Introduce IsGraphemeBreak function.

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

Index: third_party/WebKit/Source/core/editing/state_machines/StateMachineUtil.cpp
diff --git a/third_party/WebKit/Source/core/editing/state_machines/StateMachineUtil.cpp b/third_party/WebKit/Source/core/editing/state_machines/StateMachineUtil.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..fe3a4d0cfcded852f24714400f5c3025118c5b35
--- /dev/null
+++ b/third_party/WebKit/Source/core/editing/state_machines/StateMachineUtil.cpp
@@ -0,0 +1,140 @@
+// 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/state_machines/StateMachineUtil.h"
+
+#include "platform/fonts/Character.h"
+#include "wtf/Assertions.h"
+#include "wtf/text/CharacterNames.h"
+#include "wtf/text/Unicode.h"
+
+namespace blink {
+
+namespace {
+
+// Returns true if the code point has Glue_After_Zwj grapheme break property.
+// See http://www.unicode.org/Public/9.0.0/ucd/auxiliary/GraphemeBreakProperty-9.0.0d18.txt
+bool isGlueAfterZwj(uint32_t codePoint)
+{
+    return codePoint == WTF::Unicode::heavyBlackHeartCharacter
+        || codePoint == WTF::Unicode::kissMarkCharacter
+        || codePoint == WTF::Unicode::leftSpeechBubbleCharacter;
+}
+
+// Returns true if the code point has E_Basae_GAZ grapheme break property.
+// See http://www.unicode.org/Public/9.0.0/ucd/auxiliary/GraphemeBreakProperty-9.0.0d18.txt
+bool isEBaseGAZ(uint32_t codePoint)
+{
+    return codePoint == WTF::Unicode::boyCharacter
+        || codePoint == WTF::Unicode::girlCharacter
+        || codePoint == WTF::Unicode::manCharacter
+        || codePoint == WTF::Unicode::womanCharacter;
+}
+
+// The list of code points which has Indic_Syllabic_Category=Virama property.
+// Must be sorted.
+// See http://www.unicode.org/Public/9.0.0/ucd/IndicSyllabicCategory-9.0.0d2.txt
+const uint32_t kIndicSyllabicCategoryViramaList[] = {
+    0x094D, 0x09CD, 0x0A4D, 0x0ACD, 0x0B4D, 0x0BCD, 0x0C4D, 0x0CCD, 0x0D4D,
+    0x0DCA, 0x1B44, 0xA8C4, 0xA9C0, 0x11046, 0x110B9, 0x111C0, 0x11235, 0x1134D,
+    0x11442, 0x114C2, 0x115BF, 0x1163F, 0x116B6, 0x11C3F,
+};
+
+// Returns true if the code point has Indic_Syllabic_Category=Virama property.
+// See http://www.unicode.org/Public/9.0.0/ucd/IndicSyllabicCategory-9.0.0d2.txt
+bool isIndicSyllabicCategoryVirama(uint32_t codePoint)
+{
+    const int length = WTF_ARRAY_LENGTH(kIndicSyllabicCategoryViramaList);
+    return std::binary_search(kIndicSyllabicCategoryViramaList,
+        kIndicSyllabicCategoryViramaList + length,
+        codePoint);
+}
+
+} // namespace
+
+bool isGraphemeBreak(UChar32 prevCodePoint, UChar32 nextCodePoint)
+{
+    // The following breaking rules come from Unicode Standard Annex #29 on
+    // Unicode Text Segmaentation. See http://www.unicode.org/reports/tr29/
+    // Note that some of rules are in proposal.
+    // Also see http://www.unicode.org/reports/tr29/proposed.html
+    int prevProp =
+        u_getIntPropertyValue(prevCodePoint, UCHAR_GRAPHEME_CLUSTER_BREAK);
+    int nextProp =
+        u_getIntPropertyValue(nextCodePoint, UCHAR_GRAPHEME_CLUSTER_BREAK);
+
+    // Rule1 GB1 sot ÷
+    // Rule2 GB2 ÷ eot
+    // Should be handled by caller.
+
+    // Rule GB3, CR x LF
+    if (prevProp == U_GCB_CR && nextProp == U_GCB_LF)
+        return false;
+
+    // Rule GB4, (Control | CR | LF) ÷
+    if (prevProp == U_GCB_CONTROL || prevProp == U_GCB_CR
+        || prevProp == U_GCB_LF)
+        return true;
+
+    // Rule GB5, ÷ (Control | CR | LF)
+    if (nextProp == U_GCB_CONTROL || nextProp == U_GCB_CR
+        || nextProp == U_GCB_LF)
+        return true;
+
+    // Rule GB6, L x (L | V | LV | LVT)
+    if (prevProp == U_GCB_L
+        && (nextProp == U_GCB_L || nextProp == U_GCB_V || nextProp == U_GCB_LV
+            || nextProp == U_GCB_LVT))
+        return false;
+
+    // Rule GB7, (LV | V) x (V | T)
+    if ((prevProp == U_GCB_LV || prevProp == U_GCB_V)
+        && (nextProp == U_GCB_V || nextProp == U_GCB_T))
+        return false;
+
+    // Rule GB8, (LVT | T) x T
+    if ((prevProp == U_GCB_LVT || prevProp == U_GCB_T) && nextProp == U_GCB_T)
+        return false;
+
+    // Rule GB8a
+    //
+    // sot   (RI RI)* RI x RI
+    // [^RI] (RI RI)* RI x RI
+    //                RI ÷ RI
+    if (Character::isRegionalIndicator(prevCodePoint)
+        && Character::isRegionalIndicator(nextCodePoint))
+        NOTREACHED() << "Do not use this function for regional indicators.";
+
+    // Rule GB9, x (Extend | ZWJ)
+    // Rule GB9a, x SpacingMark
+    if (nextProp == U_GCB_EXTEND || nextCodePoint == zeroWidthJoinerCharacter
+        || nextProp == U_GCB_SPACING_MARK)
+        return false;
+
+    // Rule GB9b, Prepend x
+    if (prevProp == U_GCB_PREPEND)
+        return false;
+
+    // Cluster Indic syllables together.
+    if (isIndicSyllabicCategoryVirama(prevCodePoint)
+        && u_getIntPropertyValue(nextCodePoint,
+            UCHAR_GENERAL_CATEGORY) == U_OTHER_LETTER)
+        return false;
+
+    // Proposed Rule GB10, (E_Base | EBG) x E_Modifier
+    if ((Character::isEmojiModifierBase(prevCodePoint)
+        || isEBaseGAZ(prevCodePoint))
+        && Character::isModifier(nextCodePoint))
+        return false;
+
+    // Proposed Rule GB11, ZWJ x (Glue_After_Zwj | EBG)
+    if (prevCodePoint == zeroWidthJoinerCharacter
+        && (isGlueAfterZwj(nextCodePoint) || isEBaseGAZ(nextCodePoint)))
+        return false;
+
+    // Rule GB999 any ÷ any
+    return true;
+}
+
+} // namespace blink