59 lines
2.3 KiB
Elixir
59 lines
2.3 KiB
Elixir
defmodule RDF.Statement do
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@moduledoc """
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Defines a RDF Statement.
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A RDF statement is either a `RDF.Triple` or a `RDF.Quad`.
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"""
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alias RDF.{Triple, Quad, BlankNode, Literal}
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@type subject :: URI.t | BlankNode.t
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@type predicate :: URI.t
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@type object :: URI.t | BlankNode.t | Literal.t
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@type graph_name :: URI.t | BlankNode.t
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@type convertible_subject :: subject | atom | String.t
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@type convertible_predicate :: predicate | atom | String.t
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@type convertible_object :: object | atom | String.t # TODO: all basic Elixir types convertible to Literals
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@type convertible_graph_name :: graph_name | atom | String.t
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@doc false
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def convert_subject(uri)
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def convert_subject(uri = %URI{}), do: uri
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def convert_subject(bnode = %BlankNode{}), do: bnode
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def convert_subject("_:" <> identifier), do: RDF.bnode(identifier)
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def convert_subject(uri) when is_atom(uri) or is_binary(uri), do: RDF.uri(uri)
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def convert_subject(arg), do: raise RDF.Triple.InvalidSubjectError, subject: arg
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@doc false
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def convert_predicate(uri)
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def convert_predicate(uri = %URI{}), do: uri
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# Note: Although, RDF does not allow blank nodes for properties, JSON-LD allows
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# them, by introducing the notion of "generalized RDF".
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# TODO: Support an option `:strict_rdf` to explicitly disallow them or produce warnings or ...
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def convert_predicate(bnode = %BlankNode{}), do: bnode
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def convert_predicate(uri) when is_atom(uri) or is_binary(uri), do: RDF.uri(uri)
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def convert_predicate(arg), do: raise RDF.Triple.InvalidPredicateError, predicate: arg
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@doc false
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def convert_object(uri)
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def convert_object(uri = %URI{}), do: uri
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def convert_object(literal = %Literal{}), do: literal
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def convert_object(bnode = %BlankNode{}), do: bnode
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def convert_object(atom) when is_atom(atom), do: RDF.uri(atom)
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def convert_object(arg), do: Literal.new(arg)
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@doc false
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def convert_graph_name(uri)
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def convert_graph_name(nil), do: nil
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def convert_graph_name(uri = %URI{}), do: uri
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def convert_graph_name(bnode = %BlankNode{}), do: bnode
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def convert_graph_name("_:" <> identifier), do: RDF.bnode(identifier)
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def convert_graph_name(uri) when is_atom(uri) or is_binary(uri),
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do: RDF.uri(uri)
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def convert_graph_name(arg),
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do: raise RDF.Quad.InvalidGraphContextError, graph_context: arg
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end
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