scannergen-backend-kotlin.md

Scanner Generator Backend: Kotlin

This backend outputs a scanner as Kotlin source code. See scanner generator backends for what every generated scanner does and parser generator backend: Kotlin for the parser side.

It targets Kotlin 2.0 on JVM 17.

--backend-kotlin-package-name sets the package the file declares, which defaults to parser.

The scanner is the Scanner class, its tokens are the Token enum, and TokenSkipper wraps a scanner to drop the tokens marked for skipping. Both implement TokenSource, which is what a parser reads its tokens through, and the skipper hands every member but next on to the scanner it wraps by class delegation. What a scanner reports is properties rather than methods, so it is scanner.token and not scanner.token(). Lexemes are a ByteBuffer over the source rather than a copy of it.

Example

examples/calculator/kotlin/ is a calculator built on this backend. Its scanner was generated with:

golr scanner \
  --frontend golr \
  --frontend-file-path calculator.golr \
  --backend kotlin \
  --backend-file-path parser/Scanner.kt