Support dynamic switching between integrated and discrete GPUs on Mac OS X.

base/mac/scoped_generic_obj.h

+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_MAC_SCOPED_GENERIC_OBJ_H_
+#define BASE_MAC_SCOPED_GENERIC_OBJ_H_
+#pragma once
+
+#include "base/basictypes.h"
+#include "base/compiler_specific.h"
+
+namespace base {
+namespace mac {

[Mark Mentovai, 2011/10/13 21:13:01]

There is nothing Mac-ish about this. Can you move it to base/memory and rename
this namespace and #include guards appropriately?

[Ken Russell (switch to Gerrit), 2011/10/13 21:43:48]

Yes. Done.

+
+// ScopedGenericObj<> is patterned after scoped_ptr_malloc<>, except that
+// it assumes the template argument is typedef'ed to a pointer type. It
+// does not support the retain/release semantics of ScopedCFTypeRef. It
+// takes as its second template argument a functor which frees the object.

[Mark Mentovai, 2011/10/13 21:13:01]

The comment should have a sample FreeProc, since unlike scoped_ptr_malloc<>,
there is no default free functor.

[Ken Russell (switch to Gerrit), 2011/10/13 21:43:48]

OK. Added.

+
+template<class C, class FreeProc>
+class ScopedGenericObj {
+ public:
+
+  // The element type
+  typedef C element_type;
+
+  // Constructor.  Defaults to initializing with NULL.
+  // There is no way to create an uninitialized ScopedGenericObj.
+  // The input parameter must be allocated with an allocator that matches the
+  // Free functor.
+  explicit ScopedGenericObj(C p = NULL): obj_(p) {}
+
+  // Destructor.  If there is a C object, call the Free functor.
+  ~ScopedGenericObj() {
+    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 (obj_ != p) {
+      FreeProc free_proc;
+      free_proc(obj_);
+      obj_ = p;
+    }
+  }
+
+  operator C() const {
+    return obj_;
+  }
+
+  C get() const {
+    return obj_;
+  }
+
+  // Comparison operators.
+  // These return whether a ScopedGenericObj 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 obj_ == p;
+  }
+
+  bool operator!=(C p) const {
+    return obj_ != p;
+  }
+
+  // Swap two ScopedGenericObjs.
+  void swap(ScopedGenericObj& b) {
+    C tmp = b.obj_;
+    b.obj_ = obj_;
+    obj_ = 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() WARN_UNUSED_RESULT {
+    C tmp = obj_;
+    obj_ = NULL;
+    return tmp;
+  }
+
+ private:
+  C obj_;
+
+  // no reason to use these: each ScopedGenericObj should have its own object.
+  template <class C2, class GP>
+  bool operator==(ScopedGenericObj<C2, GP> const& p) const;
+  template <class C2, class GP>
+  bool operator!=(ScopedGenericObj<C2, GP> const& p) const;
+
+  // Disallow evil constructors.
+  ScopedGenericObj(const ScopedGenericObj&);
+  void operator=(const ScopedGenericObj&);
+};
+
+template<class C, class FP> inline
+void swap(ScopedGenericObj<C, FP>& a, ScopedGenericObj<C, FP>& b) {
+  a.swap(b);
+}
+
+template<class C, class FP> inline
+bool operator==(C* p, const ScopedGenericObj<C, FP>& b) {
+  return p == b.get();
+}
+
+template<class C, class FP> inline
+bool operator!=(C* p, const ScopedGenericObj<C, FP>& b) {
+  return p != b.get();
+}
+
+}  // namespace mac
+}  // namespace base
+
+#endif  // BASE_MAC_SCOPED_GENERIC_OBJ_H_