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//===-- Self contained ArrayRef type ----------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_LIBC_UTILS_CPP_ARRAYREF_H
#define LLVM_LIBC_UTILS_CPP_ARRAYREF_H
#include "Array.h"
#include "TypeTraits.h" //RemoveCVType
#include <stddef.h> // For size_t.
namespace __llvm_libc {
namespace cpp {
// The implementations of ArrayRef and MutableArrayRef in this file are based
// on the implementations of the types with the same names in
// llvm/ADT/ArrayRef.h. The implementations in this file are of a limited
// functionality, but can be extended in an as needed basis.
namespace internal {
template <typename QualifiedT> class ArrayRefBase {
public:
using value_type = RemoveCVType<QualifiedT>;
using pointer = value_type *;
using const_pointer = const value_type *;
using reference = value_type &;
using const_reference = const value_type &;
using iterator = const_pointer;
using const_iterator = const_pointer;
using size_type = size_t;
using difference_type = ptrdiff_t;
ArrayRefBase() = default;
// Construct an ArrayRefBase from a single element.
explicit ArrayRefBase(QualifiedT &OneElt) : Data(&OneElt), Length(1) {}
// Construct an ArrayRefBase from a pointer and length.
ArrayRefBase(QualifiedT *Data, size_t Length) : Data(Data), Length(Length) {}
// Construct an ArrayRefBase from a range.
ArrayRefBase(QualifiedT *Begin, QualifiedT *End)
: Data(Begin), Length(End - Begin) {}
// Construct an ArrayRefBase from a C array.
template <size_t N>
constexpr ArrayRefBase(QualifiedT (&Arr)[N]) : Data(Arr), Length(N) {}
QualifiedT *data() const { return Data; }
size_t size() const { return Length; }
auto begin() const { return data(); }
auto end() const { return data() + size(); }
bool empty() const { return size() == 0; }
auto operator[](size_t Index) const { return data()[Index]; }
// slice(n, m) - Chop off the first N elements of the array, and keep M
// elements in the array.
auto slice(size_t N, size_t M) const { return ArrayRefBase(data() + N, M); }
// slice(n) - Chop off the first N elements of the array.
auto slice(size_t N) const { return slice(N, size() - N); }
// Drop the first \p N elements of the array.
auto drop_front(size_t N = 1) const { return slice(N, size() - N); }
// Drop the last \p N elements of the array.
auto drop_back(size_t N = 1) const { return slice(0, size() - N); }
// Return a copy of *this with only the first \p N elements.
auto take_front(size_t N = 1) const {
if (N >= size())
return *this;
return drop_back(size() - N);
}
// Return a copy of *this with only the last \p N elements.
auto take_back(size_t N = 1) const {
if (N >= size())
return *this;
return drop_front(size() - N);
}
// equals - Check for element-wise equality.
bool equals(ArrayRefBase<QualifiedT> RHS) const {
if (Length != RHS.Length)
return false;
auto First1 = begin();
auto Last1 = end();
auto First2 = RHS.begin();
for (; First1 != Last1; ++First1, ++First2) {
if (!(*First1 == *First2)) {
return false;
}
}
return true;
}
private:
QualifiedT *Data = nullptr;
size_t Length = 0;
};
} // namespace internal
template <typename T> struct ArrayRef : public internal::ArrayRefBase<const T> {
private:
static_assert(IsSameV<T, RemoveCVType<T>>,
"ArrayRef must have a non-const, non-volatile value_type");
using Impl = internal::ArrayRefBase<const T>;
using Impl::Impl;
public:
// From Array.
template <size_t N> ArrayRef(const Array<T, N> &Arr) : Impl(Arr.Data, N) {}
};
template <typename T>
struct MutableArrayRef : public internal::ArrayRefBase<T> {
private:
static_assert(
IsSameV<T, RemoveCVType<T>>,
"MutableArrayRef must have a non-const, non-volatile value_type");
using Impl = internal::ArrayRefBase<T>;
using Impl::Impl;
public:
// From Array.
template <size_t N> MutableArrayRef(Array<T, N> &Arr) : Impl(Arr.Data, N) {}
};
} // namespace cpp
} // namespace __llvm_libc
#endif // LLVM_LIBC_UTILS_CPP_ARRAYREF_H
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