81 lines
3.3 KiB
Markdown
81 lines
3.3 KiB
Markdown
# [nearley](http://nearley.js.org) ↗️
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[](http://js.org)
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[](https://badge.fury.io/js/nearley)
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nearley is a simple, fast and powerful parsing toolkit. It consists of:
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1. [A powerful, modular DSL for describing
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languages](https://nearley.js.org/docs/grammar)
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2. [An efficient, lightweight Earley
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parser](https://nearley.js.org/docs/parser)
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3. [Loads of tools, editor plug-ins, and other
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goodies!](https://nearley.js.org/docs/tooling)
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nearley is a **streaming** parser with support for catching **errors**
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gracefully and providing _all_ parsings for **ambiguous** grammars. It is
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compatible with a variety of **lexers** (we recommend
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[moo](http://github.com/tjvr/moo)). It comes with tools for creating **tests**,
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**railroad diagrams** and **fuzzers** from your grammars, and has support for a
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variety of editors and platforms. It works in both node and the browser.
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Unlike most other parser generators, nearley can handle *any* grammar you can
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define in BNF (and more!). In particular, while most existing JS parsers such
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as PEGjs and Jison choke on certain grammars (e.g. [left recursive
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ones](http://en.wikipedia.org/wiki/Left_recursion)), nearley handles them
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easily and efficiently by using the [Earley parsing
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algorithm](https://en.wikipedia.org/wiki/Earley_parser).
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nearley is used by a wide variety of projects:
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- [artificial
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intelligence](https://github.com/ChalmersGU-AI-course/shrdlite-course-project)
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and
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- [computational
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linguistics](https://wiki.eecs.yorku.ca/course_archive/2014-15/W/6339/useful_handouts)
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classes at universities;
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- [file format parsers](https://github.com/raymond-h/node-dmi);
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- [data-driven markup languages](https://github.com/idyll-lang/idyll-compiler);
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- [compilers for real-world programming
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languages](https://github.com/sizigi/lp5562);
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- and nearley itself! The nearley compiler is bootstrapped.
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nearley is an npm [staff
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pick](https://www.npmjs.com/package/npm-collection-staff-picks).
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## Documentation
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Please visit our website https://nearley.js.org to get started! You will find a
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tutorial, detailed reference documents, and links to several real-world
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examples to get inspired.
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## Contributing
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Please read [this document](.github/CONTRIBUTING.md) *before* working on
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nearley. If you are interested in contributing but unsure where to start, take
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a look at the issues labeled "up for grabs" on the issue tracker, or message a
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maintainer (@kach or @tjvr on Github).
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nearley is MIT licensed.
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A big thanks to Nathan Dinsmore for teaching me how to Earley, Aria Stewart for
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helping structure nearley into a mature module, and Robin Windels for
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bootstrapping the grammar. Additionally, Jacob Edelman wrote an experimental
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JavaScript parser with nearley and contributed ideas for EBNF support. Joshua
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T. Corbin refactored the compiler to be much, much prettier. Bojidar Marinov
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implemented postprocessors-in-other-languages. Shachar Itzhaky fixed a subtle
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bug with nullables.
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## Citing nearley
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If you are citing nearley in academic work, please use the following BibTeX
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entry.
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```bibtex
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@misc{nearley,
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author = "Kartik Chandra and Tim Radvan",
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title = "{nearley}: a parsing toolkit for {JavaScript}",
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year = {2014},
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doi = {10.5281/zenodo.3897993},
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url = {https://github.com/kach/nearley}
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}
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```
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