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//===-- list.h --------------------------------------------------*- 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 SCUDO_LIST_H_
#define SCUDO_LIST_H_
#include "internal_defs.h"
namespace scudo {
// Intrusive POD singly-linked list.
// An object with all zero fields should represent a valid empty list. clear()
// should be called on all non-zero-initialized objects before using.
template <class Item> struct IntrusiveList {
friend class Iterator;
void clear() {
First = Last = nullptr;
Size = 0;
}
bool empty() const { return Size == 0; }
uptr size() const { return Size; }
void push_back(Item *X) {
if (empty()) {
X->Next = nullptr;
First = Last = X;
Size = 1;
} else {
X->Next = nullptr;
Last->Next = X;
Last = X;
Size++;
}
}
void push_front(Item *X) {
if (empty()) {
X->Next = nullptr;
First = Last = X;
Size = 1;
} else {
X->Next = First;
First = X;
Size++;
}
}
void pop_front() {
DCHECK(!empty());
First = First->Next;
if (!First)
Last = nullptr;
Size--;
}
void extract(Item *Prev, Item *X) {
DCHECK(!empty());
DCHECK_NE(Prev, nullptr);
DCHECK_NE(X, nullptr);
DCHECK_EQ(Prev->Next, X);
Prev->Next = X->Next;
if (Last == X)
Last = Prev;
Size--;
}
Item *front() { return First; }
const Item *front() const { return First; }
Item *back() { return Last; }
const Item *back() const { return Last; }
void append_front(IntrusiveList<Item> *L) {
DCHECK_NE(this, L);
if (L->empty())
return;
if (empty()) {
*this = *L;
} else if (!L->empty()) {
L->Last->Next = First;
First = L->First;
Size += L->size();
}
L->clear();
}
void append_back(IntrusiveList<Item> *L) {
DCHECK_NE(this, L);
if (L->empty())
return;
if (empty()) {
*this = *L;
} else {
Last->Next = L->First;
Last = L->Last;
Size += L->size();
}
L->clear();
}
void checkConsistency() {
if (Size == 0) {
CHECK_EQ(First, nullptr);
CHECK_EQ(Last, nullptr);
} else {
uptr Count = 0;
for (Item *I = First;; I = I->Next) {
Count++;
if (I == Last)
break;
}
CHECK_EQ(size(), Count);
CHECK_EQ(Last->Next, nullptr);
}
}
template <class ItemT> class IteratorBase {
public:
explicit IteratorBase(ItemT *CurrentItem) : Current(CurrentItem) {}
IteratorBase &operator++() {
Current = Current->Next;
return *this;
}
bool operator!=(IteratorBase Other) const {
return Current != Other.Current;
}
ItemT &operator*() { return *Current; }
private:
ItemT *Current;
};
typedef IteratorBase<Item> Iterator;
typedef IteratorBase<const Item> ConstIterator;
Iterator begin() { return Iterator(First); }
Iterator end() { return Iterator(nullptr); }
ConstIterator begin() const { return ConstIterator(First); }
ConstIterator end() const { return ConstIterator(nullptr); }
private:
uptr Size;
Item *First;
Item *Last;
};
} // namespace scudo
#endif // SCUDO_LIST_H_
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