Grammars for programming languages are traditionally specified statically. They are hard to compose and reuse due to ambiguities that inevitably arise. PetitParser combines ideas from scannerless parsing, parser combinators, parsing expression grammars and packrat parsers to model grammars and parsers as objects that can be reconfigured dynamically.

Getting Started

Although PetitParser was born as part of the Helvetia infrastructure, it can be used independently. An introduction to PetitParser can be found in the following blog posts: Writing Parsers with PetitParser and Composite Grammars with PetitParser. Also the Moose Book has a chapter on PetitParser.

Pharo Smalltalk

Pharo Smalltalk is the main development environment of PetitParser. To load the core library evaluate the following code:

Gofer new
    renggli: 'petit'; 
    package: 'PetitParser';
    load.

To get the full toolset, including a dedicated editor and some experimental tools, use the following Metacello script:

Gofer new
    renggli: 'petit';
    package: 'ConfigurationOfPetitParser';
    load.
(Smalltalk at: #ConfigurationOfPetitParser)
    perform: #loadDefault.

PetitParser has been reported to also work in Squeak.

GNU Smalltalk

To load the package PetitParser.star one can type:

gst-package http://smalltalk.gnu.org/project/petitparser/package.xml

To load the PetitParser.star into the image do:

PackageLoader fileInPackage: 'PetitParser'

There are some differences between the official PetitParser and this port. GNU Smalltalk does not support binary selectors that have more than two characters. This means that ==> and >=> had to be mapped to something else. I have picked => and >< for now.

More details can be found in the blog article of Holger Hans Peter Freyther.

Cincom Smalltalk

This requires Cincom VisualWorks 7.7 or later:

1. Choose ’Connect to Repository’ from the ’Store’ menu.
2. Provide the following information in the dialog that pops up:
   • Interface: PostgreSQLEXDIConnection
   • Environment: db.iam.unibe.ch:5432_scgStore
   • User Name: storeguest (if you have one, put yours)
   • Password: storeguest (if you have one, put yours)
   • Table Owner: BERN
3. Click on ’Save...’ and ’Connect’.
4. Choose ’Published Items’ from the ’Store’ menu.
5. Load the bundle PetitParser.

Visual Smalltalk Enterprise

There is a port of PetitParser to VSE by Leandro Caniglia.

Java

There is a version of PetitParser for Java.

Dart

There is also a version of PetitParser for Dart.

Contact

Please report bugs or ask questions in the Pharo or Moose mailing-lists.

License

PetitParser is licensed under the MIT license.

Publications

1. Fabrizio Perin, Lukas Renggli, and Jorge Ressia. Natural Language Checking with Program Checking Tools. In Smalltalks 2010, 2010. PDF →
2. Fabrizio Perin, Lukas Renggli, and Jorge Ressia. Linguistic Style Checking with Program Checking Tools. In Journal of Computer Languages, Systems and Structures, 2011. DOI PDF →
3. Lukas Renggli, Stéphane Ducasse, Tudor Gîrba, and Oscar Nierstrasz. Practical Dynamic Grammars for Dynamic Languages. In 4th Workshop on Dynamic Languages and Applications (DYLA 2010), Malaga, Spain, June 2010. PDF →