Parser calls AST node creator now

Before this commit, the PEG.js parser always created the AST using a plain JavaSctript object, but allthough simple and effective for the job, this method sacrificies performance slightly.

From now on the parser shall call a Node creator. This should help with performance, as well as in the future move some AST helpers into the new AST functions.

gulpfile.js

@@ -35,7 +35,7 @@ task( "lint", () => gulp
     .src( [
         "**/.*rc.js",
         "lib/**/*.js",
-        "!lib/parser.js",
+        "!lib/parser/index.js",
         "test/benchmark/**/*.js",
         "test/benchmark/run",
         "test/impact",
@@ -65,7 +65,7 @@ task( "benchmark", cb => {
 // Generate the grammar parser.
 task( "build:parser", cb => {
 
-    node( "bin/peg src/parser.pegjs -o lib/parser.js -c src/config.json", cb );
+    node( "bin/peg src/parser.pegjs -o lib/parser/index.js -c src/config.json", cb );
 
 } );
 

lib/parser/ast.js

@@ -0,0 +1,28 @@
+"use strict";
+
+class Node {
+
+    constructor( type, location ) {
+
+        this.type = type;
+        this.location = location;
+
+    }
+
+}
+exports.Node = Node;
+
+class Grammar extends Node {
+
+    // Creates a new AST
+    constructor( initializer, rules, location ) {
+
+        super( "grammar", location );
+
+        this.initializer = initializer;
+        this.rules = rules;
+
+    }
+
+}
+exports.Grammar = Grammar;

lib/parser/index.js

@@ -4,6 +4,9 @@
 
 "use strict";
 
+var ast = require("./ast");
+var util = require("../util");
+
 function peg$subclass(child, parent) {
   function C() { this.constructor = child; }
   C.prototype = parent.prototype;
@@ -138,61 +141,50 @@ function peg$parse(input, options) {
   var peg$startRuleFunction = peg$parseGrammar;
 
   var peg$c0 = function(initializer, rules) {
-        return {
-          type: "grammar",
-          initializer: extractOptional(initializer, 0),
-          rules: extractList(rules, 0),
-          location: location()
-        };
+        return new ast.Grammar(
+          extractOptional(initializer, 0),
+          extractList(rules, 0),
+          location(),
+        );
       };
   var peg$c1 = function(code) {
-        return { type: "initializer", code: code, location: location() };
+        return createNode( "initializer", { code: code } );
       };
   var peg$c2 = "=";
   var peg$c3 = peg$literalExpectation("=", false);
   var peg$c4 = function(name, displayName, expression) {
-        return {
-          type: "rule",
+        return createNode( "rule", {
           name: name,
           expression: displayName !== null
-            ? {
-                type: "named",
+            ? createNode( "named", {
                 name: displayName[0],
                 expression: expression,
-                location: location()
-              }
+              } )
             : expression,
-          location: location()
-        };
+        } );
       };
   var peg$c5 = "/";
   var peg$c6 = peg$literalExpectation("/", false);
   var peg$c7 = function(head, tail) {
         return tail.length > 0
-          ? {
-              type: "choice",
+          ? createNode( "choice", {
               alternatives: buildList(head, tail, 3),
-              location: location()
-            }
+            } )
           : head;
       };
   var peg$c8 = function(expression, code) {
         return code !== null
-          ? {
-              type: "action",
+          ? createNode( "action", {
               expression: expression,
               code: code[1],
-              location: location()
-            }
+            } )
           : expression;
       };
   var peg$c9 = function(head, tail) {
         return tail.length > 0
-          ? {
-              type: "sequence",
+          ? createNode( "sequence", {
               elements: buildList(head, tail, 1),
-              location: location()
-            }
+            } )
           : head;
       };
   var peg$c10 = ":";
@@ -202,19 +194,15 @@ function peg$parse(input, options) {
           error(`Label can't be a reserved word "${label[0]}".`, label[1]);
         }
 
-        return {
-          type: "labeled",
+        return createNode( "labeled", {
           label: label[0],
           expression: expression,
-          location: location()
-        };
+        } );
       };
   var peg$c13 = function(operator, expression) {
-        return {
-          type: OPS_TO_PREFIXED_TYPES[operator],
+        return createNode( OPS_TO_PREFIXED_TYPES[operator], {
           expression: expression,
-          location: location()
-        };
+        } );
       };
   var peg$c14 = "$";
   var peg$c15 = peg$literalExpectation("$", false);
@@ -223,11 +211,9 @@ function peg$parse(input, options) {
   var peg$c18 = "!";
   var peg$c19 = peg$literalExpectation("!", false);
   var peg$c20 = function(expression, operator) {
-        return {
-          type: OPS_TO_SUFFIXED_TYPES[operator],
+        return createNode( OPS_TO_SUFFIXED_TYPES[operator], {
           expression: expression,
-          location: location()
-        };
+        } );
       };
   var peg$c21 = "?";
   var peg$c22 = peg$literalExpectation("?", false);
@@ -245,18 +231,14 @@ function peg$parse(input, options) {
         // nodes that already isolate label scope themselves. This leaves us with
         // "labeled" and "sequence".
         return expression.type === "labeled" || expression.type === "sequence"
-            ? { type: "group", expression: expression, location: location() }
+            ? createNode( "group", { expression: expression } )
             : expression;
       };
   var peg$c32 = function(name) {
-        return { type: "rule_ref", name: name, location: location() };
+        return createNode( "rule_ref", { name: name } );
       };
   var peg$c33 = function(operator, code) {
-        return {
-          type: OPS_TO_SEMANTIC_PREDICATE_TYPES[operator],
-          code: code,
-          location: location()
-        };
+        return createNode( OPS_TO_SEMANTIC_PREDICATE_TYPES[operator], { code: code } );
       };
   var peg$c34 = peg$anyExpectation();
   var peg$c35 = peg$otherExpectation("whitespace");
@@ -292,12 +274,10 @@ function peg$parse(input, options) {
   var peg$c65 = peg$otherExpectation("literal");
   var peg$c66 = "i";
   var peg$c67 = function(value, ignoreCase) {
-        return {
-          type: "literal",
+        return createNode( "literal", {
           value: value,
           ignoreCase: ignoreCase !== null,
-          location: location()
-        };
+        } );
       };
   var peg$c68 = peg$otherExpectation("string");
   var peg$c69 = "\"";
@@ -309,13 +289,11 @@ function peg$parse(input, options) {
   var peg$c75 = "^";
   var peg$c76 = "]";
   var peg$c77 = function(inverted, parts, ignoreCase) {
-        return {
-          type: "class",
+        return createNode( "class", {
           parts: parts.filter(part => part !== ""),
           inverted: inverted !== null,
           ignoreCase: ignoreCase !== null,
-          location: location()
-        };
+        } );
       };
   var peg$c78 = "-";
   var peg$c79 = function(begin, end) {
@@ -351,7 +329,7 @@ function peg$parse(input, options) {
   var peg$c99 = /^[0-9a-f]/i;
   var peg$c100 = ".";
   var peg$c101 = peg$literalExpectation(".", false);
-  var peg$c102 = function() { return { type: "any", location: location() }; };
+  var peg$c102 = function() { return createNode( "any", {} ); };
   var peg$c103 = peg$otherExpectation("code block");
   var peg$c104 = "{";
   var peg$c105 = "}";
@@ -3121,6 +3099,12 @@ function peg$parse(input, options) {
       return [head].concat(extractList(tail, index));
     }
 
+    function createNode( type, details ) {
+      const node = new ast.Node( type, location() );
+      util.extend( node, details );
+      return node;
+    }
+
 
   peg$begin();
   peg$result = peg$startRuleFunction();

src/config.json

@@ -1,3 +1,7 @@
 {
-    "header": "/* eslint-disable */"
+    "header": "/* eslint-disable */",
+    "dependencies": {
+        "ast": "./ast",
+        "util": "../util"
+    }
 }

src/parser.pegjs

@@ -89,23 +89,28 @@
   function buildList(head, tail, index) {
     return [head].concat(extractList(tail, index));
   }
+
+  function createNode( type, details ) {
+    const node = new ast.Node( type, location() );
+    util.extend( node, details );
+    return node;
+  }
 }
 
 // ---- Syntactic Grammar -----
 
 Grammar
   = __ initializer:(Initializer __)? rules:(Rule __)+ {
-      return {
-        type: "grammar",
-        initializer: extractOptional(initializer, 0),
-        rules: extractList(rules, 0),
-        location: location()
-      };
+      return new ast.Grammar(
+        extractOptional(initializer, 0),
+        extractList(rules, 0),
+        location(),
+      );
     }
 
 Initializer
   = code:CodeBlock EOS {
-      return { type: "initializer", code: code, location: location() };
+      return createNode( "initializer", { code: code } );
     }
 
 Rule
@@ -114,19 +119,15 @@ Rule
     "=" __
     expression:Expression EOS
     {
-      return {
-        type: "rule",
+      return createNode( "rule", {
         name: name,
         expression: displayName !== null
-          ? {
-              type: "named",
+          ? createNode( "named", {
               name: displayName[0],
               expression: expression,
-              location: location()
-            }
+            } )
           : expression,
-        location: location()
-      };
+      } );
     }
 
 Expression
@@ -135,34 +136,28 @@ Expression
 ChoiceExpression
   = head:ActionExpression tail:(__ "/" __ ActionExpression)* {
       return tail.length > 0
-        ? {
-            type: "choice",
+        ? createNode( "choice", {
             alternatives: buildList(head, tail, 3),
-            location: location()
-          }
+          } )
         : head;
     }
 
 ActionExpression
   = expression:SequenceExpression code:(__ CodeBlock)? {
       return code !== null
-        ? {
-            type: "action",
+        ? createNode( "action", {
             expression: expression,
             code: code[1],
-            location: location()
-          }
+          } )
         : expression;
     }
 
 SequenceExpression
   = head:LabeledExpression tail:(__ LabeledExpression)* {
       return tail.length > 0
-        ? {
-            type: "sequence",
+        ? createNode( "sequence", {
             elements: buildList(head, tail, 1),
-            location: location()
-          }
+          } )
         : head;
     }
 
@@ -172,22 +167,18 @@ LabeledExpression
         error(`Label can't be a reserved word "${label[0]}".`, label[1]);
       }
 
-      return {
-        type: "labeled",
+      return createNode( "labeled", {
         label: label[0],
         expression: expression,
-        location: location()
-      };
+      } );
     }
   / PrefixedExpression
 
 PrefixedExpression
   = operator:PrefixedOperator __ expression:SuffixedExpression {
-      return {
-        type: OPS_TO_PREFIXED_TYPES[operator],
+      return createNode( OPS_TO_PREFIXED_TYPES[operator], {
         expression: expression,
-        location: location()
-      };
+      } );
     }
   / SuffixedExpression
 
@@ -198,11 +189,9 @@ PrefixedOperator
 
 SuffixedExpression
   = expression:PrimaryExpression __ operator:SuffixedOperator {
-      return {
-        type: OPS_TO_SUFFIXED_TYPES[operator],
+      return createNode( OPS_TO_SUFFIXED_TYPES[operator], {
         expression: expression,
-        location: location()
-      };
+      } );
     }
   / PrimaryExpression
 
@@ -223,22 +212,18 @@ PrimaryExpression
       // nodes that already isolate label scope themselves. This leaves us with
       // "labeled" and "sequence".
       return expression.type === "labeled" || expression.type === "sequence"
-          ? { type: "group", expression: expression, location: location() }
+          ? createNode( "group", { expression: expression } )
           : expression;
     }
 
 RuleReferenceExpression
   = name:IdentifierName !(__ (StringLiteral __)? "=") {
-      return { type: "rule_ref", name: name, location: location() };
+      return createNode( "rule_ref", { name: name } );
     }
 
 SemanticPredicateExpression
   = operator:SemanticPredicateOperator __ code:CodeBlock {
-      return {
-        type: OPS_TO_SEMANTIC_PREDICATE_TYPES[operator],
-        code: code,
-        location: location()
-      };
+      return createNode( OPS_TO_SEMANTIC_PREDICATE_TYPES[operator], { code: code } );
     }
 
 SemanticPredicateOperator
@@ -322,12 +307,10 @@ UnicodeConnectorPunctuation
 
 LiteralMatcher "literal"
   = value:StringLiteral ignoreCase:"i"? {
-      return {
-        type: "literal",
+      return createNode( "literal", {
         value: value,
         ignoreCase: ignoreCase !== null,
-        location: location()
-      };
+      } );
     }
 
 StringLiteral "string"
@@ -351,13 +334,11 @@ CharacterClassMatcher "character class"
     "]"
     ignoreCase:"i"?
     {
-      return {
-        type: "class",
+      return createNode( "class", {
         parts: parts.filter(part => part !== ""),
         inverted: inverted !== null,
         ignoreCase: ignoreCase !== null,
-        location: location()
-      };
+      } );
     }
 
 ClassCharacterRange
@@ -426,7 +407,7 @@ HexDigit
   = [0-9a-f]i
 
 AnyMatcher
-  = "." { return { type: "any", location: location() }; }
+  = "." { return createNode( "any", {} ); }
 
 CodeBlock "code block"
   = "{" code:Code "}" { return code; }