MetadataExtractor

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.

Extracts document-level metadata and source ranges from LaTeX source. Register this callback in metadataExtractors; LatexDocument calls it during document parsing.

Signature

type MetadataExtractor = (text: string) => MetadataExtractionResult

Returns

A partial metadata result. It may include built-in metadata fields, custom scalar values, and ranges to blank from ordinary body rendering.

The input has already passed through comment masking: each unescaped comment body is shortened to %, while line structure is preserved. \\today has also been expanded before extractors run.

Returned field	Consumer
Metadata values	Merged into document.metadata
custom values	Stored under metadata.custom
ranges	Blanked from body rendering while preserving source lines

Call relationships

• Called by: LatexDocument during metadata parsing, in registry array order.
• Usually calls: readMetadataCommand or shared balanced readers.
• Output merged into: PreambleData; later non-empty values can replace earlier values.

comment-masked source -> extract(source) -> metadata + hidden ranges -> LatexDocument

const EDITOR_METADATA_EXTRACTOR: MetadataExtractor = source => {
    const editor = readMetadataCommand(source, 'editor');
    return editor
        ? { custom: { editor: editor.content }, ranges: [editor.range] }
        : {};
};

Return ranges only for declarations that should disappear from body output. The document model preserves line structure needed by source mapping.

See also

• Metadata and dependency contract
• readMetadataCommand