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Unified Diff: base/scoped_generic.h

Issue 1647803004: Move base to DEPS (Closed) Base URL: git@github.com:domokit/mojo.git@master
Patch Set: Created 4 years, 11 months ago
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Index: base/scoped_generic.h
diff --git a/base/scoped_generic.h b/base/scoped_generic.h
deleted file mode 100644
index f6807e2b58f2fa3fe425b5e9b0e51a4725b5d963..0000000000000000000000000000000000000000
--- a/base/scoped_generic.h
+++ /dev/null
@@ -1,182 +0,0 @@
-// Copyright 2014 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_SCOPED_GENERIC_H_
-#define BASE_SCOPED_GENERIC_H_
-
-#include <stdlib.h>
-
-#include <algorithm>
-
-#include "base/compiler_specific.h"
-#include "base/move.h"
-
-namespace base {
-
-// This class acts like ScopedPtr with a custom deleter (although is slightly
-// less fancy in some of the more escoteric respects) except that it keeps a
-// copy of the object rather than a pointer, and we require that the contained
-// object has some kind of "invalid" value.
-//
-// Defining a scoper based on this class allows you to get a scoper for
-// non-pointer types without having to write custom code for set, reset, and
-// move, etc. and get almost identical semantics that people are used to from
-// scoped_ptr.
-//
-// It is intended that you will typedef this class with an appropriate deleter
-// to implement clean up tasks for objects that act like pointers from a
-// resource management standpoint but aren't, such as file descriptors and
-// various types of operating system handles. Using scoped_ptr for these
-// things requires that you keep a pointer to the handle valid for the lifetime
-// of the scoper (which is easy to mess up).
-//
-// For an object to be able to be put into a ScopedGeneric, it must support
-// standard copyable semantics and have a specific "invalid" value. The traits
-// must define a free function and also the invalid value to assign for
-// default-constructed and released objects.
-//
-// struct FooScopedTraits {
-// // It's assumed that this is a fast inline function with little-to-no
-// // penalty for duplicate calls. This must be a static function even
-// // for stateful traits.
-// static int InvalidValue() {
-// return 0;
-// }
-//
-// // This free function will not be called if f == InvalidValue()!
-// static void Free(int f) {
-// ::FreeFoo(f);
-// }
-// };
-//
-// typedef ScopedGeneric<int, FooScopedTraits> ScopedFoo;
-template<typename T, typename Traits>
-class ScopedGeneric {
- MOVE_ONLY_TYPE_WITH_MOVE_CONSTRUCTOR_FOR_CPP_03(ScopedGeneric)
-
- private:
- // This must be first since it's used inline below.
- //
- // Use the empty base class optimization to allow us to have a D
- // member, while avoiding any space overhead for it when D is an
- // empty class. See e.g. http://www.cantrip.org/emptyopt.html for a good
- // discussion of this technique.
- struct Data : public Traits {
- explicit Data(const T& in) : generic(in) {}
- Data(const T& in, const Traits& other) : Traits(other), generic(in) {}
- T generic;
- };
-
- public:
- typedef T element_type;
- typedef Traits traits_type;
-
- ScopedGeneric() : data_(traits_type::InvalidValue()) {}
-
- // Constructor. Takes responsibility for freeing the resource associated with
- // the object T.
- explicit ScopedGeneric(const element_type& value) : data_(value) {}
-
- // Constructor. Allows initialization of a stateful traits object.
- ScopedGeneric(const element_type& value, const traits_type& traits)
- : data_(value, traits) {
- }
-
- // Move constructor. Allows initialization from a ScopedGeneric rvalue.
- ScopedGeneric(ScopedGeneric<T, Traits>&& rvalue)
- : data_(rvalue.release(), rvalue.get_traits()) {
- }
-
- ~ScopedGeneric() {
- FreeIfNecessary();
- }
-
- // operator=. Allows assignment from a ScopedGeneric rvalue.
- ScopedGeneric& operator=(ScopedGeneric<T, Traits>&& rvalue) {
- reset(rvalue.release());
- return *this;
- }
-
- // Frees the currently owned object, if any. Then takes ownership of a new
- // object, if given. Self-resets are not allowd as on scoped_ptr. See
- // http://crbug.com/162971
- void reset(const element_type& value = traits_type::InvalidValue()) {
- if (data_.generic != traits_type::InvalidValue() && data_.generic == value)
- abort();
- FreeIfNecessary();
- data_.generic = value;
- }
-
- void swap(ScopedGeneric& other) {
- // Standard swap idiom: 'using std::swap' ensures that std::swap is
- // present in the overload set, but we call swap unqualified so that
- // any more-specific overloads can be used, if available.
- using std::swap;
- swap(static_cast<Traits&>(data_), static_cast<Traits&>(other.data_));
- swap(data_.generic, other.data_.generic);
- }
-
- // Release the object. The return value is the current object held by this
- // object. After this operation, this object will hold a null value, and
- // will not own the object any more.
- element_type release() WARN_UNUSED_RESULT {
- element_type old_generic = data_.generic;
- data_.generic = traits_type::InvalidValue();
- return old_generic;
- }
-
- const element_type& get() const { return data_.generic; }
-
- // Returns true if this object doesn't hold the special null value for the
- // associated data type.
- bool is_valid() const { return data_.generic != traits_type::InvalidValue(); }
-
- bool operator==(const element_type& value) const {
- return data_.generic == value;
- }
- bool operator!=(const element_type& value) const {
- return data_.generic != value;
- }
-
- Traits& get_traits() { return data_; }
- const Traits& get_traits() const { return data_; }
-
- private:
- void FreeIfNecessary() {
- if (data_.generic != traits_type::InvalidValue()) {
- data_.Free(data_.generic);
- data_.generic = traits_type::InvalidValue();
- }
- }
-
- // Forbid comparison. If U != T, it totally doesn't make sense, and if U ==
- // T, it still doesn't make sense because you should never have the same
- // object owned by two different ScopedGenerics.
- template <typename T2, typename Traits2> bool operator==(
- const ScopedGeneric<T2, Traits2>& p2) const;
- template <typename T2, typename Traits2> bool operator!=(
- const ScopedGeneric<T2, Traits2>& p2) const;
-
- Data data_;
-};
-
-template<class T, class Traits>
-void swap(const ScopedGeneric<T, Traits>& a,
- const ScopedGeneric<T, Traits>& b) {
- a.swap(b);
-}
-
-template<class T, class Traits>
-bool operator==(const T& value, const ScopedGeneric<T, Traits>& scoped) {
- return value == scoped.get();
-}
-
-template<class T, class Traits>
-bool operator!=(const T& value, const ScopedGeneric<T, Traits>& scoped) {
- return value != scoped.get();
-}
-
-} // namespace base
-
-#endif // BASE_SCOPED_GENERIC_H_
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