1 /* 2 * Copyright 2017 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 8 #ifndef SkArenaAllocList_DEFINED 9 #define SkArenaAllocList_DEFINED 10 11 #include "SkArenaAlloc.h" 12 13 /** 14 * A singly linked list of Ts stored in a SkArenaAlloc. The arena rather than the list owns 15 * the elements. This supports forward iteration and range based for loops. 16 */ 17 template <typename T> 18 class SkArenaAllocList { 19 private: 20 struct Node; 21 22 public: 23 SkArenaAllocList() = default; 24 25 void reset() { fHead = fTail = nullptr; } 26 27 template <typename... Args> 28 inline T& append(SkArenaAlloc* arena, Args... args); 29 30 class Iter { 31 public: 32 Iter() = default; 33 inline Iter& operator++(); 34 T& operator*() const { return fCurr->fT; } 35 T* operator->() const { return &fCurr->fT; } 36 bool operator==(const Iter& that) const { return fCurr == that.fCurr; } 37 bool operator!=(const Iter& that) const { return !(*this == that); } 38 39 private: 40 friend class SkArenaAllocList; 41 explicit Iter(Node* node) : fCurr(node) {} 42 Node* fCurr = nullptr; 43 }; 44 45 Iter begin() { return Iter(fHead); } 46 Iter end() { return Iter(); } 47 Iter tail() { return Iter(fTail); } 48 49 private: 50 struct Node { 51 template <typename... Args> 52 Node(Args... args) : fT(std::forward<Args>(args)...) {} 53 T fT; 54 Node* fNext = nullptr; 55 }; 56 Node* fHead = nullptr; 57 Node* fTail = nullptr; 58 }; 59 60 template <typename T> 61 template <typename... Args> 62 T& SkArenaAllocList<T>::append(SkArenaAlloc* arena, Args... args) { 63 SkASSERT(!fHead == !fTail); 64 auto* n = arena->make<Node>(std::forward<Args>(args)...); 65 if (!fTail) { 66 fHead = fTail = n; 67 } else { 68 fTail = fTail->fNext = n; 69 } 70 return fTail->fT; 71 } 72 73 template <typename T> 74 typename SkArenaAllocList<T>::Iter& SkArenaAllocList<T>::Iter::operator++() { 75 fCurr = fCurr->fNext; 76 return *this; 77 } 78 79 #endif 80
