%% Copyright (c) 2011, 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(cowboy_dispatcher).
-export([split_host/1, split_path/1, match/3]). %% API.
-type bindings() :: list({Key::atom(), Value::string()}).
-type path_tokens() :: list(nonempty_string()).
-type match_rule() :: '_' | '*' | list(string() | '_' | atom()).
-type dispatch_rule() :: {Host::match_rule(), list({Path::match_rule(),
Handler::module(), Opts::term()})}.
-type dispatch_rules() :: list(dispatch_rule()).
-export_type([bindings/0, path_tokens/0, dispatch_rules/0]).
-include_lib("eunit/include/eunit.hrl").
%% API.
-spec split_host(Host::string()) -> Tokens::path_tokens().
split_host(Host) ->
Host2 = case string:chr(Host, $:) of
0 -> Host;
N -> lists:sublist(Host, N - 1)
end,
string:tokens(Host2, ".").
-spec split_path(Path::string())
-> {Tokens::path_tokens(), Path::string(), Qs::string()}.
split_path(Path) ->
case string:chr(Path, $?) of
0 ->
{string:tokens(Path, "/"), Path, []};
N ->
{Path2, [$?|Qs]} = lists:split(N - 1, Path),
{string:tokens(Path2, "/"), Path2, Qs}
end.
-spec match(Host::path_tokens(), Path::path_tokens(),
Dispatch::dispatch_rules())
-> {ok, Handler::module(), Opts::term(), Binds::bindings()}
| {error, notfound, host} | {error, notfound, path}.
match(_Host, _Path, []) ->
{error, notfound, host};
match(_Host, Path, [{'_', PathMatchs}|_Tail]) ->
match_path(Path, PathMatchs, []);
match(Host, Path, [{HostMatch, PathMatchs}|Tail]) ->
case try_match(host, Host, HostMatch) of
false ->
match(Host, Path, Tail);
{true, HostBinds} ->
match_path(Path, PathMatchs, HostBinds)
end.
-spec match_path(Path::path_tokens(), list({Path::match_rule(),
Handler::module(), Opts::term()}), HostBinds::bindings())
-> {ok, Handler::module(), Opts::term(), Binds::bindings()}
| {error, notfound, path}.
match_path(_Path, [], _HostBinds) ->
{error, notfound, path};
match_path(_Path, [{'_', Handler, Opts}|_Tail], HostBinds) ->
{ok, Handler, Opts, HostBinds};
match_path('*', [{'*', Handler, Opts}|_Tail], HostBinds) ->
{ok, Handler, Opts, HostBinds};
match_path(Path, [{PathMatch, Handler, Opts}|Tail], HostBinds) ->
case try_match(path, Path, PathMatch) of
false ->
match_path(Path, Tail, HostBinds);
{true, PathBinds} ->
{ok, Handler, Opts, HostBinds ++ PathBinds}
end.
%% Internal.
-spec try_match(Type::host | path, List::path_tokens(), Match::match_rule())
-> {true, Binds::bindings()} | false.
try_match(_Type, _List, '_') ->
{true, []};
try_match(_Type, List, Match) when length(List) =/= length(Match) ->
false;
try_match(host, List, Match) ->
list_match(lists:reverse(List), lists:reverse(Match), []);
try_match(path, List, Match) ->
list_match(List, Match, []).
-spec list_match(List::path_tokens(), Match::match_rule(), Binds::bindings())
-> {true, Binds::bindings()} | false.
%% Atom '_' matches anything, continue.
list_match([_E|Tail], ['_'|TailMatch], Binds) ->
list_match(Tail, TailMatch, Binds);
%% Both values match, continue.
list_match([E|Tail], [E|TailMatch], Binds) ->
list_match(Tail, TailMatch, Binds);
%% Bind E to the variable name V and continue.
list_match([E|Tail], [V|TailMatch], Binds) when is_atom(V) ->
list_match(Tail, TailMatch, [{V, E}|Binds]);
%% Values don't match, stop.
list_match([_E|_Tail], [_F|_TailMatch], _Binds) ->
false;
%% Match complete.
list_match([], [], Binds) ->
{true, Binds}.
%% Tests.
-ifdef(TEST).
split_host_test_() ->
%% {Host, Result}
Tests = [
{"", []},
{".........", []},
{"*", ["*"]},
{"cowboy.dev-extend.eu", ["cowboy", "dev-extend", "eu"]},
{"dev-extend..eu", ["dev-extend", "eu"]},
{"dev-extend.eu", ["dev-extend", "eu"]},
{"dev-extend.eu:8080", ["dev-extend", "eu"]},
{"a.b.c.d.e.f.g.h.i.j.k.l.m.n.o.p.q.r.s.t.u.v.w.x.y.z",
["a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m",
"n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z"]}
],
[{H, fun() -> R = split_host(H) end} || {H, R} <- Tests].
split_path_test_() ->
%% {Path, Result, QueryString}
Tests = [
{"?", [], "", ""},
{"???", [], "", "??"},
{"/", [], "/", ""},
{"/users", ["users"], "/users", ""},
{"/users?", ["users"], "/users", ""},
{"/users?a", ["users"], "/users", "a"},
{"/users/42/friends?a=b&c=d&e=notsure?whatever",
["users", "42", "friends"],
"/users/42/friends", "a=b&c=d&e=notsure?whatever"}
],
[{P, fun() -> {R, RawP, Qs} = split_path(P) end} || {P, R, RawP, Qs} <- Tests].
match_test_() ->
Dispatch = [
{["www", '_', "dev-extend", "eu"], [
{["users", '_', "mails"], match_any_subdomain_users, []}
]},
{["dev-extend", "eu"], [
{["users", id, "friends"], match_extend_users_friends, []},
{'_', match_extend, []}
]},
{["dev-extend", var], [
{["threads", var], match_duplicate_vars,
[we, {expect, two}, var, here]}
]},
{["erlang", ext], [
{'_', match_erlang_ext, []}
]},
{'_', [
{["users", id, "friends"], match_users_friends, []},
{'_', match_any, []}
]}
],
%% {Host, Path, Result}
Tests = [
{["any"], [], {ok, match_any, [], []}},
{["www", "any", "dev-extend", "eu"], ["users", "42", "mails"],
{ok, match_any_subdomain_users, [], []}},
{["www", "dev-extend", "eu"], ["users", "42", "mails"],
{ok, match_any, [], []}},
{["www", "dev-extend", "eu"], [], {ok, match_any, [], []}},
{["www", "any", "dev-extend", "eu"], ["not_users", "42", "mails"],
{error, notfound, path}},
{["dev-extend", "eu"], [], {ok, match_extend, [], []}},
{["dev-extend", "eu"], ["users", "42", "friends"],
{ok, match_extend_users_friends, [], [{id, "42"}]}},
{["erlang", "fr"], '_', {ok, match_erlang_ext, [], [{ext, "fr"}]}},
{["any"], ["users", "444", "friends"],
{ok, match_users_friends, [], [{id, "444"}]}},
{["dev-extend", "fr"], ["threads", "987"],
{ok, match_duplicate_vars, [we, {expect, two}, var, here],
[{var, "fr"}, {var, "987"}]}}
],
[{lists:flatten(io_lib:format("~p, ~p", [H, P])), fun() ->
R = match(H, P, Dispatch)
end} || {H, P, R} <- Tests].
-endif.
