Add support for a custom highlighter function.

README.md

@@ -48,7 +48,49 @@ To support other Markdown or ANSI-coloring engines, set `nb.markdown` and/or `nb
 
 ## Code-Highlighting
 
-Notebook.js plays well with code-highlighting libraries. See [NBPreview](https://github.com/jsvine/nbpreview) for an example of how to add support for your preferred highlighter.
+Notebook.js plays well with code-highlighting libraries. See [NBPreview](https://github.com/jsvine/nbpreview)
+for an example of how to add support for your preferred highlighter. However, if you wish to inject your own
+highlighting, you can install a custom highlighter function by adding it under the `highlighter` name in an
+`notebookjs` instance. For instance, here is an implementation which colorizes languages using
+[Prismjs](http://prismjs.com) during page generation for a static site:
+
+```js
+var Prism = require('prismjs');
+
+var highlighter = function(code, lang) {
+    if (typeof lang === 'undefined') lang = 'markup';
+
+    if (!Prism.languages.hasOwnProperty(lang)) {
+        try {
+            require('prismjs/components/prism-' + lang + '.js');
+        } catch (e) {
+            console.warn('** failed to load Prism lang: ' + lang);
+            Prism.languages[lang] = false;
+        }
+    }
+
+    return Prism.languages[lang] ? Prism.highlight(code, Prism.languages[lang]) : code;
+};
+
+var nb = require("notebookjs");
+nb.highlighter = function(text, pre, code, lang) {
+        var language = lang || 'text';
+        pre.className = 'language-' + language;
+        if (typeof code != 'undefined') {
+            code.className = 'language-' + language;
+        }
+        return highlighter(text, language);
+    };
+```
+
+A `highlighter` function takes up to four arguments:
+
+* `text` -- text of the cell to highlight
+* `pre` -- the DOM `<pre>` node that holds the cell
+* `code` -- the DOM `<code>` node that holds the cell (if `undefined` then text is not code)
+* `lang` -- the language of the code in the cell (if `undefined` then text is not code)
+
+The function should at least return the original `text` value if it cannot perform any highlighting.
 
 ## MathJax 
 

notebook.js

@@ -58,6 +58,7 @@
         prefix: "nb-",
         markdown: getMarkdown() || ident,
         ansi: getAnsi() || ident,
+        highlighter: ident,
         VERSION: VERSION
     };
 
@@ -81,7 +82,7 @@
         var lang = this.cell.raw.language || m.language || m.language_info.name;
         code_el.setAttribute("data-language", lang);
         code_el.className = "lang-" + lang;
-        code_el.innerHTML = escapeHTML(joinText(this.raw));
+        code_el.innerHTML = nb.highlighter(escapeHTML(joinText(this.raw)), pre_el, code_el, lang);
         pre_el.appendChild(code_el);
         holder.appendChild(pre_el);
         this.el = holder;
@@ -169,7 +170,7 @@
     var render_error = function () {
         var el = makeElement("pre", [ "pyerr" ]);
         var raw = this.raw.traceback.join("\n");
-        el.innerHTML = nb.ansi(escapeHTML(raw));
+        el.innerHTML = nb.highlighter(nb.ansi(escapeHTML(raw)), el);
         return el;
     };
 
@@ -188,7 +189,7 @@
         "stream": function () {
             var el = makeElement("pre", [ (this.raw.stream || this.raw.name) ]);
             var raw = joinText(this.raw.text);
-            el.innerHTML = nb.ansi(escapeHTML(raw));
+            el.innerHTML = nb.highlighter(nb.ansi(escapeHTML(raw)), el);
             return el;
         }
     };