Asparserations

Asparserations is an LR(1) parser generator frontend written in C++. It outputs JSON representing the state machine table. A C++ backend, used to generate the grammar parser, is included in the bootstrap folder.

Features

• Outputs JSON for consumption by backends, without needing to implement the [LA]LR(1) table construction algorithm
• Productions are named instead of indexed and names are local to the nonterminal
• Preserves shift/reduce and reduce/reduce conflicts in JSON
• Used to generate the parser for grammar files
• Can be integrated with lexers easily (the grammar file lexer is lazy/a generator/monadic!)

Options

• --version, -v - Prints the software version
• --help, -h - Prints the help
• --out, -o - Specifies the output file (a.out.json by default)
• --root, -r - Specifies the root node (Root by default)
• --lalr, -l - Use LALR(1) (experimental)
• --debug, -d - Output the item sets as well as the states

Building From Source

Prerequisites

This project requires G++, GNU Make, and Python 3 in order to build from source.

Installing

$ git clone https://github.com/TheAspiringHacker/Asparserations.git
$ cd Asparserations
$ make install

The binary file is saved to ~/local/bin and can be invoked by typing asparserations [flags...] grammar_file_name.

Installing with CMake

I've decided to learn CMake by using it for this project. Use it by running:

$ git clone https://github.com/TheAspiringHacker/Asparserations.git
$ cd Asparserations
$ mkdir build
$ cd build
$ cmake ../
$ make

The resulting binary is build/bin/asparserations.

You can then run CPack:

$ cpack --config CPackConfig.cmake

(You will have to move the binary to a location in your PATH yourself.)

Trying it out

Create a file called grammar in your favorite text editor:

tokens {
  number,
  plus,
  minus,
  asterisk,
  slash
}

Term : Term plus Factor # add
     | Term minus Factor # sub
     | Factor # base_case
     ;

Factor : Factor asterisk number # mult
       | Factor slash number # div
       | number # base_case
       ;

Run:

$ asparserations -r Term -o table.json grammar
$ cat table.json