1 /* 2 * Copyright 2016 Google Inc. 3 * 4 * Use of this source code is governed by a BSD-style license that can be 5 * found in the LICENSE file. 6 */ 7 #ifndef SkSinglyLinkedList_DEFINED 8 #define SkSinglyLinkedList_DEFINED 9 10 #include <utility> 11 12 #include "SkTypes.h" 13 14 template <typename T> class SkSinglyLinkedList { 15 struct Node; 16 public: SkSinglyLinkedList()17 SkSinglyLinkedList() : fHead(nullptr), fTail(nullptr) {} ~SkSinglyLinkedList()18 ~SkSinglyLinkedList() { this->reset(); } reset()19 void reset() { 20 SkASSERT(fHead != nullptr || nullptr == fTail); 21 // Use a while loop rather than recursion to avoid stack overflow. 22 Node* node = fHead; 23 while (node) { 24 Node* next = node->fNext; 25 SkASSERT(next != nullptr || node == fTail); 26 delete node; 27 node = next; 28 } 29 fHead = nullptr; 30 fTail = nullptr; 31 } back()32 T* back() { return fTail ? &fTail->fData : nullptr; } front()33 T* front() { return fHead ? &fHead->fData : nullptr; } empty()34 bool empty() const { return fHead == nullptr; } 35 #ifdef SK_DEBUG count()36 int count() { // O(n), debug only. 37 int count = 0; 38 for (Node* node = fHead; node; node = node->fNext) { 39 ++count; 40 } 41 return count; 42 } 43 #endif pop_front()44 void pop_front() { 45 if (Node* node = fHead) { 46 fHead = node->fNext; 47 delete node; 48 if (fHead == nullptr) { 49 fTail = nullptr; 50 } 51 } 52 } emplace_front(Args &&...args)53 template <class... Args> T* emplace_front(Args&&... args) { 54 Node* n = new Node(std::forward<Args>(args)...); 55 n->fNext = fHead; 56 if (!fTail) { 57 fTail = n; 58 SkASSERT(!fHead); 59 } 60 fHead = n; 61 return &n->fData; 62 } emplace_back(Args &&...args)63 template <class... Args> T* emplace_back(Args&&... args) { 64 Node* n = new Node(std::forward<Args>(args)...); 65 if (fTail) { 66 fTail->fNext = n; 67 } else { 68 fHead = n; 69 } 70 fTail = n; 71 return &n->fData; 72 } 73 class ConstIter { 74 public: 75 void operator++() { fNode = fNode->fNext; } 76 const T& operator*() const { return fNode->fData; } 77 bool operator!=(const ConstIter& rhs) const { return fNode != rhs.fNode; } ConstIter(const Node * n)78 ConstIter(const Node* n) : fNode(n) {} 79 private: 80 const Node* fNode; 81 }; begin()82 ConstIter begin() const { return ConstIter(fHead); } end()83 ConstIter end() const { return ConstIter(nullptr); } 84 85 private: 86 struct Node { 87 T fData; 88 Node* fNext; 89 template <class... Args> NodeNode90 Node(Args&&... args) : fData(std::forward<Args>(args)...), fNext(nullptr) {} 91 }; 92 Node* fHead; 93 Node* fTail; 94 SkSinglyLinkedList(const SkSinglyLinkedList<T>&) = delete; 95 SkSinglyLinkedList& operator=(const SkSinglyLinkedList<T>&) = delete; 96 }; 97 #endif // SkSinglyLinkedList_DEFINED 98