michael@0: /*
michael@0:  * Copyright (C) 2009 The Android Open Source Project
michael@0:  *
michael@0:  * Licensed under the Apache License, Version 2.0 (the "License");
michael@0:  * you may not use this file except in compliance with the License.
michael@0:  * You may obtain a copy of the License at
michael@0:  *
michael@0:  *      http://www.apache.org/licenses/LICENSE-2.0
michael@0:  *
michael@0:  * Unless required by applicable law or agreed to in writing, software
michael@0:  * distributed under the License is distributed on an "AS IS" BASIS,
michael@0:  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
michael@0:  * See the License for the specific language governing permissions and
michael@0:  * limitations under the License.
michael@0:  */
michael@0: 
michael@0: #ifndef LOCAL_ARRAY_H_included
michael@0: #define LOCAL_ARRAY_H_included
michael@0: 
michael@0: #include <cstddef>
michael@0: #include <new>
michael@0: 
michael@0: /**
michael@0:  * A fixed-size array with a size hint. That number of bytes will be allocated
michael@0:  * on the stack, and used if possible, but if more bytes are requested at
michael@0:  * construction time, a buffer will be allocated on the heap (and deallocated
michael@0:  * by the destructor).
michael@0:  *
michael@0:  * The API is intended to be a compatible subset of C++0x's std::array.
michael@0:  */
michael@0: template <size_t STACK_BYTE_COUNT>
michael@0: class LocalArray {
michael@0: public:
michael@0:     /**
michael@0:      * Allocates a new fixed-size array of the given size. If this size is
michael@0:      * less than or equal to the template parameter STACK_BYTE_COUNT, an
michael@0:      * internal on-stack buffer will be used. Otherwise a heap buffer will
michael@0:      * be allocated.
michael@0:      */
michael@0:     LocalArray(size_t desiredByteCount) : mSize(desiredByteCount) {
michael@0:         if (desiredByteCount > STACK_BYTE_COUNT) {
michael@0:             mPtr = new char[mSize];
michael@0:         } else {
michael@0:             mPtr = &mOnStackBuffer[0];
michael@0:         }
michael@0:     }
michael@0: 
michael@0:     /**
michael@0:      * Frees the heap-allocated buffer, if there was one.
michael@0:      */
michael@0:     ~LocalArray() {
michael@0:         if (mPtr != &mOnStackBuffer[0]) {
michael@0:             delete[] mPtr;
michael@0:         }
michael@0:     }
michael@0: 
michael@0:     // Capacity.
michael@0:     size_t size() { return mSize; }
michael@0:     bool empty() { return mSize == 0; }
michael@0: 
michael@0:     // Element access.
michael@0:     char& operator[](size_t n) { return mPtr[n]; }
michael@0:     const char& operator[](size_t n) const { return mPtr[n]; }
michael@0: 
michael@0: private:
michael@0:     char mOnStackBuffer[STACK_BYTE_COUNT];
michael@0:     char* mPtr;
michael@0:     size_t mSize;
michael@0: 
michael@0:     // Disallow copy and assignment.
michael@0:     LocalArray(const LocalArray&);
michael@0:     void operator=(const LocalArray&);
michael@0: };
michael@0: 
michael@0: #endif // LOCAL_ARRAY_H_included