antlr grun

ANTLR is a powerful parser generator that can be used to build parsers for various programming languages or domain-specific languages. It generates parser code based on a given grammar file and allows you to parse input strings according to the rules defined in the grammar.

"grun" is a command-line utility that comes with ANTLR. It stands for "GRaphical UNit Test" and provides a convenient way to test and debug your generated parsers. It allows you to input a test string and see the parse tree or abstract syntax tree (AST) that is produced by the parser.

To use "grun", you typically need to have ANTLR installed and have already generated the parser code using the ANTLR tool. Once you have the parser code, you can use the following command to run "grun":

grun <grammarName> <startRule> [-tree] [-tokens] [-gui] [-ps file.ps] [-encoding encodingname] [input-filename]

Here, <grammarName> refers to the name of your grammar file (without the .g4 extension), and <startRule> is the name of the starting rule in your grammar.

The optional flags -tree, -tokens, and -gui control the output format. -tree prints the parse tree (default), -tokens prints the token stream, and -gui opens a graphical parse tree viewer.

The optional -ps file.ps flag allows you to redirect the output to a PostScript file.

The optional -encoding encodingname flag specifies the input encoding of the test string.

Finally, the optional input-filename argument is the name of a file containing the test string to be parsed. If this argument is omitted, "grun" will read input from the console.

Overall, "grun" is a useful tool for testing and debugging ANTLR-generated parsers, providing visual representations of the parse results