Introduce ForwardsTextBuffer and BackwardsTextBuffer

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

Index: third_party/WebKit/Source/core/editing/iterators/ForwardsTextBufferTest.cpp
diff --git a/third_party/WebKit/Source/core/editing/iterators/ForwardsTextBufferTest.cpp b/third_party/WebKit/Source/core/editing/iterators/ForwardsTextBufferTest.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..064d7d10465636d9ba25f30158b0186a69b4a5dc
--- /dev/null
+++ b/third_party/WebKit/Source/core/editing/iterators/ForwardsTextBufferTest.cpp
@@ -0,0 +1,89 @@
+// 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/ForwardsTextBuffer.h"
+
+#include "core/editing/EditingTestBase.h"
+
+namespace blink {
+
+class ForwardsTextBufferTest : public EditingTestBase {
+};
+
+TEST_F(ForwardsTextBufferTest, pushCharacters)
+{
+    const unsigned numPush = 16;

[yosin_UTC9, 2016/02/01 03:40:55]

This test seems to be complex.
Can we make simpler test?

For example:

ForwardsTextBuffer buffer;
buffer.pushCahracters("abc", 3);
buffer.pushCharacters("d", 1);
buffer.pushCharacters(nullptr, 0);
buffer.pushCharacters("\0", 1);

EXPECT_FALSE(buffer.isEmpty());
EXPECT_EQ(5, buffer.size());
EXPECT_EQ("abcd", buffer.data());
EXPECT_EQ('a', buffer[0]);
EXPECT_EQ('d', buffer[3]);
EXPECT_EQ('\0', buffer[4]);

[Xiaocheng, 2016/02/01 04:36:24]

I'll see if the tests can be simplified. Maybe I should also add some test for
edge cases as you implied.

However, I may still need some test cases with larger amount of data, because we
need to ensure that the correctness under buffer reallocation is tested.

+    unsigned lengths[numPush];
+    UChar chars[numPush];
+    for (unsigned i = 0; i < numPush; ++i) {
+        lengths[i] = 1 << i;
+        chars[i] = 'a' + i;
+    }
+
+    ForwardsTextBuffer buffer;
+    for (unsigned i = 0; i < numPush; ++i) {
+        buffer.pushCharacters(chars[i], lengths[i]);
+        unsigned accumulatedLength = 0;
+        for (unsigned j = 0; j <= i; ++j) {
+            for (unsigned k = 0; k < lengths[j]; ++k)
+                EXPECT_EQ(chars[j], buffer[accumulatedLength + k]);
+            accumulatedLength += lengths[j];
+        }
+    }
+}
+
+TEST_F(ForwardsTextBufferTest, pushRange)
+{
+    const unsigned numPush = 16;
+    Vector<UChar> ranges[numPush];
+    for (unsigned i = 0; i < numPush; ++i)
+        ranges[i].fill('a' + i, 1 << i);
+
+    ForwardsTextBuffer buffer;
+    for (unsigned i = 0; i < numPush; ++i) {
+        buffer.pushRange(ranges[i].data(), ranges[i].size());
+        unsigned accumulatedLength = 0;
+        for (unsigned j = 0; j <= i; ++j) {
+            for (unsigned k = 0; k < ranges[j].size(); ++k)
+                EXPECT_EQ(ranges[j][k], buffer[accumulatedLength + k]);
+            accumulatedLength += ranges[j].size();
+        }
+    }
+}
+
+TEST_F(ForwardsTextBufferTest, 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;
+    }
+
+    ForwardsTextBuffer 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 = 0; j <= i; ++j) {
+            for (unsigned k = 0; k < lengths[j]; ++k) {
+                if (pushRange[j])
+                    EXPECT_EQ(ranges[j][k], buffer[accumulatedLength + k]);
+                else
+                    EXPECT_EQ(chars[j], buffer[accumulatedLength + k]);
+            }
+            accumulatedLength += lengths[j];
+        }
+    }
+}
+} // namespace blink