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:
If you use FastParse and like it, you will probably enjoy the following book by the Author:
Hands-on Scala has uses FastParse extensively throughout the book, with the entirety of Chapter 19: Parsing Structured Text dedicated to the library and Chapter 20: Implementing a Programming Language making heavy use of it. Hands-on Scala is a great way to level up your skills in Scala in general and FastParse in particular.
For a good hands-on tutorial working through the basics of how to use this library, check out the following blog post:
This readme contains some developer docs, if you intend on working on the fastparse repo, not just using it as a library.
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/src/ and minor differences in
The three subprojects
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.
perftests/ constains performance tests for main projects in the library
readme/ contains the
documentation site, which contains several live demos of FastParse parsers
compiled to Scala.js. These all live in
mill -w fastparse.jvm[2.12.7].testruns the main testsuite. If you're hacking on FastParse, this is often where you want to go
You can run the other suites via
scalaparse.jvm, 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
mill -w fastparse.jvm[_].testto run it under different Scala versions, but again I usually don't bother
mill __.test.testis the aggregate test-all command, but is pretty slow. You can use
mill __.jvm[2.12.7].testto run all tests only under JVM/Scala-2.12, which is much faster and catches most issues
mill demo.fullOpt && sbt readme/runbuilds the documentation site, which can then be found at
- 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
The MIT License (MIT)
Copyright (c) 2014 Li Haoyi (firstname.lastname@example.org)
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.