# RDFtk: Core
This crate provides an implementation of the RDF abstract syntax along with a `Resource` type that provides a builder-like experience for models.
[](https://crates.io/crates/rdftk_core)
[](https://docs.rs/rdftk_core)
From [RDF 1.1 Concepts and Abstract Syntax](https://www.w3.org/TR/rdf11-concepts/);
> The core structure of the abstract syntax is a set of triples, each consisting of a subject, a
> predicate and an object. A set of such triples is called an RDF graph. An RDF graph can be
> visualized as a node and directed-arc diagram, in which each triple is represented as a
> node-arc-node link.
>
> 
>
> There can be three kinds of nodes in an RDF graph: IRIs, literals, and blank nodes.
In this library the triple, or statement, as well as subject, predicate, and object types are
in the module [`statement`](statement/index.html). Literal's as objects are supported in the
[`literal`](literal/index.html) module. Traits that describe graphs are provided by the
[`graph`](graph/index.html) module.
Additional features are provided such as support for data sets (module [`model.data_set`](data_set/index.html))
as well as support for extensions to the core RDF abstract model such as
[RDF-star](https://w3c.github.io/rdf-star/cg-spec/editors_draft.html).
## Example
```rust
use rdftk_core::{Literal, Statement, StatementList, SubjectNode};
use rdftk_iri::IRI;
use std::rc::Rc;
use std::str::FromStr;
pub fn make_statements() -> StatementList {
let mut statements: StatementList = Default::default();
statements.push(Statement::new(
SubjectNode::named(IRI::from_str("http://en.wikipedia.org/wiki/Tony_Benn").unwrap()),
IRI::from_str("http://purl.org/dc/elements/1.1/title").unwrap(),
Literal::new("Tony Benn").into(),
).into());
// ...
statements
}
```
## Changes
**Version 0.3.1**
* Added PrefixMappingFactory trait and a prefix_mapping_factory method on GraphFactory.
**Version 0.3.0**
* The abstract RDF API, described in module 'model', is now entirely trait based.
* An implementation, in module 'simple', provides concrete in-memory types.
* Added a new type LanguageTag to model these values more completely.
* Added notion of features which denote capabilities supported by data sets, graphs, and statements implementations.
**Version 0.2.4**
* Created new Featured trait implemented by a number of types that allow client query of various optional
capabilities. This also subsumes the has_index/has_all_indices capability as all index queries are now
feature queries.
**Version 0.2.3**
* Copied some errors from rdftk_io.
* Renamed the Io variant to ReadWrite.
**Version 0.2.2**
* Reworked APIs to take <name>Ref types and to be consistent in use of trait objects and types throughout.
* Added factory type for data sets.
* Made PrefixMappings a concrete type in the core::graph::mapping module.
* Added InvalidMatch and Io variants to ErrorKind.
* Added mutators to Statement.
**Version 0.2.1**
* Changed API, removed mutable traits for Graph and DataSet, moved methods into their base traits.
* Added factory types for graphs.
* Added Skolemization function for graphs.
**Version 0.2.0**
* A change to the API, all `Statement`, and statement components are now passed as `Rc` references.
* Added additional *_ref* constructors to allow cleaner client code.
* A change to the API, `Graph` and `DataSet` now use type parameters to describe iterators returned by *query* methods.
* A change to the API, `QName` constructors now return errors instead of panic on invalid values.
* Added more constructors for literal values.
* Added support for `chrono::Duration` in literals as well as the std version as chrono supports the correct output form.
* Added `eq_` methods on `SubjectNode` and `ObjectNode` for simple testing of inner values.
* Added documentation and examples throughout.
**Version 0.1.15**
* Fixed Clippy suggestions.
* Removed Context from statements.
* Added value_factory method to Graph.
* Placed all unit tests in tests folder.
**Version 0.1.14**
* Removed stand-alone named graph.
* Added DataSet as a way to associate names to graphs.
* Renamed CachingGraph to ValueFactory and made stand-alone.
**Version 0.1.13**
* Bug: fixed Literal constructors to produce an escape-safe literal form for strings.
**Version 0.1.12**
* Fixed: cargo fmt error.
**Version 0.1.11**
* Added: public types `StatementRef` and `StatementList` rather than having `Rc` obviously in all APIs.
**Version 0.1.10**
* **DEPRECATED** Support for [Datasets](https://www.w3.org/TR/rdf11-concepts/#section-dataset) and Quads by adding a context
(type `ContextNode`) to `Statement`.
**Version 0.1.9**
* Support for [RDF*](https://w3c.github.io/rdf-star/) in `Statement`.
* Added additional constructors to `Statement`.
* Renamed Resource method `rdf_type` to `instance_of` for compatibility with RDF schema usage.
* Added `is_valid` associated function to `QName`.
**Version 0.1.8**
* Explicit exports over `pub use *`.
**Version 0.1.7**
* Split `Graph` into `Graph` and `MutableGraph`.
* Split `NamedGraph` into `NamedGraph` and `MutableNamedGraph`.
* Added `get_default_namespace` to the `PrefixMappings` trait as a helper function.
* Altered `PrefixMappings::compress` and `PrefixMappings::expand` to take references.
**Version 0.1.6**
* Explicit version management.
**Version 0.1.5**
* Updates for rdftk_memgraph to build.
**Version 0.1.4**
* Made all local dependencies only major/minor valued.
**Version 0.1.3**
* Moved all `IRI` to `IRIRef` on interfaces.
* Moved `Graph` and associated types into core and deprecated `rdftk_graph`.
**Version 0.1.2**
* Clean-up changes.
**Version 0.1.1**
* Added `From` to allow direct construction of a `SubjectNode` from an `IRI`.
* Fixed a bug in `QName` that dropped the ":" for non-prefixed values.
**Version 0.1.0**
* First release.
## TODO
TBD
[](http://www.w3.org/2001/sw/wiki/RDF)