%% Copyright (c) 2014, 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_constraints).
-export([validate/2]).
-type constraint() :: int | nonempty | fun().
-export_type([constraint/0]).
-spec validate(binary(), [constraint()]) -> true | {true, any()} | false.
validate(Value, [Constraint]) ->
apply_constraint(Value, Constraint);
validate(Value, Constraints) when is_list(Constraints) ->
validate_list(Value, Constraints, original);
validate(Value, Constraint) ->
apply_constraint(Value, Constraint).
validate_list(_, [], original) ->
true;
validate_list(Value, [], modified) ->
{true, Value};
validate_list(Value, [Constraint|Tail], State) ->
case apply_constraint(Value, Constraint) of
true ->
validate_list(Value, Tail, State);
{true, Value2} ->
validate_list(Value2, Tail, modified);
false ->
false
end.
%% @todo {int, From, To}, etc.
apply_constraint(Value, int) ->
int(Value);
apply_constraint(Value, nonempty) ->
nonempty(Value);
apply_constraint(Value, F) when is_function(F) ->
F(Value).
%% Constraint functions.
int(Value) when is_binary(Value) ->
try {true, binary_to_integer(Value)}
catch _:_ -> false
end.
nonempty(<<>>) -> false;
nonempty(Value) when is_binary(Value) -> true.
%% @todo Perhaps return true for any other type except empty list?
