// Copyright 2013 Google Inc. All Rights Reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// Scopers help you manage ownership of a pointer, helping you easily manage the
// a pointer within a scope, and automatically destroying the pointer at the
// end of a scope. There are two main classes you will use, which correspond
// to the operators new/delete and new[]/delete[].
//
// Example usage (scoped_ptr):
// {
// scoped_ptr<Foo> foo(new Foo("wee"));
// } // foo goes out of scope, releasing the pointer with it.
//
// {
// scoped_ptr<Foo> foo; // No pointer managed.
// foo.reset(new Foo("wee")); // Now a pointer is managed.
// foo.reset(new Foo("wee2")); // Foo("wee") was destroyed.
// foo.reset(new Foo("wee3")); // Foo("wee2") was destroyed.
// foo->Method(); // Foo::Method() called.
// foo.get()->Method(); // Foo::Method() called.
// SomeFunc(foo.release()); // SomeFunc takes ownership, foo no longer
// // manages a pointer.
// foo.reset(new Foo("wee4")); // foo manages a pointer again.
// foo.reset(); // Foo("wee4") destroyed, foo no longer
// // manages a pointer.
// } // foo wasn't managing a pointer, so nothing was destroyed.
//
// Example usage (scoped_array):
// {
// scoped_array<Foo> foo(new Foo[100]);
// foo.get()->Method(); // Foo::Method on the 0th element.
// foo[10].Method(); // Foo::Method on the 10th element.
// }
#ifndef COMMON_SCOPED_PTR_H_
#define COMMON_SCOPED_PTR_H_
// This is an implementation designed to match the anticipated future TR2
// implementation of the scoped_ptr class, and its closely-related brethren,
// scoped_array, scoped_ptr_malloc.
#include <assert.h>
#include <stddef.h>
#include <stdlib.h>
namespace google_breakpad {
// A scoped_ptr<T> is like a T*, except that the destructor of scoped_ptr<T>
// automatically deletes the pointer it holds (if any).
// That is, scoped_ptr<T> owns the T object that it points to.
// Like a T*, a scoped_ptr<T> may hold either NULL or a pointer to a T object.
// Also like T*, scoped_ptr<T> is thread-compatible, and once you
// dereference it, you get the threadsafety guarantees of T.
//
// The size of a scoped_ptr is small:
// sizeof(scoped_ptr<C>) == sizeof(C*)
template <class C>
class scoped_ptr {
public:
// The element type
typedef C element_type;
// Constructor. Defaults to initializing with NULL.
// There is no way to create an uninitialized scoped_ptr.
// The input parameter must be allocated with new.
explicit scoped_ptr(C* p = NULL) : ptr_(p) { }
// Destructor. If there is a C object, delete it.
// We don't need to test ptr_ == NULL because C++ does that for us.
~scoped_ptr() {
enum { type_must_be_complete = sizeof(C) };
delete ptr_;
}
// Reset. Deletes the current owned object, if any.
// Then takes ownership of a new object, if given.
// this->reset(this->get()) works.
void reset(C* p = NULL) {
if (p != ptr_) {
enum { type_must_be_complete = sizeof(C) };
delete ptr_;
ptr_ = p;
}
}
// Accessors to get the owned object.
// operator* and operator-> will assert() if there is no current object.
C& operator*() const {
assert(ptr_ != NULL);
return *ptr_;
}
C* operator->() const {
assert(ptr_ != NULL);
return ptr_;
}
C* get() const { return ptr_; }
// Comparison operators.
// These return whether two scoped_ptr refer to the same object, not just to
// two different but equal objects.
bool operator==(C* p) const { return ptr_ == p; }
bool operator!=(C* p) const { return ptr_ != p; }
// Swap two scoped pointers.
void swap(scoped_ptr& p2) {
C* tmp = ptr_;
ptr_ = p2.ptr_;
p2.ptr_ = tmp;
}
// Release a pointer.
// The return value is the current pointer held by this object.
// If this object holds a NULL pointer, the return value is NULL.
// After this operation, this object will hold a NULL pointer,
// and will not own the object any more.
C* release() {
C* retVal = ptr_;
ptr_ = NULL;
return retVal;
}
private:
C* ptr_;
// Forbid comparison of scoped_ptr types. If C2 != C, it totally doesn't
// make sense, and if C2 == C, it still doesn't make sense because you should
// never have the same object owned by two different scoped_ptrs.
template <class C2> bool operator==(scoped_ptr<C2> const& p2) const;
template <class C2> bool operator!=(scoped_ptr<C2> const& p2) const;
// Disallow evil constructors
scoped_ptr(const scoped_ptr&);
void operator=(const scoped_ptr&);
};
// Free functions
template <class C>
void swap(scoped_ptr<C>& p1, scoped_ptr<C>& p2) {
p1.swap(p2);
}
template <class C>
bool operator==(C* p1, const scoped_ptr<C>& p2) {
return p1 == p2.get();
}
template <class C>
bool operator!=(C* p1, const scoped_ptr<C>& p2) {
return p1 != p2.get();
}
// scoped_array<C> is like scoped_ptr<C>, except that the caller must allocate
// with new [] and the destructor deletes objects with delete [].
//
// As with scoped_ptr<C>, a scoped_array<C> either points to an object
// or is NULL. A scoped_array<C> owns the object that it points to.
// scoped_array<T> is thread-compatible, and once you index into it,
// the returned objects have only the threadsafety guarantees of T.
//
// Size: sizeof(scoped_array<C>) == sizeof(C*)
template <class C>
class scoped_array {
public:
// The element type
typedef C element_type;
// Constructor. Defaults to intializing with NULL.
// There is no way to create an uninitialized scoped_array.
// The input parameter must be allocated with new [].
explicit scoped_array(C* p = NULL) : array_(p) { }
// Destructor. If there is a C object, delete it.
// We don't need to test ptr_ == NULL because C++ does that for us.
~scoped_array() {
enum { type_must_be_complete = sizeof(C) };
delete[] array_;
}
// Reset. Deletes the current owned object, if any.
// Then takes ownership of a new object, if given.
// this->reset(this->get()) works.
void reset(C* p = NULL) {
if (p != array_) {
enum { type_must_be_complete = sizeof(C) };
delete[] array_;
array_ = p;
}
}
// Get one element of the current object.
// Will assert() if there is no current object, or index i is negative.
C& operator[](ptrdiff_t i) const {
assert(i >= 0);
assert(array_ != NULL);
return array_[i];
}
// Get a pointer to the zeroth element of the current object.
// If there is no current object, return NULL.
C* get() const {
return array_;
}
// Comparison operators.
// These return whether two scoped_array refer to the same object, not just to
// two different but equal objects.
bool operator==(C* p) const { return array_ == p; }
bool operator!=(C* p) const { return array_ != p; }
// Swap two scoped arrays.
void swap(scoped_array& p2) {
C* tmp = array_;
array_ = p2.array_;
p2.array_ = tmp;
}
// Release an array.
// The return value is the current pointer held by this object.
// If this object holds a NULL pointer, the return value is NULL.
// After this operation, this object will hold a NULL pointer,
// and will not own the object any more.
C* release() {
C* retVal = array_;
array_ = NULL;
return retVal;
}
private:
C* array_;
// Forbid comparison of different scoped_array types.
template <class C2> bool operator==(scoped_array<C2> const& p2) const;
template <class C2> bool operator!=(scoped_array<C2> const& p2) const;
// Disallow evil constructors
scoped_array(const scoped_array&);
void operator=(const scoped_array&);
};
// Free functions
template <class C>
void swap(scoped_array<C>& p1, scoped_array<C>& p2) {
p1.swap(p2);
}
template <class C>
bool operator==(C* p1, const scoped_array<C>& p2) {
return p1 == p2.get();
}
template <class C>
bool operator!=(C* p1, const scoped_array<C>& p2) {
return p1 != p2.get();
}
// This class wraps the c library function free() in a class that can be
// passed as a template argument to scoped_ptr_malloc below.
class ScopedPtrMallocFree {
public:
inline void operator()(void* x) const {
free(x);
}
};
// scoped_ptr_malloc<> is similar to scoped_ptr<>, but it accepts a
// second template argument, the functor used to free the object.
template<class C, class FreeProc = ScopedPtrMallocFree>
class scoped_ptr_malloc {
public:
// The element type
typedef C element_type;
// Constructor. Defaults to initializing with NULL.
// There is no way to create an uninitialized scoped_ptr.
// The input parameter must be allocated with an allocator that matches the
// Free functor. For the default Free functor, this is malloc, calloc, or
// realloc.
explicit scoped_ptr_malloc(C* p = NULL): ptr_(p) {}
// Destructor. If there is a C object, call the Free functor.
~scoped_ptr_malloc() {
reset();
}
// Reset. Calls the Free functor on the current owned object, if any.
// Then takes ownership of a new object, if given.
// this->reset(this->get()) works.
void reset(C* p = NULL) {
if (ptr_ != p) {
FreeProc free_proc;
free_proc(ptr_);
ptr_ = p;
}
}
// Get the current object.
// operator* and operator-> will cause an assert() failure if there is
// no current object.
C& operator*() const {
assert(ptr_ != NULL);
return *ptr_;
}
C* operator->() const {
assert(ptr_ != NULL);
return ptr_;
}
C* get() const {
return ptr_;
}
// Comparison operators.
// These return whether a scoped_ptr_malloc and a plain pointer refer
// to the same object, not just to two different but equal objects.
// For compatibility with the boost-derived implementation, these
// take non-const arguments.
bool operator==(C* p) const {
return ptr_ == p;
}
bool operator!=(C* p) const {
return ptr_ != p;
}
// Swap two scoped pointers.
void swap(scoped_ptr_malloc & b) {
C* tmp = b.ptr_;
b.ptr_ = ptr_;
ptr_ = tmp;
}
// Release a pointer.
// The return value is the current pointer held by this object.
// If this object holds a NULL pointer, the return value is NULL.
// After this operation, this object will hold a NULL pointer,
// and will not own the object any more.
C* release() {
C* tmp = ptr_;
ptr_ = NULL;
return tmp;
}
private:
C* ptr_;
// no reason to use these: each scoped_ptr_malloc should have its own object
template <class C2, class GP>
bool operator==(scoped_ptr_malloc<C2, GP> const& p) const;
template <class C2, class GP>
bool operator!=(scoped_ptr_malloc<C2, GP> const& p) const;
// Disallow evil constructors
scoped_ptr_malloc(const scoped_ptr_malloc&);
void operator=(const scoped_ptr_malloc&);
};
template<class C, class FP> inline
void swap(scoped_ptr_malloc<C, FP>& a, scoped_ptr_malloc<C, FP>& b) {
a.swap(b);
}
template<class C, class FP> inline
bool operator==(C* p, const scoped_ptr_malloc<C, FP>& b) {
return p == b.get();
}
template<class C, class FP> inline
bool operator!=(C* p, const scoped_ptr_malloc<C, FP>& b) {
return p != b.get();
}
} // namespace google_breakpad
#endif // COMMON_SCOPED_PTR_H_