gecko/dom/bindings/Nullable.h

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-*/
/* vim: set ts=2 sw=2 et tw=79: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this file,
* You can obtain one at http://mozilla.org/MPL/2.0/. */
Bug 742217. Reduce the use of nested namespaces in our binding code. r=peterv,bent In the new setup, all per-interface DOM binding files are exported into mozilla/dom. General files not specific to an interface are also exported into mozilla/dom. In terms of namespaces, most things now live in mozilla::dom. Each interface Foo that has generated code has a mozilla::dom::FooBinding namespace for said generated code (and possibly a mozilla::bindings::FooBinding_workers if there's separate codegen for workers). IDL enums are a bit weird: since the name of the enum and the names of its entries all end up in the same namespace, we still generate a C++ namespace with the name of the IDL enum type with "Values" appended to it, with a ::valuelist inside for the actual C++ enum. We then typedef EnumFooValues::valuelist to EnumFoo. That makes it a bit more difficult to refer to the values, but means that values from different enums don't collide with each other. The enums with the proto and constructor IDs in them now live under the mozilla::dom::prototypes and mozilla::dom::constructors namespaces respectively. Again, this lets us deal sanely with the whole "enum value names are flattened into the namespace the enum is in" deal. The main benefit of this setup (and the reason "Binding" got appended to the per-interface namespaces) is that this way "using mozilla::dom" should Just Work for consumers and still allow C++ code to sanely use the IDL interface names for concrete classes, which is fairly desirable. --HG-- rename : dom/bindings/Utils.cpp => dom/bindings/BindingUtils.cpp rename : dom/bindings/Utils.h => dom/bindings/BindingUtils.h
2012-05-02 21:35:38 -07:00
#ifndef mozilla_dom_Nullable_h
#define mozilla_dom_Nullable_h
#include "mozilla/Assertions.h"
namespace mozilla {
namespace dom {
// Support for nullable types
template <typename T>
struct Nullable
{
private:
T mValue;
bool mIsNull;
public:
Nullable()
: mIsNull(true)
{}
Nullable(T aValue)
: mValue(aValue)
, mIsNull(false)
{}
void SetValue(T aValue) {
mValue = aValue;
mIsNull = false;
}
// For cases when |T| is some type with nontrivial copy behavior, we may want
// to get a reference to our internal copy of T and work with it directly
// instead of relying on the copying version of SetValue().
T& SetValue() {
mIsNull = false;
return mValue;
}
void SetNull() {
mIsNull = true;
}
const T& Value() const {
MOZ_ASSERT(!mIsNull);
return mValue;
}
T& Value() {
MOZ_ASSERT(!mIsNull);
return mValue;
}
bool IsNull() const {
return mIsNull;
}
};
} // namespace dom
} // namespace mozilla
Bug 742217. Reduce the use of nested namespaces in our binding code. r=peterv,bent In the new setup, all per-interface DOM binding files are exported into mozilla/dom. General files not specific to an interface are also exported into mozilla/dom. In terms of namespaces, most things now live in mozilla::dom. Each interface Foo that has generated code has a mozilla::dom::FooBinding namespace for said generated code (and possibly a mozilla::bindings::FooBinding_workers if there's separate codegen for workers). IDL enums are a bit weird: since the name of the enum and the names of its entries all end up in the same namespace, we still generate a C++ namespace with the name of the IDL enum type with "Values" appended to it, with a ::valuelist inside for the actual C++ enum. We then typedef EnumFooValues::valuelist to EnumFoo. That makes it a bit more difficult to refer to the values, but means that values from different enums don't collide with each other. The enums with the proto and constructor IDs in them now live under the mozilla::dom::prototypes and mozilla::dom::constructors namespaces respectively. Again, this lets us deal sanely with the whole "enum value names are flattened into the namespace the enum is in" deal. The main benefit of this setup (and the reason "Binding" got appended to the per-interface namespaces) is that this way "using mozilla::dom" should Just Work for consumers and still allow C++ code to sanely use the IDL interface names for concrete classes, which is fairly desirable. --HG-- rename : dom/bindings/Utils.cpp => dom/bindings/BindingUtils.cpp rename : dom/bindings/Utils.h => dom/bindings/BindingUtils.h
2012-05-02 21:35:38 -07:00
#endif /* mozilla_dom_Nullable_h */