# RDF::TriG reader/writer
[TriG][] reader/writer for [RDF.rb][RDF.rb] .
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## Description
This is a [Ruby][] implementation of a [TriG][] reader and writer for [RDF.rb][].
## Features
RDF::TriG parses [TriG][Trig] into statements or quads. It also serializes to TriG.
Install with `gem install rdf-trig`
* 100% free and unencumbered [public domain](https://unlicense.org/) software.
* Implements a complete parser and serializer for [TriG][].
* Compatible with Ruby 2.x, and JRuby 1.7+.
* Optional streaming writer, to serialize large graphs
## Usage
Instantiate a reader from a local file:
repo = RDF::Repository.load("etc/doap.trig", :format => :trig)
Define `@base` and `@prefix` definitions, and use for serialization using `:base_uri` an `:prefixes` options.
Canonicalize and validate using `:canonicalize` and `:validate` options.
Write a repository to a file:
RDF::TriG::Writer.open("etc/test.trig") do |writer|
writer << repo
end
Note that reading and writing of graphs is also possible, but as graphs have only a single context,
it is not particularly interesting for TriG.
## RDF-star
Both reader and writer include provisional support for [RDF-star][].
Internally, an `RDF::Statement` is treated as another resource, along with `RDF::URI` and `RDF::Node`, which allows an `RDF::Statement` to have a `#subject` or `#object` which is also an `RDF::Statement`.
Note that this requires the `rdfstar` option to be se.
**Note: This feature is subject to change or elimination as the standards process progresses.**
## Documentation
Full documentation available on [Rubydoc.info][TriG doc].
### Principle Classes
* {RDF::TriG::Format}
* {RDF::TriG::Reader}
* {RDF::TriG::Writer}
## Implementation Notes
This version uses a hand-written parser using the Lexer from the [EBNF][] gem instead of a general [EBNF][] LL(1) parser for faster performance.
The reader uses the [Turtle][Turtle doc] parser. The writer also is based on the Turtle writer.
The syntax is compatible with placing default triples within `{}`, but the writer does not use this for writing triples in the default graph.
There is a new `:stream` option to {RDF::TriG::Writer} which is more efficient for streaming large datasets.
## Dependencies
* [Ruby](https://ruby-lang.org/) (>= 2.6)
* [RDF.rb](https://rubygems.org/gems/rdf) (~> 3.2)
* [rdf-turtle](https://rubygems.org/gems/rdf-turtle) (~> 3.2)
## Installation
The recommended installation method is via [RubyGems](https://rubygems.org/).
To install the latest official release of the `RDF::TriG` gem, do:
% [sudo] gem install rdf-trig
## Mailing List
*
## Author
* [Gregg Kellogg](https://github.com/gkellogg) -
## Contributing
* Do your best to adhere to the existing coding conventions and idioms.
* Don't use hard tabs, and don't leave trailing whitespace on any line.
* Do document every method you add using [YARD][] annotations. Read the
[tutorial][YARD-GS] or just look at the existing code for examples.
* Don't touch the `.gemspec`, `VERSION` or `AUTHORS` files. If you need to
change them, do so on your private branch only.
* Do feel free to add yourself to the `CREDITS` file and the corresponding
list in the the `README`. Alphabetical order applies.
* Do note that in order for us to merge any non-trivial changes (as a rule
of thumb, additions larger than about 15 lines of code), we need an
explicit [public domain dedication][PDD] on record from you,
which you will be asked to agree to on the first commit to a repo within the organization.
Note that the agreement applies to all repos in the [Ruby RDF](https://github.com/ruby-rdf/) organization.
## License
This is free and unencumbered public domain software. For more information,
see or the accompanying {file:UNLICENSE} file.
A copy of the [TriG EBNF][] and derived parser files are included in the repository, which are not covered under the UNLICENSE. These files are covered via the [W3C Document License](https://www.w3.org/Consortium/Legal/2002/copyright-documents-20021231).
[Ruby]: https://ruby-lang.org/
[RDF]: https://www.w3.org/RDF/
[YARD]: https://yardoc.org/
[YARD-GS]: https://rubydoc.info/docs/yard/file/docs/GettingStarted.md
[PDD]: https://unlicense.org/#unlicensing-contributions
[RDF.rb]: https://rubydoc.info/github/ruby-rdf/rdf/master/frames
[Backports]: https://rubygems.org/gems/backports
[RDF-star]: https://w3c.github.io/rdf-star/rdf-star-cg-spec.html
[TriG]: https://www.w3.org/TR/trig/
[TriG doc]: https://rubydoc.info/github/ruby-rdf/rdf-trig/master/file/README.markdown
[TriG EBNF]: https://dvcs.w3.org/hg/rdf/raw-file/default/trig/trig.bnf
[Turtle doc]: https://rubydoc.info/github/ruby-rdf/rdf-turtle/master/file/README.markdown