Dynamic partials and partial collections

README.md

@@ -328,6 +328,82 @@ In mustache.js an object of partials may be passed as the third argument to
 `Mustache.render`. The object should be keyed by the name of the partial, and
 its value should be the partial text.
 
+### Dynamic Partials
+
+It is quite common to want to render a partial for each item in a collection.
+Sometimes this will be a common partial but often it will be dependent on each
+item in the collection.
+
+The implicit partial notation of `{{>.}}` renders a partial who's name comes
+from the `partial` key of the current item. The current item becomes the
+context of the partial.
+
+View:
+
+    {
+      "beatles": [
+        { "name": "John", "partial": "dead" },
+        { "name": "Paul", "partial": "alive" },
+        { "name": "George", "partial": "dead" },
+        { "name": "Ringo", "partial": "alive" }
+      ]
+    }
+
+Template:
+
+    base.mustache
+    {{#beatles}}
+    {{>.}}
+    {{/beatles}}
+
+    alive.mustache
+    * Keep it up {{name}}
+
+    dead.mustache
+    * Rest in peace {{name}}
+
+Output:
+
+    * Rest in peace John
+    * Keep it up Paul
+    * Rest in peace George
+    * Keep it up Ringo
+
+#### Partial Collections
+
+As this is such a common pattern, there is a shortcut that renders the named
+partial for each item in a collection. The same example can therefore also be
+accomplished with the following:
+
+View:
+
+    {
+      "beatles": [
+        { "name": "John", "partial": "dead" },
+        { "name": "Paul", "partial": "alive" },
+        { "name": "George", "partial": "dead" },
+        { "name": "Ringo", "partial": "alive" }
+      ]
+    }
+
+Template:
+
+    base.mustache
+    {{@beatles}}
+
+    alive.mustache
+    * Keep it up {{name}}
+
+    dead.mustache
+    * Rest in peace {{name}}
+
+Output:
+
+    * Rest in peace John
+    * Keep it up Paul
+    * Rest in peace George
+    * Keep it up Ringo
+
 ### Set Delimiter
 
 Set Delimiter tags start with an equals sign and change the tag delimiters from

mustache.js

@@ -48,7 +48,7 @@ var Mustache;
   var nonSpaceRe = /\S/;
   var eqRe = /\s*=/;
   var curlyRe = /\s*\}/;
-  var tagRe = /#|\^|\/|>|\{|&|=|!/;
+  var tagRe = /@|#|\^|\/|>|\{|&|=|!/;
 
   // Workaround for https://issues.apache.org/jira/browse/COUCHDB-577
   // See https://github.com/janl/mustache.js/issues/189
@@ -300,7 +300,10 @@ var Mustache;
   };
 
   Renderer.prototype._partial = function (name, context) {
-    var fn = this._partialCache[name];
+    // If the partial name is a dot, render based on the 'partial' key of
+    // the current context, otherwise use default behaviour.
+    var cache = this._partialCache,
+        fn = (name === '.' ? cache[context.lookup("partial")] : cache[name]);
 
     if (fn) {
       return fn(context);
@@ -309,6 +312,20 @@ var Mustache;
     return "";
   };
 
+  Renderer.prototype._partialCollection = function (name, context) {
+    var value = context.lookup(name), buffer = "";
+
+    // If we have an array, render the partial defined by the 'partial'
+    // key for each item in the array.
+    if (isArray(value)) {
+      for (var i = 0, len = value.length; i < len; ++i) {
+        buffer += this._partial('.', context.push(value[i]));
+      }
+    }
+
+    return buffer;
+  };
+
   Renderer.prototype._name = function (name, context, escape) {
     var value = context.lookup(name);
 
@@ -355,6 +372,9 @@ var Mustache;
       case ">":
         body.push("r._partial(" + quote(token.value) + ", c)");
         break;
+      case "@":
+        body.push("r._partialCollection(" + quote(token.value) + ", c)");
+        break;
       case "text":
         body.push(quote(token.value));
         break;

test/_files/partial_dynamic_collection.js

@@ -0,0 +1,6 @@
+({
+  items: [
+    { content: 'Hello', partial: 'partial' },
+    { content: 'Hello', partial: 'partial2' }
+  ]
+})

test/_files/partial_dynamic_collection.mustache

@@ -0,0 +1 @@
+{{@items}}

test/_files/partial_dynamic_collection.partial

@@ -0,0 +1 @@
+I am partial 1

test/_files/partial_dynamic_collection.partial2

@@ -0,0 +1 @@
+I am partial 2

test/_files/partial_dynamic_collection.txt

@@ -0,0 +1,2 @@
+I am partial 1
+I am partial 2

test/_files/partial_dynamic_collection_implicit.js

@@ -0,0 +1,7 @@
+({
+  title: 'Dynamic partial collection',
+  items: [
+    { content: 'Hello', partial: 'partial' },
+    { content: 'Hello', partial: 'partial2' }
+  ]
+})

test/_files/partial_dynamic_collection_implicit.mustache

@@ -0,0 +1,7 @@
+Header
+{{#items}}
+Before
+{{>.}}
+After
+{{/items}}
+Footer

test/_files/partial_dynamic_collection_implicit.partial

@@ -0,0 +1 @@
+I am partial 1

test/_files/partial_dynamic_collection_implicit.partial2

@@ -0,0 +1 @@
+I am partial 2

test/_files/partial_dynamic_collection_implicit.txt

@@ -0,0 +1,8 @@
+Header
+Before
+I am partial 1
+After
+Before
+I am partial 2
+After
+Footer

test/parse_test.js

@@ -49,7 +49,9 @@ var expectations = {
   "{{#a}}{{/a}}hi{{#b}}{{/b}}\n"            : [ { type: '#', value: 'a', tokens: [] }, { type: 'text', value: 'hi' }, { type: '#', value: 'b', tokens: [] }, { type: 'text', value: '\n' } ],
   "{{a}}\n{{b}}\n\n{{#c}}\n{{/c}}\n"        : [ { type: 'name', value: 'a' }, { type: 'text', value: '\n' }, { type: 'name', value: 'b' }, { type: 'text', value: '\n\n' }, { type: '#', value: 'c', tokens: [] } ],
   "{{#foo}}\n  {{#a}}\n    {{b}}\n  {{/a}}\n{{/foo}}\n"
-                                            : [ { type: "#", value: "foo", tokens: [ { type: "#", value: "a", tokens: [ { type: "text", value: "    " }, { type: "name", value: "b" }, { type: "text", value: "\n" } ] } ] } ]
+                                            : [ { type: "#", value: "foo", tokens: [ { type: "#", value: "a", tokens: [ { type: "text", value: "    " }, { type: "name", value: "b" }, { type: "text", value: "\n" } ] } ] } ],
+  "{{>.}}"                                  : [ { type: '>', value: '.' } ],
+  "{{@collection}}"                         : [ { type: '@', value: 'collection' } ]
 };
 
 var spec = {};

test/render_test.js

@@ -43,13 +43,18 @@ testNames.forEach(function (testName) {
   var template = getContents(testName, "mustache");
   var expect = getContents(testName, "txt");
   var partial = getContents(testName, "partial");
+  var partial2 = getContents(testName, "partial2");
 
   spec["knows how to render " + testName] = function () {
     Mustache.clearCache();
 
-    var output;
-    if (partial) {
-      output = Mustache.render(template, view, {partial: partial});
+    var output, partials = {};
+
+    if (partial) { partials['partial'] = partial; }
+    if (partial2) { partials['partial2'] = partial2; }
+
+    if (partial || partial2) {
+      output = Mustache.render(template, view, partials);
     } else {
       output = Mustache.render(template, view);
     }