PreprocessRule.apply

How to read this API

These are TypeScript APIs compiled into SnapTeX; a .tex project cannot load them at runtime.

• function name(...) is a helper that your rule imports and calls.
• apply(...), render(...), extract(...), and collect(...) are callbacks that your rule implements and SnapTeX calls.
• renderer.name(...), context.name(...), input.name(...), and deps.name(...) are methods SnapTeX supplies to callbacks; do not import or construct them.
• service.name(...) is an instance method called after your host or test constructs PreviewUpdateService.

Register extension declarations through SNAP_TEX_RULES in src/rules.ts. See Source API Scope for imports, value ownership, output safety, rebuilds, and testing.

Transforms one block in the legacy rendering pipeline. You implement this callback on a PreprocessRule; you do not call it directly.

Signature

apply(text: string, renderer: RenderContext): string

Parameters

Parameter	Description
text	Current block after all lower-priority legacy rules
renderer	Current document's legacy RenderContext

SmartRenderer supplies both values. The rule should treat text as its complete input and return a string for the next rule even when no match is found.

Returns

The source passed to the next legacy rule. After the final rule, Markdown-it renders the result and protected HTML is restored.

Call relationships

• Called by: SmartRenderer.renderBlockToHtml in ascending rule priority.
• Usually calls: balanced source readers, renderer.protectHtml, or renderer.renderInline.
• Does not run in: AST mode.

previous rule output -> apply(text, renderer) -> next rule input -> Markdown

const RULE: PreprocessRule = {
    priority: 200,
    apply: (text, _renderer) =>
        text.replace(/\\draftmarker\b/g, '')
};

SnapTeX still supplies the second argument. The _renderer name makes the complete callback shape visible while showing that this rule intentionally does not use the rendering context.

priority controls ordering; it does not match source. Always return the unmodified text when the rule does not apply.

See also

• Legacy rule contract
• replaceLatexCommandCalls