372 строки
12 KiB
C++
372 строки
12 KiB
C++
//===--- ArrayRef.h - Array Reference Wrapper -------------------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_ADT_ARRAYREF_H
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#define LLVM_ADT_ARRAYREF_H
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#include "llvm/ADT/None.h"
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#include "llvm/ADT/SmallVector.h"
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#include <vector>
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namespace llvm {
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/// ArrayRef - Represent a constant reference to an array (0 or more elements
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/// consecutively in memory), i.e. a start pointer and a length. It allows
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/// various APIs to take consecutive elements easily and conveniently.
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///
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/// This class does not own the underlying data, it is expected to be used in
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/// situations where the data resides in some other buffer, whose lifetime
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/// extends past that of the ArrayRef. For this reason, it is not in general
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/// safe to store an ArrayRef.
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///
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/// This is intended to be trivially copyable, so it should be passed by
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/// value.
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template<typename T>
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class ArrayRef {
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public:
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typedef const T *iterator;
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typedef const T *const_iterator;
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typedef size_t size_type;
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typedef std::reverse_iterator<iterator> reverse_iterator;
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private:
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/// The start of the array, in an external buffer.
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const T *Data;
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/// The number of elements.
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size_type Length;
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public:
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/// @name Constructors
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/// @{
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/// Construct an empty ArrayRef.
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/*implicit*/ ArrayRef() : Data(nullptr), Length(0) {}
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/// Construct an empty ArrayRef from None.
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/*implicit*/ ArrayRef(NoneType) : Data(nullptr), Length(0) {}
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/// Construct an ArrayRef from a single element.
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/*implicit*/ ArrayRef(const T &OneElt)
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: Data(&OneElt), Length(1) {}
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/// Construct an ArrayRef from a pointer and length.
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/*implicit*/ ArrayRef(const T *data, size_t length)
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: Data(data), Length(length) {}
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/// Construct an ArrayRef from a range.
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ArrayRef(const T *begin, const T *end)
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: Data(begin), Length(end - begin) {}
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/// Construct an ArrayRef from a SmallVector. This is templated in order to
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/// avoid instantiating SmallVectorTemplateCommon<T> whenever we
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/// copy-construct an ArrayRef.
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template<typename U>
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/*implicit*/ ArrayRef(const SmallVectorTemplateCommon<T, U> &Vec)
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: Data(Vec.data()), Length(Vec.size()) {
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}
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/// Construct an ArrayRef from a std::vector.
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template<typename A>
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/*implicit*/ ArrayRef(const std::vector<T, A> &Vec)
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: Data(Vec.data()), Length(Vec.size()) {}
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/// Construct an ArrayRef from a C array.
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template <size_t N>
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/*implicit*/ LLVM_CONSTEXPR ArrayRef(const T (&Arr)[N])
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: Data(Arr), Length(N) {}
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/// Construct an ArrayRef from a std::initializer_list.
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/*implicit*/ ArrayRef(const std::initializer_list<T> &Vec)
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: Data(Vec.begin() == Vec.end() ? (T*)0 : Vec.begin()),
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Length(Vec.size()) {}
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/// Construct an ArrayRef<const T*> from ArrayRef<T*>. This uses SFINAE to
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/// ensure that only ArrayRefs of pointers can be converted.
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template <typename U>
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ArrayRef(const ArrayRef<U *> &A,
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typename std::enable_if<
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std::is_convertible<U *const *, T const *>::value>::type* = 0)
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: Data(A.data()), Length(A.size()) {}
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/// Construct an ArrayRef<const T*> from a SmallVector<T*>. This is
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/// templated in order to avoid instantiating SmallVectorTemplateCommon<T>
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/// whenever we copy-construct an ArrayRef.
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template<typename U, typename DummyT>
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/*implicit*/ ArrayRef(const SmallVectorTemplateCommon<U*, DummyT> &Vec,
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typename std::enable_if<
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std::is_convertible<U *const *,
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T const *>::value>::type* = 0)
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: Data(Vec.data()), Length(Vec.size()) {
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}
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/// Construct an ArrayRef<const T*> from std::vector<T*>. This uses SFINAE
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/// to ensure that only vectors of pointers can be converted.
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template<typename U, typename A>
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ArrayRef(const std::vector<U *, A> &Vec,
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typename std::enable_if<
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std::is_convertible<U *const *, T const *>::value>::type* = 0)
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: Data(Vec.data()), Length(Vec.size()) {}
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/// @}
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/// @name Simple Operations
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/// @{
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iterator begin() const { return Data; }
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iterator end() const { return Data + Length; }
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reverse_iterator rbegin() const { return reverse_iterator(end()); }
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reverse_iterator rend() const { return reverse_iterator(begin()); }
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/// empty - Check if the array is empty.
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bool empty() const { return Length == 0; }
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const T *data() const { return Data; }
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/// size - Get the array size.
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size_t size() const { return Length; }
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/// front - Get the first element.
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const T &front() const {
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assert(!empty());
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return Data[0];
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}
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/// back - Get the last element.
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const T &back() const {
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assert(!empty());
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return Data[Length-1];
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}
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// copy - Allocate copy in Allocator and return ArrayRef<T> to it.
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template <typename Allocator> ArrayRef<T> copy(Allocator &A) {
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T *Buff = A.template Allocate<T>(Length);
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std::copy(begin(), end(), Buff);
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return ArrayRef<T>(Buff, Length);
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}
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/// equals - Check for element-wise equality.
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bool equals(ArrayRef RHS) const {
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if (Length != RHS.Length)
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return false;
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if (Length == 0)
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return true;
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return std::equal(begin(), end(), RHS.begin());
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}
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/// slice(n) - Chop off the first N elements of the array.
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ArrayRef<T> slice(unsigned N) const {
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assert(N <= size() && "Invalid specifier");
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return ArrayRef<T>(data()+N, size()-N);
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}
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/// slice(n, m) - Chop off the first N elements of the array, and keep M
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/// elements in the array.
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ArrayRef<T> slice(unsigned N, unsigned M) const {
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assert(N+M <= size() && "Invalid specifier");
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return ArrayRef<T>(data()+N, M);
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}
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// \brief Drop the last \p N elements of the array.
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ArrayRef<T> drop_back(unsigned N = 1) const {
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assert(size() >= N && "Dropping more elements than exist");
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return slice(0, size() - N);
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}
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/// @}
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/// @name Operator Overloads
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/// @{
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const T &operator[](size_t Index) const {
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assert(Index < Length && "Invalid index!");
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return Data[Index];
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}
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/// @}
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/// @name Expensive Operations
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/// @{
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std::vector<T> vec() const {
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return std::vector<T>(Data, Data+Length);
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}
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/// @}
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/// @name Conversion operators
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/// @{
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operator std::vector<T>() const {
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return std::vector<T>(Data, Data+Length);
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}
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/// @}
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};
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/// MutableArrayRef - Represent a mutable reference to an array (0 or more
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/// elements consecutively in memory), i.e. a start pointer and a length. It
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/// allows various APIs to take and modify consecutive elements easily and
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/// conveniently.
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///
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/// This class does not own the underlying data, it is expected to be used in
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/// situations where the data resides in some other buffer, whose lifetime
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/// extends past that of the MutableArrayRef. For this reason, it is not in
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/// general safe to store a MutableArrayRef.
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///
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/// This is intended to be trivially copyable, so it should be passed by
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/// value.
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template<typename T>
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class MutableArrayRef : public ArrayRef<T> {
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public:
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typedef T *iterator;
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typedef std::reverse_iterator<iterator> reverse_iterator;
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/// Construct an empty MutableArrayRef.
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/*implicit*/ MutableArrayRef() : ArrayRef<T>() {}
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/// Construct an empty MutableArrayRef from None.
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/*implicit*/ MutableArrayRef(NoneType) : ArrayRef<T>() {}
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/// Construct an MutableArrayRef from a single element.
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/*implicit*/ MutableArrayRef(T &OneElt) : ArrayRef<T>(OneElt) {}
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/// Construct an MutableArrayRef from a pointer and length.
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/*implicit*/ MutableArrayRef(T *data, size_t length)
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: ArrayRef<T>(data, length) {}
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/// Construct an MutableArrayRef from a range.
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MutableArrayRef(T *begin, T *end) : ArrayRef<T>(begin, end) {}
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/// Construct an MutableArrayRef from a SmallVector.
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/*implicit*/ MutableArrayRef(SmallVectorImpl<T> &Vec)
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: ArrayRef<T>(Vec) {}
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/// Construct a MutableArrayRef from a std::vector.
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/*implicit*/ MutableArrayRef(std::vector<T> &Vec)
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: ArrayRef<T>(Vec) {}
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/// Construct an MutableArrayRef from a C array.
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template <size_t N>
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/*implicit*/ LLVM_CONSTEXPR MutableArrayRef(T (&Arr)[N])
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: ArrayRef<T>(Arr) {}
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T *data() const { return const_cast<T*>(ArrayRef<T>::data()); }
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iterator begin() const { return data(); }
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iterator end() const { return data() + this->size(); }
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reverse_iterator rbegin() const { return reverse_iterator(end()); }
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reverse_iterator rend() const { return reverse_iterator(begin()); }
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/// front - Get the first element.
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T &front() const {
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assert(!this->empty());
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return data()[0];
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}
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/// back - Get the last element.
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T &back() const {
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assert(!this->empty());
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return data()[this->size()-1];
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}
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/// slice(n) - Chop off the first N elements of the array.
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MutableArrayRef<T> slice(unsigned N) const {
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assert(N <= this->size() && "Invalid specifier");
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return MutableArrayRef<T>(data()+N, this->size()-N);
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}
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/// slice(n, m) - Chop off the first N elements of the array, and keep M
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/// elements in the array.
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MutableArrayRef<T> slice(unsigned N, unsigned M) const {
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assert(N+M <= this->size() && "Invalid specifier");
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return MutableArrayRef<T>(data()+N, M);
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}
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MutableArrayRef<T> drop_back(unsigned N) const {
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assert(this->size() >= N && "Dropping more elements than exist");
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return slice(0, this->size() - N);
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}
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/// @}
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/// @name Operator Overloads
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/// @{
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T &operator[](size_t Index) const {
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assert(Index < this->size() && "Invalid index!");
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return data()[Index];
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}
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};
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/// @name ArrayRef Convenience constructors
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/// @{
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/// Construct an ArrayRef from a single element.
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template<typename T>
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ArrayRef<T> makeArrayRef(const T &OneElt) {
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return OneElt;
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}
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/// Construct an ArrayRef from a pointer and length.
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template<typename T>
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ArrayRef<T> makeArrayRef(const T *data, size_t length) {
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return ArrayRef<T>(data, length);
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}
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/// Construct an ArrayRef from a range.
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template<typename T>
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ArrayRef<T> makeArrayRef(const T *begin, const T *end) {
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return ArrayRef<T>(begin, end);
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}
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/// Construct an ArrayRef from a SmallVector.
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template <typename T>
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ArrayRef<T> makeArrayRef(const SmallVectorImpl<T> &Vec) {
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return Vec;
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}
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/// Construct an ArrayRef from a SmallVector.
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template <typename T, unsigned N>
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ArrayRef<T> makeArrayRef(const SmallVector<T, N> &Vec) {
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return Vec;
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}
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/// Construct an ArrayRef from a std::vector.
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template<typename T>
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ArrayRef<T> makeArrayRef(const std::vector<T> &Vec) {
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return Vec;
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}
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/// Construct an ArrayRef from a C array.
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template<typename T, size_t N>
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ArrayRef<T> makeArrayRef(const T (&Arr)[N]) {
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return ArrayRef<T>(Arr);
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}
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/// @}
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/// @name ArrayRef Comparison Operators
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/// @{
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template<typename T>
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inline bool operator==(ArrayRef<T> LHS, ArrayRef<T> RHS) {
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return LHS.equals(RHS);
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}
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template<typename T>
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inline bool operator!=(ArrayRef<T> LHS, ArrayRef<T> RHS) {
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return !(LHS == RHS);
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}
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/// @}
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// ArrayRefs can be treated like a POD type.
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template <typename T> struct isPodLike;
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template <typename T> struct isPodLike<ArrayRef<T> > {
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static const bool value = true;
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};
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}
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#endif
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