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Diffstat (limited to 'src/cow_sse.erl')
| -rw-r--r-- | src/cow_sse.erl | 214 |
1 files changed, 214 insertions, 0 deletions
diff --git a/src/cow_sse.erl b/src/cow_sse.erl new file mode 100644 index 0000000..710e9b3 --- /dev/null +++ b/src/cow_sse.erl @@ -0,0 +1,214 @@ +%% Copyright (c) 2017, Loïc Hoguin <[email protected]> +%% +%% Permission to use, copy, modify, and/or distribute this software for any +%% purpose with or without fee is hereby granted, provided that the above +%% copyright notice and this permission notice appear in all copies. +%% +%% THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES +%% WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF +%% MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR +%% ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES +%% WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN +%% ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF +%% OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. + +-module(cow_sse). + +-export([init/0]). +-export([parse/2]). + +-record(state, { + state_name = bom :: bom | events, + buffer = <<>> :: binary(), + last_event_id = <<>> :: binary(), + event_type = <<>> :: binary(), + data = [] :: iolist(), + retry = undefined :: undefined | non_neg_integer() +}). +-type state() :: #state{}. +-export_type([state/0]). + +-type event() :: #{ + last_event_id := binary(), + event_type := binary(), + data := iolist() +}. + +-spec init() -> state(). +init() -> + #state{}. + +%% @todo Add a function to retrieve the retry value from the state. + +-spec parse(binary(), state()) + -> {event, event(), State} | {more, State}. +parse(Data0, State=#state{state_name=bom, buffer=Buffer}) -> + Data1 = case Buffer of + <<>> -> Data0; + _ -> << Buffer/binary, Data0/binary >> + end, + case Data1 of + %% Skip the BOM. + << 16#fe, 16#ff, Data/bits >> -> + parse_event(Data, State#state{state_name=events, buffer= <<>>}); + %% Not enough data to know wether we have a BOM. + << 16#fe >> -> + {more, State#state{buffer=Data1}}; + <<>> -> + {more, State}; + %% No BOM. + _ -> + parse_event(Data1, State#state{state_name=events, buffer= <<>>}) + end; +%% Try to process data from the buffer if there is no new input. +parse(<<>>, State=#state{buffer=Buffer}) -> + parse_event(Buffer, State#state{buffer= <<>>}); +%% Otherwise process the input data as-is. +parse(Data, State) -> + parse_event(Data, State). + +parse_event(Data0, State0=#state{buffer=Buffer}) -> + Data = case Buffer of + <<>> -> Data0; + _ -> << Buffer/binary, Data0/binary >> + end, + case binary:split(Data, [<<"\r\n">>, <<"\r">>, <<"\n">>]) of + [Line, Rest] -> + case parse_line(Line, State0) of + {ok, State} -> + parse_event(Rest, State); + {event, Event, State} -> + {event, Event, State#state{buffer=Rest}} + end; + [_] -> + {more, State0#state{buffer=Data}} + end. + +%% Dispatch events on empty line. +parse_line(<<>>, State) -> + dispatch_event(State); +%% Ignore comments. +parse_line(<< $:, _/bits >>, State) -> + {ok, State}; +%% Normal line. +parse_line(Line, State) -> + case binary:split(Line, [<<":\s">>, <<":">>]) of + [Field, Value] -> + process_field(Field, Value, State); + [Field] -> + process_field(Field, <<>>, State) + end. + +process_field(<<"event">>, Value, State) -> + {ok, State#state{event_type=Value}}; +process_field(<<"data">>, Value, State=#state{data=Data}) -> + {ok, State#state{data=[<<$\n>>, Value|Data]}}; +process_field(<<"id">>, Value, State) -> + {ok, State#state{last_event_id=Value}}; +process_field(<<"retry">>, Value, State) -> + try + {ok, State#state{retry=binary_to_integer(Value)}} + catch _:_ -> + {ok, State} + end; +process_field(_, _, State) -> + {ok, State}. + +%% Data is an empty string; abort. +dispatch_event(State=#state{data=[]}) -> + {ok, State#state{event_type= <<>>}}; +%% Dispatch the event. +%% +%% Always remove the last linebreak from the data. +dispatch_event(State=#state{last_event_id=LastEventID, + event_type=EventType, data=[_|Data]}) -> + {event, #{ + last_event_id => LastEventID, + event_type => case EventType of + <<>> -> <<"message">>; + _ -> EventType + end, + data => lists:reverse(Data) + }, State#state{event_type= <<>>, data=[]}}. + +-ifdef(TEST). + +parse_example1_test() -> + {event, #{ + event_type := <<"message">>, + last_event_id := <<>>, + data := Data + }, State} = parse(<< + "data: YHOO\n" + "data: +2\n" + "data: 10\n" + "\n">>, init()), + <<"YHOO\n+2\n10">> = iolist_to_binary(Data), + {more, _} = parse(<<>>, State), + ok. + +parse_example2_test() -> + {event, #{ + event_type := <<"message">>, + last_event_id := <<"1">>, + data := Data1 + }, State0} = parse(<< + ": test stream\n" + "\n" + "data: first event\n" + "id: 1\n" + "\n" + "data:second event\n" + "id\n" + "\n" + "data: third event\n" + "\n">>, init()), + <<"first event">> = iolist_to_binary(Data1), + {event, #{ + event_type := <<"message">>, + last_event_id := <<>>, + data := Data2 + }, State1} = parse(<<>>, State0), + <<"second event">> = iolist_to_binary(Data2), + {event, #{ + event_type := <<"message">>, + last_event_id := <<>>, + data := Data3 + }, State} = parse(<<>>, State1), + <<" third event">> = iolist_to_binary(Data3), + {more, _} = parse(<<>>, State), + ok. + +parse_example3_test() -> + {event, #{ + event_type := <<"message">>, + last_event_id := <<>>, + data := Data1 + }, State0} = parse(<< + "data\n" + "\n" + "data\n" + "data\n" + "\n" + "data:\n">>, init()), + <<>> = iolist_to_binary(Data1), + {event, #{ + event_type := <<"message">>, + last_event_id := <<>>, + data := Data2 + }, State} = parse(<<>>, State0), + <<"\n">> = iolist_to_binary(Data2), + {more, _} = parse(<<>>, State), + ok. + +parse_example4_test() -> + {event, Event, State0} = parse(<< + "data:test\n" + "\n" + "data: test\n" + "\n">>, init()), + {event, Event, State} = parse(<<>>, State0), + {more, _} = parse(<<>>, State), + ok. + +-endif. |