Public API

Alto Code Highlight follows semantic versioning for the supported entry points and extension contracts described here. Patch and minor releases preserve their documented signatures and behavior throughout the 1.x series.

Main entry point

Highlighter is the primary facade. Its supported operations are:

• construction with a ThemeInterface, optional embedding registry, and optional language list;
• highlight() for escaped HTML output;
• getTheme() for the configured theme;
• registerLanguage() for adding or replacing a parser;
• getEmbeddedRegistry() for inspecting embedding plans;
• setEmbeddingEnabled() for toggling a configured host and target pair.

HighlighterInterface defines the portable highlighting operation for code that depends on an abstraction rather than the concrete facade.

Theme extension contract

Custom themes implement ThemeInterface. The Scope enum and its string values form the semantic vocabulary supplied to themes. The built-in theme classes and the Highlight.js, Prism, and TextMate adapters are supported public implementations.

See Creating a theme and Theme adapters for complete examples.

Language extension contract

Custom parsers implement LanguageInterface and return a ParsedStream made of ParsedToken values. StreamBuilder, TokenType, and Scope are supported building blocks for those parsers. Languages::getDefaultLanguages() returns the built-in registry.

Embedded parsers use EmbeddedLanguageCapable, EmbeddedLanguageContext, and the types under Alto\Code\Highlight\Embedded. Their documented constructors and public methods are covered by the same 1.x compatibility promise.

See Languages and Embedded languages for usage and behavior.

Exceptions

LanguageNotFoundException reports an unknown language identifier. ParseException reports source that a semantic parser cannot process. Both are part of the supported exception contract.

Compatibility boundary

The following details are not compatibility contracts:

• concrete lexer, semantic parser, state, and token classes inside a built-in language implementation;
• exact whitespace inside generated HTML;
• private methods and undocumented implementation details;
• test fixtures, documentation tooling, and generated showcase assets.

The generated element structure, documented CSS classes, source escaping, language identifiers, semantic scope values, and public signatures are covered by semantic versioning. Changes outside that boundary may occur in a minor or patch release when documented behavior remains intact.