Introduce ForwardCodePointStateMachine to traverse chars in code points

third_party/WebKit/Source/core/editing/state_machines/ForwardCodePointStateMachineTest.cpp

+// Copyright 2017 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/state_machines/ForwardCodePointStateMachine.h"
+
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace blink {
+
+namespace {
+const TextSegmentationMachineState kInvalid =
+    TextSegmentationMachineState::Invalid;
+const TextSegmentationMachineState kNeedMoreCodeUnit =
+    TextSegmentationMachineState::NeedMoreCodeUnit;
+const TextSegmentationMachineState kFinished =
+    TextSegmentationMachineState::Finished;
+}  // namespace
+
+TEST(ForwardCodePointStateMachineTest, DoNothingCase) {
+  ForwardCodePointStateMachine machine;
+  EXPECT_EQ(0, machine.getBoundaryOffset());
+}
+
+TEST(ForwardCodePointStateMachineTest, SingleCharacter) {
+  ForwardCodePointStateMachine machine;
+  EXPECT_EQ(kFinished, machine.feedFollowingCodeUnit('a'));
+  EXPECT_EQ(1, machine.getBoundaryOffset());
+
+  machine.reset();
+  EXPECT_EQ(kFinished, machine.feedFollowingCodeUnit('-'));
+  EXPECT_EQ(1, machine.getBoundaryOffset());
+
+  machine.reset();
+  EXPECT_EQ(kFinished, machine.feedFollowingCodeUnit('\t'));
+  EXPECT_EQ(1, machine.getBoundaryOffset());
+
+  machine.reset();
+  // U+3042 HIRAGANA LETTER A.
+  EXPECT_EQ(kFinished, machine.feedFollowingCodeUnit(0x3042));
+  EXPECT_EQ(1, machine.getBoundaryOffset());
+}
+
+TEST(ForwardCodePointStateMachineTest, SurrogatePair) {
+  ForwardCodePointStateMachine machine;
+
+  // U+20BB7 is \uD83D\uDDFA in UTF-16.
+  const UChar leadSurrogate = 0xD842;
+  const UChar trailSurrogate = 0xDFB7;
+
+  EXPECT_EQ(kNeedMoreCodeUnit, machine.feedFollowingCodeUnit(leadSurrogate));
+  EXPECT_EQ(kFinished, machine.feedFollowingCodeUnit(trailSurrogate));
+  EXPECT_EQ(2, machine.getBoundaryOffset());
+
+  // Edge cases
+  // Unpaired leading surrogate. Nothing to delete.
+  machine.reset();
+  EXPECT_EQ(kNeedMoreCodeUnit, machine.feedFollowingCodeUnit(leadSurrogate));
+  EXPECT_EQ(kInvalid, machine.feedFollowingCodeUnit('a'));
+  EXPECT_EQ(0, machine.getBoundaryOffset());
+
+  machine.reset();
+  EXPECT_EQ(kNeedMoreCodeUnit, machine.feedFollowingCodeUnit(leadSurrogate));
+  EXPECT_EQ(kInvalid, machine.feedFollowingCodeUnit(leadSurrogate));
+  EXPECT_EQ(0, machine.getBoundaryOffset());
+
+  // Unpaired trailing surrogate. Nothing to delete.
+  machine.reset();
+  EXPECT_EQ(kInvalid, machine.feedFollowingCodeUnit(trailSurrogate));
+  EXPECT_EQ(0, machine.getBoundaryOffset());
+}
+
+}  // namespace blink