Introduce ForwardsTextBuffer and BackwardsTextBuffer

third_party/WebKit/Source/core/editing/iterators/BackwardsTextBufferTest.cpp

Index: third_party/WebKit/Source/core/editing/iterators/BackwardsTextBufferTest.cpp
diff --git a/third_party/WebKit/Source/core/editing/iterators/BackwardsTextBufferTest.cpp b/third_party/WebKit/Source/core/editing/iterators/BackwardsTextBufferTest.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..0cfc08356582d752789c42b13e31dfdfbcdb87be
--- /dev/null
+++ b/third_party/WebKit/Source/core/editing/iterators/BackwardsTextBufferTest.cpp
@@ -0,0 +1,90 @@
+// 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.
+
+#include "core/editing/iterators/BackwardsTextBuffer.h"
+
+#include "core/editing/EditingTestBase.h"
+
+namespace blink {
+
+class BackwardsTextBufferTest : public EditingTestBase {
+};
+
+TEST_F(BackwardsTextBufferTest, pushCharacters)
+{
+    const unsigned numPush = 16;
+    unsigned lengths[numPush];
+    UChar chars[numPush];
+    for (unsigned i = 0; i < numPush; i++) {
+        lengths[i] = 1 << i;
+        chars[i] = 'a' + i;
+    }
+
+    BackwardsTextBuffer buffer;
+    for (unsigned i = 0; i < numPush; i++) {
+        buffer.pushCharacters(chars[i], lengths[i]);
+        unsigned accumulatedLength = 0;
+        for (unsigned j = i + 1; j; --j) {
+            for (unsigned k = 0; k < lengths[j - 1]; ++k)
+                EXPECT_EQ(chars[j - 1], buffer[accumulatedLength + k]);
+            accumulatedLength += lengths[j - 1];
+        }
+    }
+}
+
+TEST_F(BackwardsTextBufferTest, pushRange)
+{
+    const unsigned numPush = 16;
+    Vector<UChar> ranges[numPush];
+    for (unsigned i = 0; i < numPush; ++i)
+        ranges[i].fill('a' + i, 1 << i);
+
+    BackwardsTextBuffer buffer;
+    for (unsigned i = 0; i < numPush; ++i) {
+        buffer.pushRange(ranges[i].data(), ranges[i].size());
+        unsigned accumulatedLength = 0;
+        for (unsigned j = i + 1; j; --j) {
+            for (unsigned k = 0; k < ranges[j - 1].size(); ++k)
+                EXPECT_EQ(ranges[j - 1][k], buffer[accumulatedLength + k]);
+            accumulatedLength += ranges[j - 1].size();
+        }
+    }
+}
+
+TEST_F(BackwardsTextBufferTest, pushMixed)
+{
+    const unsigned numPush = 16;
+    unsigned lengths[numPush];
+    Vector<UChar> ranges[numPush];
+    UChar chars[numPush];
+    bool pushRange[numPush];
+    for (unsigned i = 0; i < numPush; ++i) {
+        lengths[i] = 1 << i;
+        pushRange[i] = (i % 2 == 0);
+        if (pushRange[i])
+            ranges[i].fill('a' + i, lengths[i]);
+        else
+            chars[i] = 'a' + i;
+    }
+
+    BackwardsTextBuffer buffer;
+    for (unsigned i = 0; i < numPush; ++i) {
+        if (pushRange[i])
+            buffer.pushRange(ranges[i].data(), lengths[i]);
+        else
+            buffer.pushCharacters(chars[i], lengths[i]);
+        unsigned accumulatedLength = 0;
+        for (unsigned j = i + 1; j; --j) {
+            for (unsigned k = 0; k < lengths[j - 1]; ++k) {
+                if (pushRange[j - 1])
+                    EXPECT_EQ(ranges[j - 1][k], buffer[accumulatedLength + k]);
+                else
+                    EXPECT_EQ(chars[j - 1], buffer[accumulatedLength + k]);
+            }
+            accumulatedLength += lengths[j - 1];
+        }
+    }
+}
+
+} // namespace blink