90 lines
2.1 KiB
Elixir
90 lines
2.1 KiB
Elixir
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defmodule HtmlEntities do
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@moduledoc """
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Decode and encode HTML entities in a string.
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## Examples
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Decoding:
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iex> "Tom & Jerry" |> HtmlEntities.decode
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"Tom & Jerry"
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iex> "¡Ay, caramba!" |> HtmlEntities.decode
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"¡Ay, caramba!"
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iex> "ő ő" |> HtmlEntities.decode
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"ő ő"
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Encoding:
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iex> "Tom & Jerry" |> HtmlEntities.encode
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"Tom & Jerry"
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iex> "<< KAPOW!! >>" |> HtmlEntities.encode
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"<< KAPOW!! >>"
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"""
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@external_resource "lib/html_entities_list.txt"
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@doc "Decode HTML entities in a string."
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@spec decode(String.t()) :: String.t()
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def decode(string) when is_binary(string) do
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decode(string, "")
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end
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defp decode(<<"&", rest::binary>>, acc) do
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case decode_entity(rest) do
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{character, rest} -> decode(rest, <<acc::binary, character::binary>>)
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:error -> decode(rest, <<acc::binary, ?&>>)
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end
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end
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defp decode(<<head, rest::binary>>, acc) do
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decode(rest, <<acc::binary, head>>)
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end
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defp decode(<<>>, acc) do
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acc
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end
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defp decode_entity(<<"#x", c, rest::binary>>) when c in ?0..?9 or c in ?a..?f or c in ?A..?F do
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case Integer.parse(<<c, rest::binary>>, 16) do
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{number, ";" <> rest} -> {<<number::utf8>>, rest}
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_ -> :error
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end
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rescue
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ArgumentError -> :error
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end
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defp decode_entity(<<"#", rest::binary>>) do
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case Integer.parse(rest, 10) do
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{number, ";" <> rest} -> {<<number::utf8>>, rest}
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_ -> :error
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end
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rescue
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ArgumentError -> :error
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end
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codes = HtmlEntities.Util.load_entities(@external_resource)
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for {name, _character, codepoint} <- codes do
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defp decode_entity(<<unquote(name), ?;, rest::binary>>) do
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{<<unquote(codepoint)::utf8>>, rest}
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end
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end
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defp decode_entity(_), do: :error
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@doc "Encode HTML entities in a string."
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@spec encode(String.t()) :: String.t()
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def encode(string) when is_binary(string) do
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for <<x <- string>>, into: "" do
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case x do
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?' -> "'"
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?" -> """
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?& -> "&"
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?< -> "<"
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?> -> ">"
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_ -> <<x>>
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end
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end
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end
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end
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