parsergen-backend-cpp.md

Parser Generator Backend: C++

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

It targets C++17 and is a self contained header.

--backend-cpp-namespace sets the namespace, which defaults to parser and has to be the one the scanner was generated into. --backend-cpp-scanner-include sets the header the token type is included from, which defaults to scanner.hpp.

Parser::parse returns a ParseResult holding the tree and the errors, and can be called again with a different scanner. It is a template over the scanner type rather than a function taking an interface, so any type with the members the generated scanner has will do. The tree holds std::string_view lexemes into the source, which therefore has to outlive it.

Example

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

golr parser \
  --frontend golr \
  --frontend-file-path calculator.golr \
  --backend cpp \
  --backend-cpp-namespace calculator::parser \
  --backend-file-path parser/parser.hpp