diff --git a/content/developer-tools/syntax-highlighting.md b/content/developer-tools/syntax-highlighting.md index cf80e93ed..deaa04908 100644 --- a/content/developer-tools/syntax-highlighting.md +++ b/content/developer-tools/syntax-highlighting.md @@ -13,9 +13,184 @@ slug: aliases: [/extras/highlighting/,/extras/highlight/] toc: true needsreview: true -notesforauthors: --- +Hugo provides the ability for you to highlight source code in _two different ways_ — either pre-processed server side from your content, or to defer the processing to the client side, using a JavaScript library. + +**The advantage of server side** is that it doesn’t depend on a JavaScript library and consequently works very well when read from an RSS feed. + +**The advantage of client side** is that it doesn’t cost anything when building your site and some of the highlighting scripts available cover more languages than Pygments does. + +## Server-side + +For the pre-processed approach, highlighting is performed by an external Python-based program called [Pygments](http://pygments.org/) and is triggered via an embedded Hugo shortcode (see example below). If Pygments is absent from the path, it will silently simply pass the content along unhighlighted. + +### Pygments + +If you have never worked with Pygments before, here is a brief primer: + ++ Install Python from [python.org](https://www.python.org/downloads/). Version 2.7.x is already sufficient. ++ Run `pip install Pygments` in order to install Pygments. Once installed, Pygments gives you a command `pygmentize`. Make sure it sits in your PATH, otherwise Hugo cannot find it. + +On Debian and Ubuntu systems, you may also install Pygments by running `sudo apt-get install python3-pygments`. + +Hugo gives you two options that you can set with the variable `pygmentsuseclasses` (default `false`) in `config.toml` (or `config.yaml`). + +1. Color-codes for highlighting keywords are directly inserted if `pygmentsuseclasses = false` (default). See in the example below. The color-codes depend on your choice of the `pygmentsstyle` (default `"monokai"`). You can explore the different color styles on [pygments.org](http://pygments.org/) after inserting some example code. +2. If you choose `pygmentsuseclasses = true`, Hugo includes class names in your code instead of color-codes. For class-names to be meaningful, you need to include a `.css`-file in your website representing your color-scheme. You can either generate this `.css`-files according to this [description](http://pygments.org/docs/cmdline/) or download the standard ones from the [GitHub pygments-css repository](https://github.com/richleland/pygments-css). + +### Usage + +Highlighting is carried out via the in-built shortcode `highlight`. `highlight` takes exactly one required parameter of language, and requires a closing shortcode. Note that `highlight` is _not_ used for client-side javascript highlighting. + +### Example + +``` +{{}} +
+
+

{{ .Title }}

+ {{ range .Data.Pages }} + {{ .Render "summary"}} + {{ end }} +
+
+{{}} +``` + +### Example Output + +``` +<section id="main"> + <div> + <h1 id="title">{{ .Title }}</h1> + {{ range .Data.Pages }} + {{ .Render "summary"}} + {{ end }} + </div> +</section> +``` + +### Options + +Options to control highlighting can be added as a quoted, comma separated key-value list as the second argument in the shortcode. The example below will highlight as language `go` with inline line numbers, with line number 2 and 3 highlighted. + +``` +{{}} +var a string +var b string +var c string +var d string +{{}} +``` + +Supported keywords: `style`, `encoding`, `noclasses`, `hl_lines`, `linenos`. Note that `style` and `noclasses` will override the similar setting in the global config. + +The keywords are the same you would using with Pygments from the command line, see the [Pygments doc](http://pygments.org/docs/) for more info. + +### Code fences + +It is also possible to add syntax highlighting with GitHub flavoured code fences. To enable this, set the `PygmentsCodeFences` to `true` in Hugo's configuration file. + +```` +``` html +
+
+

{{ .Title }}

+ {{ range .Data.Pages }} + {{ .Render "summary"}} + {{ end }} +
+
+``` +```` + +### Disclaimers + + * Pygments is relatively slow and _causes a performance hit when building your site_, but Hugo has been designed to cache the results to disk. + * The caching can be turned off by setting the `--ignoreCache` flag to `true`. + * Languages available depends on your Pygments installation. + +## Client-side + +Alternatively, code highlighting can be done in client-side JavaScript. + +Client-side syntax highlighting is very simple to add. You'll need to pick +a library and a corresponding theme. Some popular libraries are: + +- [Highlight.js] +- [Prism] +- [Rainbow] +- [Syntax Highlighter] +- [Google Prettify] + +### Highlight.js example + +This example uses the popular [Highlight.js] library, hosted by [Yandex], a popular Russian search engine. + +In your `./layouts/partials/` (or `./layouts/chrome/`) folder, depending on your specific theme, there will be a snippet that will be included in every generated HTML page, such as `header.html` or `header.includes.html`. Simply add the css and js to initialize [Highlight.js]: + +``` + + + +``` + +### Prism example + +Prism is another popular highlighter library, used on some major sites. Similar to Highlight.js, you simply load `prism.css` in your `` via whatever Hugo partial template is creating that part of your pages, like so: + +```html +... + +... +``` + +... and add `prism.js` near the bottom of your `` tag, again in whatever Hugo partial template is appropriate for your site or theme. + +```html +... + +... + +``` + +In this example, the local paths indicate that your own copy of these files are being added to the site, typically under `./static/`. + +### Using Client-side highlighting + +To use client-side highlighting, most of these javascript libraries expect your code to be wrapped in semantically correct `` tags, with the language expressed in a class attribute on the `` tag, such as `class="language-abc"`, where the `abc` is the code the highlighter script uses to represent that language. + +The script would be looking for classes like `language-go`, `language-html`, or `language-css`. If you look at the page's source, it would be marked up like so: + +```html +
+
+body {
+  font-family: "Noto Sans", sans-serif;
+}
+
+
+``` + +The markup in your content pages (e.g. `my-css-tutorial.md`) needs to look like the following, with the name of the language to be highlighted entered directly after the first "fence", in a fenced code block: + +
~~~css
+body {
+  font-family: "Noto Sans", sans-serif;
+}
+~~~
+ +When passed through the highlighter script, it would yield something like this output when viewed on your rendered page: + +```css +body { + font-family: "Noto Sans", sans-serif; +} +``` + +Please see individual libraries' documentation for how to implement each of the JavaScript-based libraries. + ## Code Blocks in Markdown ## Using Pygments with Hugo @@ -26,3 +201,9 @@ notesforauthors: ### Prism.js +[Prism]: http://prismjs.com +[Highlight.js]: http://highlightjs.org/ +[Rainbow]: http://craig.is/making/rainbows +[Syntax Highlighter]: http://alexgorbatchev.com/SyntaxHighlighter/ +[Google Prettify]: https://github.com/google/code-prettify +[Yandex]: http://yandex.ru/ \ No newline at end of file