parsergen-backend-java.md

Parser Generator Backend: Java

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

It targets Java 17.

--backend-java-package-name sets the package the file declares, which defaults to parser and has to be the one the scanner was generated into.

Parser.parse takes a TokenSource and returns a ParseResult record holding the tree and the errors, and can be called again with another scanner. The tree is null when the parse could not be finished. Nodes, errors and symbols are records too, and lexemes are a ByteBuffer over the source rather than a copy of it.

Example

examples/calculator/java/ is a calculator built on this backend. Its parser was generated with:

golr parser \
  --frontend golr \
  --frontend-file-path calculator.golr \
  --backend java \
  --backend-file-path parser/Parser.java