_t lookahead_bytes,
+  const TSLanguage *language
+) {
+  Subtree result = ts_subtree_new_leaf(
+    pool, symbol, padding, length_zero(), lookahead_bytes,
+    0, false, false, false, language
+  );
+  if (result.data.is_inline) {
+    result.data.is_missing = true;
+  } else {
+    ((SubtreeHeapData *)result.ptr)->is_missing = true;
+  }
+  return result;
+}
+
+void ts_subtree_retain(Subtree self) {
+  if (self.data.is_inline) return;
+  assert(self.ptr->ref_count > 0);
+  atomic_inc((volatile uint32_t *)&self.ptr->ref_count);
+  assert(self.ptr->ref_count != 0);
+}
+
+void ts_subtree_release(SubtreePool *pool, Subtree self) {
+  if (self.data.is_inline) return;
+  array_clear(&pool->tree_stack);
+
+  assert(self.ptr->ref_count > 0);
+  if (atomic_dec((volatile uint32_t *)&self.ptr->ref_count) == 0) {
+    array_push(&pool->tree_stack, ts_subtree_to_mut_unsafe(self));
+  }
+
+  while (pool->tree_stack.size > 0) {
+    MutableSubtree tree = array_pop(&pool->tree_stack);
+    if (tree.ptr->child_count > 0) {
+      Subtree *children = ts_subtree_children(tree);
+      for (uint32_t i = 0; i < tree.ptr->child_count; i++) {
+        Subtree child = children[i];
+        if (child.data.is_inline) continue;
+        assert(child.ptr->ref_count > 0);
+        if (atomic_dec((volatile uint32_t *)&child.ptr->ref_count) == 0) {
+          array_push(&pool->tree_stack, ts_subtree_to_mut_unsafe(child));
+        }
+      }
+      ts_free(children);
+    } else {
+      if (tree.ptr->has_external_tokens) {
+        ts_external_scanner_state_delete(&tree.ptr->external_scanner_state);
+      }
+      ts_subtree_pool_free(pool, tree.ptr);
+    }
+  }
+}
+
+int ts_subtree_compare(Subtree left, Subtree right) {
+  if (ts_subtree_symbol(left) < ts_subtree_symbol(right)) return -1;
+  if (ts_subtree_symbol(right) < ts_subtree_symbol(left)) return 1;
+  if (ts_subtree_child_count(left) < ts_subtree_child_count(right)) return -1;
+  if (ts_subtree_child_count(right) < ts_subtree_child_count(left)) return 1;
+  for (uint32_t i = 0, n = ts_subtree_child_count(left); i < n; i++) {
+    Subtree left_child = ts_subtree_children(left)[i];
+    Subtree right_child = ts_subtree_children(right)[i];
+    switch (ts_subtree_compare(left_child, right_child)) {
+      case -1: return -1;
+      case 1: return 1;
+      default: break;
+    }
+  }
+  return 0;
+}
+
+static inline void ts_subtree_set_has_changes(MutableSubtree *self) {
+  if (self->data.is_inline) {
+    self->data.has_changes = true;
+  } else {
+    self->ptr->has_changes = true;
+  }
+}
+
+Subtree ts_subtree_edit(Subtree self, const TSInputEdit *input_edit, SubtreePool *pool) {
+  typedef struct {
+    Subtree *tree;
+    Edit edit;
+  } EditEntry;
+
+  Array(EditEntry) stack = array_new();
+  array_push(&stack, ((EditEntry) {
+    .tree = &self,
+    .edit = (Edit) {
+      .start = {input_edit->start_byte, input_edit->start_point},
+      .old_end = {input_edit->old_end_byte, input_edit->old_end_point},
+      .new_end = {input_edit->new_end_byte, input_edit->new_end_point},
+    },
+  }));
+
+  while (stack.size) {
+    EditEntry entry = array_pop(&stack);
+    Edit edit = entry.edit;
+    bool is_noop = edit.old_end.bytes == edit.start.bytes && edit.new_end.bytes == edit.start.bytes;
+    bool is_pure_insertion = edit.old_end.bytes == edit.start.bytes;
+    bool invalidate_first_row = ts_subtree_depends_on_column(*entry.tree);
+
+    Length size = ts_subtree_size(*entry.tree);
+    Length padding = ts_subtree_padding(*entry.tree);
+    Length total_size = length_add(padding, size);
+    uint32_t lookahead_bytes = ts_subtree_lookahead_bytes(*entry.tree);
+    uint32_t end_byte = total_size.bytes + lookahead_bytes;
+    if (edit.start.bytes > end_byte || (is_noop && edit.start.bytes == end_byte)) continue;
+
+    // If the edit is entirely within the space before this subtree, then shift this
+    // subtree over according to the edit without changing its size.
+    if (edit.old_end.bytes <= padding.bytes) {
+      padding = length_add(edit.new_end, length_sub(padding, edit.old_end));
+    }
+
+    // If the edit starts in the space before this subtree and extends into this subtree,
+    // shrink the subtree's content to compensate for the change in the space before it.
+    else if (edit.start.bytes < padding.bytes) {
+      size = length_saturating_sub(size, length_sub(edit.old_end, padding));
+      padding = edit.new_end;
+    }
+
+    // If the edit is a pure insertion right at the start of the subtree,
+    // shift the subtree over according to the insertion.
+    else if (edit.start.bytes == padding.bytes && is_pure_insertion) {
+      padding = edit.new_end;
+    }
+
+    // If the edit is within this subtree, resize the subtree to reflect the edit.
+    else if (
+      edit.start.bytes < total_size.bytes ||
+      (edit.start.bytes == total_size.bytes && is_pure_insertion)
+    ) {
+      size = length_add(
+        length_sub(edit.new_end, padding),
+        length_saturating_sub(total_size, edit.old_end)
+      );
+    }
+
+    MutableSubtree result = ts_subtree_make_mut(pool, *entry.tree);
+
+    if (result.data.is_inline) {
+      if (ts_subtree_can_inline(padding, size, lookahead_bytes)) {
+        result.data.padding_bytes = padding.bytes;
+        result.data.padding_rows = padding.extent.row;
+        result.data.padding_columns = padding.extent.column;
+        result.data.size_bytes = size.bytes;
+      } else {
+        SubtreeHeapData *data = ts_subtree_pool_allocate(pool);
+        data->ref_count = 1;
+        data->padding = padding;
+        data->size = size;
+        data->lookahead_bytes = lookahead_bytes;
+        data->error_cost = 0;
+        data->child_count = 0;
+        data->symbol = result.data.symbol;
+        data->parse_state = result.data.parse_state;
+        data->visible = result.data.visible;
+        data->named = result.data.named;
+        data->extra = result.data.extra;
+        data->fragile_left = false;
+        data->fragile_right = false;
+        data->has_changes = false;
+        data->has_external_tokens = false;
+        data->depends_on_column = false;
+        data->is_missing = result.data.is_missing;
+        data->is_keyword = result.data.is_keyword;
+        result.ptr = data;
+      }
+    } else {
+      result.ptr->padding = padding;
+      result.ptr->size = size;
+    }
+
+    ts_subtree_set_has_changes(&result);
+    *entry.tree = ts_subtree_from_mut(result);
+
+    Length child_left, child_right = length_zero();
+    for (uint32_t i = 0, n = ts_subtree_child_count(*entry.tree); i < n; i++) {
+      Subtree *child = &ts_subtree_children(*entry.tree)[i];
+      Length child_size = ts_subtree_total_size(*child);
+      child_left = child_right;
+      child_right = length_add(child_left, child_size);
+
+      // If this child ends before the edit, it is not affected.
+      if (child_right.bytes + ts_subtree_lookahead_bytes(*child) < edit.start.bytes) continue;
+
+      // Keep editing child nodes until a node is reached that starts after the edit.
+      // Also, if this node's validity depends on its column position, then continue
+      // invaliditing child nodes until reaching a line break.
+      if ((
+        (child_left.bytes > edit.old_end.bytes) ||
+        (child_left.bytes == edit.old_end.bytes && child_size.bytes > 0 && i > 0)
+      ) && (
+        !invalidate_first_row ||
+        child_left.extent.row > entry.tree->ptr->padding.extent.row
+      )) {
+        break;
+      }
+
+      // Transform edit into the child's coordinate space.
+      Edit child_edit = {
+        .start = length_saturating_sub(edit.start, child_left),
+        .old_end = length_saturating_sub(edit.old_end, child_left),
+        .new_end = length_saturating_sub(edit.new_end, child_left),
+      };
+
+      // Interpret all inserted text as applying to the *first* child that touches the edit.
+      // Subsequent children are only never have any text inserted into them; they are only
+      // shrunk to compensate for the edit.
+      if (
+        child_right.bytes > edit.start.bytes ||
+        (child_right.bytes == edit.start.bytes && is_pure_insertion)
+      ) {
+        edit.new_end = edit.start;
+      }
+
+      // Children that occur before the edit are not reshaped by the edit.
+      else {
+        child_edit.old_end = child_edit.start;
+        child_edit.new_end = child_edit.start;
+      }
+
+      // Queue processing of this child's subtree.
+      array_push(&stack, ((EditEntry) {
+        .tree = child,
+        .edit = child_edit,
+      }));
+    }
+  }
+
+  array_delete(&stack);
+  return self;
+}
+
+Subtree ts_subtree_last_external_token(Subtree tree) {
+  if (!ts_subtree_has_external_tokens(tree)) return NULL_SUBTREE;
+  while (tree.ptr->child_count > 0) {
+    for (uint32_t i = tree.ptr->child_count - 1; i + 1 > 0; i--) {
+      Subtree child = ts_subtree_children(tree)[i];
+      if (ts_subtree_has_external_tokens(child)) {
+        tree = child;
+        break;
+      }
+    }
+  }
+  return tree;
+}
+
+static size_t ts_subtree__write_char_to_string(char *str, size_t n, int32_t chr) {
+  if (chr == -1)
+    return snprintf(str, n, "INVALID");
+  else if (chr == '\0')
+    return snprintf(str, n, "'\\0'");
+  else if (chr == '\n')
+    return snprintf(str, n, "'\\n'");
+  else if (chr == '\t')
+    return snprintf(str, n, "'\\t'");
+  else if (chr == '\r')
+    return snprintf(str, n, "'\\r'");
+  else if (0 < chr && chr < 128 && isprint(chr))
+    return snprintf(str, n, "'%c'", chr);
+  else
+    return snprintf(str, n, "%d", chr);
+}
+
+static const char *const ROOT_FIELD = "__ROOT__";
+
+static size_t ts_subtree__write_to_string(
+  Subtree self, char *string, size_t limit,
+  const TSLanguage *language, bool include_all,
+  TSSymbol alias_symbol, bool alias_is_named, const char *field_name
+) {
+  if (!self.ptr) return snprintf(string, limit, "(NULL)");
+
+  char *cursor = string;
+  char **writer = (limit > 1) ? &cursor : &string;
+  bool is_root = field_name == ROOT_FIELD;
+  bool is_visible =
+    include_all ||
+    ts_subtree_missing(self) ||
+    (
+      alias_symbol
+        ? alias_is_named
+        : ts_subtree_visible(self) && ts_subtree_named(self)
+    );
+
+  if (is_visible) {
+    if (!is_root) {
+      cursor += snprintf(*writer, limit, " ");
+      if (field_name) {
+        cursor += snprintf(*writer, limit, "%s: ", field_name);
+      }
+    }
+
+    if (ts_subtree_is_error(self) && ts_subtree_child_count(self) == 0 && self.ptr->size.bytes > 0) {
+      cursor += snprintf(*writer, limit, "(UNEXPECTED ");
+      cursor += ts_subtree__write_char_to_string(*writer, limit, self.ptr->lookahead_char);
+    } else {
+      TSSymbol symbol = alias_symbol ? alias_symbol : ts_subtree_symbol(self);
+      const char *symbol_name = ts_language_symbol_name(language, symbol);
+      if (ts_subtree_missing(self)) {
+        cursor += snprintf(*writer, limit, "(MISSING ");
+        if (alias_is_named || ts_subtree_named(self)) {
+          cursor += snprintf(*writer, limit, "%s", symbol_name);
+        } else {
+          cursor += snprintf(*writer, limit, "\"%s\"", symbol_name);
+        }
+      } else {
+        cursor += snprintf(*writer, limit, "(%s", symbol_name);
+      }
+    }
+  } else if (is_root) {
+    TSSymbol symbol = ts_subtree_symbol(self);
+    const char *symbol_name = ts_language_symbol_name(language, symbol);
+    cursor += snprintf(*writer, limit, "(\"%s\")", symbol_name);
+  }
+
+  if (ts_subtree_child_count(self)) {
+    const TSSymbol *alias_sequence = ts_language_alias_sequence(language, self.ptr->production_id);
+    const TSFieldMapEntry *field_map, *field_map_end;
+    ts_language_field_map(
+      language,
+      self.ptr->production_id,
+      &field_map,
+      &field_map_end
+    );
+
+    uint32_t structural_child_index = 0;
+    for (uint32_t i = 0; i < self.ptr->child_count; i++) {
+      Subtree child = ts_subtree_children(self)[i];
+      if (ts_subtree_extra(child)) {
+        cursor += ts_subtree__write_to_string(
+          child, *writer, limit,
+          language, include_all,
+          0, false, NULL
+        );
+      } else {
+        TSSymbol subtree_alias_symbol = alias_sequence
+          ? alias_sequence[structural_child_index]
+          : 0;
+        bool subtree_alias_is_named = subtree_alias_symbol
+          ? ts_language_symbol_metadata(language, subtree_alias_symbol).named
+          : false;
+
+        const char *child_field_name = is_visible ? NULL : field_name;
+        for (const TSFieldMapEntry *map = field_map; map < field_map_end; map++) {
+          if (!map->inherited && map->child_index == structural_child_index) {
+            child_field_name = language->field_names[map->field_id];
+            break;
+          }
+        }
+
+        cursor += ts_subtree__write_to_string(
+          child, *writer, limit,
+          language, include_all,
+          subtree_alias_symbol, subtree_alias_is_named, child_field_name
+        );
+        structural_child_index++;
+      }
+    }
+  }
+
+  if (is_visible) cursor += snprintf(*writer, limit, ")");
+
+  return cursor - string;
+}
+
+char *ts_subtree_string(
+  Subtree self,
+  const TSLanguage *language,
+  bool include_all
+) {
+  char scratch_string[1];
+  size_t size = ts_subtree__write_to_string(
+    self, scratch_string, 1,
+    language, include_all,
+    0, false, ROOT_FIELD
+  ) + 1;
+  char *result = ts_malloc(size * sizeof(char));
+  ts_subtree__write_to_string(
+    self, result, size,
+    language, include_all,
+    0, false, ROOT_FIELD
+  );
+  return result;
+}
+
+void ts_subtree__print_dot_graph(const Subtree *self, uint32_t start_offset,
+                                 const TSLanguage *language, TSSymbol alias_symbol,
+                                 FILE *f) {
+  TSSymbol subtree_symbol = ts_subtree_symbol(*self);
+  TSSymbol symbol = alias_symbol ? alias_symbol : subtree_symbol;
+  uint32_t end_offset = start_offset + ts_subtree_total_bytes(*self);
+  fprintf(f, "tree_%p [label=\"", (void *)self);
+  ts_language_write_symbol_as_dot_string(language, f, symbol);
+  fprintf(f, "\"");
+
+  if (ts_subtree_child_count(*self) == 0) fprintf(f, ", shape=plaintext");
+  if (ts_subtree_extra(*self)) fprintf(f, ", fontcolor=gray");
+
+  fprintf(f, ", tooltip=\""
+    "range: %u - %u\n"
+    "state: %d\n"
+    "error-cost: %u\n"
+    "has-changes: %u\n"
+    "depends-on-column: %u\n"
+    "descendant-count: %u\n"
+    "repeat-depth: %u\n"
+    "lookahead-bytes: %u",
+    start_offset, end_offset,
+    ts_subtree_parse_state(*self),
+    ts_subtree_error_cost(*self),
+    ts_subtree_has_changes(*self),
+    ts_subtree_depends_on_column(*self),
+    ts_subtree_visible_descendant_count(*self),
+    ts_subtree_repeat_depth(*self),
+    ts_subtree_lookahead_bytes(*self)
+  );
+
+  if (ts_subtree_is_error(*self) && ts_subtree_child_count(*self) == 0) {
+    fprintf(f, "\ncharacter: '%c'", self->ptr->lookahead_char);
+  }
+
+  fprintf(f, "\"]\n");
+
+  uint32_t child_start_offset = start_offset;
+  uint32_t child_info_offset =
+    language->max_alias_sequence_length *
+    ts_subtree_production_id(*self);
+  for (uint32_t i = 0, n = ts_subtree_child_count(*self); i < n; i++) {
+    const Subtree *child = &ts_subtree_children(*self)[i];
+    TSSymbol subtree_alias_symbol = 0;
+    if (!ts_subtree_extra(*child) && child_info_offset) {
+      subtree_alias_symbol = language->alias_sequences[child_info_offset];
+      child_info_offset++;
+    }
+    ts_subtree__print_dot_graph(child, child_start_offset, language, subtree_alias_symbol, f);
+    fprintf(f, "tree_%p -> tree_%p [tooltip=%u]\n", (void *)self, (void *)child, i);
+    child_start_offset += ts_subtree_total_bytes(*child);
+  }
+}
+
+void ts_subtree_print_dot_graph(Subtree self, const TSLanguage *language, FILE *f) {
+  fprintf(f, "digraph tree {\n");
+  fprintf(f, "edge [arrowhead=none]\n");
+  ts_subtree__print_dot_graph(&self, 0, language, 0, f);
+  fprintf(f, "}\n");
+}
+
+const ExternalScannerState *ts_subtree_external_scanner_state(Subtree self) {
+  static const ExternalScannerState empty_state = {{.short_data = {0}}, .length = 0};
+  if (
+    self.ptr &&
+    !self.data.is_inline &&
+    self.ptr->has_external_tokens &&
+    self.ptr->child_count == 0
+  ) {
+    return &self.ptr->external_scanner_state;
+  } else {
+    return &empty_state;
+  }
+}
+
+bool ts_subtree_external_scanner_state_eq(Subtree self, Subtree other) {
+  const ExternalScannerState *state_self = ts_subtree_external_scanner_state(self);
+  const ExternalScannerState *state_other = ts_subtree_external_scanner_state(other);
+  return ts_external_scanner_state_eq(
+    state_self,
+    ts_external_scanner_state_data(state_other),
+    state_other->length
+  );
+}