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// Copyright (c) the JPEG XL Project Authors. All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
#ifndef LIB_JXL_BASE_SPAN_H_
#define LIB_JXL_BASE_SPAN_H_
// Span (array view) is a non-owning container that provides cheap "cut"
// operations and could be used as "ArrayLike" data source for PaddedBytes.
#include <cstddef>
#include <cstdint>
#include <vector>
#include "lib/jxl/base/status.h"
namespace jxl {
template <typename T>
class Span {
public:
constexpr Span() noexcept : Span(nullptr, 0) {}
constexpr Span(T* array, size_t length) noexcept
: ptr_(array), len_(length) {}
template <size_t N>
explicit constexpr Span(T (&a)[N]) noexcept : Span(a, N) {}
template <typename U>
constexpr Span(U* array, size_t length) noexcept
: ptr_(reinterpret_cast<T*>(array)), len_(length) {
static_assert(sizeof(U) == sizeof(T), "Incompatible type of source.");
}
template <typename ArrayLike>
explicit constexpr Span(const ArrayLike& other) noexcept
: Span(reinterpret_cast<T*>(other.data()), other.size()) {
static_assert(sizeof(*other.data()) == sizeof(T),
"Incompatible type of source.");
}
constexpr T* data() const noexcept { return ptr_; }
constexpr size_t size() const noexcept { return len_; }
constexpr bool empty() const noexcept { return len_ == 0; }
constexpr T* begin() const noexcept { return data(); }
constexpr T* end() const noexcept { return data() + size(); }
constexpr T& operator[](size_t i) const noexcept {
// MSVC 2015 accepts this as constexpr, but not ptr_[i]
return *(data() + i);
}
void remove_prefix(size_t n) noexcept {
JXL_ASSERT(size() >= n);
ptr_ += n;
len_ -= n;
}
// NCT == non-const-T; compiler will complain if NCT is not compatible with T.
template <typename NCT>
void AppendTo(std::vector<NCT>* dst) const {
dst->insert(dst->end(), begin(), end());
}
private:
T* ptr_;
size_t len_;
};
typedef Span<const uint8_t> Bytes;
} // namespace jxl
#endif // LIB_JXL_BASE_SPAN_H_
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