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//
// Copyright 2018 The ANGLE Project Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//
// Observer:
// Implements the Observer pattern for sending state change notifications
// from Subject objects to dependent Observer objects.
//
// See design document:
// https://docs.google.com/document/d/15Edfotqg6_l1skTEL8ADQudF_oIdNa7i8Po43k6jMd4/
#include "libANGLE/Observer.h"
#include <algorithm>
#include "common/debug.h"
namespace angle
{
namespace
{} // anonymous namespace
// Observer implementation.
ObserverInterface::~ObserverInterface() = default;
// Subject implementation.
Subject::Subject() {}
Subject::~Subject()
{
resetObservers();
}
bool Subject::hasObservers() const
{
return !mObservers.empty();
}
void Subject::onStateChange(SubjectMessage message) const
{
if (mObservers.empty())
return;
for (const ObserverBindingBase *binding : mObservers)
{
binding->getObserver()->onSubjectStateChange(binding->getSubjectIndex(), message);
}
}
void Subject::resetObservers()
{
for (angle::ObserverBindingBase *binding : mObservers)
{
binding->onSubjectReset();
}
mObservers.clear();
}
// ObserverBinding implementation.
ObserverBinding::ObserverBinding() : ObserverBindingBase(nullptr, 0), mSubject(nullptr) {}
ObserverBinding::ObserverBinding(ObserverInterface *observer, SubjectIndex index)
: ObserverBindingBase(observer, index), mSubject(nullptr)
{
ASSERT(observer);
}
ObserverBinding::~ObserverBinding()
{
reset();
}
ObserverBinding::ObserverBinding(const ObserverBinding &other)
: ObserverBindingBase(other), mSubject(nullptr)
{
bind(other.mSubject);
}
ObserverBinding &ObserverBinding::operator=(const ObserverBinding &other)
{
reset();
ObserverBindingBase::operator=(other);
bind(other.mSubject);
return *this;
}
void ObserverBinding::bind(Subject *subject)
{
ASSERT(getObserver() || !subject);
if (mSubject)
{
mSubject->removeObserver(this);
}
mSubject = subject;
if (mSubject)
{
mSubject->addObserver(this);
}
}
void ObserverBinding::onStateChange(SubjectMessage message) const
{
getObserver()->onSubjectStateChange(getSubjectIndex(), message);
}
void ObserverBinding::onSubjectReset()
{
mSubject = nullptr;
}
} // namespace angle
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