2011-07-17 00:37:24 -07:00
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%% The MIT License
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%% Copyright (c) 2011 Alisdair Sullivan <alisdairsullivan@yahoo.ca>
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%% Permission is hereby granted, free of charge, to any person obtaining a copy
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%% of this software and associated documentation files (the "Software"), to deal
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%% in the Software without restriction, including without limitation the rights
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%% to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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%% copies of the Software, and to permit persons to whom the Software is
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%% furnished to do so, subject to the following conditions:
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%% The above copyright notice and this permission notice shall be included in
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%% all copies or substantial portions of the Software.
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%% THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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%% IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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%% FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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%% AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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%% LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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%% OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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%% THE SOFTWARE.
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-module(jsx_encoder).
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2011-07-21 06:14:48 -07:00
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-export([encoder/1]).
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2011-07-17 00:37:24 -07:00
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-include("jsx_common.hrl").
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2011-07-22 21:18:22 -07:00
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-record(opts, {
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escaped_unicode = codepoint,
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multi_term = false,
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encoding = auto
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}).
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2011-07-17 00:37:24 -07:00
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2011-07-21 06:14:48 -07:00
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-spec encoder(Opts::jsx_opts()) -> jsx_encoder().
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2011-07-17 00:37:24 -07:00
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2011-07-22 21:18:22 -07:00
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encoder(Opts) -> fun(Forms) -> start(Forms, Opts) end.
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2011-07-17 00:37:24 -07:00
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-define(ENDJSON,
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{event, end_json, fun() ->
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{incomplete, fun(Forms) -> {error, {badjson, Forms}} end}
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end}
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).
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2011-07-22 21:18:22 -07:00
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start({string, String}, _Opts) when is_list(String) ->
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{event, {string, json_escape(String)}, fun() -> ?ENDJSON end};
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start({float, Float}, _Opts) when is_list(Float) ->
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{event, {float, Float}, fun() -> ?ENDJSON end};
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start({integer, Int}, _Opts) when is_list(Int) ->
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{event, {integer, Int}, fun() -> ?ENDJSON end};
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start({literal, Atom}, _Opts) when Atom == true; Atom == false; Atom == null ->
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{event, {literal, Atom}, fun() -> ?ENDJSON end};
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%% second parameter is a stack to match end_foos to start_foos
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start(Forms, Opts) -> list_or_object(Forms, [], Opts).
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list_or_object([start_object|Forms], Stack, Opts) ->
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{event, start_object, fun() -> key(Forms, [object] ++ Stack, Opts) end};
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list_or_object([start_array|Forms], Stack, Opts) ->
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{event, start_array, fun() -> value(Forms, [array] ++ Stack, Opts) end};
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list_or_object([], Stack, Opts) ->
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{incomplete, fun(end_stream) ->
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{error, {badjson, []}}
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; (Stream) ->
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list_or_object(Stream, Stack, Opts)
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end};
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list_or_object(Forms, _, _) -> {error, {badjson, Forms}}.
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key([{key, Key}|Forms], Stack, Opts) when is_list(Key) ->
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{event, {key, json_escape(Key)}, fun() -> value(Forms, Stack, Opts) end};
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key([end_object|Forms], [object|Stack], Opts) ->
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{event, end_object, fun() -> maybe_done(Forms, Stack, Opts) end};
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key([], Stack, Opts) ->
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{incomplete, fun(end_stream) ->
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{error, {badjson, []}}
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; (Stream) ->
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key(Stream, Stack, Opts)
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end};
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key(Forms, _, _) -> {error, {badjson, Forms}}.
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value([{string, S}|Forms], Stack, Opts) when is_list(S) ->
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{event, {string, json_escape(S)}, fun() -> maybe_done(Forms, Stack, Opts) end};
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value([{float, F}|Forms], Stack, Opts) when is_list(F) ->
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{event, {float, F}, fun() -> maybe_done(Forms, Stack, Opts) end};
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value([{integer, I}|Forms], Stack, Opts) when is_list(I) ->
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{event, {integer, I}, fun() -> maybe_done(Forms, Stack, Opts) end};
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value([{literal, L}|Forms], Stack, Opts)
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when L == true; L == false; L == null ->
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{event, {literal, L}, fun() -> maybe_done(Forms, Stack, Opts) end};
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value([start_object|Forms], Stack, Opts) ->
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{event, start_object, fun() -> key(Forms, [object] ++ Stack, Opts) end};
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value([start_array|Forms], Stack, Opts) ->
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{event, start_array, fun() -> value(Forms, [array] ++ Stack, Opts) end};
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value([end_array|Forms], [array|Stack], Opts) ->
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{event, end_array, fun() -> maybe_done(Forms, Stack, Opts) end};
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value([], Stack, Opts) ->
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{incomplete, fun(end_stream) ->
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{error, {badjson, []}}
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; (Stream) ->
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value(Stream, Stack, Opts)
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end};
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value(Forms, _, _) -> {error, {badjson, Forms}}.
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maybe_done([], [], _) -> ?ENDJSON;
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maybe_done([end_json], [], _) -> ?ENDJSON;
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maybe_done([end_json|Forms], [], #opts{multi_term=true}=Opts) ->
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{event, end_json, fun() -> start(Forms, Opts) end};
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maybe_done([end_object|Forms], [object|Stack], Opts) ->
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{event, end_object, fun() -> maybe_done(Forms, Stack, Opts) end};
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maybe_done([end_array|Forms], [array|Stack], Opts) ->
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{event, end_array, fun() -> maybe_done(Forms, Stack, Opts) end};
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maybe_done(Forms, [object|_] = Stack, Opts) -> key(Forms, Stack, Opts);
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maybe_done(Forms, [array|_] = Stack, Opts) -> value(Forms, Stack, Opts);
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maybe_done([], Stack, Opts) ->
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{incomplete, fun(end_stream) ->
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{error, {badjson, []}}
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; (Stream) ->
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maybe_done(Stream, Stack, Opts)
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end};
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maybe_done(Forms, _, _) -> {error, {badjson, Forms}}.
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2011-07-17 00:37:24 -07:00
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2011-07-22 21:34:19 -07:00
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%% json string escaping. escape the json control sequences to
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%% their json equivalent, escape other control characters to \uXXXX sequences,
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%% everything else should be a legal json string component
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json_escape(String) ->
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json_escape(String, []).
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%% double quote
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json_escape([$\"|Rest], Acc) ->
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json_escape(Rest, [$\", $\\] ++ Acc);
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%% backslash \ reverse solidus
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json_escape([$\\|Rest], Acc) ->
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json_escape(Rest, [$\\, $\\] ++ Acc);
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%% backspace
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json_escape([$\b|Rest], Acc) ->
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json_escape(Rest, [$b, $\\] ++ Acc);
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%% form feed
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json_escape([$\f|Rest], Acc) ->
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json_escape(Rest, [$f, $\\] ++ Acc);
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%% newline
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json_escape([$\n|Rest], Acc) ->
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json_escape(Rest, [$n, $\\] ++ Acc);
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%% cr
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json_escape([$\r|Rest], Acc) ->
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json_escape(Rest, [$r, $\\] ++ Acc);
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%% tab
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json_escape([$\t|Rest], Acc) ->
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json_escape(Rest, [$t, $\\] ++ Acc);
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%% other control characters
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json_escape([C|Rest], Acc) when C >= 0, C < $\s ->
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json_escape(Rest, json_escape_sequence(C) ++ Acc);
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%% any other legal codepoint
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json_escape([C|Rest], Acc) ->
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json_escape(Rest, [C] ++ Acc);
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json_escape([], Acc) ->
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lists:reverse(Acc);
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json_escape(_, _) ->
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erlang:error(badarg).
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%% convert a codepoint to it's \uXXXX equiv. for laziness, this only handles
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%% codepoints this module might escape, ie, control characters
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json_escape_sequence(C) when C < 16#20 ->
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<<_:8, A:4, B:4>> = <<C:16>>, % first two hex digits are always zero
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[(to_hex(B)), (to_hex(A)), $0, $0, $u, $\\].
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to_hex(15) -> $f;
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to_hex(14) -> $e;
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to_hex(13) -> $d;
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to_hex(12) -> $c;
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to_hex(11) -> $b;
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to_hex(10) -> $a;
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to_hex(X) -> X + $0.
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2011-07-17 00:37:24 -07:00
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-ifdef(TEST).
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-include_lib("eunit/include/eunit.hrl").
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2011-07-20 07:14:59 -07:00
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encode(Terms) -> encode_whole(Terms) andalso encode_incremental(Terms).
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encode_whole(Terms) ->
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case loop((encoder([]))(Terms), []) of
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%% unwrap naked values
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{ok, [Terms]} -> true
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; {ok, Terms} -> true
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; _ -> false
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end.
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encode_incremental(Terms) when is_list(Terms) ->
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encode_incremental(Terms, encoder([]), Terms, []);
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%% we could feed naked terms to the regular encoder, but we already do that, so
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%% cheat instead
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encode_incremental(_) -> true.
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encode_incremental([Term], F, Expected, Acc) ->
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case loop(F([Term]), []) of
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{ok, R} -> Expected =:= Acc ++ R
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; _ -> false
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end;
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encode_incremental([Term|Terms], F, Expected, Acc) ->
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case loop(F([Term]), []) of
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{incomplete, Next, R} ->
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encode_incremental(Terms, Next, Expected, Acc ++ R)
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; _ ->
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false
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2011-07-17 00:37:24 -07:00
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end.
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2011-07-20 07:14:59 -07:00
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loop({error, _}, _) -> error;
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loop({incomplete, Next}, Acc) -> {incomplete, Next, lists:reverse(Acc)};
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loop({event, end_json, Next}, Acc) ->
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{incomplete, F} = Next(),
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{error, {badjson, []}} = F([]),
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{ok, lists:reverse(Acc)};
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loop({event, Event, Next}, Acc) -> loop(Next(), [Event] ++ Acc).
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encode_test_() ->
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[
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{"empty object", ?_assert(encode([start_object, end_object]))},
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{"empty array", ?_assert(encode([start_array, end_array]) =:= true)},
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{"nested empty objects", ?_assert(encode([start_object,
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{key, "empty object"},
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start_object,
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{key, "empty object"},
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start_object,
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end_object,
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end_object,
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end_object
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]))},
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{"nested empty arrays", ?_assert(encode([start_array,
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start_array,
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start_array,
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end_array,
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end_array,
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end_array
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]))},
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{"simple object", ?_assert(encode([start_object,
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{key, "a"},
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{string, "hello"},
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{key, "b"},
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{integer, "1"},
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{key, "c"},
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{float, "1.0"},
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{key, "d"},
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{literal, true},
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end_object
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]))},
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2011-07-17 00:37:24 -07:00
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{"simple array", ?_assert(encode([start_array,
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{string, "hello"},
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{integer, "1"},
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{float, "1.0"},
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{literal, true},
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end_array
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]))},
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{"unbalanced array", ?_assertNot(encode([start_array,
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end_array,
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end_array
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2011-07-20 07:14:59 -07:00
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]))},
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{"naked string", ?_assert(encode({string, "hello"}))},
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{"naked literal", ?_assert(encode({literal, true}))},
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{"naked integer", ?_assert(encode({integer, "1"}))},
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{"naked float", ?_assert(encode({float, "1.0"}))}
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2011-07-17 00:37:24 -07:00
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].
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escape_test_() ->
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[
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{"json string escaping",
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?_assert(json_escape(
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"\"\\\b\f\n\r\t"
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) =:= "\\\"\\\\\\b\\f\\n\\r\\t"
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)
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},
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{"json string hex escape",
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?_assert(json_escape(
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[1, 2, 3, 11, 26, 30, 31]
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) =:= "\\u0001\\u0002\\u0003\\u000b\\u001a\\u001e\\u001f"
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)
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}
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].
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2011-07-17 00:37:24 -07:00
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-endif.
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