Extensions

Extensions add trusted syntax, rendering, transformations, analysis, or resource-backed behavior to an immutable factory profile. Install only the capabilities required by the document format.

<?php

use Alto\Markdown\Extension\Footnote\FootnoteExtension;
use Alto\Markdown\Extension\Highlight\HighlightExtension;
use Alto\Markdown\Markdown;

$factory = Markdown::github()->with(
    new FootnoteExtension(),
    new HighlightExtension(),
);

Choose bundled extensions by outcome:

• Syntax adds author-facing Markdown constructs.
• Rendering projects or decorates document output.
• Resources resolves bounded external content.

Development

• Compatibility: understand extension versioning.
• Extension points: select the correct contract.
• Custom extension: register trusted application behavior.

Capabilities

An extension has a stable name and implements only the public capabilities its behavior requires.

Definitions, contexts, and value objects under Alto\Markdown\Extension are public unless marked @internal. Parser tapes, compact node IDs, compiler caches, and internal dispatch objects are not extension contracts.

The returned factory is immutable. Extension compilation rejects invalid names, duplicate or incompatible definitions, and unavailable parser triggers before processing a document. Extensions execute as trusted application code.