117 lines
4.0 KiB
Markdown
117 lines
4.0 KiB
Markdown
# Contributing
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Everybody is more than welcome to contribute to Oga, no matter how small the
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change. To keep everything running smoothly there are a few guidelines that one
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should follow. These are as following:
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* When changing code make sure to write RSpec tests for the changes.
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* Document code using YARD. At the very least the method arguments and return
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value(s) should be documented.
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* Wrap lines at 80 characters per line.
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* Git commits should have a <= 50 character summary, optionally followed by a
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blank line and a more in depth description of 80 characters per line.
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## Editor Setup
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Whatever editor you use doesn't matter as long as it can do two things:
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* Use spaces for indentation.
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* Hard wrap lines at 80 characters per line.
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To make this process easier Oga comes with an [EditorConfig][editorconfig]
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configuration file. If your editor supports this it will automatically apply
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the required settings for you.
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## Hacking on Oga
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Assuming you have a local Git clone of Oga, the first step should be to install
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all the required Gems:
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bundle install
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Next up, compile the required files and run the tests:
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rake
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You can compile the various parsers/extensions by running:
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rake generate
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For more information about the available tasks, run `rake -T`.
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## Extension Setup
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Oga uses native extensions for the XML lexer. This is due to Ruby sadly not
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being fast enough to chew through large amounts of XML (at least when using
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Ragel). For example, the benchmark `benchmark/lexer/big_xml_time.rb` would take
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around 6 seconds to complete on MRI 2.1.1. The native extensions on the other
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hand can complete this benchmark in roughly 600 milliseconds.
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Oga has two native extensions: one for MRI/Rubinius (written in C) and one for
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JRuby (written in Java). Both extensions share the same Ragel grammar, found in
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`ext/ragel/base_lexer.rl`. This grammar is set up in such a way that the syntax
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is compatible with both C and Java. Specific details on how the grammar is used
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can be found in the documentation of said grammar file.
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The native extensions call back in to Ruby to actually perform the task of
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creating tokens, validating input and so forth. As a result of this you'll most
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likely never have to touch the C and/or Java code when changing the behaviour
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of the lexer.
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To compile the extensions run `rake generate` using your Ruby implementation of
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choice. Note that extensions compiled for MRI can not be used on Rubinius and
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vice-versa. To compile the JRuby extension you'll have to switch your active
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Ruby version to JRuby first.
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## Thread Safety
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To ensure Oga remains thread-safe for as much as possible the usage of global
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objects and/or state is forbidden. This means that you should _only_ use
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constants/class methods for static/read-only data (e.g. an Array of static
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Strings). In other words, this is fine:
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NUMBERS = [10, 20, 30]
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NUMBERS.each do |number|
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end
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But this is not:
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TOOL = SomeFindReplaceTool.new
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output = TOOL.replace(input, 'foo', 'bar')
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The exception here are libraries that are designed to be thread-safe, clearly
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state this _and_ can prove it (e.g. by simply using a mutex). Even then global
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state is highly frowned upon.
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## Loading Libraries
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All `require` calls should be placed in `lib/oga.rb`. Any `require` calls
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specific to a Ruby implementation (e.g. JRuby) should be wrapped in a
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conditional. For example:
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if RUBY_PLATFORM == 'java'
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org.foo.bar.baz.DoSomething()
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end
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For loading files in Oga itself `require_relative` should be used, _don't_
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modify `$LOAD_PATH`.
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## Contact
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In case you have any further questions or would like to receive feedback before
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submitting a change, feel free to contact me. You can either open an issue,
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send a tweet to [@yorickpeterse][twitter] or send an Email to
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<yorickpeterse@gmail.com>.
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## Legal
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By contributing to Oga you agree with both the Developer's Certificate of
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origin, found in `doc/DCO.md` and the license, found in `LICENSE`. This applies
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to all content in this repository unless stated otherwise.
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[editorconfig]:http://editorconfig.org/
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[twitter]: https://twitter.com/yorickpeterse
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