ALL-IN-ONE: Optimization to previousBoundary() and nextBoundary()

third_party/WebKit/Source/core/editing/iterators/TextAccumulator.h

Index: third_party/WebKit/Source/core/editing/iterators/TextAccumulator.h
diff --git a/third_party/WebKit/Source/core/editing/iterators/TextAccumulator.h b/third_party/WebKit/Source/core/editing/iterators/TextAccumulator.h
new file mode 100644
index 0000000000000000000000000000000000000000..e555b6bb6e023396ec87e8e9d5da14e510beb5bb
--- /dev/null
+++ b/third_party/WebKit/Source/core/editing/iterators/TextAccumulator.h
@@ -0,0 +1,76 @@
+// Copyright 2016 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.
+
+#ifndef TextAccumulator_h
+#define TextAccumulator_h
+
+#include "core/editing/iterators/TextBuffer.h"
+
+namespace blink {
+
+template<typename Buffer>
+class TextAccumulator {
+    STACK_ALLOCATED();
+public:
+
+    TextAccumulator()
+#ifndef NDEBUG
+        : m_maxAccumulate(2)
+#else
+        : m_maxAccumulate(1024)
+#endif // NDEBUG
+        , m_accumulatedInCurrentNode(0)
+    {
+    }
+
+    const UChar* data() const { return m_buffer.data(); }
+    unsigned size() const { return m_buffer.size(); }
+    int accumulatedLengthInCurrentNode() const { return m_accumulatedInCurrentNode; }
+
+    void push(const UChar* other, unsigned length) { m_buffer.push(other, length); }
+
+    template<typename Iterator>
+    void extract(const Iterator& it)
+    {
+        ASSERT(m_maxAccumulate > 0);
+        ASSERT(m_accumulatedInCurrentNode >= 0);
+        ASSERT(m_accumulatedInCurrentNode <= it.length());
+        int accumulateLength = std::min(it.length() - m_accumulatedInCurrentNode, m_maxAccumulate);
+        if (it.isInTextSecurityMode()) {
+            // Treat bullets used in the text security mode as regular
+            // characters when looking for boundaries
+            m_buffer.push('x', accumulateLength);
+        } else {
+            accumulateLength = it.copyTextTo(m_buffer, m_accumulatedInCurrentNode, accumulateLength);
+        }
+        m_accumulatedInCurrentNode += accumulateLength;
+        if (accumulateLength >= m_maxAccumulate)
+            m_maxAccumulate *= 2;
+    }
+
+    template<typename Iterator>
+    void advance(Iterator& it)
+    {
+        ASSERT(m_accumulatedInCurrentNode >= 0);
+        ASSERT(m_accumulatedInCurrentNode <= it.length());
+        ASSERT(!it.atEnd());
+        if (m_accumulatedInCurrentNode == it.length()) {
+            m_accumulatedInCurrentNode = 0;
+            it.advance();
+        }
+    }
+
+private:
+
+    Buffer m_buffer;
+    int m_maxAccumulate;
+    int m_accumulatedInCurrentNode;
+};
+
+using ForwardsTextAccumulator = TextAccumulator<ForwardsTextBuffer>;
+using BackwardsTextAccumulator = TextAccumulator<BackwardsTextBuffer>;
+
+} // namespace blink
+
+#endif // TextAccumulator_h