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