Edit File: unicode.ex
defmodule JSON.Parser.Unicode do @moduledoc """ Implements a JSON Unicode Parser for Bitstring values """ use Bitwise @doc """ parses a valid chain of escaped unicode and returns the string representation, plus the remainder of the string ## Examples iex> JSON.Parser.parse "" {:error, :unexpected_end_of_buffer} iex> JSON.Parser.parse "face0ff" {:error, {:unexpected_token, "face0ff"}} iex> JSON.Parser.parse "-hello" {:error, {:unexpected_token, "-hello"}} """ def parse(<<?\\, ?u, json::binary>>), do: parse_escaped_unicode_codepoint(json, 0, 0) def parse(<<>>), do: {:error, :unexpected_end_of_buffer} def parse(json), do: {:error, {:unexpected_token, json}} # Parsing sugorrogate pairs # http://unicodebook.readthedocs.org/unicode_encodings.html # Inspired by Poison's function defp parse_escaped_unicode_codepoint( <<?d, hex::utf8, f1, f2, ?\\, ?u, ?d, hex2::utf8, s1, s2, json::binary>>, _, 0 ) when hex >= 56 do first_part = (List.to_integer([?d, hex, f1, f2], 16) &&& 1023) <<< 10 second_part = List.to_integer([?d, hex2, s1, s2], 16) &&& 1023 complete = 0x10000 + first_part + second_part {:ok, <<complete::utf8>>, json} end # parse_escaped_unicode_codepoint tries to parse # a valid hexadecimal (composed of 4 characters) value that potentially # represents a unicode codepoint defp parse_escaped_unicode_codepoint(json, acc, chars_parsed) when 4 === chars_parsed do {:ok, <<acc::utf8>>, json} end defp parse_escaped_unicode_codepoint(<<hex::utf8, json::binary>>, acc, chars_parsed) when hex in ?0..?9 do parse_escaped_unicode_codepoint(json, 16 * acc + hex - ?0, chars_parsed + 1) end defp parse_escaped_unicode_codepoint(<<hex::utf8, json::binary>>, acc, chars_parsed) when hex in ?a..?f do parse_escaped_unicode_codepoint(json, 16 * acc + 10 + hex - ?a, chars_parsed + 1) end defp parse_escaped_unicode_codepoint(<<hex::utf8, json::binary>>, acc, chars_parsed) when hex in ?A..?F do parse_escaped_unicode_codepoint(json, 16 * acc + 10 + hex - ?A, chars_parsed + 1) end defp parse_escaped_unicode_codepoint(<<>>, _, _), do: {:error, :unexpected_end_of_buffer} defp parse_escaped_unicode_codepoint(json, _, _), do: {:error, {:unexpected_token, json}} end
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