antlr4

# ANTLR v4

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**ANTLR** (ANother Tool for Language Recognition) is a powerful parser generator for reading, processing, executing, or translating structured text or binary files. It's widely used to build languages, tools, and frameworks. From a grammar, ANTLR generates a parser that can build parse trees and also generates a listener interface (or visitor) that makes it easy to respond to the recognition of phrases of interest.

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## Versioning

ANTLR 4 supports 10 target languages
(Cpp, CSharp, Dart, Java, JavaScript, PHP, Python3, Swift, TypeScript, Go),
and ensuring consistency across these targets is a unique and highly valuable feature.
To ensure proper support of this feature, each release of ANTLR is a complete release of the tool and the 10 runtimes, all with the same version.
As such, ANTLR versioning does not strictly follow semver semantics:

* a component may be released with the latest version number even though nothing has changed within that component since the previous release
* major version is bumped only when ANTLR is rewritten for a totally new "generation", such as ANTLR3 -> ANTLR4 (LL(\*) -> ALL(\*) parsing)
* minor version updates may include minor breaking changes, the policy is to regenerate parsers with every release (4.11 -> 4.12)
* backwards compatibility is only guaranteed for patch version bumps (4.11.1 -> 4.11.2)

If you use a semver verifier in your CI, you probably want to apply special rules for ANTLR, such as treating minor change as a major change.

## Repo branch structure

The default branch for this repo is [`master`](https://github.com/antlr/antlr4/tree/master), which is the latest stable release and has tags for the various releases; e.g., see release tag [4.9.3](https://github.com/antlr/antlr4/tree/4.9.3).  Branch [`dev`](https://github.com/antlr/antlr4/tree/dev) is where development occurs between releases and