X-Git-Url: https://git.saurik.com/apple/javascriptcore.git/blobdiff_plain/b80e619319b1def83d1e8b4f84042b661be1be7f..14957cd040308e3eeec43d26bae5d76da13fcd85:/wtf/SentinelLinkedList.h

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+/*
+ * Copyright (C) 2011 Apple Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
+ * THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+//    A SentinelLinkedList is a linked list with dummy head and tail sentinels,
+//    which allow for branch-less insertion and removal, and removal without a
+//    pointer to the list.
+//    
+//    Requires: Node is a concrete class with:
+//        Node(SentinelTag);
+//        void setPrev(Node*);
+//        Node* prev();
+//        void setNext(Node*);
+//        Node* next();
+
+#ifndef SentinelLinkedList_h
+#define SentinelLinkedList_h
+
+namespace WTF {
+
+enum SentinelTag { Sentinel };
+
+template <typename Node> class SentinelLinkedList {
+public:
+    typedef Node* iterator;
+
+    SentinelLinkedList();
+
+    void push(Node*);
+    static void remove(Node*);
+
+    iterator begin();
+    iterator end();
+
+private:
+    Node m_headSentinel;
+    Node m_tailSentinel;
+};
+
+template <typename Node> inline SentinelLinkedList<Node>::SentinelLinkedList()
+    : m_headSentinel(Sentinel)
+    , m_tailSentinel(Sentinel)
+{
+    m_headSentinel.setNext(&m_tailSentinel);
+    m_headSentinel.setPrev(0);
+
+    m_tailSentinel.setPrev(&m_headSentinel);
+    m_tailSentinel.setNext(0);
+}
+
+template <typename Node> inline typename SentinelLinkedList<Node>::iterator SentinelLinkedList<Node>::begin()
+{
+    return m_headSentinel.next();
+}
+
+template <typename Node> inline typename SentinelLinkedList<Node>::iterator SentinelLinkedList<Node>::end()
+{
+    return &m_tailSentinel;
+}
+
+template <typename Node> inline void SentinelLinkedList<Node>::push(Node* node)
+{
+    ASSERT(node);
+    Node* prev = &m_headSentinel;
+    Node* next = m_headSentinel.next();
+
+    node->setPrev(prev);
+    node->setNext(next);
+
+    prev->setNext(node);
+    next->setPrev(node);
+}
+
+template <typename Node> inline void SentinelLinkedList<Node>::remove(Node* node)
+{
+    Node* prev = node->prev();
+    Node* next = node->next();
+
+    prev->setNext(next);
+    next->setPrev(prev);
+}
+
+}
+
+using WTF::SentinelLinkedList;
+
+#endif
+