Code Highlight - ALTO PHP

Alto Code Highlight is a server-side syntax highlighter for PHP 8.4 and later. It parses source code in PHP and returns escaped, theme-ready HTML. It does not require a browser-side highlighter.

Documentation

Installation covers requirements, Composer, and a smoke test.
Getting started goes from source code to a complete HTML page.
Examples presents canonical examples and generated visual previews.

Languages

Languages lists every accepted language identifier.
Embedded languages explains HTML, SVG, Markdown, and Twig delegation.

Theming

Themes lists all built-in variants and constructors.
Theme adapters shows how to reuse local Highlight.js, Prism, or TextMate theme files.
Creating a theme implements ThemeInterface from semantic scopes to CSS.

API

Public API defines the supported entry points, extension contracts, and compatibility boundary.

Public API at a glance

Alto\Code\Highlight\Highlighter is the main entry point:

<?php
use Alto\Code\Highlight\Highlighter;
use Alto\Code\Highlight\Theme\AltoTheme;

$highlighter = new Highlighter(new AltoTheme());
$html = $highlighter->highlight('<?php echo "Hello";', 'php');
$css = $highlighter->getTheme()->getStylesheet();

The returned HTML is a <pre class="alto-highlight"> element containing a <code> element and semantic <span> elements. Source text is HTML-escaped during rendering. Add the selected theme's stylesheet once to the page, then insert the returned HTML without escaping it again.