зеркало из https://github.com/mozilla/gecko-dev.git
83 строки
2.6 KiB
C++
83 строки
2.6 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
|
|
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
|
|
/* This Source Code Form is subject to the terms of the Mozilla Public
|
|
* License, v. 2.0. If a copy of the MPL was not distributed with this
|
|
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
|
|
|
|
#ifndef mozilla_Range_h
|
|
#define mozilla_Range_h
|
|
|
|
#include "mozilla/RangedPtr.h"
|
|
#include "mozilla/Span.h"
|
|
|
|
#include <stddef.h>
|
|
#include <type_traits>
|
|
|
|
namespace mozilla {
|
|
|
|
// Range<T> is a tuple containing a pointer and a length.
|
|
template <typename T>
|
|
class Range {
|
|
template <typename U>
|
|
friend class Range;
|
|
|
|
// Reassignment of RangedPtrs is so (subtly) restrictive that we just make
|
|
// Range immutable.
|
|
const RangedPtr<T> mStart;
|
|
const RangedPtr<T> mEnd;
|
|
|
|
public:
|
|
Range() : mStart(nullptr, 0), mEnd(nullptr, 0) {}
|
|
Range(T* aPtr, size_t aLength)
|
|
: mStart(aPtr, aPtr, aPtr + aLength),
|
|
mEnd(aPtr + aLength, aPtr, aPtr + aLength) {
|
|
if (!aPtr) {
|
|
MOZ_ASSERT(!aLength,
|
|
"Range does not support nullptr with non-zero length.");
|
|
// ...because merely having a pointer to `nullptr + 1` is undefined
|
|
// behavior. UBSAN catches this as of clang-10.
|
|
}
|
|
}
|
|
Range(const RangedPtr<T>& aStart, const RangedPtr<T>& aEnd)
|
|
: mStart(aStart.get(), aStart.get(), aEnd.get()),
|
|
mEnd(aEnd.get(), aStart.get(), aEnd.get()) {
|
|
// Only accept two RangedPtrs within the same range.
|
|
aStart.checkIdenticalRange(aEnd);
|
|
MOZ_ASSERT(aStart <= aEnd);
|
|
}
|
|
|
|
template <typename U, class = std::enable_if_t<
|
|
std::is_convertible_v<U (*)[], T (*)[]>, int>>
|
|
MOZ_IMPLICIT Range(const Range<U>& aOther)
|
|
: mStart(aOther.mStart), mEnd(aOther.mEnd) {}
|
|
|
|
MOZ_IMPLICIT Range(Span<T> aSpan) : Range(aSpan.Elements(), aSpan.Length()) {}
|
|
|
|
template <typename U, class = std::enable_if_t<
|
|
std::is_convertible_v<U (*)[], T (*)[]>, int>>
|
|
MOZ_IMPLICIT Range(const Span<U>& aSpan)
|
|
: Range(aSpan.Elements(), aSpan.Length()) {}
|
|
|
|
RangedPtr<T> begin() const { return mStart; }
|
|
RangedPtr<T> end() const { return mEnd; }
|
|
size_t length() const { return mEnd - mStart; }
|
|
|
|
T& operator[](size_t aOffset) const { return mStart[aOffset]; }
|
|
|
|
explicit operator bool() const { return mStart != nullptr; }
|
|
|
|
operator Span<T>() { return Span<T>(mStart.get(), length()); }
|
|
|
|
operator Span<const T>() const { return Span<T>(mStart.get(), length()); }
|
|
};
|
|
|
|
template <typename T>
|
|
Span(Range<T>&) -> Span<T>;
|
|
|
|
template <typename T>
|
|
Span(const Range<T>&) -> Span<const T>;
|
|
|
|
} // namespace mozilla
|
|
|
|
#endif /* mozilla_Range_h */
|