From 3cd031af3885ea635b8c99d90b7de461b7926b79 Mon Sep 17 00:00:00 2001
From: Max Brunsfeld <maxbrunsfeld@gmail.com>
Date: Wed, 11 Jun 2014 12:40:49 -0700
Subject: [PATCH] Add `keypattern` rule helper

This way, pattern rules (e.g. golang's comment) can be easily given the
same precedence as keyword rules.
---
 examples/grammars/golang.cc    |  5 +----
 include/tree_sitter/compiler.h |  1 +
 src/compiler/rules/rules.cc    | 12 +++++++++---
 3 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/examples/grammars/golang.cc b/examples/grammars/golang.cc
index f5afd999..5652216b 100644
--- a/examples/grammars/golang.cc
+++ b/examples/grammars/golang.cc
@@ -161,9 +161,6 @@ namespace tree_sitter_examples {
         { "type_name", sym("_identifier") },
         { "_identifier", pattern("\\a[\\w_]*") },
         { "number", pattern("\\d+(\\.\\d+)?") },
-        
-        // TODO - make it clear how this number relates to the
-        // precedence used by the `keyword` helper.
-        { "comment", token(prec(1000, pattern("//[^\n]*"))) },
+        { "comment", keypattern("//[^\n]*") },
     }).ubiquitous_tokens({ "comment" });
 }
diff --git a/include/tree_sitter/compiler.h b/include/tree_sitter/compiler.h
index cff3f0d3..f2ea2956 100644
--- a/include/tree_sitter/compiler.h
+++ b/include/tree_sitter/compiler.h
@@ -20,6 +20,7 @@ namespace tree_sitter {
         rule_ptr pattern(const std::string &value);
         rule_ptr str(const std::string &value);
         rule_ptr keyword(const std::string &value);
+        rule_ptr keypattern(const std::string &value);
         rule_ptr err(const rule_ptr &rule);
         rule_ptr prec(int precedence, rule_ptr rule);
         rule_ptr token(rule_ptr rule);
diff --git a/src/compiler/rules/rules.cc b/src/compiler/rules/rules.cc
index d9ea3537..03578002 100644
--- a/src/compiler/rules/rules.cc
+++ b/src/compiler/rules/rules.cc
@@ -23,6 +23,8 @@ namespace tree_sitter {
     using std::map;
 
     namespace rules {
+        static const int KEYWORD_PRECEDENCE = 100;
+        
         static rule_ptr metadata(rule_ptr rule, map<MetadataKey, int> values) {
             return std::make_shared<Metadata>(rule, values);
         }
@@ -56,7 +58,11 @@ namespace tree_sitter {
         }
 
         rule_ptr keyword(const string &value) {
-            return metadata(make_shared<String>(value), { { PRECEDENCE, 100}, { IS_TOKEN, 1 } });
+            return token(prec(KEYWORD_PRECEDENCE, str(value)));
+        }
+
+        rule_ptr keypattern(const string &value) {
+            return token(prec(KEYWORD_PRECEDENCE, pattern(value)));
         }
 
         rule_ptr err(const rule_ptr &rule) {
@@ -64,11 +70,11 @@ namespace tree_sitter {
         }
 
         rule_ptr prec(int precedence, rule_ptr rule) {
-            return metadata(rule, { { PRECEDENCE, precedence } });
+            return metadata(rule, {{ PRECEDENCE, precedence }});
         }
 
         rule_ptr token(rule_ptr rule) {
-            return metadata(rule, { { IS_TOKEN, 1 } });
+            return metadata(rule, {{ IS_TOKEN, 1 }});
         }
     }
 }