KDL

This is a Ruby implementation of the KDL Document Language

Installation

Add this line to your application's Gemfile:

gem 'kdl'

And then execute:

$ bundle install

Or install it yourself as:

$ gem install kdl

Usage

require 'kdl'

KDL.parse(a_string) #=> KDL::Document
KDL.load_file('path/to/file') #=> KDL::Document

You can optionally provide your own type annotation handlers:

class Foo < KDL::Value::Custom
end

KDL.parse(a_string, type_parsers: {
  'foo' => Foo
})

The foo custom type will be called with instances of Value or Node with the type annotation (foo).

Custom types are expected to have a call method that takes the Value or Node, and the type annotation itself, as arguments, and is expected to return either an instance of KDL::Value::Custom or KDL::Node::Custom (depending on the input type) or nil to return the original value as is. Take a look at the built in custom types as a reference.

You can also disable type annotation parsing entirely (including the built in ones):

KDL.parse(a_string, parse_types: false)

KDL v1

kdl-rb maintains backwards compatibility with the KDL v1 spec. By default, KDL will attempt to parse a file with the v1 parser if it fails to parse with v2. This behaviour can be changed by specifying the version option:

KDL.parse(a_string, version: 2)

The resulting document will also serialize back to the same version it was parsed as. For example, if you parse a v2 document and call to_s on it, it will output a v2 document, and similarly with v1. This behaviour can be changed by specifying the output_version option:

KDL.parse(a_string, output_version: 2)

This allows you to to convert documents between versions:

KDL.parse('foo "bar" true', version: 1, output_version: 2).to_s #=> 'foo bar #true'

You can also convert an already parsed document between versions with to_v1 and to_v2:

doc = KDL.parse('foo "bar" true', version: 1)
doc.version #=> 1
doc.to_v2.to_s #=> 'foo bar #true'

You can also set the default version globally:

KDL.default_version = 2
KDL.default_output_version = 2

You can still force automatic version detection with auto_parse:

KDL.default_version = 2
KDL.parse('foo "bar" true') #=> Error
KDL.auto_parse('foo "bar" true') #=> KDL::V1::Document

Version directives are also respected:

KDL.parse("/- kdl-version 2\nfoo bar", version: 1)
#=> Version mismatch, document specified v2, but this is a v1 parser (Racc::ParseError)

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake test to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/danini-the-panini/kdl-rb.

License

The gem is available as open source under the terms of the MIT License.