HighlightLanguage¶

HighlightLanguage is a pure Kotlin helper that maps file extensions to highlight.js language identifiers.

It is a convenience API. SyntaxHighlightedCode and HighlightEngine.highlight() still accept a plain String language id, so you can always pass supported highlight.js names directly.

Full API in Dokka:

• HighlightLanguage

When to use it¶

• You have filenames or file extensions and need a best-effort language id.
• You want locale-safe, case-insensitive extension lookup.
• You want a simple fallback to plaintext for unknown extensions.

Core behavior¶

• fromExtension(extension) returns a highlight.js language id or null.
• Lookup is case-insensitive and locale-safe (Locale.ROOT).
• Pass extension without a leading dot.

HighlightLanguage.fromExtension("kt")   // "kotlin"
HighlightLanguage.fromExtension("KT")   // "kotlin"
HighlightLanguage.fromExtension("py")   // "python"
HighlightLanguage.fromExtension("xyz")  // null

Recommended usage pattern¶

val file = File("MainActivity.kt")
val language = HighlightLanguage.fromExtension(file.extension) ?: "plaintext"

SyntaxHighlightedCode(
    code     = file.readText(),
    language = language,
)

Practical guidance¶

• Prefer mapping by extension only when language is not known from other metadata.
• For user-selected languages, pass the chosen id directly.
• For unknown or mixed content, consider HighlightEngine.highlightAuto() instead.

Common pitfalls¶

• Passing extension with dot (".kt") instead of "kt".
• Assuming the helper mirrors every upstream highlight.js alias at all times.
• Forgetting a fallback path (?: "plaintext") for unknown extensions.

Supported extensions¶

The current extension-to-language map (source: HighlightLanguage.kt).