%% The MIT License %% Copyright (c) 2010 Alisdair Sullivan %% Permission is hereby granted, free of charge, to any person obtaining a copy %% of this software and associated documentation files (the "Software"), to deal %% in the Software without restriction, including without limitation the rights %% to use, copy, modify, merge, publish, distribute, sublicense, and/or sell %% copies of the Software, and to permit persons to whom the Software is %% furnished to do so, subject to the following conditions: %% The above copyright notice and this permission notice shall be included in %% all copies or substantial portions of the Software. %% THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR %% IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, %% FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE %% AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER %% LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, %% OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN %% THE SOFTWARE. -module(jsx). -author("alisdairsullivan@yahoo.ca"). -export([decode/1, decode/2, parser/0, parser/1]). -include("jsx_types.hrl"). %% decode takes a json binary (and optionally, a proplist of options) and returns a list %% of events corresponding to the json structure/contents. it converts incompletes into %% errors -spec decode(JSON::json()) -> {ok, [jsx_event(),...]} | {error, badjson}. -spec decode(JSON::json(), Opts::jsx_opts()) -> {ok, [jsx_event(),...]} | {error, badjson}. decode(JSON) -> decode(JSON, []). decode(JSON, Opts) -> F = parser(Opts), decode_loop(F(JSON), []). decode_loop({incomplete, _}, _) -> {error, badjson}; decode_loop({error, badjson}, _) -> {error, badjson}; decode_loop({end_json, _}, State) -> {ok, lists:reverse(State)}; decode_loop({Event, F}, State) -> decode_loop(F(), [Event] ++ State). %% parser returns an anonymous function of arity 1 that takes a json binary as it's %% argument and returns a tuple containing an error, incomplete and a new parser that %% can be handed more input to resume parsing or a single event and a function that %% can be called to get the next result -spec parser() -> jsx_parser(). -spec parser(Opts::jsx_opts()) -> jsx_parser(). parser() -> parser([]). parser(OptsList) -> F = case proplists:get_value(encoding, OptsList, auto) of utf8 -> fun jsx_utf8:parse/2 ; utf16 -> fun jsx_utf16:parse/2 ; utf32 -> fun jsx_utf32:parse/2 ; {utf16, little} -> fun jsx_utf16le:parse/2 ; {utf32, little} -> fun jsx_utf32le:parse/2 ; auto -> fun detect_encoding/2 end, start(F, OptsList). start(F, OptsList) -> Opts = parse_opts(OptsList), fun(Stream) -> F(Stream, Opts) end. parse_opts(Opts) -> parse_opts(Opts, {false, codepoint, false}). parse_opts([], Opts) -> Opts; parse_opts([{comments, Value}|Rest], {_Comments, EscapedUnicode, Stream}) -> true = lists:member(Value, [true, false]), parse_opts(Rest, {Value, EscapedUnicode, Stream}); parse_opts([{escaped_unicode, Value}|Rest], {Comments, _EscapedUnicode, Stream}) -> true = lists:member(Value, [ascii, codepoint, none]), parse_opts(Rest, {Comments, Value, Stream}); parse_opts([{stream_mode, Value}|Rest], {Comments, EscapedUnicode, _Stream}) -> true = lists:member(Value, [true, false]), parse_opts(Rest, {Comments, EscapedUnicode, Value}); parse_opts([{encoding, _}|Rest], Opts) -> parse_opts(Rest, Opts). %% first check to see if there's a bom, if not, use the rfc4627 method for determining %% encoding. this function makes some assumptions about the validity of the stream %% which may delay failure later than if an encoding is explicitly provided %% utf8 bom detection detect_encoding(<<16#ef, 16#bb, 16#bf, Rest/binary>>, Opts) -> jsx_utf8:parse(Rest, Opts); %% utf32-little bom detection (this has to come before utf16-little) detect_encoding(<<16#ff, 16#fe, 0, 0, Rest/binary>>, Opts) -> jsx_utf32le:parse(Rest, Opts); %% utf16-big bom detection detect_encoding(<<16#fe, 16#ff, Rest/binary>>, Opts) -> jsx_utf16:parse(Rest, Opts); %% utf16-little bom detection detect_encoding(<<16#ff, 16#fe, Rest/binary>>, Opts) -> jsx_utf16le:parse(Rest, Opts); %% utf32-big bom detection detect_encoding(<<0, 0, 16#fe, 16#ff, Rest/binary>>, Opts) -> jsx_utf32:parse(Rest, Opts); %% utf32-little null order detection detect_encoding(<> = JSON, Opts) when X =/= 0 -> jsx_utf32le:parse(JSON, Opts); %% utf16-big null order detection detect_encoding(<<0, X, 0, Y, _Rest/binary>> = JSON, Opts) when X =/= 0, Y =/= 0 -> jsx_utf16:parse(JSON, Opts); %% utf16-little null order detection detect_encoding(<> = JSON, Opts) when X =/= 0, Y =/= 0 -> jsx_utf16le:parse(JSON, Opts); %% utf32-big null order detection detect_encoding(<<0, 0, 0, X, _Rest/binary>> = JSON, Opts) when X =/= 0 -> jsx_utf32:parse(JSON, Opts); %% utf8 null order detection detect_encoding(<> = JSON, Opts) when X =/= 0, Y =/= 0 -> jsx_utf8:parse(JSON, Opts); %% a problem, to autodetect naked single digits' encoding, there is not enough data %% to conclusively determine the encoding correctly. below is an attempt to solve %% the problem detect_encoding(<>, Opts) when X =/= 0 -> {try {Result, _} = jsx_utf8:parse(<>, Opts), Result catch error:function_clause -> incomplete end, fun(Stream) -> detect_encoding(<>, Opts) end }; detect_encoding(<<0, X>>, Opts) when X =/= 0 -> {try {Result, _} = jsx_utf16:parse(<<0, X>>, Opts), Result catch error:function_clause -> incomplete end, fun(Stream) -> detect_encoding(<<0, X, Stream/binary>>, Opts) end }; detect_encoding(<>, Opts) when X =/= 0 -> {try {Result, _} = jsx_utf16le:parse(<>, Opts), Result catch error:function_clause -> incomplete end, fun(Stream) -> detect_encoding(<>, Opts) end }; %% not enough input, request more detect_encoding(Bin, Opts) -> {incomplete, fun(Stream) -> detect_encoding(<>, Opts) end }.