1 /* 2 * Copyright (C) 2009 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #ifndef LOCAL_ARRAY_H_included 18 #define LOCAL_ARRAY_H_included 19 20 #include <cstddef> 21 #include <new> 22 23 /** 24 * A fixed-size array with a size hint. That number of bytes will be allocated 25 * on the stack, and used if possible, but if more bytes are requested at 26 * construction time, a buffer will be allocated on the heap (and deallocated 27 * by the destructor). 28 * 29 * The API is intended to be a compatible subset of C++0x's std::array. 30 */ 31 template <size_t STACK_BYTE_COUNT> 32 class LocalArray { 33 public: 34 /** 35 * Allocates a new fixed-size array of the given size. If this size is 36 * less than or equal to the template parameter STACK_BYTE_COUNT, an 37 * internal on-stack buffer will be used. Otherwise a heap buffer will 38 * be allocated. 39 */ LocalArray(size_t desiredByteCount)40 LocalArray(size_t desiredByteCount) : mSize(desiredByteCount) { 41 if (desiredByteCount > STACK_BYTE_COUNT) { 42 mPtr = new char[mSize]; 43 } else { 44 mPtr = &mOnStackBuffer[0]; 45 } 46 } 47 48 /** 49 * Frees the heap-allocated buffer, if there was one. 50 */ ~LocalArray()51 ~LocalArray() { 52 if (mPtr != &mOnStackBuffer[0]) { 53 delete[] mPtr; 54 } 55 } 56 57 // Capacity. size()58 size_t size() { return mSize; } empty()59 bool empty() { return mSize == 0; } 60 61 // Element access. 62 char& operator[](size_t n) { return mPtr[n]; } 63 const char& operator[](size_t n) const { return mPtr[n]; } 64 65 private: 66 char mOnStackBuffer[STACK_BYTE_COUNT]; 67 char* mPtr; 68 size_t mSize; 69 70 // Disallow copy and assignment. 71 LocalArray(const LocalArray&); 72 void operator=(const LocalArray&); 73 }; 74 75 #endif // LOCAL_ARRAY_H_included 76