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