tree-sitter/src/runtime/subtree.c

#include <assert.h>
#include <ctype.h>
#include <limits.h>
#include <stdbool.h>
#include <string.h>
#include <stdio.h>
#include "runtime/alloc.h"
#include "runtime/atomic.h"
#include "runtime/subtree.h"
#include "runtime/length.h"
#include "runtime/language.h"
#include "runtime/error_costs.h"

typedef struct {
  Length start;
  Length added;
  Length removed;
} Edit;

TSStateId TS_TREE_STATE_NONE = USHRT_MAX;

static const uint32_t MAX_TREE_POOL_SIZE = 1024;

static const TSExternalTokenState empty_state = {.length = 0, .short_data = {0}};

// ExternalTokenState

void ts_external_token_state_init(TSExternalTokenState *self, const char *content, unsigned length) {
  self->length = length;
  if (length > sizeof(self->short_data)) {
    self->long_data = ts_malloc(length);
    memcpy(self->long_data, content, length);
  } else {
    memcpy(self->short_data, content, length);
  }
}

void ts_external_token_state_delete(TSExternalTokenState *self) {
  if (self->length > sizeof(self->short_data)) {
    ts_free(self->long_data);
  }
}

const char *ts_external_token_state_data(const TSExternalTokenState *self) {
  if (self->length > sizeof(self->short_data)) {
    return self->long_data;
  } else {
    return self->short_data;
  }
}

bool ts_external_token_state_eq(const TSExternalTokenState *a, const TSExternalTokenState *b) {
  return a == b ||
    (a->length == b->length &&
     memcmp(ts_external_token_state_data(a), ts_external_token_state_data(b), a->length) == 0);
}

// SubtreeArray

bool ts_subtree_array_copy(SubtreeArray self, SubtreeArray *dest) {
  Subtree **contents = NULL;
  if (self.capacity > 0) {
    contents = ts_calloc(self.capacity, sizeof(Subtree *));
    memcpy(contents, self.contents, self.size * sizeof(Subtree *));
    for (uint32_t i = 0; i < self.size; i++) {
      ts_subtree_retain(contents[i]);
    }
  }

  dest->size = self.size;
  dest->capacity = self.capacity;
  dest->contents = contents;
  return true;
}

void ts_subtree_array_delete(SubtreePool *pool, SubtreeArray *self) {
  for (uint32_t i = 0; i < self->size; i++) {
    ts_subtree_release(pool, self->contents[i]);
  }
  array_delete(self);
}

SubtreeArray ts_subtree_array_remove_trailing_extras(SubtreeArray *self) {
  SubtreeArray result = array_new();

  uint32_t i = self->size - 1;
  for (; i + 1 > 0; i--) {
    Subtree *child = self->contents[i];
    if (!child->extra) break;
    array_push(&result, child);
  }

  self->size = i + 1;
  ts_subtree_array_reverse(&result);
  return result;
}

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]);
    }
    array_delete(&self->free_trees);
  }
  if (self->tree_stack.contents) array_delete(&self->tree_stack);
}

Subtree *ts_subtree_pool_allocate(SubtreePool *self) {
  if (self->free_trees.size > 0) {
    return array_pop(&self->free_trees);
  } else {
    return ts_malloc(sizeof(Subtree));
  }
}

void ts_subtree_pool_free(SubtreePool *self, Subtree *tree) {
  if (self->free_trees.capacity > 0 && self->free_trees.size < MAX_TREE_POOL_SIZE) {
    array_push(&self->free_trees, tree);
  } else {
    ts_free(tree);
  }
}

// Subtree

Subtree *ts_subtree_make_leaf(SubtreePool *pool, TSSymbol symbol, Length padding, Length size,
                              const TSLanguage *language) {
  TSSymbolMetadata metadata = ts_language_symbol_metadata(language, symbol);
  Subtree *result = ts_subtree_pool_allocate(pool);
  *result = (Subtree){
    .ref_count = 1,
    .symbol = symbol,
    .size = size,
    .visible_child_count = 0,
    .named_child_count = 0,
    .alias_sequence_id = 0,
    .padding = padding,
    .visible = metadata.visible,
    .named = metadata.named,
    .node_count = 1,
    .has_changes = false,
    .first_leaf = {
      .symbol = symbol,
      .lex_mode = {0, 0},
    },
    .has_external_tokens = false,
  };
  return result;
}

Subtree *ts_subtree_make_error(SubtreePool *pool, Length size, Length padding,
                               int32_t lookahead_char, const TSLanguage *language) {
  Subtree *result = ts_subtree_make_leaf(pool, ts_builtin_sym_error, padding, size, language);
  result->fragile_left = true;
  result->fragile_right = true;
  result->lookahead_char = lookahead_char;
  return result;
}

Subtree *ts_subtree_make_copy(SubtreePool *pool, Subtree *self) {
  Subtree *result = ts_subtree_pool_allocate(pool);
  *result = *self;
  if (result->children.size > 0) {
    ts_subtree_array_copy(self->children, &result->children);
  }
  result->ref_count = 1;
  return result;
}

static Subtree *ts_subtree_make_mut(SubtreePool *pool, Subtree *self) {
  if (self->ref_count == 1) {
    return self;
  } else {
    Subtree *result = ts_subtree_make_copy(pool, self);
    ts_subtree_release(pool, self);
    return result;
  }
}

static void ts_subtree__compress(Subtree *self, unsigned count, const TSLanguage *language,
                                 SubtreeArray *stack) {
  unsigned initial_stack_size = stack->size;

  Subtree *tree = self;
  for (unsigned i = 0; i < count; i++) {
    if (tree->ref_count > 1 || tree->children.size != 2) break;

    Subtree *child = tree->children.contents[0];
    if (
      child->ref_count > 1 ||
      child->children.size != 2 ||
      child->symbol != tree->symbol
    ) break;

    Subtree *grandchild = child->children.contents[0];
    if (
      grandchild->ref_count > 1 ||
      grandchild->children.size != 2 ||
      grandchild->symbol != tree->symbol
    ) break;

    tree->children.contents[0] = grandchild;
    child->children.contents[0] = grandchild->children.contents[1];
    grandchild->children.contents[1] = child;
    array_push(stack, tree);
    tree = grandchild;
  }

  while (stack->size > initial_stack_size) {
    tree = array_pop(stack);
    assert(tree);
    Subtree *child = tree->children.contents[0];
    Subtree *grandchild = child->children.contents[1];
    ts_subtree_set_children(grandchild, &grandchild->children, language);
    ts_subtree_set_children(child, &child->children, language);
    ts_subtree_set_children(tree, &tree->children, language);
  }
}

void ts_subtree_balance(Subtree *self, SubtreePool *pool, const TSLanguage *language) {
  array_clear(&pool->tree_stack);
  array_push(&pool->tree_stack, self);
  while (pool->tree_stack.size > 0) {
    Subtree *tree = array_pop(&pool->tree_stack);
    assert(tree);

    if (tree->repeat_depth > 0) {
      if (tree->children.contents[0]->repeat_depth > tree->children.contents[1]->repeat_depth) {
        unsigned n = (
          tree->children.contents[0]->repeat_depth -
          tree->children.contents[1]->repeat_depth
        );
        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->children.size; i++) {
      Subtree *child = tree->children.contents[i];
      if (child->ref_count == 1) {
        array_push(&pool->tree_stack, child);
      }
    }
  }
}

void ts_subtree_set_children(Subtree *self, SubtreeArray *children, const TSLanguage *language) {
  if (self->children.size > 0 && children->contents != self->children.contents) {
    array_delete(&self->children);
  }

  self->children = *children;
  self->named_child_count = 0;
  self->visible_child_count = 0;
  self->error_cost = 0;
  self->repeat_depth = 0;
  self->node_count = 1;
  self->has_external_tokens = false;
  self->dynamic_precedence = 0;

  uint32_t non_extra_index = 0;
  const TSSymbol *alias_sequence = ts_language_alias_sequence(language, self->alias_sequence_id);

  for (uint32_t i = 0; i < self->children.size; i++) {
    Subtree *child = self->children.contents[i];

    if (i == 0) {
      self->padding = child->padding;
      self->size = child->size;
      self->bytes_scanned = child->bytes_scanned;
    } else {
      uint32_t bytes_scanned = ts_subtree_total_bytes(self) + child->bytes_scanned;
      if (bytes_scanned > self->bytes_scanned) self->bytes_scanned = bytes_scanned;
      self->size = length_add(self->size, ts_subtree_total_size(child));
    }

    if (child->symbol != ts_builtin_sym_error_repeat) {
      self->error_cost += child->error_cost;
    }
    self->dynamic_precedence += child->dynamic_precedence;
    self->node_count += child->node_count;

    if (alias_sequence && alias_sequence[non_extra_index] != 0 && !child->extra) {
      self->visible_child_count++;
      if (ts_language_symbol_metadata(language, alias_sequence[non_extra_index]).named) {
        self->named_child_count++;
      }
    } else if (child->visible) {
      self->visible_child_count++;
      if (child->named) self->named_child_count++;
    } else if (child->children.size > 0) {
      self->visible_child_count += child->visible_child_count;
      self->named_child_count += child->named_child_count;
    }

    if (child->has_external_tokens) self->has_external_tokens = true;

    if (child->symbol == ts_builtin_sym_error) {
      self->fragile_left = self->fragile_right = true;
      self->parse_state = TS_TREE_STATE_NONE;
    }

    if (!child->extra) non_extra_index++;
  }

  if (self->symbol == ts_builtin_sym_error || self->symbol == ts_builtin_sym_error_repeat) {
    self->error_cost += ERROR_COST_PER_RECOVERY +
                        ERROR_COST_PER_SKIPPED_CHAR * self->size.bytes +
                        ERROR_COST_PER_SKIPPED_LINE * self->size.extent.row;
    for (uint32_t i = 0; i < self->children.size; i++) {
      Subtree *child = self->children.contents[i];
      if (child->extra) continue;
      if (child->symbol == ts_builtin_sym_error && child->children.size == 0) continue;
      if (child->visible) {
        self->error_cost += ERROR_COST_PER_SKIPPED_TREE;
      } else {
        self->error_cost += ERROR_COST_PER_SKIPPED_TREE * child->visible_child_count;
      }
    }
  }

  if (self->children.size > 0) {
    Subtree *first_child = self->children.contents[0];
    Subtree *last_child = self->children.contents[self->children.size - 1];
    self->first_leaf = first_child->first_leaf;
    if (first_child->fragile_left) self->fragile_left = true;
    if (last_child->fragile_right) self->fragile_right = true;
    if (
      self->children.size == 2 &&
      !self->visible && !self->named &&
      first_child->symbol == self->symbol &&
      last_child->symbol == self->symbol
    ) {
      if (first_child->repeat_depth > last_child->repeat_depth) {
        self->repeat_depth = first_child->repeat_depth + 1;
      } else {
        self->repeat_depth = last_child->repeat_depth + 1;
      }
    }
  }
}

Subtree *ts_subtree_make_node(SubtreePool *pool, TSSymbol symbol, SubtreeArray *children,
                        unsigned alias_sequence_id, const TSLanguage *language) {
  Subtree *result = ts_subtree_make_leaf(pool, symbol, length_zero(), length_zero(), language);
  result->alias_sequence_id = alias_sequence_id;
  if (symbol == ts_builtin_sym_error || symbol == ts_builtin_sym_error_repeat) {
    result->fragile_left = true;
    result->fragile_right = true;
  }
  ts_subtree_set_children(result, children, language);
  return result;
}

Subtree *ts_subtree_make_error_node(SubtreePool *pool, SubtreeArray *children,
                                    const TSLanguage *language) {
  return ts_subtree_make_node(pool, ts_builtin_sym_error, children, 0, language);
}

Subtree *ts_subtree_make_missing_leaf(SubtreePool *pool, TSSymbol symbol,
                                      const TSLanguage *language) {
  Subtree *result = ts_subtree_make_leaf(pool, symbol, length_zero(), length_zero(), language);
  result->is_missing = true;
  result->error_cost = ERROR_COST_PER_MISSING_TREE + ERROR_COST_PER_RECOVERY;
  return result;
}

void ts_subtree_retain(Subtree *self) {
  assert(self->ref_count > 0);
  atomic_inc(&self->ref_count);
  assert(self->ref_count != 0);
}

void ts_subtree_release(SubtreePool *pool, Subtree *self) {
  array_clear(&pool->tree_stack);
  array_push(&pool->tree_stack, self);
  while (pool->tree_stack.size > 0) {
    Subtree *tree = array_pop(&pool->tree_stack);
    assert(tree->ref_count > 0);
    if (atomic_dec(&tree->ref_count) == 0) {
      if (tree->children.size > 0) {
        for (uint32_t i = 0; i < tree->children.size; i++) {
          array_push(&pool->tree_stack, tree->children.contents[i]);
        }
        array_delete(&tree->children);
      } else if (tree->has_external_tokens) {
        ts_external_token_state_delete(&tree->external_token_state);
      }
      ts_subtree_pool_free(pool, tree);
    }
  }
}

bool ts_subtree_eq(const Subtree *self, const Subtree *other) {
  if (self) {
    if (!other) return false;
  } else {
    return !other;
  }

  if (self->symbol != other->symbol) return false;
  if (self->visible != other->visible) return false;
  if (self->named != other->named) return false;
  if (self->padding.bytes != other->padding.bytes) return false;
  if (self->size.bytes != other->size.bytes) return false;
  if (self->symbol == ts_builtin_sym_error) return self->lookahead_char == other->lookahead_char;
  if (self->children.size != other->children.size) return false;
  if (self->visible_child_count != other->visible_child_count) return false;
  if (self->named_child_count != other->named_child_count) return false;

  for (uint32_t i = 0; i < self->children.size; i++) {
    if (!ts_subtree_eq(self->children.contents[i], other->children.contents[i])) {
      return false;
    }
  }
  return true;
}

int ts_subtree_compare(const Subtree *left, const Subtree *right) {
  if (left->symbol < right->symbol)
    return -1;
  if (right->symbol < left->symbol)
    return 1;
  if (left->children.size < right->children.size)
    return -1;
  if (right->children.size < left->children.size)
    return 1;
  for (uint32_t i = 0; i < left->children.size; i++) {
    Subtree *left_child = left->children.contents[i];
    Subtree *right_child = right->children.contents[i];
    switch (ts_subtree_compare(left_child, right_child)) {
      case -1:
        return -1;
      case 1:
        return 1;
      default:
        break;
    }
  }
  return 0;
}

Subtree *ts_subtree_invalidate_lookahead(Subtree *self, uint32_t edit_byte_offset,
                                         SubtreePool *pool) {
  if (edit_byte_offset >= self->bytes_scanned) return self;

  Subtree *result = ts_subtree_make_mut(pool, self);
  result->has_changes = true;

  if (result->children.size > 0) {
    uint32_t child_start_byte = 0;
    for (uint32_t i = 0; i < result->children.size; i++) {
      Subtree **child = &result->children.contents[i];
      if (child_start_byte > edit_byte_offset) break;
      *child = ts_subtree_invalidate_lookahead(*child, edit_byte_offset - child_start_byte, pool);
      child_start_byte += ts_subtree_total_bytes(*child);
    }
  }

  return result;
}

Subtree *ts_subtree__edit(Subtree *self, Edit edit, SubtreePool *pool) {
  Length new_end = length_add(edit.start, edit.added);
  Length old_end = length_add(edit.start, edit.removed);

  Subtree *result = ts_subtree_make_mut(pool, self);
  result->has_changes = true;

  if (old_end.bytes <= result->padding.bytes) {
    result->padding = length_add(new_end, length_sub(result->padding, old_end));
  } else if (edit.start.bytes < result->padding.bytes) {
    result->size = length_sub(result->size, length_sub(old_end, result->padding));
    result->padding = new_end;
  } else if (edit.start.bytes == result->padding.bytes && edit.removed.bytes == 0) {
    result->padding = length_add(result->padding, edit.added);
  } else {
    Length new_total_size = length_add(new_end, length_sub(ts_subtree_total_size(result), old_end));
    result->size = length_sub(new_total_size, result->padding);
  }

  Length child_left, child_right = length_zero();
  for (uint32_t i = 0; i < result->children.size; i++) {
    Subtree **child = &result->children.contents[i];
    Length child_size = ts_subtree_total_size(*child);
    child_left = child_right;
    child_right = length_add(child_left, child_size);

    if (child_left.bytes > old_end.bytes ||
        (child_left.bytes == old_end.bytes && child_size.bytes > 0 && i > 0)) break;

    if (child_right.bytes > edit.start.bytes ||
        (child_right.bytes == edit.start.bytes && edit.removed.bytes == 0)) {
      Edit child_edit = {
        .start = length_sub(edit.start, child_left),
        .added = edit.added,
        .removed = edit.removed,
      };

      if (edit.start.bytes < child_left.bytes) {
        child_edit.start = length_zero();
      }

      if (old_end.bytes > child_right.bytes) {
        child_edit.removed = length_sub(child_size, child_edit.start);
      }

      edit.added = length_zero();
      edit.removed = length_sub(edit.removed, child_edit.removed);

      *child = ts_subtree__edit(*child, child_edit, pool);
    } else if (child_left.bytes <= edit.start.bytes) {
      *child = ts_subtree_invalidate_lookahead(*child, edit.start.bytes - child_left.bytes, pool);
    }
  }

  return result;
}

Subtree *ts_subtree_edit(Subtree *self, const TSInputEdit *edit, SubtreePool *pool) {
  return ts_subtree__edit(self, (Edit) {
    .start = {edit->start_byte, edit->start_point},
    .added = {edit->bytes_added, edit->extent_added},
    .removed = {edit->bytes_removed, edit->extent_removed},
  }, pool);
}

Subtree *ts_subtree_last_external_token(Subtree *tree) {
  if (!tree->has_external_tokens) return NULL;
  while (tree->children.size > 0) {
    for (uint32_t i = tree->children.size - 1; i + 1 > 0; i--) {
      Subtree *child = tree->children.contents[i];
      if (child->has_external_tokens) {
        tree = child;
        break;
      }
    }
  }
  return tree;
}

static size_t ts_subtree__write_char_to_string(char *s, size_t n, int32_t c) {
  if (c == 0)
    return snprintf(s, n, "EOF");
  if (c == -1)
    return snprintf(s, n, "INVALID");
  else if (c == '\n')
    return snprintf(s, n, "'\\n'");
  else if (c == '\t')
    return snprintf(s, n, "'\\t'");
  else if (c == '\r')
    return snprintf(s, n, "'\\r'");
  else if (0 < c && c < 128 && isprint(c))
    return snprintf(s, n, "'%c'", c);
  else
    return snprintf(s, n, "%d", c);
}

static size_t ts_subtree__write_to_string(const Subtree *self, char *string, size_t limit,
                                       const TSLanguage *language, bool is_root,
                                       bool include_all, TSSymbol alias_symbol,
                                       bool alias_is_named) {
  if (!self) return snprintf(string, limit, "(NULL)");

  char *cursor = string;
  char **writer = (limit > 0) ? &cursor : &string;
  bool visible =
    include_all ||
    is_root ||
    self->is_missing ||
    (self->visible && self->named) ||
    alias_is_named;

  if (visible && !is_root) {
    cursor += snprintf(*writer, limit, " ");
  }

  if (visible) {
    if (self->symbol == ts_builtin_sym_error && self->children.size == 0 && self->size.bytes > 0) {
      cursor += snprintf(*writer, limit, "(UNEXPECTED ");
      cursor += ts_subtree__write_char_to_string(*writer, limit, self->lookahead_char);
    } else if (self->is_missing) {
      cursor += snprintf(*writer, limit, "(MISSING");
    } else {
      TSSymbol symbol = alias_symbol ? alias_symbol : self->symbol;
      const char *symbol_name = ts_language_symbol_name(language, symbol);
      cursor += snprintf(*writer, limit, "(%s", symbol_name);
    }
  }

  const TSSymbol *alias_sequence = ts_language_alias_sequence(language, self->alias_sequence_id);
  uint32_t structural_child_index = 0;
  for (uint32_t i = 0; i < self->children.size; i++) {
    Subtree *child = self->children.contents[i];
    if (child->extra) {
      cursor += ts_subtree__write_to_string(
        child, *writer, limit,
        language, false, include_all,
        0, false
      );
    } else {
      TSSymbol alias_symbol = alias_sequence ? alias_sequence[structural_child_index] : 0;
      cursor += ts_subtree__write_to_string(
        child, *writer, limit,
        language, false, include_all,
        alias_symbol,
        alias_symbol ? ts_language_symbol_metadata(language, alias_symbol).named : false
      );
      structural_child_index++;
    }
  }

  if (visible) cursor += snprintf(*writer, limit, ")");

  return cursor - string;
}

char *ts_subtree_string(const Subtree *self, const TSLanguage *language, bool include_all) {
  char scratch_string[1];
  size_t size = ts_subtree__write_to_string(
    self, scratch_string, 0,
    language, true,
    include_all, 0, false
  ) + 1;
  char *result = ts_malloc(size * sizeof(char));
  ts_subtree__write_to_string(self, result, size, language, true, include_all, 0, false);
  return result;
}

void ts_subtree__print_dot_graph(const Subtree *self, uint32_t byte_offset,
                              const TSLanguage *language, TSSymbol alias_symbol, FILE *f) {
  TSSymbol symbol = alias_symbol ? alias_symbol : self->symbol;
  fprintf(f, "tree_%p [label=\"%s\"", self, ts_language_symbol_name(language, symbol));

  if (self->children.size == 0)
    fprintf(f, ", shape=plaintext");
  if (self->extra)
    fprintf(f, ", fontcolor=gray");

  fprintf(f, ", tooltip=\""
    "address:%p\n"
    "range:%u - %u\n"
    "state:%d\n"
    "error-cost:%u\n"
    "repeat-depth:%u\n"
    "bytes-scanned:%u\"]\n",
    self,
    byte_offset, byte_offset + ts_subtree_total_bytes(self),
    self->parse_state,
    self->error_cost,
    self->repeat_depth,
    self->bytes_scanned
  );

  const TSSymbol *alias_sequence = ts_language_alias_sequence(language, self->alias_sequence_id);
  uint32_t structural_child_index = 0;
  for (uint32_t i = 0; i < self->children.size; i++) {
    const Subtree *child = self->children.contents[i];
    if (child->extra) {
      ts_subtree__print_dot_graph(child, byte_offset, language, 0, f);
    } else {
      TSSymbol alias_symbol = alias_sequence ? alias_sequence[structural_child_index] : 0;
      ts_subtree__print_dot_graph(child, byte_offset, language, alias_symbol, f);
      structural_child_index++;
    }
    fprintf(f, "tree_%p -> tree_%p [tooltip=%u]\n", self, child, i);
    byte_offset += ts_subtree_total_bytes(child);
  }
}

void ts_subtree_print_dot_graph(const 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");
}

bool ts_subtree_external_token_state_eq(const Subtree *self, const Subtree *other) {
  const TSExternalTokenState *state1 = &empty_state;
  const TSExternalTokenState *state2 = &empty_state;
  if (self && self->has_external_tokens) state1 = &self->external_token_state;
  if (other && other->has_external_tokens) state2 = &other->external_token_state;
  return ts_external_token_state_eq(state1, state2);
}