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// Copyright 2023 The Dawn & Tint Authors
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice, this
// list of conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright notice,
// this list of conditions and the following disclaimer in the documentation
// and/or other materials provided with the distribution.
//
// 3. Neither the name of the copyright holder nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#ifndef SRC_DAWN_COMMON_ENUMERATOR_H_
#define SRC_DAWN_COMMON_ENUMERATOR_H_
#include <type_traits>
#include <utility>
namespace dawn {
// An iterator over a range that gives both the index and the value. It can be used like so:
//
// ityp::span<Index, Value> span = ...;
// for (auto [i, value] : Enumerate(span)) {
// // Use i that's of type Index.
// // Use value that's of type Value&.
// }
template <typename Index, typename Value>
class EnumerateRange final {
public:
EnumerateRange(Index size, Value* begin) : mSize(size), mBegin(begin) {}
class Iterator final {
public:
Iterator(Index index, Value* value) : mIndex(index), mValue(value) {}
bool operator==(const Iterator& other) const { return other.mIndex == mIndex; }
bool operator!=(const Iterator& other) const { return !(*this == other); }
Iterator& operator++() {
mIndex++;
mValue++;
return *this;
}
std::pair<Index, Value&> operator*() const { return {mIndex, *mValue}; }
private:
Index mIndex;
Value* mValue;
};
Iterator begin() const { return Iterator(Index{}, mBegin); }
// Note that iterator comparison only uses mIndex, so we can save the computation of mValue for
// the end() iterator.
Iterator end() const { return Iterator(mSize, nullptr); }
private:
Index mSize;
Value* mBegin;
};
template <typename T,
typename Index = decltype(std::declval<T>().size()),
typename Value = std::remove_pointer_t<decltype(std::declval<T>().data())>>
EnumerateRange<Index, Value> Enumerate(T& v) {
return {v.size(), v.data()};
}
} // namespace dawn
#endif // SRC_DAWN_COMMON_ENUMERATOR_H_