grunt-peg

A grunt multi task that generates parsers from PEG grammars.

Getting Started

This plugin requires Grunt >=0.4.0

If you haven't used Grunt before, be sure to check out the Getting Started guide, as it explains how to create a Gruntfile as well as install and use Grunt plugins. Once you're familiar with that process, you may install this plugin with this command:

npm install grunt-peg --save-dev

One the plugin has been installed, it may be enabled inside your Gruntfile with this line of JavaScript:

grunt.loadNpmTasks('grunt-peg');

The "peg" task

Run this task with the grunt peg command.

Task targets, files and options may be specified according to the grunt Configuring tasks guide.

Options

Any specified option will be passed through directly to PEG.js, thus you can specify any option that PEG.js supports. See the PEG.js documentation for a list of supported options.

An additional option is supported:

exportVar

Type: String | function Default value: 'module.exports'

The variable to which the generated parser will be assigned in the output file.

If the exportVar is of type function, the function needs to return the variable as a String. The function gets passed the src variable to base the variable off.

Usage Examples

Default Options

In this example a PEG grammar as described in the file grammar/example.peg is used to generate parser grammar/example.js. The default export variable is used, i.e. module.exports.

grunt.initConfig({
  peg: {
    example: {
      src: "grammar/example.peg",
      dest: "grammar/example.js"
    }
  }
})

Custom Options

In this example a PEG grammar as described in the file grammar/example.peg is used to generate parser grammar/example.js, the export variable being Example.parser.

grunt.initConfig({
  peg: {
    example : {
      src: "grammar/example.peg",
      dest: "grammar/example.js",
      options: { exportVar: "Example.parser" }
    }
  }
})

Dynamic exportVar

In this example a PEG grammar as described in the file grammar/example.peg is used to generate parser grammar/example.js, the export variable being defined via a function and will result in example.

grunt.initConfig({
  peg: {
    example : {
      src: "grammar/example.peg",
      dest: "grammar/example.js",
      options: { exportVar: function(src){ return path.basename(src[0], '.peg'); } }
    }
  }
})

Passing Options to PEG

In this example a PEG grammar as described in the file grammar/example.peg is used to generate parser grammar/example.js, the export variable being Example.parser. Both the task-specific trackLineAndColumn and target-specific cache options will be passed through to PEG.js.

grunt.initConfig({
  peg: {
    options: { trackLineAndColumn: true },
    example : {
      src: "grammar/example.peg",
      dest: "grammar/example.js",
      options: {
        exportVar: "Example.parser",
        cache: true
      }
    }
  }
})

Wrap in an Angular Factory

It is also possible to wrap the generated parser in an Angular factory.

grunt.initConfig({
  peg: {
    options: { trackLineAndColumn: true },
    example : {
      src: "grammar/example.peg",
      dest: "grammar/example.js",
      options: {
        angular: {
          module: "pegjs",
          factory: "exampleParser"
        }
      }
    }
  }
})

Custom Wrapper

It is also possible to wrap the generated parser in any code you want.

grunt.initConfig({
  peg: {
    options: { trackLineAndColumn: true },
    example : {
      src: "grammar/example.peg",
      dest: "grammar/example.js",
      options: {
        wrapper: function (src, parser) {
          return 'define("example", [], function () { return ' + parser + '; });';
        }
      }
    }
  }
})

Note on plugins

If you want to pass plugins to PEG.js make sure that the plugin is installed and referenced by the module name. For example, for the pegjs-coffee-plugin one should first install the plugin

npm install --save-dev pegjs-coffee-plugin

and then configure the tasks with the module name.

grunt.initConfig({
  peg: {
    options: { trackLineAndColumn: true },
    example : {
      src: "grammar/example.peg",
      dest: "grammar/example.js",
      options: {
        plugins: [ "pegjs-coffee-plugin" ]
      }
    }
  }
})

PEG.js dependency

As described in issue #6 sometimes the wrong PEG.js version is downloaded by npm. The solution for now seems to be to call npm cache clear.

Contributing

In lieu of a formal styleguide, take care to maintain the existing coding style. Add unit tests for any new or changed functionality. Lint and test your code using Grunt.

Release History

• 2016-02-23 v2.0.1 Update grunt peer dependency
• 2015-09-11 v2.0.0 Update version of PEG.js to 0.9.0
• 2014-08-02 v1.5.0 Custom wrapper
• 2014-06-09 v1.4.0 Dynamic exportVar
• 2014-05-15 v1.3.1 Add license headers to all source files
• 2014-03-20 v1.3.0 Wrap in Angular Factory
• 2014-01-05 v1.2.0 Support plugins
• 2014-01-05 v1.1.0 Support PEG 0.8.0
• 2013-08-21 v1.0.0 Remove support for old-style options
• 2013-07-04 v0.3.0 Adhere to grunt's configuration convention
• 2013-06-02 v0.2.0 Pass options to PEG.js
• 2013-04-23 v0.1.0 Migrated to Grunt ~0.4.x

Contributors

• welwood08
• mstefaniuk
• bertrandgressier
• kmdavis
• felixhao28