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// Copyright 2019 The Dawn Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef TESTS_PARAMGENERATOR_H_
#define TESTS_PARAMGENERATOR_H_
#include <tuple>
#include <vector>
// ParamStruct is a custom struct which ParamStruct will yield when iterating.
// The types Params... should by the same as the types passed to the constructor
// of ParamStruct.
template <typename ParamStruct, typename... Params>
class ParamGenerator {
using ParamTuple = std::tuple<std::vector<Params>...>;
using Index = std::array<size_t, sizeof...(Params)>;
static constexpr auto s_indexSequence = std::make_index_sequence<sizeof...(Params)>{};
// Default template that returns the same params.
template <typename P>
static std::vector<P> FilterBackends(std::vector<P> params) {
return params;
}
// Template specialization for DawnTestParam that filters the backends by
// those supported.
template <>
static std::vector<DawnTestParam> FilterBackends(std::vector<DawnTestParam> params) {
return ::detail::FilterBackends(params.data(), params.size());
}
// Using an N-dimensional Index, extract params from ParamTuple and pass
// them to the constructor of ParamStruct.
template <size_t... Is>
static ParamStruct GetParam(const ParamTuple& params,
const Index& index,
std::index_sequence<Is...>) {
return ParamStruct(std::get<Is>(params)[std::get<Is>(index)]...);
}
// Get the last value index into a ParamTuple.
template <size_t... Is>
static Index GetLastIndex(const ParamTuple& params, std::index_sequence<Is...>) {
return Index{std::get<Is>(params).size() - 1 ...};
}
public:
using value_type = ParamStruct;
ParamGenerator(std::vector<Params>... params) : mParams(FilterBackends(params)...) {
}
class Iterator : public std::iterator<std::forward_iterator_tag, ParamStruct, size_t> {
public:
Iterator& operator++() {
// Increment the Index by 1. If the i'th place reaches the maximum,
// reset it to 0 and continue with the i+1'th place.
for (int i = mIndex.size() - 1; i >= 0; --i) {
if (mIndex[i] >= mLastIndex[i]) {
mIndex[i] = 0;
} else {
mIndex[i]++;
return *this;
}
}
// Set a marker that the iterator has reached the end.
mEnd = true;
return *this;
}
bool operator==(const Iterator& other) const {
return mEnd == other.mEnd && mIndex == other.mIndex;
}
bool operator!=(const Iterator& other) const {
return !(*this == other);
}
ParamStruct operator*() const {
return GetParam(mParams, mIndex, s_indexSequence);
}
private:
friend class ParamGenerator;
Iterator(ParamTuple params, Index index)
: mParams(params), mIndex(index), mLastIndex{GetLastIndex(params, s_indexSequence)} {
}
ParamTuple mParams;
Index mIndex;
Index mLastIndex;
bool mEnd = false;
};
Iterator begin() const {
return Iterator(mParams, {});
}
Iterator end() const {
Iterator iter(mParams, GetLastIndex(mParams, s_indexSequence));
++iter;
return iter;
}
private:
ParamTuple mParams;
};
template <typename Param, typename... Params>
auto MakeParamGenerator(std::initializer_list<Params>&&... params) {
return ParamGenerator<Param, Params...>(
std::forward<std::initializer_list<Params>&&>(params)...);
}
#endif // TESTS_PARAMGENERATOR_H_