Rename |_element| to |_expression| in AST

All nodes which have one subexpression store it in the |_expression| property
now.

lib/compiler.js

@@ -216,11 +216,11 @@ PEG.Grammar.Choice = function(alternatives) {
   this._alternatives = alternatives;
 };
 
-PEG.Grammar.Optional = function(element) { this._element = element; };
+PEG.Grammar.Optional = function(expression) { this._expression = expression; };
 
-PEG.Grammar.ZeroOrMore = function(element) { this._element = element; };
+PEG.Grammar.ZeroOrMore = function(expression) { this._expression = expression; };
 
-PEG.Grammar.OneOrMore = function(element) { this._element = element; };
+PEG.Grammar.OneOrMore = function(expression) { this._expression = expression; };
 
 PEG.Grammar.AndPredicate = function(expression) {
   this._expression = expression;
@@ -264,13 +264,13 @@ PEG.Grammar.extendNodes("checkReferencedRulesExist", {
     },
 
   Optional:
-    function(grammar) { this._element.checkReferencedRulesExist(grammar); },
+    function(grammar) { this._expression.checkReferencedRulesExist(grammar); },
 
   ZeroOrMore:
-    function(grammar) { this._element.checkReferencedRulesExist(grammar); },
+    function(grammar) { this._expression.checkReferencedRulesExist(grammar); },
 
   OneOrMore:
-    function(grammar) { this._element.checkReferencedRulesExist(grammar); },
+    function(grammar) { this._expression.checkReferencedRulesExist(grammar); },
 
   AndPredicate:
     function(grammar) { this._expression.checkReferencedRulesExist(grammar); },
@@ -320,17 +320,17 @@ PEG.Grammar.extendNodes("checkNoLeftRecursion", {
 
   Optional:
     function(grammar, appliedRules) {
-      this._element.checkNoLeftRecursion(grammar, appliedRules);
+      this._expression.checkNoLeftRecursion(grammar, appliedRules);
     },
 
   ZeroOrMore:
     function(grammar, appliedRules) {
-      this._element.checkNoLeftRecursion(grammar, appliedRules);
+      this._expression.checkNoLeftRecursion(grammar, appliedRules);
     },
 
   OneOrMore:
     function(grammar, appliedRules) {
-      this._element.checkNoLeftRecursion(grammar, appliedRules);
+      this._expression.checkNoLeftRecursion(grammar, appliedRules);
     },
 
   AndPredicate:
@@ -891,55 +891,55 @@ PEG.Grammar.Choice.prototype.compile = function(resultVar) {
 };
 
 PEG.Grammar.Optional.prototype.compile = function(resultVar) {
-  var elementResultVar = PEG.Compiler.generateUniqueIdentifier("result");
+  var expressionResultVar = PEG.Compiler.generateUniqueIdentifier("result");
 
   return PEG.Compiler.formatCode(
-    "${elementCode}",
-    "var ${resultVar} = ${elementResultVar} !== null ? ${elementResultVar} : '';",
+    "${expressionCode}",
+    "var ${resultVar} = ${expressionResultVar} !== null ? ${expressionResultVar} : '';",
     {
-      elementCode:      this._element.compile(elementResultVar),
-      elementResultVar: elementResultVar,
-      resultVar:        resultVar
+      expressionCode:      this._expression.compile(expressionResultVar),
+      expressionResultVar: expressionResultVar,
+      resultVar:           resultVar
     }
   );
 };
 
 PEG.Grammar.ZeroOrMore.prototype.compile = function(resultVar) {
-  var elementResultVar = PEG.Compiler.generateUniqueIdentifier("result");
+  var expressionResultVar = PEG.Compiler.generateUniqueIdentifier("result");
 
   return PEG.Compiler.formatCode(
     "var ${resultVar} = [];",
-    "${elementCode}",
-    "while (${elementResultVar} !== null) {",
-    "  ${resultVar}.push(${elementResultVar});",
-    "  ${elementCode}",
+    "${expressionCode}",
+    "while (${expressionResultVar} !== null) {",
+    "  ${resultVar}.push(${expressionResultVar});",
+    "  ${expressionCode}",
     "}",
     {
-      elementCode:      this._element.compile(elementResultVar),
-      elementResultVar: elementResultVar,
-      resultVar:        resultVar
+      expressionCode:      this._expression.compile(expressionResultVar),
+      expressionResultVar: expressionResultVar,
+      resultVar:           resultVar
     }
   );
 };
 
 PEG.Grammar.OneOrMore.prototype.compile = function(resultVar) {
-  var elementResultVar = PEG.Compiler.generateUniqueIdentifier("result");
+  var expressionResultVar = PEG.Compiler.generateUniqueIdentifier("result");
 
   return PEG.Compiler.formatCode(
-    "${elementCode}",
-    "if (${elementResultVar} !== null) {",
+    "${expressionCode}",
+    "if (${expressionResultVar} !== null) {",
     "  var ${resultVar} = [];",
-    "  while (${elementResultVar} !== null) {",
-    "    ${resultVar}.push(${elementResultVar});",
-    "    ${elementCode}",
+    "  while (${expressionResultVar} !== null) {",
+    "    ${resultVar}.push(${expressionResultVar});",
+    "    ${expressionCode}",
     "  }",
     "} else {",
     "  var ${resultVar} = null;",
     "}",
     {
-      elementCode:      this._element.compile(elementResultVar),
-      elementResultVar: elementResultVar,
-      resultVar:        resultVar
+      expressionCode:      this._expression.compile(expressionResultVar),
+      expressionResultVar: expressionResultVar,
+      resultVar:           resultVar
     }
   );
 };