From 7b68f616e49235267eeac8db51aadade6d60e243 Mon Sep 17 00:00:00 2001
From: tsepez <tsepez@chromium.org>
Date: Wed, 7 Sep 2016 14:11:27 -0700
Subject: Make Observers into a templated class

Review-Url: https://codereview.chromium.org/2311343003
---
 core/fxcrt/include/cfx_observable.h | 66 +++++++++++++++++++++++++++++++++++++
 1 file changed, 66 insertions(+)
 create mode 100644 core/fxcrt/include/cfx_observable.h

(limited to 'core/fxcrt')

diff --git a/core/fxcrt/include/cfx_observable.h b/core/fxcrt/include/cfx_observable.h
new file mode 100644
index 0000000000..b669e0d3d5
--- /dev/null
+++ b/core/fxcrt/include/cfx_observable.h
@@ -0,0 +1,66 @@
+// Copyright 2016 PDFium 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 CORE_FXCRT_INCLUDE_CFX_OBSERVABLE_H_
+#define CORE_FXCRT_INCLUDE_CFX_OBSERVABLE_H_
+
+#include <set>
+
+#include "core/fxcrt/include/fx_system.h"
+#include "third_party/base/stl_util.h"
+
+template <class T>
+class CFX_Observable {
+ public:
+  class Observer {
+   public:
+    Observer() : m_pWatchedPtr(nullptr) {}
+    Observer(T** pWatchedPtr) : m_pWatchedPtr(pWatchedPtr) {
+      if (m_pWatchedPtr)
+        (*m_pWatchedPtr)->AddObserver(this);
+    }
+    Observer(const Observer& that) = delete;
+    ~Observer() {
+      if (m_pWatchedPtr)
+        (*m_pWatchedPtr)->RemoveObserver(this);
+    }
+    void SetWatchedPtr(T** pWatchedPtr) {
+      if (m_pWatchedPtr)
+        (*m_pWatchedPtr)->RemoveObserver(this);
+      m_pWatchedPtr = pWatchedPtr;
+      if (m_pWatchedPtr)
+        (*m_pWatchedPtr)->AddObserver(this);
+    }
+    void OnDestroy() {
+      ASSERT(m_pWatchedPtr);
+      *m_pWatchedPtr = nullptr;
+      m_pWatchedPtr = nullptr;
+    }
+    Observer& operator=(const Observer& that) = delete;
+
+   private:
+    T** m_pWatchedPtr;
+  };
+
+  CFX_Observable() {}
+  CFX_Observable(const CFX_Observable& that) = delete;
+  ~CFX_Observable() {
+    for (auto* pObserver : m_Observers)
+      pObserver->OnDestroy();
+  }
+  void AddObserver(Observer* pObserver) {
+    ASSERT(!pdfium::ContainsKey(m_Observers, pObserver));
+    m_Observers.insert(pObserver);
+  }
+  void RemoveObserver(Observer* pObserver) {
+    ASSERT(pdfium::ContainsKey(m_Observers, pObserver));
+    m_Observers.erase(pObserver);
+  }
+  CFX_Observable& operator=(const CFX_Observable& that) = delete;
+
+ private:
+  std::set<Observer*> m_Observers;
+};
+
+#endif  // CORE_FXCRT_INCLUDE_CFX_OBSERVABLE_H_
-- 
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