highlight.php is a server-side syntax highlighter written in PHP that currently supports 185 languages. It's a port of highlight.js by Ivan Sagalaev that makes full use of the language and style definitions of the original JavaScript project.

This is the README for highlight.php v10, which is currently under development. The latest stable release is the 9.18.x series.

• Installation + Setup
  • Composer Version Constraints
• Usage
  • Explicit Mode
  • Automatic Language Detection Mode
  • Stylesheets
• Highlighter Utilities
• Versioning
  • Backward Compatibility Promise
• Some History
• License

The recommended approach is to install the project through Composer.

composer require scrivo/highlight.php

If you're not using Composer, ensure that the classes defined in the Highlight namespace can be found either by inclusion or by an autoloader. A trivial autoloader for this purpose is included in this project as Highlight\Autoloader.php

When requiring this project in your composer.json, it is recommended you use the caret version range and use only the major and minor values; i.e. ^9.14.

It's come to our attention that a lot of tutorials and projects out there are locking themselves into highly specific versions of this project; e.g. "scrivo/highlight.php": "v9.12.0.1". Please do not do this or encourage it. We promise a reliable backward compatibility policy so there's no reason to lock yourself to such a specific version. By doing this, you are preventing yourself or your users from receiving updates to language definitions and bug fixes.

The \Highlight\Highlighter class contains the syntax highlighting functionality. You can choose between two highlighting modes:

1. explicit mode
2. automatic language detection mode

In explicit mode, you must define which language you will be highlighting as.

// Instantiate the Highlighter.
$hl = new \Highlight\Highlighter();
$code = file_get_contents('some_ruby_script.rb');

try {
    // Highlight some code.
    $highlighted = $hl->highlight('ruby', $code);

    echo "<pre><code class=\"hljs {$highlighted->language}\">";
    echo $highlighted->value;
    echo "</code></pre>";
}
catch (DomainException $e) {
    // This is thrown if the specified language does not exist

    echo "<pre><code>";
    echo htmlentities($code);
    echo "</code></pre>";
}

Alternatively you can use the automatic detection mode, which highlights your code with the language the library thinks is best. It is highly recommended you explicitly choose the language or limit the number of languages to automatically detect to reduce the number of inaccuracies.

Warning: Auto-detection occurs in a brute force fashion and the language with the most accurate result will be selected. This is extremely inefficient as you supply more languages and may not always be 100% accurate if similar languages are configured.

$hl = new \Highlight\Highlighter();
$hl->setAutodetectLanguages(array('ruby', 'python', 'perl'));

$highlighted = $hl->highlightAuto(file_get_contents('some_ruby_script.rb'));

echo "<pre><code class=\"hljs {$highlighted->language}\">";
echo $highlighted->value;
echo "</code></pre>";

If no autodetect languages are set in the highlighter, then every language will be used and cause significant performance issues.

The same stylesheets available in the highlight.js project are available in the styles directory of this project and may be included in your own CSS or made accessible to your web server.

The core of the project is loyal port of highlight.js and is available under the main Highlight namespace. A series of convenience functions are provided under the HighlightUtilities namespace to introduce additional functionality without the need for another dependency.

Available functions:

• getAvailableStyleSheets(bool $filePaths = false): string[]
• getStyleSheet(string $name): false|string
• getStyleSheetFolder(): string
• getStyleSheetPath(string $name): string
• getLanguagesFolder(): string
• getLanguageDefinitionPath(string $name): string
• getThemeBackgroundColor(string $name): float[]
• splitCodeIntoArray(string $html): false|string[]

This project will follow the same version numbers as the highlight.js project with regards to languages, meaning that a language definition available in highlight.js 9.12.0 will be available in highlight.php 9.12.0. However, there are times where bugs may arise in this project or its translated definition files, so there'll be one more number appended to the version number. For example, version 9.12.0.1 will contain all of the same languages as highlight.js 9.12.0 but also contain fixes solely to this project. This is done so this project can have version bumps without conflicts should highlight.js release version 9.12.1.

Despite the fact that the semantic versioning used in this project mirrors that of highlight.js, this project will adhere to Symfony's Backward Compatibility Promise. You can rest assured that there will be no breaking changes during 9.x and any deprecations will be marked with @deprecated and won't be removed until the next major release.

Geert Bergman Sep 30, 2013

JavaScript code highlighting is very convenient and in many cases just what you want to use. Especially for programming blogs I would not advice you to use otherwise. But there are occasions where you're better off with a more 'static' approach, for instance if you want to send highlighted code in an email or for API documents. For this I needed a code highlighting program preferably written in PHP.

I couldn't found any satisfactory PHP solution so I decided to port one from JavaScript. After some comparison of different highlighting programs based on license, technology, language support highlight.js came out most favorable in my opinion.

It was my decision not to make a PHP highlighter but to do a port of highlight.js, these are different things. The goal was to make it work exactly as highlight.js to make as much use as possible of the language definitions and CSS files of the original program.

Happy coding!

BSD