treesitter: update runtime

Since tree-sitter PR 615, predicates are not parsed the same.
"Old" way of writing predicates is still supported.

src/tree_sitter/language.c

@@ -33,8 +33,8 @@ void ts_language_table_entry(
     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->count;
-    result->is_reusable = entry->reusable;
+    result->action_count = entry->entry.count;
+    result->is_reusable = entry->entry.reusable;
     result->actions = (const TSParseAction *)(entry + 1);
   }
 }

src/tree_sitter/language.h

@@ -93,7 +93,7 @@ static inline TSStateId ts_language_next_state(const TSLanguage *self,
     if (count > 0) {
       TSParseAction action = actions[count - 1];
       if (action.type == TSParseActionTypeShift) {
-        return action.params.extra ? state : action.params.state;
+        return action.params.shift.extra ? state : action.params.shift.state;
       }
     }
     return 0;

src/tree_sitter/parser.c

@@ -951,15 +951,15 @@ static bool ts_parser__do_all_potential_reductions(
         switch (action.type) {
           case TSParseActionTypeShift:
           case TSParseActionTypeRecover:
-            if (!action.params.extra && !action.params.repetition) has_shift_action = true;
+            if (!action.params.shift.extra && !action.params.shift.repetition) has_shift_action = true;
             break;
           case TSParseActionTypeReduce:
-            if (action.params.child_count > 0)
+            if (action.params.reduce.child_count > 0)
               ts_reduce_action_set_add(&self->reduce_actions, (ReduceAction){
-                .symbol = action.params.symbol,
-                .count = action.params.child_count,
-                .dynamic_precedence = action.params.dynamic_precedence,
-                .production_id = action.params.production_id,
+                .symbol = action.params.reduce.symbol,
+                .count = action.params.reduce.child_count,
+                .dynamic_precedence = action.params.reduce.dynamic_precedence,
+                .production_id = action.params.reduce.production_id,
               });
           default:
             break;
@@ -1250,7 +1250,7 @@ static void ts_parser__recover(
   // be counted in error cost calculations.
   unsigned n;
   const TSParseAction *actions = ts_language_actions(self->language, 1, ts_subtree_symbol(lookahead), &n);
-  if (n > 0 && actions[n - 1].type == TSParseActionTypeShift && actions[n - 1].params.extra) {
+  if (n > 0 && actions[n - 1].type == TSParseActionTypeShift && actions[n - 1].params.shift.extra) {
     MutableSubtree mutable_lookahead = ts_subtree_make_mut(&self->tree_pool, lookahead);
     ts_subtree_set_extra(&mutable_lookahead);
     lookahead = ts_subtree_from_mut(mutable_lookahead);
@@ -1379,9 +1379,9 @@ static bool ts_parser__advance(
 
       switch (action.type) {
         case TSParseActionTypeShift: {
-          if (action.params.repetition) break;
+          if (action.params.shift.repetition) break;
           TSStateId next_state;
-          if (action.params.extra) {
+          if (action.params.shift.extra) {
 
             // TODO: remove when TREE_SITTER_LANGUAGE_VERSION 9 is out.
             if (state == ERROR_STATE) continue;
@@ -1389,7 +1389,7 @@ static bool ts_parser__advance(
             next_state = state;
             LOG("shift_extra");
           } else {
-            next_state = action.params.state;
+            next_state = action.params.shift.state;
             LOG("shift state:%u", next_state);
           }
 
@@ -1398,7 +1398,7 @@ static bool ts_parser__advance(
             next_state = ts_language_next_state(self->language, state, ts_subtree_symbol(lookahead));
           }
 
-          ts_parser__shift(self, version, next_state, lookahead, action.params.extra);
+          ts_parser__shift(self, version, next_state, lookahead, action.params.shift.extra);
           if (did_reuse) reusable_node_advance(&self->reusable_node);
           return true;
         }
@@ -1406,10 +1406,10 @@ static bool ts_parser__advance(
         case TSParseActionTypeReduce: {
           bool is_fragile = table_entry.action_count > 1;
           bool is_extra = lookahead.ptr == NULL;
-          LOG("reduce sym:%s, child_count:%u", SYM_NAME(action.params.symbol), action.params.child_count);
+          LOG("reduce sym:%s, child_count:%u", SYM_NAME(action.params.reduce.symbol), action.params.reduce.child_count);
           StackVersion reduction_version = ts_parser__reduce(
-            self, version, action.params.symbol, action.params.child_count,
-            action.params.dynamic_precedence, action.params.production_id,
+            self, version, action.params.reduce.symbol, action.params.reduce.child_count,
+            action.params.reduce.dynamic_precedence, action.params.reduce.production_id,
             is_fragile, is_extra
           );
           if (reduction_version != STACK_VERSION_NONE) {

src/tree_sitter/parser.h

@@ -62,13 +62,13 @@ typedef struct {
       TSStateId state;
       bool extra : 1;
       bool repetition : 1;
-    };
+    } shift;
     struct {
       TSSymbol symbol;
       int16_t dynamic_precedence;
       uint8_t child_count;
       uint8_t production_id;
-    };
+    } reduce;
   } params;
   TSParseActionType type : 4;
 } TSParseAction;
@@ -83,7 +83,7 @@ typedef union {
   struct {
     uint8_t count;
     bool reusable : 1;
-  };
+  } entry;
 } TSParseActionEntry;
 
 struct TSLanguage {
@@ -167,22 +167,28 @@ struct TSLanguage {
 
 #define ACTIONS(id) id
 
-#define SHIFT(state_value)              \
-  {                                     \
-    {                                   \
-      .type = TSParseActionTypeShift,   \
-      .params = {.state = state_value}, \
-    }                                   \
+#define SHIFT(state_value)                \
+  {                                       \
+    {                                     \
+      .params = {                         \
+        .shift = {                        \
+          .state = state_value            \
+        }                                 \
+      },                                  \
+      .type = TSParseActionTypeShift      \
+    }                                     \
   }
 
 #define SHIFT_REPEAT(state_value)     \
   {                                   \
     {                                 \
-      .type = TSParseActionTypeShift, \
       .params = {                     \
-        .state = state_value,         \
-        .repetition = true            \
+        .shift = {                    \
+          .state = state_value,       \
+          .repetition = true          \
+        }                             \
       },                              \
+      .type = TSParseActionTypeShift  \
     }                                 \
   }
 
@@ -194,20 +200,26 @@ struct TSLanguage {
 #define SHIFT_EXTRA()                 \
   {                                   \
     {                                 \
-      .type = TSParseActionTypeShift, \
-      .params = {.extra = true}       \
+      .params = {                     \
+        .shift = {                    \
+          .extra = true               \
+        }                             \
+      },                              \
+      .type = TSParseActionTypeShift  \
     }                                 \
   }
 
 #define REDUCE(symbol_val, child_count_val, ...) \
   {                                              \
     {                                            \
-      .type = TSParseActionTypeReduce,           \
       .params = {                                \
-        .symbol = symbol_val,                    \
-        .child_count = child_count_val,          \
-        __VA_ARGS__                              \
-      }                                          \
+        .reduce = {                              \
+          .symbol = symbol_val,                  \
+          .child_count = child_count_val,        \
+          __VA_ARGS__                            \
+        },                                       \
+      },                                         \
+      .type = TSParseActionTypeReduce            \
     }                                            \
   }
 

src/tree_sitter/query.c

@@ -27,7 +27,7 @@ typedef struct {
  * represented as a sequence of these steps. Fields:
  *
  * - `symbol` - The grammar symbol to match. A zero value represents the
- *    wildcard symbol, '*'.
+ *    wildcard symbol, '_'.
  * - `field` - The field name to match. A zero value means that a field name
  *    was not specified.
  * - `capture_id` - An integer representing the name of the capture associated
@@ -35,21 +35,21 @@ typedef struct {
  *    captured in this pattern.
  * - `depth` - The depth where this node occurs in the pattern. The root node
  *    of the pattern has depth zero.
- * - `repeat_step_index` - If this step is part of a repetition, the index of
- *    the beginning of the repetition. A `NONE` value means this step is not
- *    part of a repetition.
+ * - `alternative_index` - The index of a different query step that serves as
+ *    an alternative to this step.
  */
 typedef struct {
   TSSymbol symbol;
   TSFieldId field;
   uint16_t capture_ids[MAX_STEP_CAPTURE_COUNT];
-  uint16_t repeat_step_index;
-  uint16_t depth: 11;
+  uint16_t alternative_index;
+  uint8_t depth;
   bool contains_captures: 1;
   bool is_pattern_start: 1;
   bool is_immediate: 1;
   bool is_last: 1;
-  bool is_repeated: 1;
+  bool is_placeholder: 1;
+  bool alternative_is_immediate: 1;
 } QueryStep;
 
 /*
@@ -88,7 +88,25 @@ typedef struct {
  * QueryState - The state of an in-progress match of a particular pattern
  * in a query. While executing, a `TSQueryCursor` must keep track of a number
  * of possible in-progress matches. Each of those possible matches is
- * represented as one of these states.
+ * represented as one of these states. Fields:
+ * - `id` - A numeric id that is exposed to the public API. This allows the
+ *    caller to remove a given match, preventing any more of its captures
+ *    from being returned.
+ * - `start_depth` - The depth in the tree where the first step of the state's
+ *    pattern was matched.
+ * - `pattern_index` - The pattern that the state is matching.
+ * - `consumed_capture_count` - The number of captures from this match that
+ *    have already been returned.
+ * - `capture_list_id` - A numeric id that can be used to retrieve the state's
+ *    list of captures from the `CaptureListPool`.
+ * - `seeking_immediate_match` - A flag that indicates that the state's next
+ *    step must be matched by the very next sibling. This is used when
+ *    processing repetitions.
+ * - `has_in_progress_alternatives` - A flag that indicates that there is are
+ *    other states that have the same captures as this state, but are at
+ *    different steps in their pattern. This means that in order to obey the
+ *    'longest-match' rule, this state should not be returned as a match until
+ *    it is clear that there can be no longer match.
  */
 typedef struct {
   uint32_t id;
@@ -96,10 +114,9 @@ typedef struct {
   uint16_t pattern_index;
   uint16_t step_index;
   uint16_t consumed_capture_count;
-  uint16_t repeat_match_count;
-  uint16_t step_index_on_failure;
   uint8_t capture_list_id;
-  bool seeking_non_match;
+  bool seeking_immediate_match: 1;
+  bool has_in_progress_alternatives: 1;
 } QueryState;
 
 typedef Array(TSQueryCapture) CaptureList;
@@ -417,12 +434,13 @@ static QueryStep query_step__new(
     .depth = depth,
     .field = 0,
     .capture_ids = {NONE, NONE, NONE, NONE},
+    .alternative_index = NONE,
     .contains_captures = false,
-    .is_repeated = false,
     .is_last = false,
     .is_pattern_start = false,
+    .is_placeholder = false,
     .is_immediate = is_immediate,
-    .repeat_step_index = NONE,
+    .alternative_is_immediate = false,
   };
 }
 
@@ -511,13 +529,14 @@ static inline bool ts_query__pattern_map_search(
 static inline void ts_query__pattern_map_insert(
   TSQuery *self,
   TSSymbol symbol,
-  uint32_t start_step_index
+  uint32_t start_step_index,
+  uint32_t pattern_index
 ) {
   uint32_t index;
   ts_query__pattern_map_search(self, symbol, &index);
   array_insert(&self->pattern_map, index, ((PatternEntry) {
     .step_index = start_step_index,
-    .pattern_index = self->pattern_map.size,
+    .pattern_index = pattern_index,
   }));
 }
 
@@ -548,12 +567,22 @@ static TSQueryError ts_query__parse_predicate(
   TSQuery *self,
   Stream *stream
 ) {
-  if (stream->next == ')') return PARENT_DONE;
-  if (stream->next != '(') return TSQueryErrorSyntax;
-  stream_advance(stream);
+  if (!stream_is_ident_start(stream)) return TSQueryErrorSyntax;
+  const char *predicate_name = stream->input;
+  stream_scan_identifier(stream);
+  uint32_t length = stream->input - predicate_name;
+  uint16_t id = symbol_table_insert_name(
+    &self->predicate_values,
+    predicate_name,
+    length
+  );
+  array_back(&self->predicates_by_pattern)->length++;
+  array_push(&self->predicate_steps, ((TSQueryPredicateStep) {
+    .type = TSQueryPredicateStepTypeString,
+    .value_id = id,
+  }));
   stream_skip_whitespace(stream);
 
-  unsigned step_count = 0;
   for (;;) {
     if (stream->next == ')') {
       stream_advance(stream);
@@ -658,7 +687,6 @@ static TSQueryError ts_query__parse_predicate(
       return TSQueryErrorSyntax;
     }
 
-    step_count++;
     stream_skip_whitespace(stream);
   }
 
@@ -684,93 +712,141 @@ static TSQueryError ts_query__parse_pattern(
     return PARENT_DONE;
   }
 
-  // Parse a parenthesized node expression
+  // An open parenthesis can be the start of three possible constructs:
+  // * A grouped sequence
+  // * A predicate
+  // * A named node
   else if (stream->next == '(') {
     stream_advance(stream);
     stream_skip_whitespace(stream);
 
-    // Parse a nested list, which represents a pattern followed by
-    // zero-or-more predicates.
-    if (stream->next == '(' && depth == 0) {
-      TSQueryError e = ts_query__parse_pattern(self, stream, 0, capture_count, is_immediate);
-      if (e) return e;
-
-      // Parse the predicates.
-      stream_skip_whitespace(stream);
+    // If this parenthesis is followed by a node, then it represents a grouped sequence.
+    if (stream->next == '(' || stream->next == '"') {
+      bool child_is_immediate = false;
       for (;;) {
-        TSQueryError e = ts_query__parse_predicate(self, stream);
-        if (e == PARENT_DONE) {
+        if (stream->next == '.') {
+          child_is_immediate = true;
           stream_advance(stream);
           stream_skip_whitespace(stream);
-          return 0;
+        }
+        TSQueryError e = ts_query__parse_pattern(
+          self,
+          stream,
+          depth,
+          capture_count,
+          child_is_immediate
+        );
+        if (e == PARENT_DONE) {
+          stream_advance(stream);
+          break;
         } else if (e) {
           return e;
         }
+
+        child_is_immediate = false;
       }
     }
 
-    TSSymbol symbol;
-
-    // Parse the wildcard symbol
-    if (stream->next == '*') {
-      symbol = depth > 0 ? NAMED_WILDCARD_SYMBOL : WILDCARD_SYMBOL;
+    // A pound character indicates the start of a predicate.
+    else if (stream->next == '#') {
       stream_advance(stream);
+      return ts_query__parse_predicate(self, stream);
     }
 
-    // Parse a normal node name
-    else if (stream_is_ident_start(stream)) {
-      const char *node_name = stream->input;
-      stream_scan_identifier(stream);
-      uint32_t length = stream->input - node_name;
-      symbol = ts_language_symbol_for_name(
-        self->language,
-        node_name,
-        length,
-        true
-      );
-      if (!symbol) {
-        stream_reset(stream, node_name);
-        return TSQueryErrorNodeType;
-      }
-    } else {
-      return TSQueryErrorSyntax;
-    }
+    // Otherwise, this parenthesis is the start of a named node.
+    else {
+      TSSymbol symbol;
 
-    // Add a step for the node.
-    array_push(&self->steps, query_step__new(symbol, depth, is_immediate));
+      // Parse the wildcard symbol
+      if (
+        stream->next == '_' ||
 
-    // Parse the child patterns
-    stream_skip_whitespace(stream);
-    bool child_is_immediate = false;
-    uint16_t child_start_step_index = self->steps.size;
-    for (;;) {
-      if (stream->next == '.') {
-        child_is_immediate = true;
+        // TODO - remove.
+        // For temporary backward compatibility, handle '*' as a wildcard.
+        stream->next == '*'
+      ) {
+        symbol = depth > 0 ? NAMED_WILDCARD_SYMBOL : WILDCARD_SYMBOL;
         stream_advance(stream);
-        stream_skip_whitespace(stream);
       }
 
-      TSQueryError e = ts_query__parse_pattern(
-        self,
-        stream,
-        depth + 1,
-        capture_count,
-        child_is_immediate
-      );
-      if (e == PARENT_DONE) {
-        if (child_is_immediate) {
-          self->steps.contents[child_start_step_index].is_last = true;
+      // Parse a normal node name
+      else if (stream_is_ident_start(stream)) {
+        const char *node_name = stream->input;
+        stream_scan_identifier(stream);
+        uint32_t length = stream->input - node_name;
+
+        // TODO - remove.
+        // For temporary backward compatibility, handle predicates without the leading '#' sign.
+        if (length > 0 && (node_name[length - 1] == '!' || node_name[length - 1] == '?')) {
+          stream_reset(stream, node_name);
+          return ts_query__parse_predicate(self, stream);
         }
-        stream_advance(stream);
-        break;
-      } else if (e) {
-        return e;
+
+        symbol = ts_language_symbol_for_name(
+          self->language,
+          node_name,
+          length,
+          true
+        );
+        if (!symbol) {
+          stream_reset(stream, node_name);
+          return TSQueryErrorNodeType;
+        }
+      } else {
+        return TSQueryErrorSyntax;
       }
 
-      child_is_immediate = false;
+      // Add a step for the node.
+      array_push(&self->steps, query_step__new(symbol, depth, is_immediate));
+
+      // Parse the child patterns
+      stream_skip_whitespace(stream);
+      bool child_is_immediate = false;
+      uint16_t child_start_step_index = self->steps.size;
+      for (;;) {
+        if (stream->next == '.') {
+          child_is_immediate = true;
+          stream_advance(stream);
+          stream_skip_whitespace(stream);
+        }
+
+        TSQueryError e = ts_query__parse_pattern(
+          self,
+          stream,
+          depth + 1,
+          capture_count,
+          child_is_immediate
+        );
+        if (e == PARENT_DONE) {
+          if (child_is_immediate) {
+            self->steps.contents[child_start_step_index].is_last = true;
+          }
+          stream_advance(stream);
+          break;
+        } else if (e) {
+          return e;
+        }
+
+        child_is_immediate = false;
+      }
     }
   }
 
+  // Parse a wildcard pattern
+  else if (
+    stream->next == '_' ||
+
+    // TODO remove.
+    // For temporary backward compatibility, handle '*' as a wildcard.
+    stream->next == '*'
+  ) {
+    stream_advance(stream);
+    stream_skip_whitespace(stream);
+
+    // Add a step that matches any kind of node
+    array_push(&self->steps, query_step__new(WILDCARD_SYMBOL, depth, is_immediate));
+  }
+
   // Parse a double-quoted anonymous leaf node expression
   else if (stream->next == '"') {
     stream_advance(stream);
@@ -842,15 +918,6 @@ static TSQueryError ts_query__parse_pattern(
     self->steps.contents[step_index].field = field_id;
   }
 
-  // Parse a wildcard pattern
-  else if (stream->next == '*') {
-    stream_advance(stream);
-    stream_skip_whitespace(stream);
-
-    // Add a step that matches any kind of node
-    array_push(&self->steps, query_step__new(WILDCARD_SYMBOL, depth, is_immediate));
-  }
-
   else {
     return TSQueryErrorSyntax;
   }
@@ -863,9 +930,29 @@ static TSQueryError ts_query__parse_pattern(
 
     if (stream->next == '+') {
       stream_advance(stream);
-      step->is_repeated = true;
-      array_back(&self->steps)->repeat_step_index = starting_step_index;
       stream_skip_whitespace(stream);
+      QueryStep repeat_step = query_step__new(WILDCARD_SYMBOL, depth, false);
+      repeat_step.alternative_index = starting_step_index;
+      repeat_step.is_placeholder = true;
+      repeat_step.alternative_is_immediate = true;
+      array_push(&self->steps, repeat_step);
+    }
+
+    else if (stream->next == '?') {
+      stream_advance(stream);
+      stream_skip_whitespace(stream);
+      step->alternative_index = self->steps.size;
+    }
+
+    else if (stream->next == '*') {
+      stream_advance(stream);
+      stream_skip_whitespace(stream);
+      QueryStep repeat_step = query_step__new(WILDCARD_SYMBOL, depth, false);
+      repeat_step.alternative_index = starting_step_index;
+      repeat_step.is_placeholder = true;
+      repeat_step.alternative_is_immediate = true;
+      array_push(&self->steps, repeat_step);
+      step->alternative_index = self->steps.size;
     }
 
     // Parse an '@'-prefixed capture pattern
@@ -950,6 +1037,7 @@ TSQuery *ts_query_new(
   Stream stream = stream_new(source, source_len);
   stream_skip_whitespace(&stream);
   while (stream.input < stream.end) {
+    uint32_t pattern_index = self->predicates_by_pattern.size;
     uint32_t start_step_index = self->steps.size;
     uint32_t capture_count = 0;
     array_push(&self->start_bytes_by_pattern, stream.input - source);
@@ -980,14 +1068,18 @@ TSQuery *ts_query_new(
     }
 
     // Maintain a map that can look up patterns for a given root symbol.
-    self->steps.contents[start_step_index].is_pattern_start = true;
-    ts_query__pattern_map_insert(
-      self,
-      self->steps.contents[start_step_index].symbol,
-      start_step_index
-    );
-    if (self->steps.contents[start_step_index].symbol == WILDCARD_SYMBOL) {
-      self->wildcard_root_pattern_count++;
+    for (;;) {
+      QueryStep *step = &self->steps.contents[start_step_index];
+      step->is_pattern_start = true;
+      ts_query__pattern_map_insert(self, step->symbol, start_step_index, pattern_index);
+      if (step->symbol == WILDCARD_SYMBOL) {
+        self->wildcard_root_pattern_count++;
+      }
+      if (step->alternative_index != NONE) {
+        start_step_index = step->alternative_index;
+      } else {
+        break;
+      }
     }
   }
 
@@ -1191,23 +1283,85 @@ static bool ts_query_cursor__first_in_progress_capture(
   return result;
 }
 
-static bool ts_query__cursor_add_state(
+// Determine which node is first in a depth-first traversal
+int ts_query_cursor__compare_nodes(TSNode left, TSNode right) {
+  if (left.id != right.id) {
+    uint32_t left_start = ts_node_start_byte(left);
+    uint32_t right_start = ts_node_start_byte(right);
+    if (left_start < right_start) return -1;
+    if (left_start > right_start) return 1;
+    uint32_t left_node_count = ts_node_end_byte(left);
+    uint32_t right_node_count = ts_node_end_byte(right);
+    if (left_node_count > right_node_count) return -1;
+    if (left_node_count < right_node_count) return 1;
+  }
+  return 0;
+}
+
+// Determine if either state contains a superset of the other state's captures.
+void ts_query_cursor__compare_captures(
+  TSQueryCursor *self,
+  QueryState *left_state,
+  QueryState *right_state,
+  bool *left_contains_right,
+  bool *right_contains_left
+) {
+  CaptureList *left_captures = capture_list_pool_get(
+    &self->capture_list_pool,
+    left_state->capture_list_id
+  );
+  CaptureList *right_captures = capture_list_pool_get(
+    &self->capture_list_pool,
+    right_state->capture_list_id
+  );
+  *left_contains_right = true;
+  *right_contains_left = true;
+  unsigned i = 0, j = 0;
+  for (;;) {
+    if (i < left_captures->size) {
+      if (j < right_captures->size) {
+        TSQueryCapture *left = &left_captures->contents[i];
+        TSQueryCapture *right = &right_captures->contents[j];
+        if (left->node.id == right->node.id && left->index == right->index) {
+          i++;
+          j++;
+        } else {
+          switch (ts_query_cursor__compare_nodes(left->node, right->node)) {
+            case -1:
+              *right_contains_left = false;
+              i++;
+              break;
+            case 1:
+              *left_contains_right = false;
+              j++;
+              break;
+            default:
+              *right_contains_left = false;
+              *left_contains_right = false;
+              i++;
+              j++;
+              break;
+          }
+        }
+      } else {
+        *right_contains_left = false;
+        break;
+      }
+    } else {
+      if (j < right_captures->size) {
+        *left_contains_right = false;
+      }
+      break;
+    }
+  }
+}
+
+static bool ts_query_cursor__add_state(
   TSQueryCursor *self,
   const PatternEntry *pattern
 ) {
   QueryStep *step = &self->query->steps.contents[pattern->step_index];
 
-  // If this pattern begins with a repetition, then avoid creating
-  // new states after already matching the repetition one or more times.
-  // The query should only one match for the repetition - the one that
-  // started the earliest.
-  if (step->is_repeated) {
-    for (unsigned i = 0; i < self->states.size; i++) {
-      QueryState *state = &self->states.contents[i];
-      if (state->step_index == pattern->step_index) return true;
-    }
-  }
-
   uint32_t list_id = capture_list_pool_acquire(&self->capture_list_pool);
 
   // If there are no capture lists left in the pool, then terminate whichever
@@ -1244,21 +1398,23 @@ static bool ts_query__cursor_add_state(
     .pattern_index = pattern->pattern_index,
     .start_depth = self->depth - step->depth,
     .consumed_capture_count = 0,
-    .repeat_match_count = 0,
-    .step_index_on_failure = NONE,
-    .seeking_non_match = false,
+    .seeking_immediate_match = false,
   }));
   return true;
 }
 
+// Duplicate the given state and insert the newly-created state immediately after
+// the given state in the `states` array.
 static QueryState *ts_query__cursor_copy_state(
   TSQueryCursor *self,
   const QueryState *state
 ) {
   uint32_t new_list_id = capture_list_pool_acquire(&self->capture_list_pool);
   if (new_list_id == NONE) return NULL;
-  array_push(&self->states, *state);
-  QueryState *new_state = array_back(&self->states);
+  uint32_t index = (state - self->states.contents) + 1;
+  QueryState copy = *state;
+  array_insert(&self->states, index, copy);
+  QueryState *new_state = &self->states.contents[index];
   new_state->capture_list_id = new_list_id;
   CaptureList *old_captures = capture_list_pool_get(
     &self->capture_list_pool,
@@ -1281,56 +1437,62 @@ static inline bool ts_query_cursor__advance(TSQueryCursor *self) {
     if (self->ascending) {
       LOG("leave node. type:%s\n", ts_node_type(ts_tree_cursor_current_node(&self->cursor)));
 
-      // When leaving a node, remove any unfinished states whose next step
-      // needed to match something within that node.
-      uint32_t deleted_count = 0;
-      for (unsigned i = 0, n = self->states.size; i < n; i++) {
-        QueryState *state = &self->states.contents[i];
-        QueryStep *step = &self->query->steps.contents[state->step_index];
-
-        if ((uint32_t)state->start_depth + (uint32_t)step->depth > self->depth) {
-          LOG(
-            "  failed to match. pattern:%u, step:%u\n",
-            state->pattern_index,
-            state->step_index
-          );
-
-          capture_list_pool_release(
-            &self->capture_list_pool,
-            state->capture_list_id
-          );
-          deleted_count++;
-        } else if (deleted_count > 0) {
-          self->states.contents[i - deleted_count] = *state;
-        }
-      }
-
-      self->states.size -= deleted_count;
-
+      // Leave this node by stepping to its next sibling or to its parent.
+      bool did_move = true;
       if (ts_tree_cursor_goto_next_sibling(&self->cursor)) {
         self->ascending = false;
       } else if (ts_tree_cursor_goto_parent(&self->cursor)) {
         self->depth--;
       } else {
+        did_move = false;
+      }
+
+      // After leaving a node, remove any states that cannot make further progress.
+      uint32_t deleted_count = 0;
+      for (unsigned i = 0, n = self->states.size; i < n; i++) {
+        QueryState *state = &self->states.contents[i];
+        QueryStep *step = &self->query->steps.contents[state->step_index];
+
+        // If a state completed its pattern inside of this node, but was deferred from finishing
+        // in order to search for longer matches, mark it as finished.
+        if (step->depth == PATTERN_DONE_MARKER) {
+          if (state->start_depth > self->depth || !did_move) {
+            LOG("  finish pattern %u\n", state->pattern_index);
+            state->id = self->next_state_id++;
+            array_push(&self->finished_states, *state);
+            deleted_count++;
+            continue;
+          }
+        }
+
+        // If a state needed to match something within this node, then remove that state
+        // as it has failed to match.
+        else if ((uint32_t)state->start_depth + (uint32_t)step->depth > self->depth) {
+          LOG(
+            "  failed to match. pattern:%u, step:%u\n",
+            state->pattern_index,
+            state->step_index
+          );
+          capture_list_pool_release(
+            &self->capture_list_pool,
+            state->capture_list_id
+          );
+          deleted_count++;
+          continue;
+        }
+
+        if (deleted_count > 0) {
+          self->states.contents[i - deleted_count] = *state;
+        }
+      }
+      self->states.size -= deleted_count;
+
+      if (!did_move) {
         return self->finished_states.size > 0;
       }
     } else {
-      bool has_later_siblings;
-      bool can_have_later_siblings_with_this_field;
-      TSFieldId field_id = ts_tree_cursor_current_status(
-        &self->cursor,
-        &has_later_siblings,
-        &can_have_later_siblings_with_this_field
-      );
+      // If this node is before the selected range, then avoid descending into it.
       TSNode node = ts_tree_cursor_current_node(&self->cursor);
-      TSSymbol symbol = ts_node_symbol(node);
-      bool is_named = ts_node_is_named(node);
-      if (symbol != ts_builtin_sym_error && self->query->symbol_map) {
-        symbol = self->query->symbol_map[symbol];
-      }
-
-      // If this node is before the selected range, then avoid descending
-      // into it.
       if (
         ts_node_end_byte(node) <= self->start_byte ||
         point_lte(ts_node_end_point(node), self->start_point)
@@ -1347,18 +1509,26 @@ static inline bool ts_query_cursor__advance(TSQueryCursor *self) {
         point_lte(self->end_point, ts_node_start_point(node))
       ) return false;
 
+      // Get the properties of the current node.
+      TSSymbol symbol = ts_node_symbol(node);
+      bool is_named = ts_node_is_named(node);
+      if (symbol != ts_builtin_sym_error && self->query->symbol_map) {
+        symbol = self->query->symbol_map[symbol];
+      }
+      bool can_have_later_siblings;
+      bool can_have_later_siblings_with_this_field;
+      TSFieldId field_id = ts_tree_cursor_current_status(
+        &self->cursor,
+        &can_have_later_siblings,
+        &can_have_later_siblings_with_this_field
+      );
       LOG(
-        "enter node. "
-        "type:%s, field:%s, row:%u state_count:%u, "
-        "finished_state_count:%u, has_later_siblings:%d, "
-        "can_have_later_siblings_with_this_field:%d\n",
+        "enter node. type:%s, field:%s, row:%u state_count:%u, finished_state_count:%u\n",
         ts_node_type(node),
         ts_language_field_name_for_id(self->query->language, field_id),
         ts_node_start_point(node).row,
         self->states.size,
-        self->finished_states.size,
-        has_later_siblings,
-        can_have_later_siblings_with_this_field
+        self->finished_states.size
       );
 
       // Add new states for any patterns whose root node is a wildcard.
@@ -1369,7 +1539,7 @@ static inline bool ts_query_cursor__advance(TSQueryCursor *self) {
         // If this node matches the first step of the pattern, then add a new
         // state at the start of this pattern.
         if (step->field && field_id != step->field) continue;
-        if (!ts_query__cursor_add_state(self, pattern)) break;
+        if (!ts_query_cursor__add_state(self, pattern)) break;
       }
 
       // Add new states for any patterns whose root node matches this node.
@@ -1381,7 +1551,7 @@ static inline bool ts_query_cursor__advance(TSQueryCursor *self) {
           // If this node matches the first step of the pattern, then add a new
           // state at the start of this pattern.
           if (step->field && field_id != step->field) continue;
-          if (!ts_query__cursor_add_state(self, pattern)) break;
+          if (!ts_query_cursor__add_state(self, pattern)) break;
 
           // Advance to the next pattern whose root node matches this node.
           i++;
@@ -1392,9 +1562,10 @@ static inline bool ts_query_cursor__advance(TSQueryCursor *self) {
       }
 
       // Update all of the in-progress states with current node.
-      for (unsigned i = 0, n = self->states.size; i < n; i++) {
+      for (unsigned i = 0; i < self->states.size; i++) {
         QueryState *state = &self->states.contents[i];
         QueryStep *step = &self->query->steps.contents[state->step_index];
+        state->has_in_progress_alternatives = false;
 
         // Check that the node matches all of the criteria for the next
         // step of the pattern.
@@ -1407,11 +1578,11 @@ static inline bool ts_query_cursor__advance(TSQueryCursor *self) {
           step->symbol == symbol ||
           step->symbol == WILDCARD_SYMBOL ||
           (step->symbol == NAMED_WILDCARD_SYMBOL && is_named);
-        bool later_sibling_can_match = has_later_siblings;
-        if (step->is_immediate && is_named) {
+        bool later_sibling_can_match = can_have_later_siblings;
+        if ((step->is_immediate && is_named) || state->seeking_immediate_match) {
           later_sibling_can_match = false;
         }
-        if (step->is_last && has_later_siblings) {
+        if (step->is_last && can_have_later_siblings) {
           node_does_match = false;
         }
         if (step->field) {
@@ -1424,25 +1595,8 @@ static inline bool ts_query_cursor__advance(TSQueryCursor *self) {
           }
         }
 
+        // Remove states immediately if it is ever clear that they cannot match.
         if (!node_does_match) {
-          // If this QueryState has processed a repeating sequence, and that repeating
-          // sequence has ended, move on to the *next* step of this state's pattern.
-          if (
-            state->step_index_on_failure != NONE &&
-            (!later_sibling_can_match || step->is_repeated)
-          ) {
-            LOG(
-              "  finish repetition state. pattern:%u, step:%u\n",
-              state->pattern_index,
-              state->step_index
-            );
-            state->step_index = state->step_index_on_failure;
-            state->step_index_on_failure = NONE;
-            state->repeat_match_count = 0;
-            i--;
-            continue;
-          }
-
           if (!later_sibling_can_match) {
             LOG(
               "  discard state. pattern:%u, step:%u\n",
@@ -1455,114 +1609,158 @@ static inline bool ts_query_cursor__advance(TSQueryCursor *self) {
             );
             array_erase(&self->states, i);
             i--;
-            n--;
           }
-
-          state->seeking_non_match = false;
           continue;
         }
 
-        // The `seeking_non_match` flag indicates that a previous QueryState
-        // has already begun processing this repeating sequence, so that *this*
-        // QueryState should not begin matching until a separate repeating sequence
-        // is found.
-        if (state->seeking_non_match) continue;
-
-        // Some patterns can match their root node in multiple ways,
-        // capturing different children. If this pattern step could match
-        // later children within the same parent, then this query state
-        // cannot simply be updated in place. It must be split into two
-        // states: one that matches this node, and one which skips over
-        // this node, to preserve the possibility of matching later
-        // siblings.
-        QueryState *next_state = state;
+        // Some patterns can match their root node in multiple ways, capturing different
+        // children. If this pattern step could match later children within the same
+        // parent, then this query state cannot simply be updated in place. It must be
+        // split into two states: one that matches this node, and one which skips over
+        // this node, to preserve the possibility of matching later siblings.
         if (
-          !step->is_pattern_start &&
-          step->contains_captures &&
           later_sibling_can_match &&
-          state->repeat_match_count == 0
+          !step->is_pattern_start &&
+          step->contains_captures
         ) {
-          QueryState *copy = ts_query__cursor_copy_state(self, state);
-
-          // The QueryState that matched this node has begun matching a repeating
-          // sequence. The QueryState that *skipped* this node should not start
-          // matching later elements of the same repeating sequence.
-          if (step->is_repeated) {
-            state->seeking_non_match = true;
-          }
-
-          if (copy) {
+          if (ts_query__cursor_copy_state(self, state)) {
             LOG(
-              "  split state. pattern:%u, step:%u\n",
-              copy->pattern_index,
-              copy->step_index
+              "  split state for capture. pattern:%u, step:%u\n",
+              state->pattern_index,
+              state->step_index
             );
-            next_state = copy;
-          } else {
-            LOG("  cannot split state.\n");
+            i++;
           }
         }
 
-        // If the current node is captured in this pattern, add it to the
-        // capture list.
+        // If the current node is captured in this pattern, add it to the capture list.
+        CaptureList *capture_list = capture_list_pool_get(
+          &self->capture_list_pool,
+          state->capture_list_id
+        );
         for (unsigned j = 0; j < MAX_STEP_CAPTURE_COUNT; j++) {
           uint16_t capture_id = step->capture_ids[j];
           if (step->capture_ids[j] == NONE) break;
-          CaptureList *capture_list = capture_list_pool_get(
-            &self->capture_list_pool,
-            next_state->capture_list_id
-          );
-          array_push(capture_list, ((TSQueryCapture) {
-            node,
-            capture_id
-          }));
+          array_push(capture_list, ((TSQueryCapture) { node, capture_id }));
           LOG(
             "  capture node. pattern:%u, capture_id:%u, capture_count:%u\n",
-            next_state->pattern_index,
+            state->pattern_index,
             capture_id,
             capture_list->size
           );
         }
 
-        // If this is the end of a repetition, then jump back to the beginning
-        // of that repetition.
-        if (step->repeat_step_index != NONE) {
-          next_state->step_index_on_failure = next_state->step_index + 1;
-          next_state->step_index = step->repeat_step_index;
-          next_state->repeat_match_count++;
-          LOG(
-            "  continue repeat. pattern:%u, match_count:%u\n",
-            next_state->pattern_index,
-            next_state->repeat_match_count
-          );
-        } else {
-          next_state->step_index++;
-          LOG(
-            "  advance state. pattern:%u, step:%u\n",
-            next_state->pattern_index,
-            next_state->step_index
-          );
+        // Advance this state to the next step of its pattern.
+        state->step_index++;
+        state->seeking_immediate_match = false;
+        LOG(
+          "  advance state. pattern:%u, step:%u\n",
+          state->pattern_index,
+          state->step_index
+        );
 
-          QueryStep *next_step = step + 1;
-
-          // If the pattern is now done, then remove it from the list of
-          // in-progress states, and add it to the list of finished states.
-          if (next_step->depth == PATTERN_DONE_MARKER) {
-            LOG("  finish pattern %u\n", next_state->pattern_index);
-
-            next_state->id = self->next_state_id++;
-            array_push(&self->finished_states, *next_state);
-            if (next_state == state) {
-              array_erase(&self->states, i);
-              i--;
-              n--;
-            } else {
-              self->states.size--;
+        // If this state's next step has an 'alternative' step (the step is either optional,
+        // or is the end of a repetition), then copy the state in order to pursue both
+        // alternatives. The alternative step itself may have an alternative, so this is
+        // an interative process.
+        unsigned start_index = state - self->states.contents;
+        unsigned end_index = start_index + 1;
+        for (unsigned j = start_index; j < end_index; j++) {
+          QueryState *state = &self->states.contents[j];
+          QueryStep *next_step = &self->query->steps.contents[state->step_index];
+          if (next_step->alternative_index != NONE) {
+            QueryState *copy = ts_query__cursor_copy_state(self, state);
+            if (next_step->is_placeholder) {
+              state->step_index++;
+              j--;
+            }
+            if (copy) {
+              i++;
+              end_index++;
+              copy->step_index = next_step->alternative_index;
+              if (next_step->alternative_is_immediate) {
+                copy->seeking_immediate_match = true;
+              }
+              LOG(
+                "  split state for branch. pattern:%u, step:%u, step:%u\n",
+                copy->pattern_index,
+                state->step_index,
+                copy->step_index
+              );
             }
           }
         }
       }
 
+      for (unsigned i = 0; i < self->states.size; i++) {
+        QueryState *state = &self->states.contents[i];
+        bool did_remove = false;
+
+        // Enfore the longest-match criteria. When a query pattern contains optional or
+        // repeated nodes, this is necesssary to avoid multiple redundant states, where
+        // one state has a strict subset of another state's captures.
+        for (unsigned j = i + 1; j < self->states.size; j++) {
+          QueryState *other_state = &self->states.contents[j];
+          if (
+            state->pattern_index == other_state->pattern_index &&
+            state->start_depth == other_state->start_depth
+          ) {
+            bool left_contains_right, right_contains_left;
+            ts_query_cursor__compare_captures(
+              self,
+              state,
+              other_state,
+              &left_contains_right,
+              &right_contains_left
+            );
+            if (left_contains_right) {
+              if (state->step_index == other_state->step_index) {
+                LOG(
+                  "  drop shorter state. pattern: %u, step_index: %u\n",
+                  state->pattern_index,
+                  state->step_index
+                );
+                capture_list_pool_release(&self->capture_list_pool, other_state->capture_list_id);
+                array_erase(&self->states, j);
+                j--;
+                continue;
+              }
+              other_state->has_in_progress_alternatives = true;
+            }
+            if (right_contains_left) {
+              if (state->step_index == other_state->step_index) {
+                LOG(
+                  "  drop shorter state. pattern: %u, step_index: %u\n",
+                  state->pattern_index,
+                  state->step_index
+                );
+                capture_list_pool_release(&self->capture_list_pool, state->capture_list_id);
+                array_erase(&self->states, i);
+                did_remove = true;
+                break;
+              }
+              state->has_in_progress_alternatives = true;
+            }
+          }
+        }
+
+        // If there the state is at the end of its pattern, remove it from the list
+        // of in-progress states and add it to the list of finished states.
+        if (!did_remove) {
+          QueryStep *next_step = &self->query->steps.contents[state->step_index];
+          if (next_step->depth == PATTERN_DONE_MARKER) {
+            if (state->has_in_progress_alternatives) {
+              LOG("  defer finishing pattern %u\n", state->pattern_index);
+            } else {
+              LOG("  finish pattern %u\n", state->pattern_index);
+              state->id = self->next_state_id++;
+              array_push(&self->finished_states, *state);
+              array_erase(&self->states, state - self->states.contents);
+              i--;
+            }
+          }
+        }
+      }
 
       // Continue descending if possible.
       if (ts_tree_cursor_goto_first_child(&self->cursor)) {

src/tree_sitter/subtree.c

@@ -21,7 +21,7 @@ typedef struct {
 #define TS_MAX_INLINE_TREE_LENGTH UINT8_MAX
 #define TS_MAX_TREE_POOL_SIZE 32
 
-static const ExternalScannerState empty_state = {.length = 0, .short_data = {0}};
+static const ExternalScannerState empty_state = {{.short_data = {0}}, .length = 0};
 
 // ExternalScannerState
 
@@ -208,7 +208,7 @@ Subtree ts_subtree_new_leaf(
       .has_external_tokens = has_external_tokens,
       .is_missing = false,
       .is_keyword = is_keyword,
-      .first_leaf = {.symbol = 0, .parse_state = 0},
+      {{.first_leaf = {.symbol = 0, .parse_state = 0}}}
     };
     return (Subtree) {.ptr = data};
   }
@@ -464,15 +464,17 @@ MutableSubtree ts_subtree_new_node(SubtreePool *pool, TSSymbol symbol,
   *data = (SubtreeHeapData) {
     .ref_count = 1,
     .symbol = symbol,
-    .production_id = production_id,
     .visible = metadata.visible,
     .named = metadata.named,
     .has_changes = false,
     .fragile_left = fragile,
     .fragile_right = fragile,
     .is_keyword = false,
-    .node_count = 0,
-    .first_leaf = {.symbol = 0, .parse_state = 0},
+    {{
+      .node_count = 0,
+      .production_id = production_id,
+      .first_leaf = {.symbol = 0, .parse_state = 0},
+    }}
   };
   MutableSubtree result = {.ptr = data};
   ts_subtree_set_children(result, children->contents, children->size, language);

test/functional/lua/treesitter_spec.lua

@@ -240,15 +240,15 @@ static int nlua_schedule(lua_State *const lstate)
 ; TODO(bfredl): overlapping matches are unreliable,
 ; we need a proper priority mechanism
 ;(type_identifier) @type
-((type_identifier) @Special (eq? @Special "LuaRef"))
+((type_identifier) @Special (#eq? @Special "LuaRef"))
 
 (primitive_type) @type
 (sized_type_specifier) @type
 
 ; defaults to very magic syntax, for best compatibility
-((identifier) @Identifier (match? @Identifier "^l(u)a_"))
+((identifier) @Identifier (#match? @Identifier "^l(u)a_"))
 ; still support \M etc prefixes
-((identifier) @Constant (match? @Constant "\M^\[A-Z_]\+$"))
+((identifier) @Constant (#match? @Constant "\M^\[A-Z_]\+$"))
 
 ((binary_expression left: (identifier) @WarningMsg.left right: (identifier) @WarningMsg.right) (eq? @WarningMsg.left @WarningMsg.right))