Add location information to AST nodes

This will allow to add location information to |GrammarError| exceptions
thrown in various passes.

lib/parser.js

@@ -35,10 +35,13 @@ module.exports = (function() {
               return {
                 type:        "grammar",
                 initializer: extractOptional(initializer, 0),
-                rules:       extractList(rules, 0)
+                rules:       extractList(rules, 0),
+                location:    location()
               };
             },
-        peg$c1 = function(code) { return { type: "initializer", code: code }; },
+        peg$c1 = function(code) {
+              return { type: "initializer", code: code, location: location() };
+            },
         peg$c2 = "=",
         peg$c3 = { type: "literal", value: "=", description: "\"=\"" },
         peg$c4 = function(name, displayName, expression) {
@@ -49,35 +52,59 @@ module.exports = (function() {
                   ? {
                       type:       "named",
                       name:       displayName[0],
-                      expression: expression
+                      expression: expression,
+                      location:   location()
                     }
-                  : expression
+                  : expression,
+                location:    location()
               };
             },
         peg$c5 = "/",
         peg$c6 = { type: "literal", value: "/", description: "\"/\"" },
         peg$c7 = function(first, rest) {
               return rest.length > 0
-                ? { type: "choice", alternatives: buildList(first, rest, 3) }
+                ? {
+                    type:         "choice",
+                    alternatives: buildList(first, rest, 3),
+                    location:     location()
+                  }
                 : first;
             },
         peg$c8 = function(expression, code) {
               return code !== null
-                ? { type: "action", expression: expression, code: code[1] }
+                ? {
+                    type:       "action",
+                    expression: expression,
+                    code:       code[1],
+                    location:   location()
+                  }
                 : expression;
             },
         peg$c9 = function(first, rest) {
               return rest.length > 0
-                ? { type: "sequence", elements: buildList(first, rest, 1) }
+                ? {
+                    type:     "sequence",
+                    elements: buildList(first, rest, 1),
+                    location: location()
+                  }
                 : first;
             },
         peg$c10 = ":",
         peg$c11 = { type: "literal", value: ":", description: "\":\"" },
         peg$c12 = function(label, expression) {
-              return { type: "labeled", label: label, expression: expression };
+              return {
+                type:       "labeled",
+                label:      label,
+                expression: expression,
+                location:   location()
+              };
             },
         peg$c13 = function(operator, expression) {
-              return { type: OPS_TO_PREFIXED_TYPES[operator], expression: expression };
+              return {
+                type:       OPS_TO_PREFIXED_TYPES[operator],
+                expression: expression,
+                location:   location()
+              };
             },
         peg$c14 = "$",
         peg$c15 = { type: "literal", value: "$", description: "\"$\"" },
@@ -86,7 +113,11 @@ module.exports = (function() {
         peg$c18 = "!",
         peg$c19 = { type: "literal", value: "!", description: "\"!\"" },
         peg$c20 = function(expression, operator) {
-              return { type: OPS_TO_SUFFIXED_TYPES[operator], expression: expression };
+              return {
+                type:       OPS_TO_SUFFIXED_TYPES[operator],
+                expression: expression,
+                location:   location()
+              };
             },
         peg$c21 = "?",
         peg$c22 = { type: "literal", value: "?", description: "\"?\"" },
@@ -100,10 +131,14 @@ module.exports = (function() {
         peg$c30 = { type: "literal", value: ")", description: "\")\"" },
         peg$c31 = function(expression) { return expression; },
         peg$c32 = function(name) {
-              return { type: "rule_ref", name: name };
+              return { type: "rule_ref", name: name, location: location() };
             },
         peg$c33 = function(operator, code) {
-              return { type: OPS_TO_SEMANTIC_PREDICATE_TYPES[operator], code: code };
+              return {
+                type:     OPS_TO_SEMANTIC_PREDICATE_TYPES[operator],
+                code:     code,
+                location: location()
+              };
             },
         peg$c34 = { type: "any", description: "any character" },
         peg$c35 = { type: "other", description: "whitespace" },
@@ -155,7 +190,12 @@ module.exports = (function() {
         peg$c81 = "i",
         peg$c82 = { type: "literal", value: "i", description: "\"i\"" },
         peg$c83 = function(value, ignoreCase) {
-              return { type: "literal", value: value, ignoreCase: ignoreCase !== null };
+              return {
+                type:       "literal",
+                value:      value,
+                ignoreCase: ignoreCase !== null,
+                location:   location()
+              };
             },
         peg$c84 = { type: "other", description: "string" },
         peg$c85 = "\"",
@@ -177,7 +217,8 @@ module.exports = (function() {
                 parts:      filterEmptyStrings(parts),
                 inverted:   inverted !== null,
                 ignoreCase: ignoreCase !== null,
-                rawText:    text()
+                rawText:    text(),
+                location:   location()
               };
             },
         peg$c99 = "-",
@@ -226,7 +267,7 @@ module.exports = (function() {
         peg$c132 = { type: "class", value: "[0-9a-f]i", description: "[0-9a-f]i" },
         peg$c133 = ".",
         peg$c134 = { type: "literal", value: ".", description: "\".\"" },
-        peg$c135 = function() { return { type: "any" }; },
+        peg$c135 = function() { return { type: "any", location: location() }; },
         peg$c136 = { type: "other", description: "code block" },
         peg$c137 = "{",
         peg$c138 = { type: "literal", value: "{", description: "\"{\"" },

spec/unit/parser.spec.js

@@ -98,6 +98,74 @@ describe("PEG.js grammar parser", function() {
         rules:       [ruleA, ruleB]
       };
 
+  var stripLocation = (function() {
+    function buildVisitor(functions) {
+      return function(node) {
+        return functions[node.type].apply(null, arguments);
+      };
+    }
+
+    function stripLeaf(node) {
+      delete node.location;
+    }
+
+    function stripExpression(node) {
+      delete node.location;
+
+      strip(node.expression);
+    }
+
+    function stripChildren(property) {
+      return function(node) {
+        var i;
+
+        delete node.location;
+
+        for (i = 0; i < node[property].length; i++) {
+          strip(node[property][i]);
+        }
+      };
+    }
+
+    var strip = buildVisitor({
+      grammar: function(node) {
+        var i;
+
+        delete node.location;
+
+        if (node.initializer) {
+          strip(node.initializer);
+        }
+
+        for (i = 0; i < node.rules.length; i++) {
+          strip(node.rules[i]);
+        }
+      },
+
+      initializer:  stripLeaf,
+      rule:         stripExpression,
+      named:        stripExpression,
+      choice:       stripChildren("alternatives"),
+      action:       stripExpression,
+      sequence:     stripChildren("elements"),
+      labeled:      stripExpression,
+      text:         stripExpression,
+      simple_and:   stripExpression,
+      simple_not:   stripExpression,
+      optional:     stripExpression,
+      zero_or_more: stripExpression,
+      one_or_more:  stripExpression,
+      semantic_and: stripLeaf,
+      semantic_not: stripLeaf,
+      rule_ref:     stripLeaf,
+      literal:      stripLeaf,
+      "class":      stripLeaf,
+      any:          stripLeaf
+    });
+
+    return strip;
+  })();
+
   beforeEach(function() {
     this.addMatchers({
       toParseAs:     function(expected) {
@@ -106,6 +174,8 @@ describe("PEG.js grammar parser", function() {
         try {
           result = PEG.parser.parse(this.actual);
 
+          stripLocation(result);
+
           this.message = function() {
             return "Expected " + jasmine.pp(this.actual) + " "
                  + (this.isNot ? "not " : "")
@@ -132,6 +202,8 @@ describe("PEG.js grammar parser", function() {
         try {
           result = PEG.parser.parse(this.actual);
 
+          stripLocation(result);
+
           this.message = function() {
             return "Expected " + jasmine.pp(this.actual) + " to fail to parse"
                  + (details ? " with details " + jasmine.pp(details) : "") + ", "

src/parser.pegjs

@@ -79,12 +79,15 @@ Grammar
       return {
         type:        "grammar",
         initializer: extractOptional(initializer, 0),
-        rules:       extractList(rules, 0)
+        rules:       extractList(rules, 0),
+        location:    location()
       };
     }
 
 Initializer
-  = code:CodeBlock EOS { return { type: "initializer", code: code }; }
+  = code:CodeBlock EOS {
+      return { type: "initializer", code: code, location: location() };
+    }
 
 Rule
   = name:IdentifierName __
@@ -99,9 +102,11 @@ Rule
           ? {
               type:       "named",
               name:       displayName[0],
-              expression: expression
+              expression: expression,
+              location:   location()
             }
-          : expression
+          : expression,
+        location:    location()
       };
     }
 
@@ -111,33 +116,55 @@ Expression
 ChoiceExpression
   = first:ActionExpression rest:(__ "/" __ ActionExpression)* {
       return rest.length > 0
-        ? { type: "choice", alternatives: buildList(first, rest, 3) }
+        ? {
+            type:         "choice",
+            alternatives: buildList(first, rest, 3),
+            location:     location()
+          }
         : first;
     }
 
 ActionExpression
   = expression:SequenceExpression code:(__ CodeBlock)? {
       return code !== null
-        ? { type: "action", expression: expression, code: code[1] }
+        ? {
+            type:       "action",
+            expression: expression,
+            code:       code[1],
+            location:   location()
+          }
         : expression;
     }
 
 SequenceExpression
   = first:LabeledExpression rest:(__ LabeledExpression)* {
       return rest.length > 0
-        ? { type: "sequence", elements: buildList(first, rest, 1) }
+        ? {
+            type:     "sequence",
+            elements: buildList(first, rest, 1),
+            location: location()
+          }
         : first;
     }
 
 LabeledExpression
   = label:Identifier __ ":" __ expression:PrefixedExpression {
-      return { type: "labeled", label: label, expression: expression };
+      return {
+        type:       "labeled",
+        label:      label,
+        expression: expression,
+        location:   location()
+      };
     }
   / PrefixedExpression
 
 PrefixedExpression
   = operator:PrefixedOperator __ expression:SuffixedExpression {
-      return { type: OPS_TO_PREFIXED_TYPES[operator], expression: expression };
+      return {
+        type:       OPS_TO_PREFIXED_TYPES[operator],
+        expression: expression,
+        location:   location()
+      };
     }
   / SuffixedExpression
 
@@ -148,7 +175,11 @@ PrefixedOperator
 
 SuffixedExpression
   = expression:PrimaryExpression __ operator:SuffixedOperator {
-      return { type: OPS_TO_SUFFIXED_TYPES[operator], expression: expression };
+      return {
+        type:       OPS_TO_SUFFIXED_TYPES[operator],
+        expression: expression,
+        location:   location()
+      };
     }
   / PrimaryExpression
 
@@ -167,12 +198,16 @@ PrimaryExpression
 
 RuleReferenceExpression
   = name:IdentifierName !(__ (StringLiteral __)? "=") {
-      return { type: "rule_ref", name: name };
+      return { type: "rule_ref", name: name, location: location() };
     }
 
 SemanticPredicateExpression
   = operator:SemanticPredicateOperator __ code:CodeBlock {
-      return { type: OPS_TO_SEMANTIC_PREDICATE_TYPES[operator], code: code };
+      return {
+        type:     OPS_TO_SEMANTIC_PREDICATE_TYPES[operator],
+        code:     code,
+        location: location()
+      };
     }
 
 SemanticPredicateOperator
@@ -306,7 +341,12 @@ BooleanLiteral
 
 LiteralMatcher "literal"
   = value:StringLiteral ignoreCase:"i"? {
-      return { type: "literal", value: value, ignoreCase: ignoreCase !== null };
+      return {
+        type:       "literal",
+        value:      value,
+        ignoreCase: ignoreCase !== null,
+        location:   location()
+      };
     }
 
 StringLiteral "string"
@@ -335,7 +375,8 @@ CharacterClassMatcher "character class"
         parts:      filterEmptyStrings(parts),
         inverted:   inverted !== null,
         ignoreCase: ignoreCase !== null,
-        rawText:    text()
+        rawText:    text(),
+        location:   location()
       };
     }
 
@@ -405,7 +446,7 @@ HexDigit
   = [0-9a-f]i
 
 AnyMatcher
-  = "." { return { type: "any" }; }
+  = "." { return { type: "any", location: location() }; }
 
 CodeBlock "code block"
   = "{" code:Code "}" { return code; }