From 6cf4ccb8408bc3e5ba71ef958de7a4cfb57bd1d6 Mon Sep 17 00:00:00 2001
From: Max Brunsfeld <maxbrunsfeld@gmail.com>
Date: Sat, 19 Nov 2016 13:53:16 -0800
Subject: [PATCH] Represent rule metadata as a struct, not a map

---
 spec/compiler/build_tables/lex_item_spec.cc   | 15 ++--
 .../build_tables/rule_can_be_blank_spec.cc    |  4 +-
 .../prepare_grammar/expand_tokens_spec.cc     | 14 ++--
 spec/helpers/rule_helpers.cc                  | 13 +--
 spec/helpers/rule_helpers.h                   |  2 +-
 src/compiler/build_tables/build_lex_table.cc  |  9 +--
 src/compiler/build_tables/lex_item.cc         |  6 +-
 .../build_tables/lex_item_transitions.cc      | 20 ++---
 src/compiler/prepare_grammar/expand_tokens.cc | 10 +--
 .../prepare_grammar/extract_choices.cc        |  3 +-
 .../prepare_grammar/extract_tokens.cc         |  2 +-
 .../prepare_grammar/flatten_grammar.cc        | 16 ++--
 src/compiler/prepare_grammar/is_token.cc      |  2 +-
 src/compiler/rules/metadata.cc                | 80 +++++++++++++------
 src/compiler/rules/metadata.h                 | 28 ++++---
 src/compiler/rules/rules.cc                   | 40 +++++++---
 src/compiler/rules/visitor.cc                 |  2 +-
 17 files changed, 158 insertions(+), 108 deletions(-)

diff --git a/spec/compiler/build_tables/lex_item_spec.cc b/spec/compiler/build_tables/lex_item_spec.cc
index 4a867915..94997956 100644
--- a/spec/compiler/build_tables/lex_item_spec.cc
+++ b/spec/compiler/build_tables/lex_item_spec.cc
@@ -19,8 +19,12 @@ describe("LexItem", []() {
       AssertThat(item1.completion_status().precedence, Equals(PrecedenceRange()));
       AssertThat(item1.completion_status().is_string, IsFalse());
 
+      MetadataParams params;
+      params.precedence = 3;
+      params.has_precedence = true;
+      params.is_string = 1;
       LexItem item2(Symbol(0, true), choice({
-        metadata(blank(), { {PRECEDENCE, 3}, {IS_STRING, 1} }),
+        metadata(blank(), params),
         character({ 'a', 'b', 'c' })
       }));
 
@@ -59,10 +63,11 @@ describe("LexItemSet::transitions()", [&]() {
   });
 
   it("marks transitions that are within the main token (as opposed to separators)", [&]() {
+    MetadataParams params;
+    params.is_main_token = true;
+
     LexItemSet item_set({
-      LexItem(Symbol(1), metadata(character({ 'x' }), {
-        {MAIN_TOKEN, true}
-      })),
+      LexItem(Symbol(1), metadata(character({ 'x' }), params)),
     });
 
     AssertThat(
@@ -72,7 +77,7 @@ describe("LexItemSet::transitions()", [&]() {
           CharacterSet().include('x'),
           Transition{
             LexItemSet({
-              LexItem(Symbol(1), metadata(blank(), { {MAIN_TOKEN, true}})),
+              LexItem(Symbol(1), metadata(blank(), params)),
             }),
             PrecedenceRange(),
             true
diff --git a/spec/compiler/build_tables/rule_can_be_blank_spec.cc b/spec/compiler/build_tables/rule_can_be_blank_spec.cc
index c5074df9..61aa92bc 100644
--- a/spec/compiler/build_tables/rule_can_be_blank_spec.cc
+++ b/spec/compiler/build_tables/rule_can_be_blank_spec.cc
@@ -49,10 +49,10 @@ describe("rule_can_be_blank", [&]() {
   });
 
   it("ignores metadata rules", [&]() {
-    rule = make_shared<rules::Metadata>(blank(), map<rules::MetadataKey, int>());
+    rule = make_shared<rules::Metadata>(blank(), MetadataParams());
     AssertThat(rule_can_be_blank(rule), IsTrue());
 
-    rule = make_shared<rules::Metadata>(sym("one"), map<rules::MetadataKey, int>());
+    rule = make_shared<rules::Metadata>(sym("one"), MetadataParams());
     AssertThat(rule_can_be_blank(rule), IsFalse());
   });
 });
diff --git a/spec/compiler/prepare_grammar/expand_tokens_spec.cc b/spec/compiler/prepare_grammar/expand_tokens_spec.cc
index a2e11538..0aa83b3a 100644
--- a/spec/compiler/prepare_grammar/expand_tokens_spec.cc
+++ b/spec/compiler/prepare_grammar/expand_tokens_spec.cc
@@ -9,6 +9,10 @@ using namespace rules;
 using prepare_grammar::expand_tokens;
 
 describe("expand_tokens", []() {
+  MetadataParams string_token_params;
+  string_token_params.is_string = true;
+  string_token_params.is_token = true;
+
   describe("string rules", [&]() {
     it("replaces strings with sequences of character sets", [&]() {
       LexicalGrammar grammar{{
@@ -29,10 +33,7 @@ describe("expand_tokens", []() {
             character({ 'x' }),
             character({ 'y' }),
             character({ 'z' }),
-          }), {
-            {IS_STRING, 1},
-            {IS_TOKEN, 1},
-          }),
+          }), string_token_params),
           i_sym(11),
         })),
       })));
@@ -50,10 +51,7 @@ describe("expand_tokens", []() {
           character({ 945 }),
           character({ ' ' }),
           character({ 946 }),
-        }), {
-          {IS_STRING, 1},
-          {IS_TOKEN, 1},
-        })),
+        }), string_token_params)),
       })));
     });
   });
diff --git a/spec/helpers/rule_helpers.cc b/spec/helpers/rule_helpers.cc
index 31141d3e..8bf32360 100644
--- a/spec/helpers/rule_helpers.cc
+++ b/spec/helpers/rule_helpers.cc
@@ -35,15 +35,16 @@ namespace tree_sitter {
     return make_shared<rules::Symbol>(index, true);
   }
 
-  rule_ptr metadata(rule_ptr rule, map<rules::MetadataKey, int> values) {
-    return make_shared<rules::Metadata>(rule, values);
+  rule_ptr metadata(rule_ptr rule, rules::MetadataParams params) {
+    return rules::Metadata::build(rule, params);
   }
 
   rule_ptr active_prec(int precedence, rule_ptr rule) {
-    return std::make_shared<rules::Metadata>(rule, map<rules::MetadataKey, int>({
-      { rules::PRECEDENCE, precedence },
-      { rules::IS_ACTIVE, true }
-    }));
+    rules::MetadataParams params;
+    params.precedence = precedence;
+    params.has_precedence = true;
+    params.is_active = true;
+    return rules::Metadata::build(rule, params);
   }
 
   bool operator==(const Variable &left, const Variable &right) {
diff --git a/spec/helpers/rule_helpers.h b/spec/helpers/rule_helpers.h
index e29208e8..a985d294 100644
--- a/spec/helpers/rule_helpers.h
+++ b/spec/helpers/rule_helpers.h
@@ -8,7 +8,7 @@
 #include "compiler/variable.h"
 
 namespace tree_sitter {
-  rule_ptr metadata(rule_ptr, std::map<rules::MetadataKey, int>);
+  rule_ptr metadata(rule_ptr, rules::MetadataParams params);
   rule_ptr character(const std::set<uint32_t> &);
   rule_ptr character(const std::set<uint32_t> &, bool sign);
   rule_ptr i_sym(size_t index);
diff --git a/src/compiler/build_tables/build_lex_table.cc b/src/compiler/build_tables/build_lex_table.cc
index d55e1c94..151da7cf 100644
--- a/src/compiler/build_tables/build_lex_table.cc
+++ b/src/compiler/build_tables/build_lex_table.cc
@@ -34,9 +34,6 @@ using rules::Repeat;
 using rules::Symbol;
 using rules::Metadata;
 using rules::Seq;
-using rules::MAIN_TOKEN;
-using rules::PRECEDENCE;
-using rules::IS_ACTIVE;
 
 class LexTableBuilder {
   LexTable lex_table;
@@ -160,12 +157,10 @@ class LexTableBuilder {
         for (const rule_ptr &separator_rule : separator_rules)
           result.entries.insert(LexItem(
             symbol,
-            Metadata::build(
+            Metadata::separator(
               Seq::build({
                 separator_rule,
-                Metadata::build(rule, { { PRECEDENCE, 0 }, { MAIN_TOKEN, 1 } }),
-              }),
-              { { PRECEDENCE, INT_MIN }, { IS_ACTIVE, true } })));
+                Metadata::main_token(rule) }))));
     return result;
   }
 
diff --git a/src/compiler/build_tables/lex_item.cc b/src/compiler/build_tables/lex_item.cc
index 5272f3bd..152b2469 100644
--- a/src/compiler/build_tables/lex_item.cc
+++ b/src/compiler/build_tables/lex_item.cc
@@ -41,9 +41,9 @@ LexItem::CompletionStatus LexItem::completion_status() const {
     CompletionStatus apply_to(const rules::Metadata *rule) {
       CompletionStatus result = apply(rule->rule);
       if (result.is_done) {
-        if (result.precedence.empty && rule->value_for(rules::PRECEDENCE).second)
-          result.precedence.add(rule->value_for(rules::PRECEDENCE).first);
-        if (rule->value_for(rules::IS_STRING).second)
+        if (result.precedence.empty && rule->params.has_precedence)
+          result.precedence.add(rule->params.precedence);
+        if (rule->params.is_string)
           result.is_string = true;
       }
       return result;
diff --git a/src/compiler/build_tables/lex_item_transitions.cc b/src/compiler/build_tables/lex_item_transitions.cc
index f1050ead..9dc4f762 100644
--- a/src/compiler/build_tables/lex_item_transitions.cc
+++ b/src/compiler/build_tables/lex_item_transitions.cc
@@ -25,14 +25,10 @@ using std::vector;
 using rules::CharacterSet;
 using rules::Symbol;
 using rules::Blank;
-using rules::MetadataKey;
 using rules::Choice;
 using rules::Seq;
 using rules::Repeat;
 using rules::Metadata;
-using rules::PRECEDENCE;
-using rules::IS_ACTIVE;
-using rules::MAIN_TOKEN;
 typedef LexItemSet::Transition Transition;
 typedef LexItemSet::TransitionMap TransitionMap;
 
@@ -141,16 +137,16 @@ class TransitionBuilder : public rules::RuleFn<void> {
   }
 
   void apply_to(const Metadata *metadata) {
-    bool has_active_precedence = metadata->value_for(IS_ACTIVE).second;
+    bool has_active_precedence = metadata->params.is_active;
     if (has_active_precedence)
-      precedence_stack->push_back(metadata->value_for(PRECEDENCE).first);
+      precedence_stack->push_back(metadata->params.precedence);
 
-    if (metadata->value_for(MAIN_TOKEN).second)
+    if (metadata->params.is_main_token)
       in_main_token = true;
 
-    auto metadata_value = metadata->value;
-    if (metadata_value.count(PRECEDENCE))
-      metadata_value.insert({ IS_ACTIVE, true });
+    rules::MetadataParams params = metadata->params;
+    if (params.has_precedence)
+      params.is_active = true;
 
     TransitionMap content_transitions;
     TransitionBuilder(&content_transitions, this).apply(metadata->rule);
@@ -158,8 +154,8 @@ class TransitionBuilder : public rules::RuleFn<void> {
     for (const auto &pair : content_transitions) {
       add_transition(
         transitions, pair.first,
-        transform_transition(pair.second, [&metadata_value](rule_ptr rule) {
-          return Metadata::build(rule, metadata_value);
+        transform_transition(pair.second, [&params](rule_ptr rule) {
+          return Metadata::build(rule, params);
         }));
     }
 
diff --git a/src/compiler/prepare_grammar/expand_tokens.cc b/src/compiler/prepare_grammar/expand_tokens.cc
index 4f49244b..b024e27c 100644
--- a/src/compiler/prepare_grammar/expand_tokens.cc
+++ b/src/compiler/prepare_grammar/expand_tokens.cc
@@ -44,11 +44,11 @@ class ExpandTokens : public rules::IdentityRuleFn {
       elements.push_back(rules::CharacterSet().include(el).copy());
     }
 
-    return make_shared<rules::Metadata>(
-      rules::Seq::build(elements),
-      std::map<rules::MetadataKey, int>({
-        { rules::IS_TOKEN, 1 }, { rules::IS_STRING, 1 },
-      }));
+    rules::MetadataParams params;
+    params.is_token = true;
+    params.is_string = true;
+
+    return rules::Metadata::build(rules::Seq::build(elements), params);
   }
 
   rule_ptr apply_to(const Pattern *rule) {
diff --git a/src/compiler/prepare_grammar/extract_choices.cc b/src/compiler/prepare_grammar/extract_choices.cc
index 043b5653..6262001c 100644
--- a/src/compiler/prepare_grammar/extract_choices.cc
+++ b/src/compiler/prepare_grammar/extract_choices.cc
@@ -10,7 +10,6 @@
 namespace tree_sitter {
 namespace prepare_grammar {
 
-using std::make_shared;
 using std::vector;
 
 class ExtractChoices : public rules::RuleFn<vector<rule_ptr>> {
@@ -29,7 +28,7 @@ class ExtractChoices : public rules::RuleFn<vector<rule_ptr>> {
   vector<rule_ptr> apply_to(const rules::Metadata *rule) {
     vector<rule_ptr> result;
     for (auto entry : apply(rule->rule))
-      result.push_back(make_shared<rules::Metadata>(entry, rule->value));
+      result.push_back(rules::Metadata::build(entry, rule->params));
     return result;
   }
 
diff --git a/src/compiler/prepare_grammar/extract_tokens.cc b/src/compiler/prepare_grammar/extract_tokens.cc
index ebc7a36e..bf7ac514 100644
--- a/src/compiler/prepare_grammar/extract_tokens.cc
+++ b/src/compiler/prepare_grammar/extract_tokens.cc
@@ -79,7 +79,7 @@ class TokenExtractor : public rules::IdentityRuleFn {
   }
 
   rule_ptr apply_to(const rules::Metadata *rule) {
-    if (rule->value_for(rules::IS_TOKEN).second)
+    if (rule->params.is_token)
       return apply_to_token(rule->rule.get(), VariableTypeAuxiliary);
     else
       return rules::IdentityRuleFn::apply_to(rule);
diff --git a/src/compiler/prepare_grammar/flatten_grammar.cc b/src/compiler/prepare_grammar/flatten_grammar.cc
index 85093298..fa253718 100644
--- a/src/compiler/prepare_grammar/flatten_grammar.cc
+++ b/src/compiler/prepare_grammar/flatten_grammar.cc
@@ -29,24 +29,20 @@ class FlattenRule : public rules::RuleFn<void> {
   }
 
   void apply_to(const rules::Metadata *metadata) {
-    auto precedence = metadata->value_for(rules::PRECEDENCE);
-    auto associativity = metadata->value_for(rules::ASSOCIATIVITY);
-
-    if (precedence.second)
-      precedence_stack.push_back(precedence.first);
-    if (associativity.second)
-      associativity_stack.push_back(
-        static_cast<rules::Associativity>(associativity.first));
+    if (metadata->params.has_precedence)
+      precedence_stack.push_back(metadata->params.precedence);
+    if (metadata->params.has_associativity)
+      associativity_stack.push_back(metadata->params.associativity);
 
     apply(metadata->rule);
 
-    if (precedence.second) {
+    if (metadata->params.has_precedence) {
       last_precedence = precedence_stack.back();
       precedence_stack.pop_back();
       production.back().precedence = precedence_stack.back();
     }
 
-    if (associativity.second) {
+    if (metadata->params.has_associativity) {
       last_associativity = associativity_stack.back();
       associativity_stack.pop_back();
       production.back().associativity = associativity_stack.back();
diff --git a/src/compiler/prepare_grammar/is_token.cc b/src/compiler/prepare_grammar/is_token.cc
index b7dfab1f..4d209882 100644
--- a/src/compiler/prepare_grammar/is_token.cc
+++ b/src/compiler/prepare_grammar/is_token.cc
@@ -18,7 +18,7 @@ class IsToken : public rules::RuleFn<bool> {
   }
 
   bool apply_to(const rules::Metadata *rule) {
-    return rule->value_for(rules::IS_TOKEN).second;
+    return rule->params.is_token;
   }
 };
 
diff --git a/src/compiler/rules/metadata.cc b/src/compiler/rules/metadata.cc
index 97fd0fed..5b9724d8 100644
--- a/src/compiler/rules/metadata.cc
+++ b/src/compiler/rules/metadata.cc
@@ -1,6 +1,7 @@
 #include "compiler/rules/metadata.h"
 #include <string>
 #include <map>
+#include <climits>
 #include "compiler/rules/visitor.h"
 #include "compiler/rules/blank.h"
 #include "compiler/util/hash_combine.h"
@@ -13,47 +14,80 @@ using std::map;
 using std::pair;
 using util::hash_combine;
 
-Metadata::Metadata(rule_ptr rule, map<MetadataKey, int> values)
-    : rule(rule), value(values) {}
+MetadataParams::MetadataParams() :
+  precedence{0},
+  associativity{AssociativityNone},
+  has_precedence{false},
+  has_associativity{false},
+  is_token{false},
+  is_string{false},
+  is_active{false},
+  is_main_token{false} {}
 
-rule_ptr Metadata::build(rule_ptr rule, map<MetadataKey, int> values) {
-  return std::make_shared<Metadata>(rule, values);
+bool MetadataParams::operator==(const MetadataParams &other) const {
+  return
+    precedence == other.precedence &&
+    associativity == other.associativity &&
+    has_precedence == other.has_precedence &&
+    has_associativity == other.has_associativity &&
+    is_token == other.is_token &&
+    is_string == other.is_string &&
+    is_active == other.is_active &&
+    is_main_token == other.is_main_token;
+}
+
+Metadata::Metadata(rule_ptr rule, MetadataParams params)
+    : rule(rule), params(params) {}
+
+rule_ptr Metadata::build(rule_ptr rule, MetadataParams params) {
+  return std::make_shared<Metadata>(rule, params);
+}
+
+rule_ptr Metadata::main_token(rule_ptr rule) {
+  MetadataParams params;
+  params.has_precedence = true;
+  params.precedence = 0;
+  params.is_main_token = true;
+  return Metadata::build(rule, params);
+}
+
+rule_ptr Metadata::separator(rule_ptr rule) {
+  MetadataParams params;
+  params.has_precedence = true;
+  params.precedence = INT_MIN;
+  params.is_active = true;
+  return Metadata::build(rule, params);
 }
 
 bool Metadata::operator==(const Rule &rule) const {
   auto other = rule.as<Metadata>();
-  return other && other->value == value && other->rule->operator==(*this->rule);
+  return other && other->params == params && other->rule->operator==(*this->rule);
 }
 
 size_t Metadata::hash_code() const {
   size_t result = 0;
-  hash_combine(&result, value.size());
-  for (auto &pair : value) {
-    hash_combine<int>(&result, pair.first);
-    hash_combine(&result, pair.second);
-  }
+  hash_combine(&result, params.precedence);
+  hash_combine<int>(&result, params.associativity);
+  hash_combine(&result, params.has_precedence);
+  hash_combine(&result, params.has_associativity);
+  hash_combine(&result, params.is_token);
+  hash_combine(&result, params.is_string);
+  hash_combine(&result, params.is_active);
+  hash_combine(&result, params.is_main_token);
   return result;
 }
 
 rule_ptr Metadata::copy() const {
-  return make_shared<Metadata>(rule->copy(), value);
-}
-
-pair<int, bool> Metadata::value_for(MetadataKey key) const {
-  auto entry = value.find(key);
-  if (entry == value.end())
-    return { 0, false };
-  else
-    return { entry->second, true };
+  return make_shared<Metadata>(rule->copy(), params);
 }
 
 std::string Metadata::to_string() const {
-  auto precedence = value_for(rules::PRECEDENCE);
-  if (precedence.second && value_for(rules::IS_ACTIVE).second)
-    return "(metadata prec:" + std::to_string(precedence.first) + " " +
+  if (params.has_precedence) {
+    return "(metadata prec:" + std::to_string(params.precedence) + " " +
            rule->to_string() + ")";
-  else
+  } else {
     return "(metadata " + rule->to_string() + ")";
+  }
 }
 
 void Metadata::accept(Visitor *visitor) const {
diff --git a/src/compiler/rules/metadata.h b/src/compiler/rules/metadata.h
index 72cdbed0..a9f43c2f 100644
--- a/src/compiler/rules/metadata.h
+++ b/src/compiler/rules/metadata.h
@@ -14,29 +14,35 @@ enum Associativity {
   AssociativityRight,
 };
 
-enum MetadataKey {
-  MAIN_TOKEN,
-  PRECEDENCE,
-  ASSOCIATIVITY,
-  IS_TOKEN,
-  IS_STRING,
-  IS_ACTIVE,
+struct MetadataParams {
+  int precedence;
+  Associativity associativity;
+  bool has_precedence;
+  bool has_associativity;
+  bool is_token;
+  bool is_string;
+  bool is_active;
+  bool is_main_token;
+
+  MetadataParams();
+  bool operator==(const MetadataParams &) const;
 };
 
 class Metadata : public Rule {
  public:
-  Metadata(rule_ptr rule, std::map<MetadataKey, int> value);
-  static rule_ptr build(rule_ptr rule, std::map<MetadataKey, int> value);
+  Metadata(rule_ptr rule, MetadataParams);
+  static rule_ptr build(rule_ptr rule, MetadataParams);
+  static rule_ptr main_token(rule_ptr rule);
+  static rule_ptr separator(rule_ptr rule);
 
   bool operator==(const Rule &other) const;
   size_t hash_code() const;
   rule_ptr copy() const;
   std::string to_string() const;
   void accept(Visitor *visitor) const;
-  std::pair<int, bool> value_for(MetadataKey key) const;
 
   const rule_ptr rule;
-  const std::map<MetadataKey, int> value;
+  MetadataParams params;
 };
 
 }  // namespace rules
diff --git a/src/compiler/rules/rules.cc b/src/compiler/rules/rules.cc
index b61358e8..fdb0ebdf 100644
--- a/src/compiler/rules/rules.cc
+++ b/src/compiler/rules/rules.cc
@@ -22,9 +22,10 @@ using std::string;
 using std::set;
 using std::vector;
 using std::map;
+using rules::MetadataParams;
 
-static rule_ptr metadata(rule_ptr rule, map<rules::MetadataKey, int> values) {
-  return std::make_shared<rules::Metadata>(rule, values);
+static rule_ptr metadata(rule_ptr rule, MetadataParams params) {
+  return std::make_shared<rules::Metadata>(rule, params);
 }
 
 rule_ptr blank() {
@@ -60,29 +61,48 @@ rule_ptr str(const string &value) {
 }
 
 rule_ptr prec_left(const rule_ptr &rule) {
-  return metadata(rule, { { rules::ASSOCIATIVITY, rules::AssociativityLeft } });
+  MetadataParams params;
+  params.has_associativity = true;
+  params.associativity = rules::AssociativityLeft;
+  return metadata(rule, params);
 }
 
 rule_ptr prec_left(int precedence, const rule_ptr &rule) {
-  return metadata(rule, { { rules::PRECEDENCE, precedence },
-                          { rules::ASSOCIATIVITY, rules::AssociativityLeft } });
+  MetadataParams params;
+  params.has_associativity = true;
+  params.associativity = rules::AssociativityLeft;
+  params.has_precedence = true;
+  params.precedence = precedence;
+  return metadata(rule, params);
 }
 
 rule_ptr prec_right(const rule_ptr &rule) {
-  return metadata(rule, { { rules::ASSOCIATIVITY, rules::AssociativityRight } });
+  MetadataParams params;
+  params.has_associativity = true;
+  params.associativity = rules::AssociativityRight;
+  return metadata(rule, params);
 }
 
 rule_ptr prec_right(int precedence, const rule_ptr &rule) {
-  return metadata(rule, { { rules::PRECEDENCE, precedence },
-                          { rules::ASSOCIATIVITY, rules::AssociativityRight } });
+  MetadataParams params;
+  params.has_associativity = true;
+  params.associativity = rules::AssociativityRight;
+  params.has_precedence = true;
+  params.precedence = precedence;
+  return metadata(rule, params);
 }
 
 rule_ptr prec(int precedence, const rule_ptr &rule) {
-  return metadata(rule, { { rules::PRECEDENCE, precedence } });
+  MetadataParams params;
+  params.has_precedence = true;
+  params.precedence = precedence;
+  return metadata(rule, params);
 }
 
 rule_ptr token(const rule_ptr &rule) {
-  return metadata(rule, { { rules::IS_TOKEN, 1 } });
+  MetadataParams params;
+  params.is_token = true;
+  return metadata(rule, params);
 }
 
 }  // namespace tree_sitter
diff --git a/src/compiler/rules/visitor.cc b/src/compiler/rules/visitor.cc
index db3600ce..e06f6c7f 100644
--- a/src/compiler/rules/visitor.cc
+++ b/src/compiler/rules/visitor.cc
@@ -37,7 +37,7 @@ rule_ptr IdentityRuleFn::apply_to(const Repeat *rule) {
 }
 
 rule_ptr IdentityRuleFn::apply_to(const Metadata *rule) {
-  return std::make_shared<Metadata>(apply(rule->rule), rule->value);
+  return Metadata::build(apply(rule->rule), rule->params);
 }
 
 }  // namespace rules