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/*
* Created by Martin on 23/2/2019.
*
* 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_GENERATORS_GENERIC_HPP_INCLUDED
#define TWOBLUECUBES_CATCH_GENERATORS_GENERIC_HPP_INCLUDED
#include "catch_generators.hpp"
namespace Catch {
namespace Generators {
template <typename T>
class TakeGenerator : public IGenerator<T> {
GeneratorWrapper<T> m_generator;
size_t m_returned = 0;
size_t m_target;
public:
TakeGenerator(size_t target, GeneratorWrapper<T>&& generator):
m_generator(std::move(generator)),
m_target(target)
{
assert(target != 0 && "Empty generators are not allowed");
}
T const& get() const override {
return m_generator.get();
}
bool next() override {
++m_returned;
if (m_returned >= m_target) {
return false;
}
const auto success = m_generator.next();
// If the underlying generator does not contain enough values
// then we cut short as well
if (!success) {
m_returned = m_target;
}
return success;
}
};
template <typename T>
GeneratorWrapper<T> take(size_t target, GeneratorWrapper<T>&& generator) {
return GeneratorWrapper<T>(pf::make_unique<TakeGenerator<T>>(target, std::move(generator)));
}
template <typename T, typename Predicate>
class FilterGenerator : public IGenerator<T> {
GeneratorWrapper<T> m_generator;
Predicate m_predicate;
public:
template <typename P = Predicate>
FilterGenerator(P&& pred, GeneratorWrapper<T>&& generator):
m_generator(std::move(generator)),
m_predicate(std::forward<P>(pred))
{
if (!m_predicate(m_generator.get())) {
// It might happen that there are no values that pass the
// filter. In that case we throw an exception.
auto has_initial_value = next();
if (!has_initial_value) {
Catch::throw_exception(GeneratorException("No valid value found in filtered generator"));
}
}
}
T const& get() const override {
return m_generator.get();
}
bool next() override {
bool success = m_generator.next();
if (!success) {
return false;
}
while (!m_predicate(m_generator.get()) && (success = m_generator.next()) == true);
return success;
}
};
template <typename T, typename Predicate>
GeneratorWrapper<T> filter(Predicate&& pred, GeneratorWrapper<T>&& generator) {
return GeneratorWrapper<T>(std::unique_ptr<IGenerator<T>>(pf::make_unique<FilterGenerator<T, Predicate>>(std::forward<Predicate>(pred), std::move(generator))));
}
template <typename T>
class RepeatGenerator : public IGenerator<T> {
GeneratorWrapper<T> m_generator;
mutable std::vector<T> m_returned;
size_t m_target_repeats;
size_t m_current_repeat = 0;
size_t m_repeat_index = 0;
public:
RepeatGenerator(size_t repeats, GeneratorWrapper<T>&& generator):
m_generator(std::move(generator)),
m_target_repeats(repeats)
{
assert(m_target_repeats > 0 && "Repeat generator must repeat at least once");
}
T const& get() const override {
if (m_current_repeat == 0) {
m_returned.push_back(m_generator.get());
return m_returned.back();
}
return m_returned[m_repeat_index];
}
bool next() override {
// There are 2 basic cases:
// 1) We are still reading the generator
// 2) We are reading our own cache
// In the first case, we need to poke the underlying generator.
// If it happily moves, we are left in that state, otherwise it is time to start reading from our cache
if (m_current_repeat == 0) {
const auto success = m_generator.next();
if (!success) {
++m_current_repeat;
}
return m_current_repeat < m_target_repeats;
}
// In the second case, we need to move indices forward and check that we haven't run up against the end
++m_repeat_index;
if (m_repeat_index == m_returned.size()) {
m_repeat_index = 0;
++m_current_repeat;
}
return m_current_repeat < m_target_repeats;
}
};
template <typename T>
GeneratorWrapper<T> repeat(size_t repeats, GeneratorWrapper<T>&& generator) {
return GeneratorWrapper<T>(pf::make_unique<RepeatGenerator<T>>(repeats, std::move(generator)));
}
template <typename T, typename U, typename Func>
class MapGenerator : public IGenerator<T> {
// TBD: provide static assert for mapping function, for friendly error message
GeneratorWrapper<U> m_generator;
Func m_function;
// To avoid returning dangling reference, we have to save the values
T m_cache;
public:
template <typename F2 = Func>
MapGenerator(F2&& function, GeneratorWrapper<U>&& generator) :
m_generator(std::move(generator)),
m_function(std::forward<F2>(function)),
m_cache(m_function(m_generator.get()))
{}
T const& get() const override {
return m_cache;
}
bool next() override {
const auto success = m_generator.next();
if (success) {
m_cache = m_function(m_generator.get());
}
return success;
}
};
#if defined(__cpp_lib_is_invocable) && __cpp_lib_is_invocable >= 201703
// std::result_of is deprecated in C++17 and removed in C++20. Hence, it is
// replaced with std::invoke_result here. Also *_t format is preferred over
// typename *::type format.
template <typename Func, typename U>
using MapFunctionReturnType = std::remove_reference_t<std::remove_cv_t<std::invoke_result_t<Func, U>>>;
#else
template <typename Func, typename U>
using MapFunctionReturnType = typename std::remove_reference<typename std::remove_cv<typename std::result_of<Func(U)>::type>::type>::type;
#endif
template <typename Func, typename U, typename T = MapFunctionReturnType<Func, U>>
GeneratorWrapper<T> map(Func&& function, GeneratorWrapper<U>&& generator) {
return GeneratorWrapper<T>(
pf::make_unique<MapGenerator<T, U, Func>>(std::forward<Func>(function), std::move(generator))
);
}
template <typename T, typename U, typename Func>
GeneratorWrapper<T> map(Func&& function, GeneratorWrapper<U>&& generator) {
return GeneratorWrapper<T>(
pf::make_unique<MapGenerator<T, U, Func>>(std::forward<Func>(function), std::move(generator))
);
}
template <typename T>
class ChunkGenerator final : public IGenerator<std::vector<T>> {
std::vector<T> m_chunk;
size_t m_chunk_size;
GeneratorWrapper<T> m_generator;
bool m_used_up = false;
public:
ChunkGenerator(size_t size, GeneratorWrapper<T> generator) :
m_chunk_size(size), m_generator(std::move(generator))
{
m_chunk.reserve(m_chunk_size);
m_chunk.push_back(m_generator.get());
for (size_t i = 1; i < m_chunk_size; ++i) {
if (!m_generator.next()) {
Catch::throw_exception(GeneratorException("Not enough values to initialize the first chunk"));
}
m_chunk.push_back(m_generator.get());
}
}
std::vector<T> const& get() const override {
return m_chunk;
}
bool next() override {
m_chunk.clear();
for (size_t idx = 0; idx < m_chunk_size; ++idx) {
if (!m_generator.next()) {
return false;
}
m_chunk.push_back(m_generator.get());
}
return true;
}
};
template <typename T>
GeneratorWrapper<std::vector<T>> chunk(size_t size, GeneratorWrapper<T>&& generator) {
return GeneratorWrapper<std::vector<T>>(
pf::make_unique<ChunkGenerator<T>>(size, std::move(generator))
);
}
} // namespace Generators
} // namespace Catch
#endif // TWOBLUECUBES_CATCH_GENERATORS_GENERIC_HPP_INCLUDED
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