Themes: Added truncation to hbs content helper

Fixes #256

- Developed and linked new module, downsize, for tag-safe truncation
- Altered existing content handler to accept options for truncation
- Added tests for handler

Using truncation:

{{content words=10}}
{{content characters=256}}

core/server/helpers/index.js

@@ -1,5 +1,6 @@
 var _ = require('underscore'),
     moment = require('moment'),
+    downsize = require('downsize'),
     when = require('when'),
     hbs = require('express-hbs'),
     errors = require('../errorHandling'),
@@ -29,8 +30,29 @@ coreHelpers = function (ghost) {
     });
 
     // ### Content Helper
-    // Turns content html into a safestring so that the user doesn't have to escape it
+    // 
+    // *Usage example:*
+    // `{{content}}`
+    // `{{content words=20}}`
+    // `{{content characters=256}}`
+    // 
+    // Turns content html into a safestring so that the user doesn't have to
+    // escape it or tell handlebars to leave it alone with a triple-brace.
+    // 
+    // Enables tag-safe truncation of content by characters or words.
+    // 
+    // **returns** SafeString content html, complete or truncated.
+    //
     ghost.registerThemeHelper('content', function (options) {
+        var truncateOptions = (options || {}).hash || {};
+        truncateOptions = _.pick(truncateOptions, ["words", "characters"]);
+
+        if (truncateOptions.words || truncateOptions.characters) {
+            return new hbs.handlebars.SafeString(
+                downsize(this.content, truncateOptions)
+            );
+        }
+
         return new hbs.handlebars.SafeString(this.content);
     });
 

core/test/unit/frontend_helpers_index_spec.js

@@ -31,6 +31,34 @@ describe('Core Helpers', function () {
             should.exist(rendered);
             rendered.string.should.equal(content);
         });
+        
+        it('can truncate content by word', function () {
+            var content = "<p>Hello <strong>World! It's me!</strong></p>",
+                rendered = (
+                    handlebars.helpers.content
+                        .call(
+                            {content: content},
+                            {"hash":{"words": 2}}
+                        )
+                );
+
+            should.exist(rendered);
+            rendered.string.should.equal("<p>Hello <strong>World</strong></p>");
+        });
+        
+        it('can truncate content by character', function () {
+            var content = "<p>Hello <strong>World! It's me!</strong></p>",
+                rendered = (
+                    handlebars.helpers.content
+                        .call(
+                            {content: content},
+                            {"hash":{"characters": 8}}
+                        )
+                );
+
+            should.exist(rendered);
+            rendered.string.should.equal("<p>Hello <strong>Wo</strong></p>");
+        });
     });
 
     describe('Navigation Helper', function () {

package.json

@@ -26,7 +26,8 @@
         "node-uuid": "1.4.0",
         "colors": "0.6.1",
         "semver": "2.1.0",
-        "fs-extra": "0.6.3"
+        "fs-extra": "0.6.3",
+        "downsize": "0.0.2"
     },
     "devDependencies": {
         "grunt": "~0.4.1",