Filtered events.

chrome/common/extensions/value_counter.cc

Index: chrome/common/extensions/value_counter.cc
diff --git a/chrome/common/extensions/value_counter.cc b/chrome/common/extensions/value_counter.cc
new file mode 100644
index 0000000000000000000000000000000000000000..bce9d55d77c70b1a7173db0a2fb2aeba93c175f7
--- /dev/null
+++ b/chrome/common/extensions/value_counter.cc
@@ -0,0 +1,64 @@
+// Copyright (c) 2012 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.
+
+#include "chrome/common/extensions/value_counter.h"
+
+#include "base/values.h"
+
+namespace extensions {
+
+ValueCounter::ValueCounter() {
+}
+
+ValueCounter::~ValueCounter() {
+}
+
+ValueCounter::Entry::Entry(const base::Value& value)
+    : value(value.DeepCopy()),
+      count(1) {
+}
+
+ValueCounter::Entry::~Entry() {
+}
+
+int ValueCounter::Entry::Increment() {
+  return ++count;
+}
+
+int ValueCounter::Entry::Decrement() {
+  return --count;
+}
+
+int ValueCounter::Add(const base::Value& value) {
+  return AddImpl(value, true);
+}
+
+int ValueCounter::Remove(const base::Value& value) {
+  for (EntryList::iterator it = entries_.begin(); it != entries_.end(); it++) {
+    (*it)->value->GetType();
+    if ((*it)->value->Equals(&value)) {
+      int remaining = --(*it)->count;
+      if (remaining == 0) {
+        entries_.erase(it);
+      }
+      return remaining;
+    }
+  }
+  return 0;
+}
+
+int ValueCounter::AddIfMissing(const base::Value& value) {
+  return AddImpl(value, false);
+}
+
+int ValueCounter::AddImpl(const base::Value& value, bool increment) {
+  for (EntryList::iterator it = entries_.begin(); it != entries_.end(); it++) {
+    if ((*it)->value->Equals(&value))
+      return increment ? (*it)->Increment() : (*it)->count;
+  }
+  entries_.push_back(linked_ptr<Entry>(new Entry(value)));
+  return 1;
+}
+
+}  // namespace extensions