lib/erl/src/thrift_protocol.erl - thrift - Git at Google

 %%
 %% 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.
 %%

 -module(thrift_protocol).

 -export([new/2,
          write/2,
          read/2,
          read/3,
          skip/2,
          flush_transport/1,
          close_transport/1,
          typeid_to_atom/1
         ]).

 -export([behaviour_info/1]).

 -include("thrift_constants.hrl").
 -include("thrift_protocol.hrl").

 -record(protocol, {module, data}).

 behaviour_info(callbacks) ->
     [
      {read, 2},
      {write, 2},
      {flush_transport, 1},
      {close_transport, 1}
     ];
 behaviour_info(_Else) -> undefined.

 new(Module, Data) when is_atom(Module) ->
     {ok, #protocol{module = Module,
                    data = Data}}.

 -spec flush_transport(#protocol{}) -> {#protocol{}, ok}.
 flush_transport(Proto = #protocol{module = Module,
                                   data = Data}) ->
     {NewData, Result} = Module:flush_transport(Data),
     {Proto#protocol{data = NewData}, Result}.

 -spec close_transport(#protocol{}) -> ok.
 close_transport(#protocol{module = Module,
                           data = Data}) ->
     Module:close_transport(Data).

 typeid_to_atom(?tType_STOP) -> field_stop;
 typeid_to_atom(?tType_VOID) -> void;
 typeid_to_atom(?tType_BOOL) -> bool;
 typeid_to_atom(?tType_DOUBLE) -> double;
 typeid_to_atom(?tType_I8) -> byte;
 typeid_to_atom(?tType_I16) -> i16;
 typeid_to_atom(?tType_I32) -> i32;
 typeid_to_atom(?tType_I64) -> i64;
 typeid_to_atom(?tType_STRING) -> string;
 typeid_to_atom(?tType_STRUCT) -> struct;
 typeid_to_atom(?tType_MAP) -> map;
 typeid_to_atom(?tType_SET) -> set;
 typeid_to_atom(?tType_LIST) -> list.

 term_to_typeid(void) -> ?tType_VOID;
 term_to_typeid(bool) -> ?tType_BOOL;
 term_to_typeid(byte) -> ?tType_I8;
 term_to_typeid(double) -> ?tType_DOUBLE;
 term_to_typeid(i8) -> ?tType_I8;
 term_to_typeid(i16) -> ?tType_I16;
 term_to_typeid(i32) -> ?tType_I32;
 term_to_typeid(i64) -> ?tType_I64;
 term_to_typeid(string) -> ?tType_STRING;
 term_to_typeid({struct, _}) -> ?tType_STRUCT;
 term_to_typeid({map, _, _}) -> ?tType_MAP;
 term_to_typeid({set, _}) -> ?tType_SET;
 term_to_typeid({list, _}) -> ?tType_LIST.

 %% Structure is like:
 %%    [{Fid, Type}, ...]
 -spec read(#protocol{}, {struct, _StructDef}, atom()) -> {#protocol{}, {ok, tuple()}}.
 read(IProto0, {struct, Structure}, Tag)
   when is_list(Structure), is_atom(Tag) ->

     % If we want a tagged tuple, we need to offset all the tuple indices
     % by 1 to avoid overwriting the tag.
     Offset = if Tag =/= undefined -> 1; true -> 0 end,
     IndexList = case length(Structure) of
                     N when N > 0 -> lists:seq(1 + Offset, N + Offset);
                     _ -> []
                 end,

     SWithIndices = [{Fid, {Type, Index}} ||
                        {{Fid, Type}, Index} <-
                            lists:zip(Structure, IndexList)],
     % Fid -> {Type, Index}
     SDict = dict:from_list(SWithIndices),

     {IProto1, ok} = read(IProto0, struct_begin),
     RTuple0 = erlang:make_tuple(length(Structure) + Offset, undefined),
     RTuple1 = if Tag =/= undefined -> setelement(1, RTuple0, Tag);
                  true              -> RTuple0
               end,

     {IProto2, RTuple2} = read_struct_loop(IProto1, SDict, RTuple1),
     {IProto2, {ok, RTuple2}}.


 %% NOTE: Keep this in sync with thrift_protocol_behaviour:read
 -spec read
         (#protocol{}, {struct, _Info}) ->    {#protocol{}, {ok, tuple()}      | {error, _Reason}};
         (#protocol{}, tprot_cont_tag()) ->   {#protocol{}, {ok, any()}        | {error, _Reason}};
         (#protocol{}, tprot_empty_tag()) ->  {#protocol{},  ok                | {error, _Reason}};
         (#protocol{}, tprot_header_tag()) -> {#protocol{}, tprot_header_val() | {error, _Reason}};
         (#protocol{}, tprot_data_tag()) ->   {#protocol{}, {ok, any()}        | {error, _Reason}}.

 read(IProto, {struct, {Module, StructureName}}) when is_atom(Module),
                                                      is_atom(StructureName) ->
     read(IProto, Module:struct_info(StructureName), StructureName);

 read(IProto, S={struct, Structure}) when is_list(Structure) ->
     read(IProto, S, undefined);

 read(IProto0, {list, Type}) ->
     {IProto1, #protocol_list_begin{etype = EType, size = Size}} =
         read(IProto0, list_begin),
     {EType, EType} = {term_to_typeid(Type), EType},
     {List, IProto2} = lists:mapfoldl(fun(_, ProtoS0) ->
                                              {ProtoS1, {ok, Item}} = read(ProtoS0, Type),
                                              {Item, ProtoS1}
                                      end,
                                      IProto1,
                                      lists:duplicate(Size, 0)),
     {IProto3, ok} = read(IProto2, list_end),
     {IProto3, {ok, List}};

 read(IProto0, {map, KeyType, ValType}) ->
     {IProto1, #protocol_map_begin{size = Size, ktype = KType, vtype = VType}} =
         read(IProto0, map_begin),
     _ = case Size of
       0 -> 0;
       _ ->
         {KType, KType} = {term_to_typeid(KeyType), KType},
         {VType, VType} = {term_to_typeid(ValType), VType}
     end,
     {List, IProto2} = lists:mapfoldl(fun(_, ProtoS0) ->
                                              {ProtoS1, {ok, Key}} = read(ProtoS0, KeyType),
                                              {ProtoS2, {ok, Val}} = read(ProtoS1, ValType),
                                              {{Key, Val}, ProtoS2}
                                      end,
                                      IProto1,
                                      lists:duplicate(Size, 0)),
     {IProto3, ok} = read(IProto2, map_end),
     {IProto3, {ok, dict:from_list(List)}};

 read(IProto0, {set, Type}) ->
     {IProto1, #protocol_set_begin{etype = EType, size = Size}} =
         read(IProto0, set_begin),
     {EType, EType} = {term_to_typeid(Type), EType},
     {List, IProto2} = lists:mapfoldl(fun(_, ProtoS0) ->
                                              {ProtoS1, {ok, Item}} = read(ProtoS0, Type),
                                              {Item, ProtoS1}
                                      end,
                                      IProto1,
                                      lists:duplicate(Size, 0)),
     {IProto3, ok} = read(IProto2, set_end),
     {IProto3, {ok, sets:from_list(List)}};

 read(Protocol, ProtocolType) ->
     read_specific(Protocol, ProtocolType).

 %% NOTE: Keep this in sync with thrift_protocol_behaviour:read
 -spec read_specific
         (#protocol{}, tprot_empty_tag()) ->  {#protocol{},  ok                | {error, _Reason}};
         (#protocol{}, tprot_header_tag()) -> {#protocol{}, tprot_header_val() | {error, _Reason}};
         (#protocol{}, tprot_data_tag()) ->   {#protocol{}, {ok, any()}        | {error, _Reason}}.
 read_specific(Proto = #protocol{module = Module,
                                 data = ModuleData}, ProtocolType) ->
     {NewData, Result} = Module:read(ModuleData, ProtocolType),
     {Proto#protocol{data = NewData}, Result}.

 read_struct_loop(IProto0, SDict, RTuple) ->
     {IProto1, #protocol_field_begin{type = FType, id = Fid}} =
         thrift_protocol:read(IProto0, field_begin),
     case {FType, Fid} of
         {?tType_STOP, _} ->
             {IProto2, ok} = read(IProto1, struct_end),
             {IProto2, RTuple};
         _Else ->
             case dict:find(Fid, SDict) of
                 {ok, {Type, Index}} ->
                     case term_to_typeid(Type) of
                         FType ->
                             {IProto2, {ok, Val}} = read(IProto1, Type),
                             {IProto3, ok} = thrift_protocol:read(IProto2, field_end),
                             NewRTuple = setelement(Index, RTuple, Val),
                             read_struct_loop(IProto3, SDict, NewRTuple);
                         Expected ->
                             error_logger:info_msg(
                               "Skipping field ~p with wrong type (~p != ~p)~n",
                               [Fid, FType, Expected]),
                             skip_field(FType, IProto1, SDict, RTuple)
                     end;
                 _Else2 ->
                     skip_field(FType, IProto1, SDict, RTuple)
             end
     end.

 skip_field(FType, IProto0, SDict, RTuple) ->
     {IProto1, ok} = skip(IProto0, typeid_to_atom(FType)),
     {IProto2, ok} = read(IProto1, field_end),
     read_struct_loop(IProto2, SDict, RTuple).

 -spec skip(#protocol{}, atom()) -> {#protocol{}, ok}.

 skip(Proto0, struct) ->
     {Proto1, ok} = read(Proto0, struct_begin),
     {Proto2, ok} = skip_struct_loop(Proto1),
     {Proto3, ok} = read(Proto2, struct_end),
     {Proto3, ok};

 skip(Proto0, map) ->
     {Proto1, Map} = read(Proto0, map_begin),
     {Proto2, ok} = skip_map_loop(Proto1, Map),
     {Proto3, ok} = read(Proto2, map_end),
     {Proto3, ok};

 skip(Proto0, set) ->
     {Proto1, Set} = read(Proto0, set_begin),
     {Proto2, ok} = skip_set_loop(Proto1, Set),
     {Proto3, ok} = read(Proto2, set_end),
     {Proto3, ok};

 skip(Proto0, list) ->
     {Proto1, List} = read(Proto0, list_begin),
     {Proto2, ok} = skip_list_loop(Proto1, List),
     {Proto3, ok} = read(Proto2, list_end),
     {Proto3, ok};

 skip(Proto0, Type) when is_atom(Type) ->
     {Proto1, _Ignore} = read(Proto0, Type),
     {Proto1, ok}.


 skip_struct_loop(Proto0) ->
     {Proto1, #protocol_field_begin{type = Type}} = read(Proto0, field_begin),
     case Type of
         ?tType_STOP ->
             {Proto1, ok};
         _Else ->
             {Proto2, ok} = skip(Proto1, typeid_to_atom(Type)),
             {Proto3, ok} = read(Proto2, field_end),
             skip_struct_loop(Proto3)
     end.

 skip_map_loop(Proto0, Map = #protocol_map_begin{ktype = Ktype,
                                                 vtype = Vtype,
                                                 size = Size}) ->
     case Size of
         N when N > 0 ->
             {Proto1, ok} = skip(Proto0, typeid_to_atom(Ktype)),
             {Proto2, ok} = skip(Proto1, typeid_to_atom(Vtype)),
             skip_map_loop(Proto2,
                           Map#protocol_map_begin{size = Size - 1});
         0 -> {Proto0, ok}
     end.

 skip_set_loop(Proto0, Map = #protocol_set_begin{etype = Etype,
                                                 size = Size}) ->
     case Size of
         N when N > 0 ->
             {Proto1, ok} = skip(Proto0, typeid_to_atom(Etype)),
             skip_set_loop(Proto1,
                           Map#protocol_set_begin{size = Size - 1});
         0 -> {Proto0, ok}
     end.

 skip_list_loop(Proto0, Map = #protocol_list_begin{etype = Etype,
                                                   size = Size}) ->
     case Size of
         N when N > 0 ->
             {Proto1, ok} = skip(Proto0, typeid_to_atom(Etype)),
             skip_list_loop(Proto1,
                            Map#protocol_list_begin{size = Size - 1});
         0 -> {Proto0, ok}
     end.


 %%--------------------------------------------------------------------
 %% Function: write(OProto, {Type, Data}) -> ok
 %%
 %% Type = {struct, StructDef} |
 %%        {list, Type} |
 %%        {map, KeyType, ValType} |
 %%        {set, Type} |
 %%        BaseType
 %%
 %% Data =
 %%         tuple()  -- for struct
 %%       | list()   -- for list
 %%       | dictionary()   -- for map
 %%       | set()    -- for set
 %%       | any()    -- for base types
 %%
 %% Description:
 %%--------------------------------------------------------------------
 -spec write(#protocol{}, any()) -> {#protocol{}, ok | {error, _Reason}}.

 write(Proto0, {{struct, StructDef}, Data})
   when is_list(StructDef), is_tuple(Data), length(StructDef) == size(Data) - 1 ->

     [StructName | Elems] = tuple_to_list(Data),
     {Proto1, ok} = write(Proto0, #protocol_struct_begin{name = StructName}),
     {Proto2, ok} = struct_write_loop(Proto1, StructDef, Elems),
     {Proto3, ok} = write(Proto2, struct_end),
     {Proto3, ok};

 write(Proto, {{struct, {Module, StructureName}}, Data})
   when is_atom(Module),
        is_atom(StructureName),
        element(1, Data) =:= StructureName ->
     write(Proto, {Module:struct_info(StructureName), Data});

 write(_, {{struct, {Module, StructureName}}, Data})
   when is_atom(Module),
        is_atom(StructureName) ->
     erlang:error(struct_unmatched, {{provided, element(1, Data)},
                              {expected, StructureName}});

 write(Proto0, {{list, Type}, Data})
   when is_list(Data) ->
     {Proto1, ok} = write(Proto0,
                #protocol_list_begin{
                  etype = term_to_typeid(Type),
                  size = length(Data)
                 }),
     Proto2 = lists:foldl(fun(Elem, ProtoIn) ->
                                  {ProtoOut, ok} = write(ProtoIn, {Type, Elem}),
                                  ProtoOut
                          end,
                          Proto1,
                          Data),
     {Proto3, ok} = write(Proto2, list_end),
     {Proto3, ok};

 write(Proto0, {{map, KeyType, ValType}, Data}) ->
     {Proto1, ok} = write(Proto0,
                          #protocol_map_begin{
                            ktype = term_to_typeid(KeyType),
                            vtype = term_to_typeid(ValType),
                            size  = dict:size(Data)
                           }),
     Proto2 = dict:fold(fun(KeyData, ValData, ProtoS0) ->
                                {ProtoS1, ok} = write(ProtoS0, {KeyType, KeyData}),
                                {ProtoS2, ok} = write(ProtoS1, {ValType, ValData}),
                                ProtoS2
                        end,
                        Proto1,
                        Data),
     {Proto3, ok} = write(Proto2, map_end),
     {Proto3, ok};

 write(Proto0, {{set, Type}, Data}) ->
     true = sets:is_set(Data),
     {Proto1, ok} = write(Proto0,
                          #protocol_set_begin{
                            etype = term_to_typeid(Type),
                            size  = sets:size(Data)
                           }),
     Proto2 = sets:fold(fun(Elem, ProtoIn) ->
                                {ProtoOut, ok} = write(ProtoIn, {Type, Elem}),
                                ProtoOut
                        end,
                        Proto1,
                        Data),
     {Proto3, ok} = write(Proto2, set_end),
     {Proto3, ok};

 write(Proto = #protocol{module = Module,
                         data = ModuleData}, Data) ->
     {NewData, Result} = Module:write(ModuleData, Data),
     {Proto#protocol{data = NewData}, Result}.

 struct_write_loop(Proto0, [{Fid, Type} | RestStructDef], [Data | RestData]) ->
     NewProto = case Data of
                    undefined ->
                        Proto0; % null fields are skipped in response
                    _ ->
                        {Proto1, ok} = write(Proto0,
                                            #protocol_field_begin{
                                              type = term_to_typeid(Type),
                                              id = Fid
                                             }),
                        {Proto2, ok} = write(Proto1, {Type, Data}),
                        {Proto3, ok} = write(Proto2, field_end),
                        Proto3
                end,
     struct_write_loop(NewProto, RestStructDef, RestData);
 struct_write_loop(Proto, [], []) ->
     write(Proto, field_stop).
	%%
	%% 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.
	%%

	-module(thrift_protocol).

	-export([new/2,
	write/2,
	read/2,
	read/3,
	skip/2,
	flush_transport/1,
	close_transport/1,
	typeid_to_atom/1
	]).

	-export([behaviour_info/1]).

	-include("thrift_constants.hrl").
	-include("thrift_protocol.hrl").

	-record(protocol, {module, data}).

	behaviour_info(callbacks) ->
	[
	{read, 2},
	{write, 2},
	{flush_transport, 1},
	{close_transport, 1}
	];
	behaviour_info(_Else) -> undefined.

	new(Module, Data) when is_atom(Module) ->
	{ok, #protocol{module = Module,
	data = Data}}.

	-spec flush_transport(#protocol{}) -> {#protocol{}, ok}.
	flush_transport(Proto = #protocol{module = Module,
	data = Data}) ->
	{NewData, Result} = Module:flush_transport(Data),
	{Proto#protocol{data = NewData}, Result}.

	-spec close_transport(#protocol{}) -> ok.
	close_transport(#protocol{module = Module,
	data = Data}) ->
	Module:close_transport(Data).

	typeid_to_atom(?tType_STOP) -> field_stop;
	typeid_to_atom(?tType_VOID) -> void;
	typeid_to_atom(?tType_BOOL) -> bool;
	typeid_to_atom(?tType_DOUBLE) -> double;
	typeid_to_atom(?tType_I8) -> byte;
	typeid_to_atom(?tType_I16) -> i16;
	typeid_to_atom(?tType_I32) -> i32;
	typeid_to_atom(?tType_I64) -> i64;
	typeid_to_atom(?tType_STRING) -> string;
	typeid_to_atom(?tType_STRUCT) -> struct;
	typeid_to_atom(?tType_MAP) -> map;
	typeid_to_atom(?tType_SET) -> set;
	typeid_to_atom(?tType_LIST) -> list.

	term_to_typeid(void) -> ?tType_VOID;
	term_to_typeid(bool) -> ?tType_BOOL;
	term_to_typeid(byte) -> ?tType_I8;
	term_to_typeid(double) -> ?tType_DOUBLE;
	term_to_typeid(i8) -> ?tType_I8;
	term_to_typeid(i16) -> ?tType_I16;
	term_to_typeid(i32) -> ?tType_I32;
	term_to_typeid(i64) -> ?tType_I64;
	term_to_typeid(string) -> ?tType_STRING;
	term_to_typeid({struct, _}) -> ?tType_STRUCT;
	term_to_typeid({map, _, _}) -> ?tType_MAP;
	term_to_typeid({set, _}) -> ?tType_SET;
	term_to_typeid({list, _}) -> ?tType_LIST.

	%% Structure is like:
	%% [{Fid, Type}, ...]
	-spec read(#protocol{}, {struct, _StructDef}, atom()) -> {#protocol{}, {ok, tuple()}}.
	read(IProto0, {struct, Structure}, Tag)
	when is_list(Structure), is_atom(Tag) ->

	% If we want a tagged tuple, we need to offset all the tuple indices
	% by 1 to avoid overwriting the tag.
	Offset = if Tag =/= undefined -> 1; true -> 0 end,
	IndexList = case length(Structure) of
	N when N > 0 -> lists:seq(1 + Offset, N + Offset);
	_ -> []
	end,

	SWithIndices = [{Fid, {Type, Index}} \|\|
	{{Fid, Type}, Index} <-
	lists:zip(Structure, IndexList)],
	% Fid -> {Type, Index}
	SDict = dict:from_list(SWithIndices),

	{IProto1, ok} = read(IProto0, struct_begin),
	RTuple0 = erlang:make_tuple(length(Structure) + Offset, undefined),
	RTuple1 = if Tag =/= undefined -> setelement(1, RTuple0, Tag);
	true -> RTuple0
	end,

	{IProto2, RTuple2} = read_struct_loop(IProto1, SDict, RTuple1),
	{IProto2, {ok, RTuple2}}.


	%% NOTE: Keep this in sync with thrift_protocol_behaviour:read
	-spec read
	(#protocol{}, {struct, _Info}) -> {#protocol{}, {ok, tuple()} \| {error, _Reason}};
	(#protocol{}, tprot_cont_tag()) -> {#protocol{}, {ok, any()} \| {error, _Reason}};
	(#protocol{}, tprot_empty_tag()) -> {#protocol{}, ok \| {error, _Reason}};
	(#protocol{}, tprot_header_tag()) -> {#protocol{}, tprot_header_val() \| {error, _Reason}};
	(#protocol{}, tprot_data_tag()) -> {#protocol{}, {ok, any()} \| {error, _Reason}}.

	read(IProto, {struct, {Module, StructureName}}) when is_atom(Module),
	is_atom(StructureName) ->
	read(IProto, Module:struct_info(StructureName), StructureName);

	read(IProto, S={struct, Structure}) when is_list(Structure) ->
	read(IProto, S, undefined);

	read(IProto0, {list, Type}) ->
	{IProto1, #protocol_list_begin{etype = EType, size = Size}} =
	read(IProto0, list_begin),
	{EType, EType} = {term_to_typeid(Type), EType},
	{List, IProto2} = lists:mapfoldl(fun(_, ProtoS0) ->
	{ProtoS1, {ok, Item}} = read(ProtoS0, Type),
	{Item, ProtoS1}
	end,
	IProto1,
	lists:duplicate(Size, 0)),
	{IProto3, ok} = read(IProto2, list_end),
	{IProto3, {ok, List}};

	read(IProto0, {map, KeyType, ValType}) ->
	{IProto1, #protocol_map_begin{size = Size, ktype = KType, vtype = VType}} =
	read(IProto0, map_begin),
	_ = case Size of
	0 -> 0;
	_ ->
	{KType, KType} = {term_to_typeid(KeyType), KType},
	{VType, VType} = {term_to_typeid(ValType), VType}
	end,
	{List, IProto2} = lists:mapfoldl(fun(_, ProtoS0) ->
	{ProtoS1, {ok, Key}} = read(ProtoS0, KeyType),
	{ProtoS2, {ok, Val}} = read(ProtoS1, ValType),
	{{Key, Val}, ProtoS2}
	end,
	IProto1,
	lists:duplicate(Size, 0)),
	{IProto3, ok} = read(IProto2, map_end),
	{IProto3, {ok, dict:from_list(List)}};

	read(IProto0, {set, Type}) ->
	{IProto1, #protocol_set_begin{etype = EType, size = Size}} =
	read(IProto0, set_begin),
	{EType, EType} = {term_to_typeid(Type), EType},
	{List, IProto2} = lists:mapfoldl(fun(_, ProtoS0) ->
	{ProtoS1, {ok, Item}} = read(ProtoS0, Type),
	{Item, ProtoS1}
	end,
	IProto1,
	lists:duplicate(Size, 0)),
	{IProto3, ok} = read(IProto2, set_end),
	{IProto3, {ok, sets:from_list(List)}};

	read(Protocol, ProtocolType) ->
	read_specific(Protocol, ProtocolType).

	%% NOTE: Keep this in sync with thrift_protocol_behaviour:read
	-spec read_specific
	(#protocol{}, tprot_empty_tag()) -> {#protocol{}, ok \| {error, _Reason}};
	(#protocol{}, tprot_header_tag()) -> {#protocol{}, tprot_header_val() \| {error, _Reason}};
	(#protocol{}, tprot_data_tag()) -> {#protocol{}, {ok, any()} \| {error, _Reason}}.
	read_specific(Proto = #protocol{module = Module,
	data = ModuleData}, ProtocolType) ->
	{NewData, Result} = Module:read(ModuleData, ProtocolType),
	{Proto#protocol{data = NewData}, Result}.

	read_struct_loop(IProto0, SDict, RTuple) ->
	{IProto1, #protocol_field_begin{type = FType, id = Fid}} =
	thrift_protocol:read(IProto0, field_begin),
	case {FType, Fid} of
	{?tType_STOP, _} ->
	{IProto2, ok} = read(IProto1, struct_end),
	{IProto2, RTuple};
	_Else ->
	case dict:find(Fid, SDict) of
	{ok, {Type, Index}} ->
	case term_to_typeid(Type) of
	FType ->
	{IProto2, {ok, Val}} = read(IProto1, Type),
	{IProto3, ok} = thrift_protocol:read(IProto2, field_end),
	NewRTuple = setelement(Index, RTuple, Val),
	read_struct_loop(IProto3, SDict, NewRTuple);
	Expected ->
	error_logger:info_msg(
	"Skipping field ~p with wrong type (~p != ~p)~n",
	[Fid, FType, Expected]),
	skip_field(FType, IProto1, SDict, RTuple)
	end;
	_Else2 ->
	skip_field(FType, IProto1, SDict, RTuple)
	end
	end.

	skip_field(FType, IProto0, SDict, RTuple) ->
	{IProto1, ok} = skip(IProto0, typeid_to_atom(FType)),
	{IProto2, ok} = read(IProto1, field_end),
	read_struct_loop(IProto2, SDict, RTuple).

	-spec skip(#protocol{}, atom()) -> {#protocol{}, ok}.

	skip(Proto0, struct) ->
	{Proto1, ok} = read(Proto0, struct_begin),
	{Proto2, ok} = skip_struct_loop(Proto1),
	{Proto3, ok} = read(Proto2, struct_end),
	{Proto3, ok};

	skip(Proto0, map) ->
	{Proto1, Map} = read(Proto0, map_begin),
	{Proto2, ok} = skip_map_loop(Proto1, Map),
	{Proto3, ok} = read(Proto2, map_end),
	{Proto3, ok};

	skip(Proto0, set) ->
	{Proto1, Set} = read(Proto0, set_begin),
	{Proto2, ok} = skip_set_loop(Proto1, Set),
	{Proto3, ok} = read(Proto2, set_end),
	{Proto3, ok};

	skip(Proto0, list) ->
	{Proto1, List} = read(Proto0, list_begin),
	{Proto2, ok} = skip_list_loop(Proto1, List),
	{Proto3, ok} = read(Proto2, list_end),
	{Proto3, ok};

	skip(Proto0, Type) when is_atom(Type) ->
	{Proto1, _Ignore} = read(Proto0, Type),
	{Proto1, ok}.


	skip_struct_loop(Proto0) ->
	{Proto1, #protocol_field_begin{type = Type}} = read(Proto0, field_begin),
	case Type of
	?tType_STOP ->
	{Proto1, ok};
	_Else ->
	{Proto2, ok} = skip(Proto1, typeid_to_atom(Type)),
	{Proto3, ok} = read(Proto2, field_end),
	skip_struct_loop(Proto3)
	end.

	skip_map_loop(Proto0, Map = #protocol_map_begin{ktype = Ktype,
	vtype = Vtype,
	size = Size}) ->
	case Size of
	N when N > 0 ->
	{Proto1, ok} = skip(Proto0, typeid_to_atom(Ktype)),
	{Proto2, ok} = skip(Proto1, typeid_to_atom(Vtype)),
	skip_map_loop(Proto2,
	Map#protocol_map_begin{size = Size - 1});
	0 -> {Proto0, ok}
	end.

	skip_set_loop(Proto0, Map = #protocol_set_begin{etype = Etype,
	size = Size}) ->
	case Size of
	N when N > 0 ->
	{Proto1, ok} = skip(Proto0, typeid_to_atom(Etype)),
	skip_set_loop(Proto1,
	Map#protocol_set_begin{size = Size - 1});
	0 -> {Proto0, ok}
	end.

	skip_list_loop(Proto0, Map = #protocol_list_begin{etype = Etype,
	size = Size}) ->
	case Size of
	N when N > 0 ->
	{Proto1, ok} = skip(Proto0, typeid_to_atom(Etype)),
	skip_list_loop(Proto1,
	Map#protocol_list_begin{size = Size - 1});
	0 -> {Proto0, ok}
	end.


	%%--------------------------------------------------------------------
	%% Function: write(OProto, {Type, Data}) -> ok
	%%
	%% Type = {struct, StructDef} \|
	%% {list, Type} \|
	%% {map, KeyType, ValType} \|
	%% {set, Type} \|
	%% BaseType
	%%
	%% Data =
	%% tuple() -- for struct
	%% \| list() -- for list
	%% \| dictionary() -- for map
	%% \| set() -- for set
	%% \| any() -- for base types
	%%
	%% Description:
	%%--------------------------------------------------------------------
	-spec write(#protocol{}, any()) -> {#protocol{}, ok \| {error, _Reason}}.

	write(Proto0, {{struct, StructDef}, Data})
	when is_list(StructDef), is_tuple(Data), length(StructDef) == size(Data) - 1 ->

	[StructName \| Elems] = tuple_to_list(Data),
	{Proto1, ok} = write(Proto0, #protocol_struct_begin{name = StructName}),
	{Proto2, ok} = struct_write_loop(Proto1, StructDef, Elems),
	{Proto3, ok} = write(Proto2, struct_end),
	{Proto3, ok};

	write(Proto, {{struct, {Module, StructureName}}, Data})
	when is_atom(Module),
	is_atom(StructureName),
	element(1, Data) =:= StructureName ->
	write(Proto, {Module:struct_info(StructureName), Data});

	write(_, {{struct, {Module, StructureName}}, Data})
	when is_atom(Module),
	is_atom(StructureName) ->
	erlang:error(struct_unmatched, {{provided, element(1, Data)},
	{expected, StructureName}});

	write(Proto0, {{list, Type}, Data})
	when is_list(Data) ->
	{Proto1, ok} = write(Proto0,
	#protocol_list_begin{
	etype = term_to_typeid(Type),
	size = length(Data)
	}),
	Proto2 = lists:foldl(fun(Elem, ProtoIn) ->
	{ProtoOut, ok} = write(ProtoIn, {Type, Elem}),
	ProtoOut
	end,
	Proto1,
	Data),
	{Proto3, ok} = write(Proto2, list_end),
	{Proto3, ok};

	write(Proto0, {{map, KeyType, ValType}, Data}) ->
	{Proto1, ok} = write(Proto0,
	#protocol_map_begin{
	ktype = term_to_typeid(KeyType),
	vtype = term_to_typeid(ValType),
	size = dict:size(Data)
	}),
	Proto2 = dict:fold(fun(KeyData, ValData, ProtoS0) ->
	{ProtoS1, ok} = write(ProtoS0, {KeyType, KeyData}),
	{ProtoS2, ok} = write(ProtoS1, {ValType, ValData}),
	ProtoS2
	end,
	Proto1,
	Data),
	{Proto3, ok} = write(Proto2, map_end),
	{Proto3, ok};

	write(Proto0, {{set, Type}, Data}) ->
	true = sets:is_set(Data),
	{Proto1, ok} = write(Proto0,
	#protocol_set_begin{
	etype = term_to_typeid(Type),
	size = sets:size(Data)
	}),
	Proto2 = sets:fold(fun(Elem, ProtoIn) ->
	{ProtoOut, ok} = write(ProtoIn, {Type, Elem}),
	ProtoOut
	end,
	Proto1,
	Data),
	{Proto3, ok} = write(Proto2, set_end),
	{Proto3, ok};

	write(Proto = #protocol{module = Module,
	data = ModuleData}, Data) ->
	{NewData, Result} = Module:write(ModuleData, Data),
	{Proto#protocol{data = NewData}, Result}.

	struct_write_loop(Proto0, [{Fid, Type} \| RestStructDef], [Data \| RestData]) ->
	NewProto = case Data of
	undefined ->
	Proto0; % null fields are skipped in response
	_ ->
	{Proto1, ok} = write(Proto0,
	#protocol_field_begin{
	type = term_to_typeid(Type),
	id = Fid
	}),
	{Proto2, ok} = write(Proto1, {Type, Data}),
	{Proto3, ok} = write(Proto2, field_end),
	Proto3
	end,
	struct_write_loop(NewProto, RestStructDef, RestData);
	struct_write_loop(Proto, [], []) ->
	write(Proto, field_stop).