65 lines
2 KiB
Elixir
65 lines
2 KiB
Elixir
defmodule RDF.Quad do
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@moduledoc """
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Defines a RDF Quad.
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A Quad is a plain Elixir tuple consisting of four valid RDF values for
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subject, predicate, object and a graph context.
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"""
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alias RDF.{BlankNode, Literal}
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import RDF.Triple, except: [new: 1, new: 3]
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@type graph_context :: URI.t | BlankNode.t
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@type convertible_graph_context :: graph_context | atom | String.t
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@doc """
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Creates a `RDF.Quad` with proper RDF values.
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An error is raised when the given elements are not convertible to RDF values.
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Note: The `RDF.quad` function is a shortcut to this function.
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# Examples
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iex> RDF.Quad.new("http://example.com/S", "http://example.com/p", 42, "http://example.com/Graph")
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{RDF.uri("http://example.com/S"), RDF.uri("http://example.com/p"), RDF.literal(42), RDF.uri("http://example.com/Graph")}
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"""
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def new(subject, predicate, object, graph_context) do
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{
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convert_subject(subject),
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convert_predicate(predicate),
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convert_object(object),
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convert_graph_context(graph_context)
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}
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end
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@doc """
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Creates a `RDF.Quad` with proper RDF values.
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An error is raised when the given elements are not convertible to RDF values.
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Note: The `RDF.quad` function is a shortcut to this function.
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# Examples
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iex> RDF.Quad.new {"http://example.com/S", "http://example.com/p", 42, "http://example.com/Graph"}
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{RDF.uri("http://example.com/S"), RDF.uri("http://example.com/p"), RDF.literal(42), RDF.uri("http://example.com/Graph")}
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"""
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def new({subject, predicate, object, graph_context}),
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do: new(subject, predicate, object, graph_context)
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@doc false
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def convert_graph_context(uri)
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def convert_graph_context(nil), do: nil
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def convert_graph_context(uri = %URI{}), do: uri
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def convert_graph_context(bnode = %BlankNode{}), do: bnode
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def convert_graph_context(uri) when is_atom(uri) or is_binary(uri),
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do: RDF.uri(uri)
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def convert_graph_context(arg),
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do: raise RDF.Quad.InvalidGraphContextError, graph_context: arg
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end
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