working on issue zaach#348: reconstructed the 'empty action call' det…

…ection logic so that the Jison code itself delivers an 'empty call' to compare against. The bug in zaach#348 is most probably due to the replacements of comment start/end markers in `preprocessActionCode()` and `postprocessActionCode()` while the original comparison happens between these calls, screwing up the detection, which drives the code stripper which removes the `this.performAction.call` code. Still ho-hum, though, as I don't see this happen... Anyway, this bit of rework is necessary anyway as now we're better equipped to keep detecting empty performAction functions.

lib/jison.js

@@ -1530,20 +1530,6 @@ generator.buildProductionActions = function buildProductionActions() {
         return provideSymbolAsSourcecode(sym);
     });
 
-    var actionsBaseline = [
-        'function parser__PerformAction(' + parameters + ') {',
-        '/* this == yyval */',
-        'var yy = this.yy;',
-        '',
-        'switch (yystate) {',
-        '}',
-        '}'
-    ].join('\n');
-
-    // report whether there are actually any custom actions at all (or any custom actions' prep code); this
-    // flag will be set when the generated function is essentially *empty*:
-    this.actionsAreAllDefault = (actionsBaseline.replace(/\s+/g, ' ') === this.performAction.replace(/\s+/g, ' '));
-
     this.actionsUseYYLENG = analyzeFeatureUsage(this.performAction, /\byyleng\b/g, 1);
     this.actionsUseYYLINENO = analyzeFeatureUsage(this.performAction, /\byylineno\b/g, 1);
     this.actionsUseYYTEXT = analyzeFeatureUsage(this.performAction, /\byytext\b/g, 1);
@@ -1572,6 +1558,44 @@ generator.buildProductionActions = function buildProductionActions() {
     this.actionsUseYYSSTACK = analyzeFeatureUsage(this.performAction, /\byysstack\b/g, 1);
     this.actionsUseYYSTACKPOINTER = analyzeFeatureUsage(this.performAction, /\byysp\b/g, 1);
 
+    this.performAction = this.performAction
+    .replace(/\byyerror\b/g, 'yy.parser.yyError')
+    .replace(/\byyerrok\b(?:\s*\(\s*\))?/g, 'yy.parser.yyErrOk()')
+    .replace(/\byyclearin\b(?:\s*\(\s*\))?/g, 'yy.parser.yyClearIn()');
+
+    // Now that we've completed all macro expansions, it's time to execute
+    // the recovery code, i.e. the postprocess:
+    this.performAction = postprocessActionCode(this.performAction);
+
+    // Now obtain an *EMPTY* `parser__PerformAction()` to compare against and see if all the work
+    // actually delivered any code that is important and needs executing.
+    // If not, we can discard the entire function!
+    //
+    // Since we'll recursively invoke this implementation (but with a completely different
+    // `this` reference!), we MUST check if we're currently already constructing such an
+    // 'empty call':
+    var actionsBaseline = '';
+    if (!this.__constructing_empty_PerformAction_function) {
+      var empty_parser = {
+        __constructing_empty_PerformAction_function: true,
+
+        parseParams: this.parseParams,
+        moduleInclude: '',
+        moduleInit: [],
+        actionInclude: '',
+        productions: [],
+        nonterminals: [],
+        symbols: [],
+        operators: [],
+      };
+      buildProductionActions.call(empty_parser);
+      var actionsBaseline = empty_parser.performAction;
+
+      // report whether there are actually any custom actions at all (or any custom actions' prep code); this
+      // flag will be set when the generated function is essentially *empty*:
+      this.actionsAreAllDefault = (actionsBaseline.replace(/\s+/g, ' ') === this.performAction.replace(/\s+/g, ' '));
+    }
+
     if (devDebug || this.DEBUG) {
         Jison.print('Optimization analysis: ', {
             actionsAreAllDefault: this.actionsAreAllDefault,
@@ -1596,15 +1620,6 @@ generator.buildProductionActions = function buildProductionActions() {
         });
     }
 
-    this.performAction = this.performAction
-    .replace(/\byyerror\b/g, 'yy.parser.yyError')
-    .replace(/\byyerrok\b(?:\s*\(\s*\))?/g, 'yy.parser.yyErrOk()')
-    .replace(/\byyclearin\b(?:\s*\(\s*\))?/g, 'yy.parser.yyClearIn()');
-
-    // Now that we've completed all macro expansions, it's time to execute
-    // the recovery code, i.e. the postprocess:
-    this.performAction = postprocessActionCode(this.performAction);
-
     // And before we leave, as a SIDE EFFECT of this call, we also fixup
     // the other code chunks specified in the grammar file:
     //