Merge WebKit at r75315: Initial merge by git.

Change-Id: I570314b346ce101c935ed22a626b48c2af266b84

1 files changed, 122 insertions, 0 deletions

diff --git a/Source/WebCore/platform/text/SuffixTree.h b/Source/WebCore/platform/text/SuffixTree.h
new file mode 100644
index 0000000..f11fd23
--- /dev/null
+++ b/Source/WebCore/platform/text/SuffixTree.h
@@ -0,0 +1,122 @@
+/*
+ * Copyright (C) 2010 Adam Barth. 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. ``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 COMPUTER, INC. OR
+ * 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.
+ */
+
+#ifndef SuffixTree_h
+#define SuffixTree_h
+
+#include "PlatformString.h"
+#include <wtf/Vector.h>
+
+namespace WebCore {
+
+class UnicodeCodebook {
+public:
+    static int codeWord(UChar c) { return c; }
+    enum { codeSize = 1 << 8 * sizeof(UChar) };
+};
+
+class ASCIICodebook {
+public:
+    static int codeWord(UChar c) { return c & (codeSize - 1); }
+    enum { codeSize = 1 << (8 * sizeof(char) - 1) };
+};
+
+template<typename Codebook>
+class SuffixTree {
+public:
+    SuffixTree(const String& text, unsigned depth)
+        : m_depth(depth)
+        , m_leaf(true)
+    {
+        build(text);
+    }
+
+    bool mightContain(const String& query)
+    {
+        Node* current = &m_root;
+        int limit = std::min(m_depth, query.length());
+        for (int i = 0; i < limit; ++i) {
+            current = current->at(Codebook::codeWord(query[i]));
+            if (!current)
+                return false;
+        }
+        return true;
+    }
+
+private:
+    class Node {
+    public:
+        Node(bool isLeaf = false)
+        {
+            m_children.resize(Codebook::codeSize);
+            m_children.fill(0);
+            m_isLeaf = isLeaf;
+        }
+
+        ~Node()
+        {
+            for (unsigned i = 0; i < m_children.size(); ++i) {
+                Node* child = m_children.at(i);
+                if (child && !child->m_isLeaf)
+                    delete child;
+            }
+        }
+
+        Node*& at(int codeWord) { return m_children.at(codeWord); }
+
+    private:
+        typedef Vector<Node*, Codebook::codeSize> ChildrenVector;
+
+        ChildrenVector m_children;
+        bool m_isLeaf;
+    };
+
+    void build(const String& text)
+    {
+        for (unsigned base = 0; base < text.length(); ++base) {
+            Node* current = &m_root;
+            unsigned limit = std::min(base + m_depth, text.length());
+            for (unsigned offset = 0; base + offset < limit; ++offset) {
+                ASSERT(current != &m_leaf);
+                Node*& child = current->at(Codebook::codeWord(text[base + offset]));
+                if (!child)
+                    child = base + offset + 1 == limit ? &m_leaf : new Node();
+                current = child;
+            }
+        }
+    }
+
+    Node m_root;
+    unsigned m_depth;
+
+    // Instead of allocating a fresh empty leaf node for ever leaf in the tree
+    // (there can be a lot of these), we alias all the leaves to this "static"
+    // leaf node.
+    Node m_leaf;
+};
+
+} // namespace WebCore
+
+#endif // SuffixTree_h