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// Copyright 2025 Google LLC
//
// 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 SOURCE_UTIL_SPAN_H_
#define SOURCE_UTIL_SPAN_H_
#include <cstddef>
#include <iterator>
#include <type_traits>
namespace spvtools {
namespace utils {
// Implement a subset of the C++20 std::span, using at most C++17 functionality.
// Replace this when SPIRV-Tools can use C++20.
template <class T>
class Span {
public:
using element_type = T;
using value_type = std::remove_cv_t<T>;
using size_type = std::size_t;
using difference_type = std::ptrdiff_t;
using pointer = T*;
using const_pointer = const T*;
using reference = T&;
using const_reference = const T&;
using iterator = T*;
using const_iterator = const T*;
Span() {}
Span(iterator first, size_type count) : first_(first), count_(count) {}
iterator begin() const { return first_; }
iterator end() const { return first_ ? first_ + count_ : nullptr; }
const_iterator cbegin() const { return first_; }
const_iterator cend() const { return first_ ? first_ + count_ : nullptr; }
size_type size() const { return count_; }
size_type size_bytes() const { return count_ * sizeof(T); }
bool empty() const { return first_ == nullptr || count_ == 0; }
reference front() const { return *first_; }
reference back() const { return *(first_ + count_ - 1); }
pointer data() const { return first_; }
reference operator[](size_type idx) const { return first_[idx]; }
Span<T> subspan(size_type offset) const {
if (count_ > offset) {
return Span(first_ + offset, count_ - offset);
}
return Span<T>();
}
private:
T* first_ = nullptr;
size_type count_ = 0;
};
} // namespace utils
} // namespace spvtools
#endif // SOURCE_UTIL_SPAN_H_
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