# Grammars-v4 House Rules

## Ground Rules

* All contributions are welcome ranging from spelling mistakes to new grammars. Grammars-v4 aims to be a welcoming community in which both novice and expert contributors are welcome.  "How do I?" questions are welcomed, and encouraged.
* The repository owner [teverett](https://github.com/teverett/), holds final approval on all commits, and changes to the repository
* No hate speech, racism, sexism, or ethnocentrism is tolerated. Trolling and personal attacks are not welcome.

## Contributing

New grammars and bug fixes are welcome.  All changes must pass CI in order to be pulled.  Examples for new grammars are strongly encouraged.  If new features or bug fixes are added to grammars, examples that exercise the feature or fix are also strongly encouraged.

## Traditions 

* In general, contributors are thanked for every commit
* Symbol conflicts are generally resolved by appending an underscore to identifiers. For example "id" becomes "id_"
* The formatting style produced by [Antlr4Formatter](https://github.com/antlr/Antlr4Formatter) is the typical code formatting for grammars

## History of Grammars-V4

The grammars-v4 repository was created `Tue Sep 25 16:45:12 2012 -0700`.  The repository was created as a place to hold grammars for [Antlr4](https://www.antlr.org/).  There is also a [grammars-v3](https://github.com/antlr/grammars-v3) repository here which has the grammars from the legacy [grammars-v3 list](https://www.antlr3.org/grammar/list.html).

In Sept of 2012, the only library of formal grammars was the [grammars-v3 list](https://www.antlr3.org/grammar/list.html), and it really wasn't possible to know if the grammars on that list would pass minimal tests.

In order to ensure that the grammars on the tree worked, to a minimal degree, [antlr4test-maven-plugin](https://github.com/antlr/antlr4test-maven-plugin) was written and Travis CI/CD was set up to ensure that every grammar on the tree passed these tests:

* The grammar is parseable by the current version of Antlr
* The generated lexer-parser will parse at least one sample input with the current version of Antlr.

There is no single license for the Antlr4 grammars.  Some of the grammars on the tree were forward-ported from grammrs-v3 and in those cases the original author information was usually included.  Many of the grammars have licensing information in the .g4 file(s).

It has long been the intention of grammars-v4 to provide an ecosystem of grammars for Antlr4 that would enable Antlr4 users to create parsers for the source and target language of thier choice for a wide variety of source languages.  At this time there are a little less than 300-ish source language grammars, and Antlr4 supports many targets including C, Java, C#, Python, JS, Swift and others. 

It is a tradition to thank every contributor to grammars-v4 for the time and effort they put into their pull requests.  There is a "thank-you" for every PR when it is pulled onto the tree.  Additionally grammars-v4 aims to be a welcoming community for all contributors both experienced and novice to contribute to, and to learn from.