82 lines
2.3 KiB
Elixir
82 lines
2.3 KiB
Elixir
defmodule RDF.Double do
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use RDF.Datatype, id: RDF.Datatype.NS.XSD.double
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def build_literal_by_value(value, opts) do
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case convert(value, opts) do
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float when is_float(float) ->
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build_literal(float, decimal_form(float), opts)
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nil ->
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build_literal(nil, invalid_lexical(value), opts)
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special_value when is_atom(special_value) ->
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build_literal(special_value, nil, opts)
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end
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end
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def convert(value, _) when is_float(value), do: value
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def convert(value, _) when is_integer(value), do: value / 1
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def convert(value, opts) when is_binary(value) do
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case Float.parse(value) do
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{float, ""} ->
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float
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{float, remainder} ->
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# 1.E-8 is not a valid Elixir float literal and consequently not fully parsed with Float.parse
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if Regex.match?(~r/^\.e?[\+\-]?\d+$/i, remainder) do
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convert(to_string(float) <> String.trim_leading(remainder, "."), opts)
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else
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super(value, opts)
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end
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:error ->
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case String.upcase(value) do
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"INF" -> :positive_infinity
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"+INF" -> :positive_infinity
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"-INF" -> :negative_infinity
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"NAN" -> :nan
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_ -> super(value, opts)
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end
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end
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end
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def convert(value, _)
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when value in ~W[positive_infinity negative_infinity nan]a,
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do: value
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def convert(value, opts), do: super(value, opts)
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def canonical_lexical(value) do
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case value do
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:nan -> "NaN"
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:positive_infinity -> "INF"
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:negative_infinity -> "-INF"
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float when is_float(float) -> exponential_form(float)
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_ -> to_string(value)
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end
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end
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def decimal_form(float) when is_float(float) do
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to_string(float)
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end
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def exponential_form(float) when is_float(float) do
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# Can't use simple %f transformation due to special requirements from
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# N3 tests in representation
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[i, f, e] =
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:io_lib.format("~.15e", [float])
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|> List.first
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|> to_string
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|> String.split(~r/[\.e]/)
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f =
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case String.replace(f, ~r/0*$/, "", global: false) do # remove any trailing zeroes
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"" -> "0" # ...but there must be a digit to the right of the decimal point
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f -> f
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end
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e = String.trim_leading(e, "+")
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"#{i}.#{f}E#{e}"
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end
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end
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