Arithmetics Parser Example

PEG.js: Parser Generator for JavaScript ======================================= PEG.js is a parser generator for JavaScript based on the [parsing expression grammar](http://en.wikipedia.org/wiki/Parsing_expression_grammar) formalism. It is designed to be used either from your browser or from the command line (using [Rhino](http://www.mozilla.org/rhino/) JavaScript interpreter). Features -------- * Usable [from your browser](http://pegjs.majda.cz/online) or [from a command-line](http://pegjs.majda.cz/documentation#generating-a-parser) * Simple and expressive [grammar syntax](http://pegjs.majda.cz/documentation#grammar) * No separate lexical analysis step—both lexical and syntactical analysis are handled by one tool * Handles wide class of grammars (strict superset of LL(k) and LR(k)) * Precise and human-friendly error reporting Usage ----- To use PEG.js, you need to generate a parser from your grammar and then use the generated parser in your project. ### Generating a Parser To generate a parser, you can use the [online generator](http://pegjs.majda.cz/online) or the command line. For the second option, you need to have Java installed. Than you can generate the parser using the `bin/pegjs` script on Unix or `bin/pegjs.bat` batch file on Windows: $ bin/pegjs arithmeticsParser examples/arithmetics.pegjs This command will create the parser from the `examples/arithmetics.pegjs` file and put in into the `examples/arithmetics.js` file. The generated parser will be available in the `arithmeticsParser` global variable. The generator has several useful options—to learn more about them, use `--help`. ### Using the Generated Parser To use the parser in a web page, follow the following example: Arithmetics Parser Example

The `parse` method of the generated parser will return either the result of the parsing (dependent on the actions you specified in the grammar) or throw `PEG.Parser.SyntaxError` exception if the input contains a syntax error. The exception has properties `message`, `line` and `column`, which contain details about the error. Grammar ------- For detailed description of the grammar see the [online documentation](http://pegjs.majda.cz/documentation#grammar). Compatibility ------------- Both the parser generator and generated parsers should run well in IE6+ and recent versions of Firefox, Chrome, Safari and Opera, as well as Rhino JavaScript engine.