%% Copyright (c) 2014, Loïc Hoguin %% %% 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, list_to_integer(binary_to_list(Value))} catch _:_ -> false end. nonempty(<<>>) -> false; nonempty(Value) when is_binary(Value) -> true.