Create a new mapping between file extensions and engine names at load

time that powers a real implementation of getEngineNameForPattern!

Author: geoffp

builder/pattern_engines/pattern_engines.js

@@ -8,6 +8,7 @@
  *
  */
 
+
 (function () {
   'use strict';
 
@@ -17,6 +18,9 @@
     'handlebars'
   ];
 
+  // mapping of file extensions to engine names, for lookup use
+  var engineNameForExtension = {};
+
   // Object/hash of all loaded pattern engines, empty at first.
   // My intention here is to make this return an object that can be used to
   // obtain any loaded PatternEngine by addressing them like this:
@@ -25,8 +29,17 @@
   // var Mustache = PatternEngines['mustache'];
   //
   var PatternEngines = Object.create({
+    supportedPatternEngineNames: supportedPatternEngineNames,
+
     getEngineNameForPattern: function (pattern) {
-      console.log('pattern file name: ', pattern.fileName);
+      // avoid circular dependency by putting this in here. TODO: is this slow?
+      var of = require('../object_factory');
+
+      if (pattern instanceof of.oPattern) {
+        return engineNameForExtension[pattern.fileExtension];
+      }
+      // otherwise, assume it's a plain mustache template string and act
+      // accordingly
       return 'mustache';
     },
     getEngineForPattern: function (pattern) {
@@ -36,13 +49,29 @@
   });
 
   // try to load all supported engines
-  supportedPatternEngineNames.forEach(function (engineName) {
-    try {
-      PatternEngines[engineName] = require('./engine_' + engineName);
-    } catch (err) {
-      console.log(err, 'pattern engine "' + engineName + '" not loaded. Did you install its dependency with npm?');
-    }
-  });
+  (function loadAllEngines() {
+    supportedPatternEngineNames.forEach(function (engineName) {
+      try {
+        PatternEngines[engineName] = require('./engine_' + engineName);
+      } catch (err) {
+        console.log(err, 'pattern engine "' + engineName + '" not loaded. Did you install its dependency with npm?');
+      }
+    });
+  })();
+
+  // produce a mapping between file extension and engine name for each of the
+  // loaded engines
+  engineNameForExtension = (function () {
+    var mapping = {};
+
+    Object.keys(PatternEngines).forEach(function (engineName) {
+      var extensionForEngine = PatternEngines[engineName].fileExtension;
+      mapping[extensionForEngine] = engineName;
+    });
+
+    return mapping;
+  })();
+
 
   module.exports = PatternEngines;
 })();