67 lines
1.7 KiB
Elixir
67 lines
1.7 KiB
Elixir
defmodule RDF.Namespace do
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@moduledoc """
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A behaviour for resolvers of atoms to `RDF.IRI`s.
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Currently there's only one type of such namespaces: `RDF.Vocabulary.Namespace`,
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but other types are thinkable and might be implemented in the future, eg.
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namespaces for JSON-LD contexts.
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"""
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alias RDF.IRI
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@doc """
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Resolves a term to a `RDF.IRI`.
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"""
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@callback __resolve_term__(atom) :: IRI.t
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@doc """
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All terms of a `RDF.Namespace`.
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"""
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@callback __terms__() :: [atom]
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@doc """
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Resolves a qualified term to a `RDF.IRI`.
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It determines a `RDF.Namespace` from the qualifier of the given term and
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delegates to remaining part of the term to `__resolve_term__/1` of this
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determined namespace.
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"""
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@spec resolve_term(IRI.t | module) :: IRI.t
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def resolve_term(expr)
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def resolve_term(%IRI{} = iri), do: iri
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def resolve_term(namespaced_term) when is_atom(namespaced_term) do
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namespaced_term
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|> to_string()
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|> do_resolve_term()
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end
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defp do_resolve_term("Elixir." <> _ = namespaced_term) do
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{term, namespace} =
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namespaced_term
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|> Module.split
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|> List.pop_at(-1)
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do_resolve_term(Module.concat(namespace), String.to_atom(term))
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end
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defp do_resolve_term(namespaced_term) do
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raise RDF.Namespace.UndefinedTermError,
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"#{namespaced_term} is not a term on a RDF.Namespace"
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end
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defp do_resolve_term(RDF, term), do: do_resolve_term(RDF.NS.RDF, term)
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defp do_resolve_term(namespace, term) do
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if Code.ensure_compiled?(namespace) and
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Keyword.has_key?(namespace.__info__(:functions), :__resolve_term__)do
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namespace.__resolve_term__(term)
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else
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raise RDF.Namespace.UndefinedTermError,
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"#{namespace} is not a RDF.Namespace"
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end
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end
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end
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