Allow auto-loading of partials

Fixes #247

CHANGES

@@ -1,6 +1,8 @@
 = HEAD
 
   * Rename Renderer => Writer.
+  * Allow partials to be loaded dynamically using a callback (thanks @TiddoLangerak
+    for the suggestion).
   * Fixed a bug with higher-order sections that prevented them from being
     passed the raw text of the section from the original template.
   * More concise token format. Tokens also include start/end indices in the

mustache.js

@@ -212,8 +212,12 @@ var Mustache;
       var self = this;
       cache[key] = function (view, partials) {
         if (partials) {
-          for (var name in partials) {
-            self.compilePartial(name, partials[name]);
+          if (typeof partials === "function") {
+            self._loadPartial = partials;
+          } else {
+            for (var name in partials) {
+              self.compilePartial(name, partials[name]);
+            }
           }
         }
 
@@ -269,7 +273,12 @@ var Mustache;
   };
 
   Writer.prototype._partial = function (name, context) {
+    if (!(name in this._partialCache) && this._loadPartial) {
+      this.compilePartial(name, this._loadPartial(name));
+    }
+
     var fn = this._partialCache[name];
+
     return fn ? fn(context) : "";
   };
 
@@ -306,9 +315,8 @@ var Mustache;
   }
 
   /**
-   * Low-level function that compiles the given `tokens` into a
-   * function that accepts two arguments: a Context and a
-   * Writer.
+   * Low-level function that compiles the given `tokens` into a function
+   * that accepts two arguments: a Context and a Writer.
    */
   function compileTokens(tokens) {
     var subRenders = {};

test/parse_test.js

@@ -1,6 +1,6 @@
 var assert = require('assert');
 var vows = require('vows');
-var parse = require('./../mustache').parse;
+var Mustache = require('./../mustache');
 
 // A map of templates to their expected token output. Tokens are in the format:
 // [type, value, startIndex, endIndex].
@@ -59,7 +59,7 @@ var spec = {};
 for (var template in expectations) {
   (function (template, tokens) {
     spec['knows how to parse ' + JSON.stringify(template)] = function () {
-      assert.deepEqual(parse(template), tokens);
+      assert.deepEqual(Mustache.parse(template), tokens);
     };
   })(template, expectations[template]);
 }

test/render_test.js

@@ -2,15 +2,12 @@ var fs = require("fs");
 var path = require("path");
 var assert = require("assert");
 var vows = require("vows");
+var Mustache = require("./../mustache");
 
-var Mustache = require(path.join(__dirname, "..", "mustache"));
 var _files = path.join(__dirname, "_files");
 
 function getContents(testName, ext) {
-  var file = path.join(_files, testName + "." + ext);
-  try {
-    return fs.readFileSync(file, "utf8");
-  } catch (e) {}
+  return fs.readFileSync(path.join(_files, testName + "." + ext), "utf8");
 }
 
 // You can put the name of a specific test to run in the TEST environment
@@ -42,7 +39,13 @@ testNames.forEach(function (testName) {
 
   var template = getContents(testName, "mustache");
   var expect = getContents(testName, "txt");
-  var partial = getContents(testName, "partial");
+
+  var partial;
+  try {
+    partial = getContents(testName, "partial");
+  } catch (e) {
+    // No big deal.
+  }
 
   spec["knows how to render " + testName] = function () {
     Mustache.clearCache();

test/writer_test.js

@@ -0,0 +1,21 @@
+var assert = require("assert");
+var vows = require("vows");
+var Writer = require("./../mustache").Writer;
+
+vows.describe("Mustache.Writer").addBatch({
+  "A Writer": {
+    topic: function () {
+      var writer = new Writer();
+      return writer;
+    },
+    "loads partials correctly": function (writer) {
+      var partial = "The content of the partial.";
+      var result = writer.render("{{>partial}}", {}, function (name) {
+        assert.equal(name, "partial");
+        return partial;
+      });
+
+      assert.equal(result, partial);
+    }
+  }
+}).export(module);