2016-10-15 16:26:56 +00:00
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defmodule RDF.Literal do
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@moduledoc """
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RDF literals are leaf nodes of a RDF graph containing raw data, like strings and numbers.
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"""
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defstruct [:value, :datatype, :language]
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@type t :: module
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2016-10-30 18:36:46 +00:00
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alias RDF.{XSD, RDFS}
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2016-10-15 16:26:56 +00:00
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@doc """
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Creates a new `RDF.Literal` of the given value and tries to infer an appropriate XSD datatype.
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Note: The `RDF.literal` function is a shortcut to this function.
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The following mapping of Elixir types to XSD datatypes is applied:
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| Elixir type | XSD datatype |
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| :---------- | :----------- |
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| string | |
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| boolean | `boolean` |
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| integer | `integer` |
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| float | `float` |
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| atom | |
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| ... | |
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# Examples
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iex> RDF.Literal.new(42)
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%RDF.Literal{value: 42, language: nil, datatype: RDF.uri(RDF.XSD.integer)}
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"""
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def new(value)
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2016-10-30 18:36:46 +00:00
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def new(value) when is_binary(value),
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do: %RDF.Literal{value: value, datatype: XSD.string}
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2016-10-15 16:26:56 +00:00
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def new(value) when is_boolean(value),
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do: %RDF.Literal{value: value, datatype: XSD.boolean}
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def new(value) when is_integer(value),
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do: %RDF.Literal{value: value, datatype: XSD.integer}
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def new(value) when is_float(value),
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do: %RDF.Literal{value: value, datatype: XSD.float}
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# def new(value) when is_atom(value), do:
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# def new(value) when is_bitstring(value), do:
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# def new(value) when is_list(value), do:
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# def new(value) when is_tuple(value), do:
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# def new(value) when is_map(value), do:
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# def new(value) when is_function(value), do:
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# def new(value) when is_pid(value), do:
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# def new(value) when is_port(value), do:
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# def new(value) when is_reference(value), do:
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def new(value) do
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2016-11-04 21:13:06 +00:00
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raise RDF.InvalidLiteralError, "#{inspect value} not convertible to a RDF.Literal"
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2016-10-15 16:26:56 +00:00
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end
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2016-10-30 18:36:46 +00:00
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def new(value, language: language) when is_binary(value) do
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%RDF.Literal{value: value, datatype: RDF.langString, language: language}
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end
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def new(value, datatype: datatype) when is_binary(value) do
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datatype_uri = RDF.uri(datatype)
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cond do
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datatype_uri == XSD.string -> %RDF.Literal{value: value, datatype: datatype_uri}
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datatype_uri == XSD.integer -> %RDF.Literal{value: String.to_integer(value), datatype: datatype_uri}
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# TODO: datatype_uri == XSD.byte -> nil # %RDF.Literal{value: String.to_integer(value), datatype: datatype_uri}
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# TODO: datatype_uri == RDF.uri(RDFS.XMLLiteral) -> nil # %RDF.Literal{value: String.to_integer(value), datatype: datatype_uri}
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# TODO: Should we support more values, like "1" etc.?
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# TODO: Should we exclude any non-useful value?
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datatype_uri == XSD.boolean -> %RDF.Literal{value: String.downcase(value) == "true", datatype: datatype_uri}
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true -> %RDF.Literal{value: value, datatype: datatype_uri}
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end
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end
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def new(value, datatype: datatype) when is_integer(value) do
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datatype_uri = RDF.uri(datatype)
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cond do
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datatype_uri == XSD.string -> %RDF.Literal{value: to_string(value), datatype: datatype_uri}
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datatype_uri == XSD.integer -> %RDF.Literal{value: value, datatype: datatype_uri}
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end
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end
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def new(value, datatype: datatype) when is_boolean(value) do
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datatype_uri = RDF.uri(datatype)
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cond do
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datatype_uri == XSD.boolean -> %RDF.Literal{value: value, datatype: datatype_uri}
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# TODO: Should we exclude any non-useful value?
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datatype_uri == XSD.string -> %RDF.Literal{value: to_string(value), datatype: datatype_uri}
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datatype_uri == XSD.integer -> %RDF.Literal{value: (if value, do: 1, else: 0), datatype: datatype_uri}
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end
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end
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2016-10-15 16:26:56 +00:00
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end
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