From e07c25f563b85a4b6e0065c46464aa4880b2c2e1 Mon Sep 17 00:00:00 2001
From: Alexey Shamrin <shamrin@gmail.com>
Date: Thu, 12 Apr 2012 18:57:47 +0400
Subject: [PATCH] pretty 'rule not defined' message; SyntaxNode.message now
 accept the message

---
 lib/compiledgrammar.js | 31 +++++++++++++++++++------------
 lib/parser.js          |  7 +++++--
 2 files changed, 24 insertions(+), 14 deletions(-)

diff --git a/lib/compiledgrammar.js b/lib/compiledgrammar.js
index 18cc543..31325f5 100644
--- a/lib/compiledgrammar.js
+++ b/lib/compiledgrammar.js
@@ -35,14 +35,15 @@ function CompiledGrammar(/*String*/ aGrammar)
 
     var tree = getLanguageParser().parse(aGrammar);
 
-    compileOpcodeTableFromRules(this.table, this.nameToUID, buildRulesFromSyntaxTree(tree));
+    var r = buildRulesFromSyntaxTree(tree);
+    compileOpcodeTableFromRules(this.table, this.nameToUID, r.rules, r.firstUsageNodes)
 
     return this;
 }
 
 module.exports = CompiledGrammar;
 
-function compileOpcodeTableFromRules(/*Array*/ table, /*Object*/ nameToUID, /*Object*/ rules)
+function compileOpcodeTableFromRules(/*Array*/ table, /*Object*/ nameToUID, /*Object*/ rules, /*Object*/ firstUsageNodes)
 {
     table[0] = [0, "source", 1];
     table.length = 1;
@@ -102,8 +103,8 @@ function compileOpcodeTableFromRules(/*Array*/ table, /*Object*/ nameToUID, /*Ob
         return true;
     }
 
-    traverseRulesAnchoredAtName(rules, "start", process);
-    traverseRulesAnchoredAtName(rules, "%start", process);
+    traverseRulesAnchoredAtName(rules, firstUsageNodes, "start", process);
+    traverseRulesAnchoredAtName(rules, firstUsageNodes, "%start", process);
 
     var hasOwnProperty = Object.prototype.hasOwnProperty,
         remainingRules = { };
@@ -137,7 +138,7 @@ function compileOpcodeTableFromRules(/*Array*/ table, /*Object*/ nameToUID, /*Ob
     }
 }
 
-function traverseRulesAnchoredAtName(/*Object*/ rules, /*String*/ aName, /*Function*/ process)
+function traverseRulesAnchoredAtName(/*Object*/ rules, /*Object*/ firstUsageNodes, /*String*/ aName, /*Function*/ process)
 {
     var index = 0,
         stack = [aName];
@@ -148,7 +149,7 @@ function traverseRulesAnchoredAtName(/*Object*/ rules, /*String*/ aName, /*Funct
             rule = rules[hash];
 
         if (!rule)
-            throw "Rule \"" + hash +  "\" is not defined.";
+            throw firstUsageNodes[hash].message("Rule \"" + hash +  "\" is not defined.");
 
         if (process(rule) === false)
             continue;
@@ -163,14 +164,15 @@ function traverseRulesAnchoredAtName(/*Object*/ rules, /*String*/ aName, /*Funct
 function buildRulesFromSyntaxTree(/*SyntaxNode*/ aNode)
 {
     var rules = { },
-        walker = { traversesTextNodes:false };
+        walker = { traversesTextNodes:false },
+        firstUsageNodes = { };
 
     walker.exitedNode = function(aNode)
     {
         var builder = RULE_BUILDERS[aNode.name];
 
         if (builder)
-            aNode.hash = builder(aNode, rules);
+            aNode.hash = builder(aNode, rules, firstUsageNodes);
     }
 
     aNode.traverse(walker);
@@ -181,12 +183,12 @@ function buildRulesFromSyntaxTree(/*SyntaxNode*/ aNode)
             builder = RULE_BUILDERS["%" + name] || RULE_BUILDERS[name];
 
         if (builder)
-            aNode.hash = builder(aNode, rules);
+            aNode.hash = builder(aNode, rules, firstUsageNodes);
     }
 
     aNode.traverse(walker);
 
-    return rules;
+    return {rules: rules, firstUsageNodes: firstUsageNodes};
 }
 
 var RULE_BUILDERS = { };
@@ -289,9 +291,14 @@ RULE_BUILDERS["%ErrorChoiceExpression"] = function(aNode, rules)
     return hash;
 }
 
-RULE_BUILDERS["Identifier"] = function(aNode, rules)
+RULE_BUILDERS["Identifier"] = function(aNode, rules, firstUsageNodes)
 {
-    return aNode.innerText();
+    var hash = aNode.innerText();
+
+    if(!firstUsageNodes[hash])
+        firstUsageNodes[hash] = aNode;
+
+    return hash;
 }
 
 RULE_BUILDERS["%Identifier"] = function(aNode, rules)
diff --git a/lib/parser.js b/lib/parser.js
index b8862bb..e356a7d 100644
--- a/lib/parser.js
+++ b/lib/parser.js
@@ -277,8 +277,11 @@ function SyntaxNode(/*String*/ aName, /*String*/ aSource, /*Number*/ aLocation,
         this.error = anErrorMessage;
 }
 
-SyntaxNode.prototype.message = function()
+SyntaxNode.prototype.message = function(error)
 {
+    if(!error)
+        error = this.error;
+
     var source = this.source,
         lineNumber = 1,
         index = 0,
@@ -302,7 +305,7 @@ SyntaxNode.prototype.message = function()
 
     message += (new Array(this.range.location - start + 1)).join(" ");
     message += (new Array(Math.min(range.length, line.length) + 1)).join("^") + "\n";
-    message += "ERROR line " + lineNumber + ": " + this.error;
+    message += "ERROR line " + lineNumber + ": " + error;
 
     return message;
 }