256 lines
8.0 KiB
Elixir
256 lines
8.0 KiB
Elixir
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defmodule Jason.Formatter do
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@moduledoc ~S"""
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Pretty-printing and minimizing functions for JSON-encoded data.
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Input is required to be in an 8-bit-wide encoding such as UTF-8 or Latin-1
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in `t:iodata/0` format. Input must have valid JSON, invalid JSON may produce
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unexpected results or errors.
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"""
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@type opts :: [
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{:indent, iodata}
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| {:line_separator, iodata}
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| {:record_separator, iodata}
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| {:after_colon, iodata}
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]
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import Record
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defrecordp :opts, [:indent, :line, :record, :colon]
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@dialyzer :no_improper_lists
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@doc ~S"""
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Pretty-prints JSON-encoded `input`.
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`input` may contain multiple JSON objects or arrays, optionally separated
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by whitespace (e.g., one object per line). Objects in output will be
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separated by newlines. No trailing newline is emitted.
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## Options
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* `:indent` - used for nested objects and arrays (default: two spaces - `" "`);
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* `:line_separator` - used in nested objects (default: `"\n"`);
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* `:record_separator` - separates root-level objects and arrays
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(default is the value for `:line_separator` option);
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* `:after_colon` - printed after a colon inside objects (default: one space - `" "`).
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## Examples
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iex> Jason.Formatter.pretty_print(~s|{"a":{"b": [1, 2]}}|)
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~s|{
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"a": {
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"b": [
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1,
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2
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]
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}
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"""
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@spec pretty_print(iodata, opts) :: binary
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def pretty_print(input, opts \\ []) do
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input
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|> pretty_print_to_iodata(opts)
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|> IO.iodata_to_binary()
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end
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@doc ~S"""
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Pretty-prints JSON-encoded `input` and returns iodata.
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This function should be preferred to `pretty_print/2`, if the pretty-printed
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JSON will be handed over to one of the IO functions or sent
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over the socket. The Erlang runtime is able to leverage vectorised
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writes and avoid allocating a continuous buffer for the whole
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resulting string, lowering memory use and increasing performance.
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"""
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@spec pretty_print_to_iodata(iodata, opts) :: iodata
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def pretty_print_to_iodata(input, opts \\ []) do
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opts = parse_opts(opts, " ", "\n", nil, " ")
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depth = :first
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empty = false
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{output, _state} = pp_iodata(input, [], depth, empty, opts)
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output
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end
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@doc ~S"""
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Minimizes JSON-encoded `input`.
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`input` may contain multiple JSON objects or arrays, optionally
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separated by whitespace (e.g., one object per line). Minimized
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output will contain one object per line. No trailing newline is emitted.
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## Options
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* `:record_separator` - controls the string used as newline (default: `"\n"`).
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## Examples
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iex> Jason.Formatter.minimize(~s|{ "a" : "b" , "c": \n\n 2}|)
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~s|{"a":"b","c":2}|
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"""
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@spec minimize(iodata, opts) :: binary
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def minimize(input, opts \\ []) do
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input
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|> minimize_to_iodata(opts)
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|> IO.iodata_to_binary()
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end
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@doc ~S"""
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Minimizes JSON-encoded `input` and returns iodata.
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This function should be preferred to `minimize/2`, if the minimized
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JSON will be handed over to one of the IO functions or sent
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over the socket. The Erlang runtime is able to leverage vectorised
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writes and avoid allocating a continuous buffer for the whole
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resulting string, lowering memory use and increasing performance.
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"""
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@spec minimize_to_iodata(iodata, opts) :: iodata
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def minimize_to_iodata(input, opts) do
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record = Keyword.get(opts, :record_separator, "\n")
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opts = opts(indent: "", line: "", record: record, colon: "")
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depth = :first
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empty = false
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{output, _state} = pp_iodata(input, [], depth, empty, opts)
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output
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end
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defp parse_opts([{option, value} | opts], indent, line, record, colon) do
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value = IO.iodata_to_binary(value)
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case option do
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:indent -> parse_opts(opts, value, line, record, colon)
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:record_separator -> parse_opts(opts, indent, line, value, colon)
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:after_colon -> parse_opts(opts, indent, line, record, value)
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:line_separator -> parse_opts(opts, indent, value, record || value, colon)
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end
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end
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defp parse_opts([], indent, line, record, colon) do
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opts(indent: indent, line: line, record: record || line, colon: colon)
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end
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for depth <- 1..16 do
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defp tab(" ", unquote(depth)), do: unquote(String.duplicate(" ", depth))
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end
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defp tab("", _), do: ""
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defp tab(indent, depth), do: List.duplicate(indent, depth)
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defp pp_iodata(<<>>, output_acc, depth, empty, opts) do
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{output_acc, &pp_iodata(&1, &2, depth, empty, opts)}
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end
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defp pp_iodata(<<byte, rest::binary>>, output_acc, depth, empty, opts) do
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pp_byte(byte, rest, output_acc, depth, empty, opts)
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end
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defp pp_iodata([], output_acc, depth, empty, opts) do
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{output_acc, &pp_iodata(&1, &2, depth, empty, opts)}
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end
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defp pp_iodata([byte | rest], output_acc, depth, empty, opts) when is_integer(byte) do
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pp_byte(byte, rest, output_acc, depth, empty, opts)
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end
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defp pp_iodata([head | tail], output_acc, depth, empty, opts) do
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{output_acc, cont} = pp_iodata(head, output_acc, depth, empty, opts)
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cont.(tail, output_acc)
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end
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defp pp_byte(byte, rest, output, depth, empty, opts) when byte in ' \n\r\t' do
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pp_iodata(rest, output, depth, empty, opts)
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end
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defp pp_byte(byte, rest, output, depth, empty, opts) when byte in '{[' do
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{out, depth} =
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cond do
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depth == :first -> {byte, 1}
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depth == 0 -> {[opts(opts, :record), byte], 1}
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empty -> {[opts(opts, :line), tab(opts(opts, :indent), depth), byte], depth + 1}
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true -> {byte, depth + 1}
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end
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empty = true
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pp_iodata(rest, [output, out], depth, empty, opts)
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end
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defp pp_byte(byte, rest, output, depth, true = _empty, opts) when byte in '}]' do
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empty = false
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depth = depth - 1
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pp_iodata(rest, [output, byte], depth, empty, opts)
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end
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defp pp_byte(byte, rest, output, depth, false = empty, opts) when byte in '}]' do
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depth = depth - 1
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out = [opts(opts, :line), tab(opts(opts, :indent), depth), byte]
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pp_iodata(rest, [output, out], depth, empty, opts)
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end
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defp pp_byte(byte, rest, output, depth, _empty, opts) when byte in ',' do
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empty = false
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out = [byte, opts(opts, :line), tab(opts(opts, :indent), depth)]
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pp_iodata(rest, [output, out], depth, empty, opts)
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end
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defp pp_byte(byte, rest, output, depth, empty, opts) when byte in ':' do
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out = [byte, opts(opts, :colon)]
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pp_iodata(rest, [output, out], depth, empty, opts)
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end
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defp pp_byte(byte, rest, output, depth, empty, opts) do
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out = if empty, do: [opts(opts, :line), tab(opts(opts, :indent), depth), byte], else: byte
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empty = false
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if byte == ?" do
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pp_string(rest, [output, out], _in_bs = false, &pp_iodata(&1, &2, depth, empty, opts))
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else
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pp_iodata(rest, [output, out], depth, empty, opts)
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end
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end
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defp pp_string(<<>>, output_acc, in_bs, cont) do
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{output_acc, &pp_string(&1, &2, in_bs, cont)}
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end
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defp pp_string(binary, output_acc, true = _in_bs, cont) when is_binary(binary) do
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<<byte, rest::binary>> = binary
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pp_string(rest, [output_acc, byte], false, cont)
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end
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defp pp_string(binary, output_acc, false = _in_bs, cont) when is_binary(binary) do
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case :binary.match(binary, ["\"", "\\"]) do
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:nomatch ->
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{[output_acc | binary], &pp_string(&1, &2, false, cont)}
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{pos, 1} ->
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{head, tail} = :erlang.split_binary(binary, pos + 1)
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case :binary.at(binary, pos) do
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?\\ -> pp_string(tail, [output_acc | head], true, cont)
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?" -> cont.(tail, [output_acc | head])
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end
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end
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end
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defp pp_string([], output_acc, in_bs, cont) do
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{output_acc, &pp_string(&1, &2, in_bs, cont)}
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end
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defp pp_string([byte | rest], output_acc, in_bs, cont) when is_integer(byte) do
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cond do
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in_bs -> pp_string(rest, [output_acc, byte], false, cont)
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byte == ?" -> cont.(rest, [output_acc, byte])
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true -> pp_string(rest, [output_acc, byte], byte == ?\\, cont)
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end
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end
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defp pp_string([head | tail], output_acc, in_bs, cont) do
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{output_acc, cont} = pp_string(head, output_acc, in_bs, cont)
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cont.(tail, output_acc)
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end
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end
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