1 files changed, 60 insertions, 0 deletions
diff --git a/src/cowboy_constraints.erl b/src/cowboy_constraints.erl
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+++ b/src/cowboy_constraints.erl
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+%% 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, list_to_integer(binary_to_list(Value))}
+	catch _:_ -> false
+	end.
+
+nonempty(<<>>) -> false;
+nonempty(Value) when is_binary(Value) -> true.