Rename and generalize |generateCache{Header,Footer}|

Rename |generateCache{Header,Footer}| to |generateRule{Header,Footer}|
and change their responsibility to generate overall header/footer of a
rule function (when optimizing for speed) or the |peg$parseRule|
function (when optimizing for speed). This creates a natural place where
to generate tracing code (coming soon).

lib/compiler/passes/generate-javascript.js

@@ -37,24 +37,40 @@ function generateJavascript(ast, options) {
     }
   }
 
-  function generateCacheHeader(ruleIndexCode) {
-    return [
-      'var key    = peg$currPos * ' + ast.rules.length + ' + ' + ruleIndexCode + ',',
-      '    cached = peg$cache[key];',
-      '',
-      'if (cached) {',
-      '  peg$currPos = cached.nextPos;',
-      '  return cached.result;',
-      '}',
-      ''
-    ].join('\n');
+  function generateRuleHeader(ruleIndexCode) {
+    if (options.cache) {
+      return [
+        '',
+        'var key    = peg$currPos * ' + ast.rules.length + ' + ' + ruleIndexCode + ',',
+        '    cached = peg$cache[key];',
+        '',
+        'if (cached) {',
+        '  peg$currPos = cached.nextPos;',
+        '  return cached.result;',
+        '}',
+        ''
+      ].join('\n');
+    } else {
+      return '';
+    }
   }
 
-  function generateCacheFooter(resultCode) {
-    return [
+  function generateRuleFooter(resultCode) {
+    var parts = [];
+
+    if (options.cache) {
+      parts.push([
+        '',
+        'peg$cache[key] = { nextPos: peg$currPos, result: ' + resultCode + ' };'
+      ].join('\n'));
+    }
+
+    parts.push([
       '',
-      'peg$cache[key] = { nextPos: peg$currPos, result: ' + resultCode + ' };'
-    ].join('\n');
+      'return ' + resultCode + ';'
+    ].join('\n'));
+
+    return parts.join('\n');
   }
 
   function generateInterpreter() {
@@ -140,12 +156,9 @@ function generateJavascript(ast, options) {
       '      ends  = [],',
       '      stack = [],',
       '      params, i;',
-      ''
     ].join('\n'));
 
-    if (options.cache) {
-      parts.push(indent2(generateCacheHeader('index')));
-    }
+    parts.push(indent2(generateRuleHeader('index')));
 
     parts.push([
       /*
@@ -324,15 +337,8 @@ function generateJavascript(ast, options) {
       '  }'
     ].join('\n'));
 
-    if (options.cache) {
-      parts.push(indent2(generateCacheFooter('stack[0]')));
-    }
-
-    parts.push([
-      '',
-      '  return stack[0];',
-      '}'
-    ].join('\n'));
+    parts.push(indent2(generateRuleFooter('stack[0]')));
+    parts.push('}');
 
     return parts.join('\n');
   }
@@ -649,26 +655,13 @@ function generateJavascript(ast, options) {
     parts.push([
       'function peg$parse' + rule.name + '() {',
       '  var ' + arrays.map(arrays.range(0, stack.maxSp + 1), s).join(', ') + ';',
-      ''
     ].join('\n'));
 
-    if (options.cache) {
-      parts.push(indent2(
-        generateCacheHeader(asts.indexOfRule(ast, rule.name))
-      ));
-    }
-
+    parts.push(indent2(generateRuleHeader(asts.indexOfRule(ast, rule.name))));
     parts.push(indent2(code));
+    parts.push(indent2(generateRuleFooter(s(0))));
 
-    if (options.cache) {
-      parts.push(indent2(generateCacheFooter(s(0))));
-    }
-
-    parts.push([
-      '',
-      '  return ' + s(0) + ';',
-      '}'
-    ].join('\n'));
+    parts.push('}');
 
     return parts.join('\n');
   }