Switch scoped_ptr.h to a compatible google3 implementation.

This is Chromium's base/memory/scoped_ptr.h at r98718, which split off
from the google3 version at a later point than Breakpad's copy. It is a
drop in replacement and the only changes are:
- removal of WARN_UNUSED_RESULT.
- moving it into the google_breakpad namespace.

BUG=534
R=mark@chromium.org

Review URL: https://breakpad.appspot.com/964002

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@1265 4c0a9323-5329-0410-9bdc-e9ce6186880e

1 files changed, 278 insertions, 209 deletions

diff --git a/src/common/scoped_ptr.h b/src/common/scoped_ptr.h
index 2dbc40df..d137c186 100644
--- a/src/common/scoped_ptr.h
+++ b/src/common/scoped_ptr.h
@@ -1,231 +1,285 @@
-//  (C) Copyright Greg Colvin and Beman Dawes 1998, 1999.
-//  Copyright (c) 2001, 2002 Peter Dimov
+// Copyright 2013 Google Inc. All Rights Reserved.
 //
-//  Permission to copy, use, modify, sell and distribute this software
-//  is granted provided this copyright notice appears in all copies.
-//  This software is provided "as is" without express or implied
-//  warranty, and with no claim as to its suitability for any purpose.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
 //
-//  See http://www.boost.org/libs/smart_ptr/scoped_ptr.htm for documentation.
+//     * 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.
 //
-
-//  scoped_ptr mimics a built-in pointer except that it guarantees deletion
-//  of the object pointed to, either on destruction of the scoped_ptr or via
-//  an explicit reset(). scoped_ptr is a simple solution for simple needs;
-//  use shared_ptr or std::auto_ptr if your needs are more complex.
-
-//  *** NOTE ***
-//  If your scoped_ptr is a class member of class FOO pointing to a 
-//  forward declared type BAR (as shown below), then you MUST use a non-inlined 
-//  version of the destructor.  The destructor of a scoped_ptr (called from
-//  FOO's destructor) must have a complete definition of BAR in order to 
-//  destroy it.  Example:
+// 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[].
 //
-//  -- foo.h --
-//  class BAR;
+// Example usage (scoped_ptr):
+//   {
+//     scoped_ptr<Foo> foo(new Foo("wee"));
+//   }  // foo goes out of scope, releasing the pointer with it.
 //
-//  class FOO {
-//   public:
-//    FOO();
-//    ~FOO();  // Required for sources that instantiate class FOO to compile!
-//    
-//   private:
-//    scoped_ptr<BAR> bar_;
-//  };
+//   {
+//     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.
 //
-//  -- foo.cc --
-//  #include "foo.h"
-//  FOO::~FOO() {} // Empty, but must be non-inlined to FOO's class definition.
-
-//  scoped_ptr_malloc added by Google
-//  When one of these goes out of scope, instead of doing a delete or
-//  delete[], it calls free().  scoped_ptr_malloc<char> is likely to see
-//  much more use than any other specializations.
-
-//  release() added by Google
-//  Use this to conditionally transfer ownership of a heap-allocated object
-//  to the caller, usually on method success.
+// 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_
 
-#include <cstddef>            // for std::ptrdiff_t
-#include <assert.h>           // for assert
-#include <stdlib.h>           // for free() decl
+// 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 {
 
-template <typename T>
+// 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 {
- private:
-
-  T* ptr;
-
-  scoped_ptr(scoped_ptr const &);
-  scoped_ptr & operator=(scoped_ptr const &);
-
  public:
 
-  typedef T element_type;
+  // The element type
+  typedef C element_type;
 
-  explicit scoped_ptr(T* p = 0): ptr(p) {}
+  // 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() {
-    typedef char type_must_be_complete[sizeof(T)];
-    delete ptr;
+    enum { type_must_be_complete = sizeof(C) };
+    delete ptr_;
   }
 
-  void reset(T* p = 0) {
-    typedef char type_must_be_complete[sizeof(T)];
-
-    if (ptr != p) {
-      delete ptr;
-      ptr = p;
+  // 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;
     }
   }
 
-  T& operator*() const {
-    assert(ptr != 0);
-    return *ptr;
-  }
-
-  T* operator->() const  {
-    assert(ptr != 0);
-    return ptr;
+  // 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_;
   }
-
-  bool operator==(T* p) const {
-    return ptr == p;
-  }
-
-  bool operator!=(T* p) const {
-    return ptr != p;
+  C* operator->() const  {
+    assert(ptr_ != NULL);
+    return ptr_;
   }
-
-  T* get() const  {
-    return ptr;
-  }
-
-  void swap(scoped_ptr & b) {
-    T* tmp = b.ptr;
-    b.ptr = ptr;
-    ptr = tmp;
+  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;
   }
 
-  T* release() {
-    T* tmp = ptr;
-    ptr = 0;
-    return 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;
 
-  // no reason to use these: each scoped_ptr should have its own object
-  template <typename U> bool operator==(scoped_ptr<U> const& p) const;
-  template <typename U> bool operator!=(scoped_ptr<U> const& p) const;
+  // Disallow evil constructors
+  scoped_ptr(const scoped_ptr&);
+  void operator=(const scoped_ptr&);
 };
 
-template<typename T> inline
-void swap(scoped_ptr<T>& a, scoped_ptr<T>& b) {
-  a.swap(b);
+// Free functions
+template <class C>
+void swap(scoped_ptr<C>& p1, scoped_ptr<C>& p2) {
+  p1.swap(p2);
 }
 
-template<typename T> inline
-bool operator==(T* p, const scoped_ptr<T>& b) {
-  return p == b.get();
+template <class C>
+bool operator==(C* p1, const scoped_ptr<C>& p2) {
+  return p1 == p2.get();
 }
 
-template<typename T> inline
-bool operator!=(T* p, const scoped_ptr<T>& b) {
-  return p != b.get();
+template <class C>
+bool operator!=(C* p1, const scoped_ptr<C>& p2) {
+  return p1 != p2.get();
 }
 
-//  scoped_array extends scoped_ptr to arrays. Deletion of the array pointed to
-//  is guaranteed, either on destruction of the scoped_array or via an explicit
-//  reset(). Use shared_array or std::vector if your needs are more complex.
-
-template<typename T>
+// 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 {
- private:
-
-  T* ptr;
-
-  scoped_array(scoped_array const &);
-  scoped_array & operator=(scoped_array const &);
-
  public:
 
-  typedef T element_type;
+  // The element type
+  typedef C element_type;
 
-  explicit scoped_array(T* p = 0) : ptr(p) {}
+  // 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() {
-    typedef char type_must_be_complete[sizeof(T)];
-    delete[] ptr;
+    enum { type_must_be_complete = sizeof(C) };
+    delete[] array_;
   }
 
-  void reset(T* p = 0) {
-    typedef char type_must_be_complete[sizeof(T)];
-
-    if (ptr != p) {
-      delete [] ptr;
-      ptr = p;
+  // 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;
     }
   }
 
-  T& operator[](std::ptrdiff_t i) const {
-    assert(ptr != 0);
+  // 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);
-    return ptr[i];
-  }
-
-  bool operator==(T* p) const {
-    return ptr == p;
+    assert(array_ != NULL);
+    return array_[i];
   }
 
-  bool operator!=(T* p) const {
-    return ptr != p;
+  // Get a pointer to the zeroth element of the current object.
+  // If there is no current object, return NULL.
+  C* get() const {
+    return array_;
   }
 
-  T* get() const {
-    return ptr;
+  // 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;
   }
 
-  void swap(scoped_array & b) {
-    T* tmp = b.ptr;
-    b.ptr = ptr;
-    ptr = tmp;
-  }
-
-  T* release() {
-    T* tmp = ptr;
-    ptr = 0;
-    return 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_;
 
-  // no reason to use these: each scoped_array should have its own object
-  template <typename U> bool operator==(scoped_array<U> const& p) const;
-  template <typename U> bool operator!=(scoped_array<U> const& p) const;
+  // 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&);
 };
 
-template<class T> inline
-void swap(scoped_array<T>& a, scoped_array<T>& b) {
-  a.swap(b);
+// Free functions
+template <class C>
+void swap(scoped_array<C>& p1, scoped_array<C>& p2) {
+  p1.swap(p2);
 }
 
-template<typename T> inline
-bool operator==(T* p, const scoped_array<T>& b) {
-  return p == b.get();
+template <class C>
+bool operator==(C* p1, const scoped_array<C>& p2) {
+  return p1 == p2.get();
 }
 
-template<typename T> inline
-bool operator!=(T* p, const scoped_array<T>& b) {
-  return p != b.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 {
@@ -238,95 +292,110 @@ class ScopedPtrMallocFree {
 // scoped_ptr_malloc<> is similar to scoped_ptr<>, but it accepts a
 // second template argument, the functor used to free the object.
 
-template<typename T, typename FreeProc = ScopedPtrMallocFree>
+template<class C, class FreeProc = ScopedPtrMallocFree>
 class scoped_ptr_malloc {
- private:
-
-  T* ptr;
-
-  scoped_ptr_malloc(scoped_ptr_malloc const &);
-  scoped_ptr_malloc & operator=(scoped_ptr_malloc const &);
-
  public:
 
-  typedef T element_type;
+  // The element type
+  typedef C element_type;
 
-  explicit scoped_ptr_malloc(T* p = 0): ptr(p) {}
+  // 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() {
-    typedef char type_must_be_complete[sizeof(T)];
-    free_((void*) ptr);
+    reset();
   }
 
-  void reset(T* p = 0) {
-    typedef char type_must_be_complete[sizeof(T)];
-
-    if (ptr != p) {
-      free_((void*) ptr);
-      ptr = p;
+  // 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;
     }
   }
 
-  T& operator*() const {
-    assert(ptr != 0);
-    return *ptr;
+  // 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_;
   }
 
-  T* operator->() const {
-    assert(ptr != 0);
-    return ptr;
+  C* operator->() const {
+    assert(ptr_ != NULL);
+    return ptr_;
   }
 
-  bool operator==(T* p) const {
-    return ptr == p;
+  C* get() const {
+    return ptr_;
   }
 
-  bool operator!=(T* p) const {
-    return ptr != p;
+  // 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;
   }
 
-  T* get() const {
-    return ptr;
+  bool operator!=(C* p) const {
+    return ptr_ != p;
   }
 
+  // Swap two scoped pointers.
   void swap(scoped_ptr_malloc & b) {
-    T* tmp = b.ptr;
-    b.ptr = ptr;
-    ptr = tmp;
+    C* tmp = b.ptr_;
+    b.ptr_ = ptr_;
+    ptr_ = tmp;
   }
 
-  T* release() {
-    T* tmp = ptr;
-    ptr = 0;
+  // 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 <typename U, typename GP>
-  bool operator==(scoped_ptr_malloc<U, GP> const& p) const;
-  template <typename U, typename GP>
-  bool operator!=(scoped_ptr_malloc<U, GP> const& p) const;
-
-  static FreeProc const free_;
+  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<typename T, typename FP>
-FP const scoped_ptr_malloc<T,FP>::free_ = FP();
-
-template<typename T, typename FP> inline
-void swap(scoped_ptr_malloc<T,FP>& a, scoped_ptr_malloc<T,FP>& b) {
+template<class C, class FP> inline
+void swap(scoped_ptr_malloc<C, FP>& a, scoped_ptr_malloc<C, FP>& b) {
   a.swap(b);
 }
 
-template<typename T, typename FP> inline
-bool operator==(T* p, const scoped_ptr_malloc<T,FP>& b) {
+template<class C, class FP> inline
+bool operator==(C* p, const scoped_ptr_malloc<C, FP>& b) {
   return p == b.get();
 }
 
-template<typename T, typename FP> inline
-bool operator!=(T* p, const scoped_ptr_malloc<T,FP>& b) {
+template<class C, class FP> inline
+bool operator!=(C* p, const scoped_ptr_malloc<C, FP>& b) {
   return p != b.get();
 }