Guard against redefinition of |undefined|

In most cases, code pattern x === undefined was transformed to typeof(x) === "undefined" and similarly with |!==|. In the generated code, the condition was simply made less strict to avoid performance penalty of string comparison (I don't think JavaScript VMs optimize this specific pattern to avoid it).
15 years ago · 4e968892be
parent d85bfcb2e9
commit 4e968892be
2 changed files with 58 additions and 58 deletions
--- a/lib/compiler.js
+++ b/lib/compiler.js
@ -45,7 +45,7 @@ PEG.GrammarError.prototype = Error.prototype;
 PEG.ArrayUtils = {
  /* Like Python's |range|, but without |step|. */
  range: function(start, stop) {
-    if (stop === undefined) {
+    if (typeof(stop) === "undefined") {
      stop = start;
      start = 0;
    }
@ -199,11 +199,11 @@ PEG.Compiler = {
          /\$\{([a-zA-Z_][a-zA-Z0-9_]*)(\|([a-zA-Z_][a-zA-Z0-9_]*))?\}/g,
          function(match, name, dummy, filter) {
            var value = vars[name];
-            if (value === undefined) {
+            if (typeof(value) === "undefined") {
              throw new Error("Undefined variable: \"" + name + "\".");
            }

-            if (filter !== undefined && filter != "") { // JavaScript engines differ here.
+            if (typeof(filter) !== "undefined" && filter != "") { // JavaScript engines differ here.
              if (filter === "string") {
                return PEG.StringUtils.quote(value);
              } else {
@ -284,7 +284,7 @@ PEG.Compiler = {

        rule_ref:
          function(node) {
-            if (ast[node.name] === undefined) {
+            if (typeof(ast[node.name]) === "undefined") {
              throw new PEG.GrammarError(
                "Referenced rule \"" + node.name + "\" does not exist."
              );
@ -305,7 +305,7 @@ PEG.Compiler = {

    /* Checks that the start rule is defined. */
    function(ast, startRule) {
-      if (ast[startRule] === undefined) {
+      if (typeof(ast[startRule]) === "undefined") {
        throw new PEG.GrammarError(
          "Missing \"" + startRule + "\" rule."
        );
@ -403,7 +403,7 @@ PEG.Compiler = {
        "_parse_${name}: function(context) {",
        "  var cacheKey = ${name|string} + '@' + this._pos;",
        "  var cachedResult = this._cache[cacheKey];",
-        "  if (cachedResult !== undefined) {",
+        "  if (cachedResult) {",
        "    this._pos = cachedResult.nextPos;",
        "    return cachedResult.result;",
        "  }",
--- a/lib/metagrammar.js
+++ b/lib/metagrammar.js
@ -49,7 +49,7 @@ PEG.grammarParser = (function(){
    _parse_grammar: function(context) {
      var cacheKey = "grammar" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -100,7 +100,7 @@ PEG.grammarParser = (function(){
    _parse_rule: function(context) {
      var cacheKey = "rule" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -175,7 +175,7 @@ PEG.grammarParser = (function(){
    _parse_expression: function(context) {
      var cacheKey = "expression" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -197,7 +197,7 @@ PEG.grammarParser = (function(){
    _parse_choice: function(context) {
      var cacheKey = "choice" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -279,7 +279,7 @@ PEG.grammarParser = (function(){
    _parse_sequence: function(context) {
      var cacheKey = "sequence" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -359,7 +359,7 @@ PEG.grammarParser = (function(){
    _parse_prefixed: function(context) {
      var cacheKey = "prefixed" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -428,7 +428,7 @@ PEG.grammarParser = (function(){
    _parse_suffixed: function(context) {
      var cacheKey = "suffixed" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -518,7 +518,7 @@ PEG.grammarParser = (function(){
    _parse_primary: function(context) {
      var cacheKey = "primary" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -653,7 +653,7 @@ PEG.grammarParser = (function(){
    _parse_action: function(context) {
      var cacheKey = "action" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -694,7 +694,7 @@ PEG.grammarParser = (function(){
    _parse_braced: function(context) {
      var cacheKey = "braced" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -779,7 +779,7 @@ PEG.grammarParser = (function(){
    _parse_nonBraceCharacters: function(context) {
      var cacheKey = "nonBraceCharacters" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -813,7 +813,7 @@ PEG.grammarParser = (function(){
    _parse_nonBraceCharacter: function(context) {
      var cacheKey = "nonBraceCharacter" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -846,7 +846,7 @@ PEG.grammarParser = (function(){
    _parse_colon: function(context) {
      var cacheKey = "colon" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -892,7 +892,7 @@ PEG.grammarParser = (function(){
    _parse_slash: function(context) {
      var cacheKey = "slash" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -938,7 +938,7 @@ PEG.grammarParser = (function(){
    _parse_and: function(context) {
      var cacheKey = "and" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -984,7 +984,7 @@ PEG.grammarParser = (function(){
    _parse_not: function(context) {
      var cacheKey = "not" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -1030,7 +1030,7 @@ PEG.grammarParser = (function(){
    _parse_question: function(context) {
      var cacheKey = "question" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -1076,7 +1076,7 @@ PEG.grammarParser = (function(){
    _parse_star: function(context) {
      var cacheKey = "star" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -1122,7 +1122,7 @@ PEG.grammarParser = (function(){
    _parse_plus: function(context) {
      var cacheKey = "plus" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -1168,7 +1168,7 @@ PEG.grammarParser = (function(){
    _parse_lparen: function(context) {
      var cacheKey = "lparen" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -1214,7 +1214,7 @@ PEG.grammarParser = (function(){
    _parse_rparen: function(context) {
      var cacheKey = "rparen" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -1260,7 +1260,7 @@ PEG.grammarParser = (function(){
    _parse_dot: function(context) {
      var cacheKey = "dot" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -1306,7 +1306,7 @@ PEG.grammarParser = (function(){
    _parse_identifier: function(context) {
      var cacheKey = "identifier" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -1463,7 +1463,7 @@ PEG.grammarParser = (function(){
    _parse_literal: function(context) {
      var cacheKey = "literal" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -1514,7 +1514,7 @@ PEG.grammarParser = (function(){
    _parse_doubleQuotedLiteral: function(context) {
      var cacheKey = "doubleQuotedLiteral" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -1579,7 +1579,7 @@ PEG.grammarParser = (function(){
    _parse_doubleQuotedCharacter: function(context) {
      var cacheKey = "doubleQuotedCharacter" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -1631,7 +1631,7 @@ PEG.grammarParser = (function(){
    _parse_simpleDoubleQuotedCharacter: function(context) {
      var cacheKey = "simpleDoubleQuotedCharacter" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -1718,7 +1718,7 @@ PEG.grammarParser = (function(){
    _parse_singleQuotedLiteral: function(context) {
      var cacheKey = "singleQuotedLiteral" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -1783,7 +1783,7 @@ PEG.grammarParser = (function(){
    _parse_singleQuotedCharacter: function(context) {
      var cacheKey = "singleQuotedCharacter" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -1835,7 +1835,7 @@ PEG.grammarParser = (function(){
    _parse_simpleSingleQuotedCharacter: function(context) {
      var cacheKey = "simpleSingleQuotedCharacter" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -1922,7 +1922,7 @@ PEG.grammarParser = (function(){
    _parse_class: function(context) {
      var cacheKey = "class" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -2033,7 +2033,7 @@ PEG.grammarParser = (function(){
    _parse_classCharacterRange: function(context) {
      var cacheKey = "classCharacterRange" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -2099,7 +2099,7 @@ PEG.grammarParser = (function(){
    _parse_classCharacter: function(context) {
      var cacheKey = "classCharacter" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -2126,7 +2126,7 @@ PEG.grammarParser = (function(){
    _parse_bracketDelimitedCharacter: function(context) {
      var cacheKey = "bracketDelimitedCharacter" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -2178,7 +2178,7 @@ PEG.grammarParser = (function(){
    _parse_simpleBracketDelimitedCharacter: function(context) {
      var cacheKey = "simpleBracketDelimitedCharacter" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -2265,7 +2265,7 @@ PEG.grammarParser = (function(){
    _parse_simpleEscapeSequence: function(context) {
      var cacheKey = "simpleEscapeSequence" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -2379,7 +2379,7 @@ PEG.grammarParser = (function(){
    _parse_zeroEscapeSequence: function(context) {
      var cacheKey = "zeroEscapeSequence" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -2435,7 +2435,7 @@ PEG.grammarParser = (function(){
    _parse_hexEscapeSequence: function(context) {
      var cacheKey = "hexEscapeSequence" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -2489,7 +2489,7 @@ PEG.grammarParser = (function(){
    _parse_unicodeEscapeSequence: function(context) {
      var cacheKey = "unicodeEscapeSequence" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -2555,7 +2555,7 @@ PEG.grammarParser = (function(){
    _parse_eolEscapeSequence: function(context) {
      var cacheKey = "eolEscapeSequence" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -2601,7 +2601,7 @@ PEG.grammarParser = (function(){
    _parse_digit: function(context) {
      var cacheKey = "digit" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -2631,7 +2631,7 @@ PEG.grammarParser = (function(){
    _parse_hexDigit: function(context) {
      var cacheKey = "hexDigit" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -2661,7 +2661,7 @@ PEG.grammarParser = (function(){
    _parse_letter: function(context) {
      var cacheKey = "letter" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -2693,7 +2693,7 @@ PEG.grammarParser = (function(){
    _parse_lowerCaseLetter: function(context) {
      var cacheKey = "lowerCaseLetter" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -2723,7 +2723,7 @@ PEG.grammarParser = (function(){
    _parse_upperCaseLetter: function(context) {
      var cacheKey = "upperCaseLetter" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -2753,7 +2753,7 @@ PEG.grammarParser = (function(){
    _parse___: function(context) {
      var cacheKey = "__" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -2810,7 +2810,7 @@ PEG.grammarParser = (function(){
    _parse_comment: function(context) {
      var cacheKey = "comment" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -2845,7 +2845,7 @@ PEG.grammarParser = (function(){
    _parse_singleLineComment: function(context) {
      var cacheKey = "singleLineComment" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -2955,7 +2955,7 @@ PEG.grammarParser = (function(){
    _parse_multiLineComment: function(context) {
      var cacheKey = "multiLineComment" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -3095,7 +3095,7 @@ PEG.grammarParser = (function(){
    _parse_eol: function(context) {
      var cacheKey = "eol" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -3185,7 +3185,7 @@ PEG.grammarParser = (function(){
    _parse_eolChar: function(context) {
      var cacheKey = "eolChar" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }
@ -3215,7 +3215,7 @@ PEG.grammarParser = (function(){
    _parse_whitespace: function(context) {
      var cacheKey = "whitespace" + '@' + this._pos;
      var cachedResult = this._cache[cacheKey];
-      if (cachedResult !== undefined) {
+      if (cachedResult) {
        this._pos = cachedResult.nextPos;
        return cachedResult.result;
      }