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/*
* Copyright (C) 2010 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef UNIQUE_PTR_H_included
#define UNIQUE_PTR_H_included
#include <cstdlib> // For NULL.
// Default deleter for pointer types.
template <typename T>
struct DefaultDelete {
enum { type_must_be_complete = sizeof(T) };
DefaultDelete() {}
void operator()(T* p) const {
delete p;
}
};
// Default deleter for array types.
template <typename T>
struct DefaultDelete<T[]> {
enum { type_must_be_complete = sizeof(T) };
void operator()(T* p) const {
delete[] p;
}
};
// A smart pointer that deletes the given pointer on destruction.
// Equivalent to C++0x's std::unique_ptr (a combination of boost::scoped_ptr
// and boost::scoped_array).
// Named to be in keeping with Android style but also to avoid
// collision with any other implementation, until we can switch over
// to unique_ptr.
// Use thus:
// UniquePtr<C> c(new C);
template <typename T, typename D = DefaultDelete<T> >
class UniquePtr {
public:
// Construct a new UniquePtr, taking ownership of the given raw pointer.
explicit UniquePtr(T* ptr = NULL) : mPtr(ptr) {
}
~UniquePtr() {
reset();
}
// Accessors.
T& operator*() const { return *mPtr; }
T* operator->() const { return mPtr; }
T* get() const { return mPtr; }
// Returns the raw pointer and hands over ownership to the caller.
// The pointer will not be deleted by UniquePtr.
T* release() {
T* result = mPtr;
mPtr = NULL;
return result;
}
// Takes ownership of the given raw pointer.
// If this smart pointer previously owned a different raw pointer, that
// raw pointer will be freed.
void reset(T* ptr = NULL) {
if (ptr != mPtr) {
D()(mPtr);
mPtr = ptr;
}
}
private:
// The raw pointer.
T* mPtr;
// Comparing unique pointers is probably a mistake, since they're unique.
template <typename T2> bool operator==(const UniquePtr<T2>& p) const;
template <typename T2> bool operator!=(const UniquePtr<T2>& p) const;
// Disallow copy and assignment.
UniquePtr(const UniquePtr&);
void operator=(const UniquePtr&);
};
// Partial specialization for array types. Like std::unique_ptr, this removes
// operator* and operator-> but adds operator[].
template <typename T, typename D>
class UniquePtr<T[], D> {
public:
explicit UniquePtr(T* ptr = NULL) : mPtr(ptr) {
}
~UniquePtr() {
reset();
}
T& operator[](size_t i) const {
return mPtr[i];
}
T* get() const { return mPtr; }
T* release() {
T* result = mPtr;
mPtr = NULL;
return result;
}
void reset(T* ptr = NULL) {
if (ptr != mPtr) {
D()(mPtr);
mPtr = ptr;
}
}
private:
T* mPtr;
// Disallow copy and assignment.
UniquePtr(const UniquePtr&);
void operator=(const UniquePtr&);
};
#if UNIQUE_PTR_TESTS
// Run these tests with:
// g++ -g -DUNIQUE_PTR_TESTS -x c++ UniquePtr.h && ./a.out
#include <stdio.h>
static void assert(bool b) {
if (!b) {
fprintf(stderr, "FAIL\n");
abort();
}
fprintf(stderr, "OK\n");
}
static int cCount = 0;
struct C {
C() { ++cCount; }
~C() { --cCount; }
};
static bool freed = false;
struct Freer {
void operator()(int* p) {
assert(*p == 123);
free(p);
freed = true;
}
};
int main(int argc, char* argv[]) {
//
// UniquePtr<T> tests...
//
// Can we free a single object?
{
UniquePtr<C> c(new C);
assert(cCount == 1);
}
assert(cCount == 0);
// Does release work?
C* rawC;
{
UniquePtr<C> c(new C);
assert(cCount == 1);
rawC = c.release();
}
assert(cCount == 1);
delete rawC;
// Does reset work?
{
UniquePtr<C> c(new C);
assert(cCount == 1);
c.reset(new C);
assert(cCount == 1);
}
assert(cCount == 0);
//
// UniquePtr<T[]> tests...
//
// Can we free an array?
{
UniquePtr<C[]> cs(new C[4]);
assert(cCount == 4);
}
assert(cCount == 0);
// Does release work?
{
UniquePtr<C[]> c(new C[4]);
assert(cCount == 4);
rawC = c.release();
}
assert(cCount == 4);
delete[] rawC;
// Does reset work?
{
UniquePtr<C[]> c(new C[4]);
assert(cCount == 4);
c.reset(new C[2]);
assert(cCount == 2);
}
assert(cCount == 0);
//
// Custom deleter tests...
//
assert(!freed);
{
UniquePtr<int, Freer> i(reinterpret_cast<int*>(malloc(sizeof(int))));
*i = 123;
}
assert(freed);
return 0;
}
#endif
#endif // UNIQUE_PTR_H_included
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