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diff --git a/Source/WebCore/contentextensions/DFABytecode.h b/Source/WebCore/contentextensions/DFABytecode.h
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+++ b/Source/WebCore/contentextensions/DFABytecode.h
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+/*
+ * Copyright (C) 2015 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.
+ */
+
+#pragma once
+
+#if ENABLE(CONTENT_EXTENSIONS)
+
+namespace WebCore {
+    
+namespace ContentExtensions {
+
+typedef uint8_t DFABytecode;
+
+// Increment UserContentExtensionStore::CurrentContentExtensionFileVersion
+// when making any non-backwards-compatible changes to the bytecode.
+// FIXME: Changes here should not require changes in WebKit2.  Move all versioning to WebCore.
+enum class DFABytecodeInstruction : uint8_t {
+
+    // CheckValue has two arguments:
+    // The value to check (1 byte),
+    // The distance to jump if the values are equal (1-4 bytes, signed).
+    CheckValueCaseInsensitive = 0x0,
+    CheckValueCaseSensitive = 0x1,
+
+    // Jump table if the input value is within a certain range.
+    // The lower value (1 byte).
+    // The higher value (1 byte).
+    // The distance to jump if the value is in the range
+    // for every character in the range (1-4 bytes, signed).
+    JumpTableCaseInsensitive = 0x2,
+    JumpTableCaseSensitive = 0x3,
+
+    // Jump to an offset if the input value is within a certain range.
+    // The lower value (1 byte).
+    // The higher value (1 byte).
+    // The distance to jump if the value is in the range (1-4 bytes, signed).
+    CheckValueRangeCaseInsensitive = 0x4,
+    CheckValueRangeCaseSensitive = 0x5,
+
+    // AppendAction has one argument:
+    // The action to append (4 bytes).
+    AppendAction = 0x6,
+    AppendActionWithIfDomain = 0x7,
+    
+    // TestFlagsAndAppendAction has two arguments:
+    // The flags to check before appending (2 bytes).
+    // The action to append (4 bytes).
+    TestFlagsAndAppendAction = 0x8,
+    TestFlagsAndAppendActionWithIfDomain = 0x9,
+
+    // Terminate has no arguments.
+    Terminate = 0xA,
+
+    // Jump has one argument:
+    // The distance to jump (1-4 bytes, signed).
+    Jump = 0xB,
+};
+
+// The last four bits contain the instruction type.
+const uint8_t DFABytecodeInstructionMask = 0x0F;
+const uint8_t DFABytecodeJumpSizeMask = 0xF0;
+
+// DFA bytecode starts with a 4 byte header which contains the size of this DFA.
+typedef uint32_t DFAHeader;
+
+// A DFABytecodeJumpSize is stored in the top four bits of the DFABytecodeInstructions that have a jump.
+enum DFABytecodeJumpSize {
+    Int8 = 0x10,
+    Int16 = 0x20,
+    Int24 = 0x30,
+    Int32 = 0x40,
+};
+const int32_t Int24Max = (1 << 23) - 1;
+const int32_t Int24Min = -(1 << 23);
+
+static inline DFABytecodeJumpSize smallestPossibleJumpSize(int32_t longestPossibleJump)
+{
+    if (longestPossibleJump <= std::numeric_limits<int8_t>::max() && longestPossibleJump >= std::numeric_limits<int8_t>::min())
+        return Int8;
+    if (longestPossibleJump <= std::numeric_limits<int16_t>::max() && longestPossibleJump >= std::numeric_limits<int16_t>::min())
+        return Int16;
+    if (longestPossibleJump <= Int24Max && longestPossibleJump >= Int24Min)
+        return Int24;
+    return Int32;
+}
+    
+static inline size_t instructionSizeWithArguments(DFABytecodeInstruction instruction)
+{
+    switch (instruction) {
+    case DFABytecodeInstruction::CheckValueCaseSensitive:
+    case DFABytecodeInstruction::CheckValueCaseInsensitive:
+    case DFABytecodeInstruction::JumpTableCaseInsensitive:
+    case DFABytecodeInstruction::JumpTableCaseSensitive:
+    case DFABytecodeInstruction::CheckValueRangeCaseSensitive:
+    case DFABytecodeInstruction::CheckValueRangeCaseInsensitive:
+    case DFABytecodeInstruction::Jump:
+        RELEASE_ASSERT_NOT_REACHED(); // Variable instruction size.
+    case DFABytecodeInstruction::AppendAction:
+    case DFABytecodeInstruction::AppendActionWithIfDomain:
+        return sizeof(DFABytecodeInstruction) + sizeof(uint32_t);
+    case DFABytecodeInstruction::TestFlagsAndAppendAction:
+    case DFABytecodeInstruction::TestFlagsAndAppendActionWithIfDomain:
+        return sizeof(DFABytecodeInstruction) + sizeof(uint16_t) + sizeof(uint32_t);
+    case DFABytecodeInstruction::Terminate:
+        return sizeof(DFABytecodeInstruction);
+    }
+}
+    
+} // namespace ContentExtensions    
+} // namespace WebCore
+
+#endif // ENABLE(CONTENT_EXTENSIONS)