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%%
%% Licensed to the Apache Software Foundation (ASF) under one
%% or more contributor license agreements. See the NOTICE file
%% distributed with this work for additional information
%% regarding copyright ownership. The ASF licenses this file
%% to you under the Apache License, Version 2.0 (the
%% "License"); you may not use this file except in compliance
%% with the License. You may obtain a copy of the License at
%%
%% http://www.apache.org/licenses/LICENSE-2.0
%%
%% Unless required by applicable law or agreed to in writing,
%% software distributed under the License is distributed on an
%% "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
%% KIND, either express or implied. See the License for the
%% specific language governing permissions and limitations
%% under the License.
%%
%% The JSON protocol implementation was created by
%% Peter Neumark <neumark.peter@gmail.com> based on
%% the binary protocol implementation.
-module(thrift_json_protocol).
-behaviour(thrift_protocol).
-include("thrift_constants.hrl").
-include("thrift_protocol.hrl").
-export([new/1, new/2,
read/2,
write/2,
flush_transport/1,
close_transport/1,
new_protocol_factory/2
]).
-record(json_context, {
% the type of json_context: array or object
type,
% fields read or written
fields_processed = 0
}).
-record(json_protocol, {
transport,
context_stack = [],
jsx
}).
-type state() :: #json_protocol{}.
-include("thrift_protocol_behaviour.hrl").
-define(VERSION_1, 1).
-define(JSON_DOUBLE_PRECISION, 16).
typeid_to_json(?tType_BOOL) -> "tf";
typeid_to_json(?tType_BYTE) -> "i8";
typeid_to_json(?tType_DOUBLE) -> "dbl";
typeid_to_json(?tType_I8) -> "i8";
typeid_to_json(?tType_I16) -> "i16";
typeid_to_json(?tType_I32) -> "i32";
typeid_to_json(?tType_I64) -> "i64";
typeid_to_json(?tType_STRING) -> "str";
typeid_to_json(?tType_STRUCT) -> "rec";
typeid_to_json(?tType_MAP) -> "map";
typeid_to_json(?tType_SET) -> "set";
typeid_to_json(?tType_LIST) -> "lst".
json_to_typeid("tf") -> ?tType_BOOL;
json_to_typeid("dbl") -> ?tType_DOUBLE;
json_to_typeid("i8") -> ?tType_I8;
json_to_typeid("i16") -> ?tType_I16;
json_to_typeid("i32") -> ?tType_I32;
json_to_typeid("i64") -> ?tType_I64;
json_to_typeid("str") -> ?tType_STRING;
json_to_typeid("rec") -> ?tType_STRUCT;
json_to_typeid("map") -> ?tType_MAP;
json_to_typeid("set") -> ?tType_SET;
json_to_typeid("lst") -> ?tType_LIST.
start_context(object) -> "{";
start_context(array) -> "[".
end_context(object) -> "}";
end_context(array) -> "]".
new(Transport) ->
new(Transport, _Options = []).
new(Transport, _Options) ->
State = #json_protocol{transport = Transport},
thrift_protocol:new(?MODULE, State).
flush_transport(This = #json_protocol{transport = Transport}) ->
{NewTransport, Result} = thrift_transport:flush(Transport),
{This#json_protocol{
transport = NewTransport,
context_stack = []
}, Result}.
close_transport(This = #json_protocol{transport = Transport}) ->
{NewTransport, Result} = thrift_transport:close(Transport),
{This#json_protocol{
transport = NewTransport,
context_stack = [],
jsx = undefined
}, Result}.
%%%
%%% instance methods
%%%
% places a new context on the stack:
write(#json_protocol{context_stack = Stack} = State0, {enter_context, Type}) ->
{State1, ok} = write_values(State0, [{context_pre_item, false}]),
State2 = State1#json_protocol{context_stack = [
#json_context{type=Type}|Stack]},
write_values(State2, [list_to_binary(start_context(Type))]);
% removes the topmost context from stack
write(#json_protocol{context_stack = [CurrCtxt|Stack]} = State0, {exit_context}) ->
Type = CurrCtxt#json_context.type,
State1 = State0#json_protocol{context_stack = Stack},
write_values(State1, [
list_to_binary(end_context(Type)),
{context_post_item, false}
]);
% writes necessary prelude to field or container depending on current context
write(#json_protocol{context_stack = []} = This0,
{context_pre_item, _}) -> {This0, ok};
write(#json_protocol{context_stack = [Context|_CtxtTail]} = This0,
{context_pre_item, MayNeedQuotes}) ->
FieldNo = Context#json_context.fields_processed,
CtxtType = Context#json_context.type,
Rem = FieldNo rem 2,
case {CtxtType, FieldNo, Rem, MayNeedQuotes} of
{array, N, _, _} when N > 0 -> % array element (not first)
write(This0, <<",">>);
{object, 0, _, true} -> % non-string object key (first)
write(This0, <<"\"">>);
{object, N, 0, true} when N > 0 -> % non-string object key (not first)
write(This0, <<",\"">>);
{object, N, 0, false} when N > 0-> % string object key (not first)
write(This0, <<",">>);
_ -> % no pre-field necessary
{This0, ok}
end;
% writes necessary postlude to field or container depending on current context
write(#json_protocol{context_stack = []} = This0,
{context_post_item, _}) -> {This0, ok};
write(#json_protocol{context_stack = [Context|CtxtTail]} = This0,
{context_post_item, MayNeedQuotes}) ->
FieldNo = Context#json_context.fields_processed,
CtxtType = Context#json_context.type,
Rem = FieldNo rem 2,
{This1, ok} = case {CtxtType, Rem, MayNeedQuotes} of
{object, 0, true} -> % non-string object key
write(This0, <<"\":">>);
{object, 0, false} -> % string object key
write(This0, <<":">>);
_ -> % no pre-field necessary
{This0, ok}
end,
NewContext = Context#json_context{fields_processed = FieldNo + 1},
{This1#json_protocol{context_stack=[NewContext|CtxtTail]}, ok};
write(This0, #protocol_message_begin{
name = Name,
type = Type,
seqid = Seqid}) ->
write_values(This0, [
{enter_context, array},
{i32, ?VERSION_1},
{string, Name},
{i32, Type},
{i32, Seqid}
]);
write(This, message_end) ->
write_values(This, [{exit_context}]);
% Example field expression: "1":{"dbl":3.14}
write(This0, #protocol_field_begin{
name = _Name,
type = Type,
id = Id}) ->
write_values(This0, [
% entering 'outer' object
{i16, Id},
% entering 'outer' object
{enter_context, object},
{string, typeid_to_json(Type)}
]);
write(This, field_stop) ->
{This, ok};
write(This, field_end) ->
write_values(This,[{exit_context}]);
% Example message with map: [1,"testMap",1,0,{"1":{"map":["i32","i32",3,{"7":77,"8":88,"9":99}]}}]
write(This0, #protocol_map_begin{
ktype = Ktype,
vtype = Vtype,
size = Size}) ->
write_values(This0, [
{enter_context, array},
{string, typeid_to_json(Ktype)},
{string, typeid_to_json(Vtype)},
{i32, Size},
{enter_context, object}
]);
write(This, map_end) ->
write_values(This,[
{exit_context},
{exit_context}
]);
write(This0, #protocol_list_begin{
etype = Etype,
size = Size}) ->
write_values(This0, [
{enter_context, array},
{string, typeid_to_json(Etype)},
{i32, Size}
]);
write(This, list_end) ->
write_values(This,[
{exit_context}
]);
% example message with set: [1,"testSet",1,0,{"1":{"set":["i32",3,1,2,3]}}]
write(This0, #protocol_set_begin{
etype = Etype,
size = Size}) ->
write_values(This0, [
{enter_context, array},
{string, typeid_to_json(Etype)},
{i32, Size}
]);
write(This, set_end) ->
write_values(This,[
{exit_context}
]);
% example message with struct: [1,"testStruct",1,0,{"1":{"rec":{"1":{"str":"worked"},"4":{"i8":1},"9":{"i32":1073741824},"11":{"i64":1152921504606847000}}}}]
write(This, #protocol_struct_begin{}) ->
write_values(This, [
{enter_context, object}
]);
write(This, struct_end) ->
write_values(This,[
{exit_context}
]);
write(This, {bool, true}) -> write_values(This, [
{context_pre_item, true},
<<"true">>,
{context_post_item, true}
]);
write(This, {bool, false}) -> write_values(This, [
{context_pre_item, true},
<<"false">>,
{context_post_item, true}
]);
write(This, {byte, Byte}) -> write_values(This, [
{context_pre_item, true},
list_to_binary(integer_to_list(Byte)),
{context_post_item, true}
]);
write(This, {i16, I16}) ->
write(This, {byte, I16});
write(This, {i32, I32}) ->
write(This, {byte, I32});
write(This, {i64, I64}) ->
write(This, {byte, I64});
write(This, {double, Double}) -> write_values(This, [
{context_pre_item, true},
list_to_binary(io_lib:format("~.*f", [?JSON_DOUBLE_PRECISION,Double])),
{context_post_item, true}
]);
write(This0, {string, Str}) -> write_values(This0, [
{context_pre_item, false},
case is_binary(Str) of
true -> Str;
false -> <<"\"", (list_to_binary(Str))/binary, "\"">>
end,
{context_post_item, false}
]);
%% TODO: binary fields should be base64 encoded?
%% Data :: iolist()
write(This = #json_protocol{transport = Trans}, Data) ->
%io:format("Data ~p Ctxt ~p~n~n", [Data, This#json_protocol.context_stack]),
{NewTransport, Result} = thrift_transport:write(Trans, Data),
{This#json_protocol{transport = NewTransport}, Result}.
write_values(This0, ValueList) ->
FinalState = lists:foldl(
fun(Val, ThisIn) ->
{ThisOut, ok} = write(ThisIn, Val),
ThisOut
end,
This0,
ValueList),
{FinalState, ok}.
%% I wish the erlang version of the transport interface included a
%% read_all function (like eg. the java implementation). Since it doesn't,
%% here's my version (even though it probably shouldn't be in this file).
%%
%% The resulting binary is immediately send to the JSX stream parser.
%% Subsequent calls to read actually operate on the events returned by JSX.
read_all(#json_protocol{transport = Transport0} = State) ->
{Transport1, Bin} = read_all_1(Transport0, []),
P = thrift_json_parser:parser(),
[First|Rest] = P(Bin),
State#json_protocol{
transport = Transport1,
jsx = {event, First, Rest}
}.
read_all_1(Transport0, IoList) ->
{Transport1, Result} = thrift_transport:read(Transport0, 1),
case Result of
{ok, <<>>} -> % nothing read: assume we're done
{Transport1, iolist_to_binary(lists:reverse(IoList))};
{ok, Data} -> % character successfully read; read more
read_all_1(Transport1, [Data|IoList]);
{error, 'EOF'} -> % we're done
{Transport1, iolist_to_binary(lists:reverse(IoList))}
end.
% Expect reads an event from the JSX event stream. It receives an event or data
% type as input. Comparing the read event from the one is was passed, it
% returns an error if something other than the expected value is encountered.
% Expect also maintains the context stack in #json_protocol.
expect(#json_protocol{jsx={event, {Type, Data}=Ev, [Next|Rest]}}=State, ExpectedType) ->
NextState = State#json_protocol{jsx={event, Next, Rest}},
case Type == ExpectedType of
true ->
{NextState, {ok, convert_data(Type, Data)}};
false ->
{NextState, {error, {unexpected_json_event, Ev}}}
end;
expect(#json_protocol{jsx={event, Event, Next}}=State, ExpectedEvent) ->
expect(State#json_protocol{jsx={event, {Event, none}, Next}}, ExpectedEvent).
convert_data(integer, I) -> list_to_integer(I);
convert_data(float, F) -> list_to_float(F);
convert_data(_, D) -> D.
expect_many(State, ExpectedList) ->
expect_many_1(State, ExpectedList, [], ok).
expect_many_1(State, [], ResultList, Status) ->
{State, {Status, lists:reverse(ResultList)}};
expect_many_1(State, [Expected|ExpTail], ResultList, _PrevStatus) ->
{State1, {Status, Data}} = expect(State, Expected),
NewResultList = [Data|ResultList],
case Status of
% in case of error, end prematurely
error -> expect_many_1(State1, [], NewResultList, Status);
ok -> expect_many_1(State1, ExpTail, NewResultList, Status)
end.
% wrapper around expect to make life easier for container opening/closing functions
expect_nodata(This, ExpectedList) ->
case expect_many(This, ExpectedList) of
{State, {ok, _}} ->
{State, ok};
Error ->
Error
end.
read_field(#json_protocol{jsx={event, Field, [Next|Rest]}} = State) ->
NewState = State#json_protocol{jsx={event, Next, Rest}},
{NewState, Field}.
read(This0, message_begin) ->
% call read_all to get the contents of the transport buffer into JSX.
This1 = read_all(This0),
case expect_many(This1,
[start_array, integer, string, integer, integer]) of
{This2, {ok, [_, Version, Name, Type, SeqId]}} ->
case Version =:= ?VERSION_1 of
true ->
{This2, #protocol_message_begin{name = Name,
type = Type,
seqid = SeqId}};
false ->
{This2, {error, no_json_protocol_version}}
end;
Other -> Other
end;
read(This, message_end) ->
expect_nodata(This, [end_array]);
read(This, struct_begin) ->
expect_nodata(This, [start_object]);
read(This, struct_end) ->
expect_nodata(This, [end_object]);
read(This0, field_begin) ->
{This1, Read} = expect_many(This0,
[%field id
key,
% {} surrounding field
start_object,
% type of field
key]),
case Read of
{ok, [FieldIdStr, _, FieldType]} ->
{This1, #protocol_field_begin{
type = json_to_typeid(FieldType),
id = list_to_integer(FieldIdStr)}}; % TODO: do we need to wrap this in a try/catch?
{error,[{unexpected_json_event, {end_object,none}}]} ->
{This1, #protocol_field_begin{type = ?tType_STOP}};
Other ->
io:format("**** OTHER branch selected ****"),
{This1, Other}
end;
read(This, field_end) ->
expect_nodata(This, [end_object]);
% Example message with map: [1,"testMap",1,0,{"1":{"map":["i32","i32",3,{"7":77,"8":88,"9":99}]}}]
read(This0, map_begin) ->
case expect_many(This0,
[start_array,
% key type
string,
% value type
string,
% size
integer,
% the following object contains the map
start_object]) of
{This1, {ok, [_, Ktype, Vtype, Size, _]}} ->
{This1, #protocol_map_begin{ktype = Ktype,
vtype = Vtype,
size = Size}};
Other -> Other
end;
read(This, map_end) ->
expect_nodata(This, [end_object, end_array]);
read(This0, list_begin) ->
case expect_many(This0,
[start_array,
% element type
string,
% size
integer]) of
{This1, {ok, [_, Etype, Size]}} ->
{This1, #protocol_list_begin{
etype = Etype,
size = Size}};
Other -> Other
end;
read(This, list_end) ->
expect_nodata(This, [end_array]);
% example message with set: [1,"testSet",1,0,{"1":{"set":["i32",3,1,2,3]}}]
read(This0, set_begin) ->
case expect_many(This0,
[start_array,
% element type
string,
% size
integer]) of
{This1, {ok, [_, Etype, Size]}} ->
{This1, #protocol_set_begin{
etype = Etype,
size = Size}};
Other -> Other
end;
read(This, set_end) ->
expect_nodata(This, [end_array]);
read(This0, field_stop) ->
{This0, ok};
%%
read(This0, bool) ->
{This1, Field} = read_field(This0),
Value = case Field of
{literal, I} ->
{ok, I};
_Other ->
{error, unexpected_event_for_boolean}
end,
{This1, Value};
read(This0, byte) ->
{This1, Field} = read_field(This0),
Value = case Field of
{key, K} ->
{ok, list_to_integer(K)};
{integer, I} ->
{ok, list_to_integer(I)};
_Other ->
{error, unexpected_event_for_integer}
end,
{This1, Value};
read(This0, i16) ->
read(This0, byte);
read(This0, i32) ->
read(This0, byte);
read(This0, i64) ->
read(This0, byte);
read(This0, double) ->
{This1, Field} = read_field(This0),
Value = case Field of
{float, I} ->
{ok, list_to_float(I)};
_Other ->
{error, unexpected_event_for_double}
end,
{This1, Value};
% returns a binary directly, call binary_to_list if necessary
read(This0, string) ->
{This1, Field} = read_field(This0),
Value = case Field of
{string, I} ->
{ok, I};
{key, J} ->
{ok, J};
_Other ->
{error, unexpected_event_for_string}
end,
{This1, Value}.
%%%% FACTORY GENERATION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% returns a (fun() -> thrift_protocol())
new_protocol_factory(TransportFactory, _Options) ->
% Only strice read/write are implemented
F = fun() ->
{ok, Transport} = TransportFactory(),
thrift_json_protocol:new(Transport, [])
end,
{ok, F}.