Introduce Character::IsBidiControl()

This patch introduces a utility function to check if a unicode character
is a bidi control character defined in UAX9:

http://unicode.org/reports/tr9/#Directional_Formatting_Characters

This is also preparation for crrev.com/c/1039145

Bug: 822575
Change-Id: I6a011f7fc871c3508c811c41cb21208139fa71cd
Reviewed-on: https://chromium-review.googlesource.com/1040648Reviewed-by: Emil A Eklund <eae@chromium.org>
Commit-Queue: Emil A Eklund <eae@chromium.org>
Cr-Commit-Position: refs/heads/master@{#555588}

third_party/blink/renderer/platform/text/character.cc

@@ -118,6 +118,10 @@ bool Character::IsPotentialCustomElementNameChar(UChar32 character) {
   RETURN_HAS_PROPERTY(character, kIsPotentialCustomElementNameChar);
 }
 
+bool Character::IsBidiControl(UChar32 character) {
+  RETURN_HAS_PROPERTY(character, kIsBidiControl);
+}
+
 unsigned Character::ExpansionOpportunityCount(const LChar* characters,
                                               size_t length,
                                               TextDirection direction,

third_party/blink/renderer/platform/text/character.h

@@ -102,6 +102,9 @@ class PLATFORM_EXPORT Character {
   }
   static bool IsPotentialCustomElementNameChar(UChar32 character);
 
+  // http://unicode.org/reports/tr9/#Directional_Formatting_Characters
+  static bool IsBidiControl(UChar32 character);
+
   static bool TreatAsSpace(UChar32 c) {
     return c == kSpaceCharacter || c == kTabulationCharacter ||
            c == kNewlineCharacter || c == kNoBreakSpaceCharacter;

third_party/blink/renderer/platform/text/character_property.h

@@ -15,6 +15,7 @@ enum class CharacterProperty : CharacterPropertyType {
   kIsCJKIdeographOrSymbol = 0x0001,
   kIsUprightInMixedVertical = 0x0002,
   kIsPotentialCustomElementNameChar = 0x0004,
+  kIsBidiControl = 0x0008,
 };
 
 inline CharacterProperty operator|(CharacterProperty a, CharacterProperty b) {

third_party/blink/renderer/platform/text/character_property_data_generator.cc

@@ -81,6 +81,7 @@ static void Generate(FILE* fp) {
   SET(kIsCJKIdeographOrSymbol);
   SET(kIsUprightInMixedVertical);
   SET(kIsPotentialCustomElementNameChar);
+  SET(kIsBidiControl);
 
   // Create a trie from the value array.
   UErrorCode error = U_ZERO_ERROR;

third_party/blink/renderer/platform/text/character_property_data_generator.h

@@ -223,6 +223,13 @@ static const UChar32 kIsPotentialCustomElementNameCharRanges[] = {
     0xF900, 0xFDCF, 0xFDF0, 0xFFFD, 0x10000, 0xEFFFF,
 };
 
+// http://unicode.org/reports/tr9/#Directional_Formatting_Characters
+static const UChar32 kIsBidiControlArray[] = {0x061C, 0x200E, 0x200F};
+
+static const UChar32 kIsBidiControlRanges[] = {
+    0x202A, 0x202E, 0x2066, 0x2069,
+};
+
 }  // namespace blink
 
 #endif

third_party/blink/renderer/platform/text/character_test.cc

@@ -331,4 +331,22 @@ TEST(CharacterTest, Truncation) {
   EXPECT_FALSE(Character::IsNormalizedCanvasSpaceCharacter(test_char));
 }
 
+TEST(CharacterTest, IsBidiControl) {
+  EXPECT_TRUE(Character::IsBidiControl(0x202A));  // LEFT-TO-RIGHT EMBEDDING
+  EXPECT_TRUE(Character::IsBidiControl(0x202B));  // RIGHT-TO-LEFT EMBEDDING
+  EXPECT_TRUE(Character::IsBidiControl(0x202D));  // LEFT-TO-RIGHT OVERRIDE
+  EXPECT_TRUE(Character::IsBidiControl(0x202E));  // RIGHT-TO-LEFT OVERRIDE
+  EXPECT_TRUE(Character::IsBidiControl(0x202C));  // POP DIRECTIONAL FORMATTING
+  EXPECT_TRUE(Character::IsBidiControl(0x2066));  // LEFT-TO-RIGHT ISOLATE
+  EXPECT_TRUE(Character::IsBidiControl(0x2067));  // RIGHT-TO-LEFT ISOLATE
+  EXPECT_TRUE(Character::IsBidiControl(0x2068));  // FIRST STRONG ISOLATE
+  EXPECT_TRUE(Character::IsBidiControl(0x2069));  // POP DIRECTIONAL ISOLATE
+  EXPECT_TRUE(Character::IsBidiControl(0x200E));  // LEFT-TO-RIGHT MARK
+  EXPECT_TRUE(Character::IsBidiControl(0x200F));  // RIGHT-TO-LEFT MARK
+  EXPECT_TRUE(Character::IsBidiControl(0x061C));  // ARABIC LETTER MARK
+  EXPECT_FALSE(Character::IsBidiControl('A'));
+  EXPECT_FALSE(Character::IsBidiControl('0'));
+  EXPECT_FALSE(Character::IsBidiControl(0x05D0));
+}
+
 }  // namespace blink