Writing Fast Parsers Fast in Scala
Scala Python JavaScript Java
Latest commit 98b79cb Jan 17, 2017 @SethTisue SethTisue committed with be Scala 2.13 friendly (#139)
for the Scala 2.13 community build (yes, there is one already)

README.md

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This is where the code for the FastParse parsing library lives! If you want to use Fastparse, you probably will want to check out the documentation:

This readme contains some developer docs, if you intend on working on the fastparse repo, not just using it as a library.

Developer Docs

The core of FastParse lives in the fastparse/ folder. It is cross-built ScalaJVM/Scala.js codebase, with almost everything shared between the two platforms in the fastparse/shared/ and minor differences in fastparse/js/ and fastparse/jvm/.

The three subprojects scalaparse/, pythonparse/ and cssparse/ are FastParse parsers for those respective languages. These are both usable as standalone libraries, and also serve as extensive test-suites and use-cases for FastParse itself. Each of those projects clones & parses large quantities of code from Github as part of their own test suites. byteparse module has also two subprojects classparse and BMP parser. The first one is parser for .class files for java-bytecode.

perftests/ constains performance tests for main projects in the library including ScalaParse, PythonParse, CssParse, ClassParse and ByteParse. util/ contains some basic utilities that FastParse uses that aren't specific to parsers: bitsets, escaping, tries, etc.. readme/ contains the documentation site, which contains several live demos of FastParse parsers compiled to Scala.js. These all live in demo/.

Common Commands

  • sbt ~fastparseJVM/test runs the main testsuite. If you're hacking on FastParse, this is often where you want to go
  • You can run the other suites for fastparseJS, scalaparseJVM, etc. if you wish, but I typically don't and leave that to CI unless I'm actively working on the sub-project
  • You can use + to run it under different Scala versions, but again I usually don't bother
  • +modules/test is the aggregate test-all command, and +modules/publishSigned is publish-all. Other things (compile, etc.) can also be run on modules
  • readme/run builds the documentation site, which can then be found at readme/target/scalatex/index.html

Contribution Guidelines

  • If you're not sure if something is a bug or not, ask on Gitter first =)
  • All code PRs should come with: a meaningful description, inline comments for important things, unit tests, and a green build
  • Non-trivial changes, including bug fixes, should appear in the changelog. Feel free to add your name and link to your github profile!
  • New features should be added to the relevant parts of the documentation
  • To a large extent, FastParse is designed so that you can extend it in your own code without needing to modify the core. If you want to add features, be prepared to argue why it should be built-in and not just part of your own code.
  • It's entirely possible your changes won't be merged, or will get ripped out later. This is also the case for my changes, as the Author!
  • Even a rejected/reverted PR is valuable! It helps explore the solution space, and know what works and what doesn't. For every line in the repo, at least three lines were tried, committed, and reverted/refactored, and more than 10 were tried without committing.
  • Feel free to send Proof-Of-Concept PRs that you don't intend to get merged.
  • No binary or source compatibility is guaranteed between any releases. FastParse is still in the 0.x.y phase of development, which means it's still under rapid development and things do change. On the other hand, upgrading is usually trivial, and I don't expect existing functionality to go away

License

The MIT License (MIT)

Copyright (c) 2014 Li Haoyi (haoyi.sg@gmail.com)

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.