anpa

A C++17 header only generic monadic parser combinator library loosely based on Haskell's parsec.

Features

All parsers and combinators are constexpr meaning no run time cost for constructing a parser.

In addition, all parsers and combinators, with two exceptions (many_to_vector and many_to_map), are allocation free, and can be evaluated at compile time. This enables compile time parsing as long as used operations on the input iterators and corresponding elements are constexpr.

Examples

See the provided test parsers

• JSON parser: JSON DOM parser. It's only ~30 LOC and gives a good overview on how to use the library, including recursive parsers.
• Simple syntax parser: a parser for a simple example syntax inteded for an application launcher/information dashboard.
• Expression parser: a simple expression evaluator supporting basic arithmetic operations with correct precedence. This example showcases how to use chain to eliminate left recursion in expression grammars.

Dependencies

For library: None

For tests: Catch2

Installing

$ git clone https://github.com/habbbe/anpa
$ cd anpa
$ cmake -B <BUILD_DIR> -DCMAKE_INSTALL_PREFIX=<PREFIX>
$ cmake --install build

If you want to build and run the tests instead, use

$ cmake -B <BUILD_DIR> -DBUILD_TESTS=ON
$ cmake --build <BUILD_DIR> -j <NUM_OF_PARALLEL_JOBS> --target anpa_tests test

Tips

Try increasing the inlining limit for your compiler for better performance (your mileage may vary).

As an example, using -finline-limit=3500 in GCC 9.2.0 resulted in a ~14% performance increase for the JSON parser on my machine.

TODO

• Add "Getting started"/wiki
• More extensive test cases
• Improve compilation errors (somewhat done). A parser is not type checked until a parse is commenced with some input. If a complex parser doesn't type check, a flywheel scroll or a very tall display is highly recommended.