oga/CONTRIBUTING.md

Contributing

Everybody is more than welcome to contribute to Oga, no matter how small the change. To keep everything running smoothly there are a few guidelines that one should follow. These are as following:

• When changing code make sure to write RSpec tests for the changes.
• Document code using YARD. At the very least the method arguments and return value(s) should be documented.
• Wrap lines at 80 characters per line.
• Git commits should have a <= 50 character summary, optionally followed by a blank line and a more in depth description of 72 characters per line.

Editor Setup

Whatever editor you use doesn't matter as long as it can do two things:

• Use spaces for indentation.
• Hard wrap lines at 80 characters per line.

To make this process easier Oga comes with an EditorConfig configuration file. If your editor supports this it will automatically apply the required settings for you.

Hacking on Oga

Before you start hacking on Oga make sure the following libraries/tools are installed:

• Ragel 6.x (6.9 recommended)
• gunzip (to unpack the fixtures)
• javac (only when using JRuby)

Assuming you have the above tools installed and a local Git clone of Oga, lets install the required Gems:

bundle install

Next up, compile the required files and run the tests:

rake

You can compile the various parsers/extensions by running:

rake generate

For more information about the available tasks, run rake -T.

Running Benchmarks

Benchmarks are located in the benchmark directory. Some of these require fixture files which can be generated by running rake fixtures. Running a benchmark is just a matter of running a Ruby script, for example:

ruby benchmark/xml/parser/parser_bench.rb

Continuous Integration

Two continuous integration services are used to ensure the tests of Oga pass at all times:

• Travis CI: https://travis-ci.org/YorickPeterse/oga
• AppVeyor (Windows): https://ci.appveyor.com/project/YorickPeterse/oga

Please note that I will not accept patches that break any tests unless stated otherwise.

Extension Setup

Oga uses native extensions for the XML lexer. This is due to Ruby sadly not being fast enough to chew through large amounts of XML (at least when using Ragel). For example, the benchmark benchmark/lexer/big_xml_time.rb would take around 6 seconds to complete on MRI 2.1.1. The native extensions on the other hand can complete this benchmark in roughly 600 milliseconds.

Oga has two native extensions: one for MRI/Rubinius (written in C) and one for JRuby (written in Java). Both extensions share the same Ragel grammar, found in ext/ragel/base_lexer.rl. This grammar is set up in such a way that the syntax is compatible with both C and Java. Specific details on how the grammar is used can be found in the documentation of said grammar file.

The native extensions call back in to Ruby to actually perform the task of creating tokens, validating input and so forth. As a result of this you'll most likely never have to touch the C and/or Java code when changing the behaviour of the lexer.

To compile the extensions run rake generate using your Ruby implementation of choice. Note that extensions compiled for MRI can not be used on Rubinius and vice-versa. To compile the JRuby extension you'll have to switch your active Ruby version to JRuby first.

Thread Safety

To ensure Oga remains thread-safe for as much as possible the usage of global objects and/or state is forbidden. This means that you should only use constants/class methods for static/read-only data (e.g. an Array of static Strings). In other words, this is fine:

NUMBERS = [10, 20, 30]

NUMBERS.each do |number|

end

But this is not:

TOOL = SomeFindReplaceTool.new

output = TOOL.replace(input, 'foo', 'bar')

The exception here are libraries that are designed to be thread-safe, clearly state this and can prove it (e.g. by simply using a mutex). Even then global state is highly frowned upon.

Loading Libraries

All require calls should be placed in lib/oga.rb. Any require calls specific to a Ruby implementation (e.g. JRuby) should be wrapped in a conditional. For example:

if RUBY_PLATFORM == 'java'
  org.foo.bar.baz.DoSomething()
end

For loading files in Oga itself require_relative should be used, don't modify $LOAD_PATH.

Contact

In case you have any further questions or would like to receive feedback before submitting a change, feel free to contact me. You can either open an issue, send a tweet to @yorickpeterse or send an Email to yorickpeterse@gmail.com.