catch2/include/internal/catch_matchers_generic.hpp
Martin Hořeňovský 1ca8f43b01 Add PredicateMatcher that takes an arbitrary predicate functions
Also adds `Predicate` helper function to create `PredicateMatcher`.
Because of limitations in type inference it needs to be explicitly
typed, like so
`Predicate<std::string>([](std::string const& str) { ... })`.
It also takes an optional second argument for description of the
predicate.

It is possible to infer the argument with sufficient TMP, see
https://stackoverflow.com/questions/43560492/how-to-extract-lambdas-return-type-and-variadic-parameters-pack-back-from-gener/43561563#43561563
but I don't think that the magic is worth introducing ATM.

Closes #1236
2018-04-04 11:14:19 +02:00

59 lines
1.7 KiB
C++

/*
* Created by Martin Hořeňovský on 03/04/2017.
*
* Distributed under the Boost Software License, Version 1.0. (See accompanying
* file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
*/
#ifndef TWOBLUECUBES_CATCH_MATCHERS_GENERIC_HPP_INCLUDED
#define TWOBLUECUBES_CATCH_MATCHERS_GENERIC_HPP_INCLUDED
#include "catch_common.h"
#include "catch_matchers.h"
#include <functional>
#include <string>
namespace Catch {
namespace Matchers {
namespace Generic {
namespace Detail {
std::string finalizeDescription(const std::string& desc);
}
template <typename T>
class PredicateMatcher : public MatcherBase<T> {
std::function<bool(T const&)> m_predicate;
std::string m_description;
public:
PredicateMatcher(std::function<bool(T const&)> const& elem, std::string const& descr)
:m_predicate(std::move(elem)),
m_description(Detail::finalizeDescription(descr))
{}
bool match( T const& item ) const override {
return m_predicate(item);
}
std::string describe() const override {
return m_description;
}
};
} // namespace Generic
// The following functions create the actual matcher objects.
// The user has to explicitly specify type to the function, because
// infering std::function<bool(T const&)> is hard (but possible) and
// requires a lot of TMP.
template<typename T>
Generic::PredicateMatcher<T> Predicate(std::function<bool(T const&)> const& predicate, std::string const& description = "") {
return Generic::PredicateMatcher<T>(predicate, description);
}
} // namespace Matchers
} // namespace Catch
#endif // TWOBLUECUBES_CATCH_MATCHERS_GENERIC_HPP_INCLUDED