java.util.regex.Grapheme Maven / Gradle / Ivy
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package java.util.regex;
import java.util.Objects;
final class Grapheme {
/**
* Look for the next extended grapheme cluster boundary in a CharSequence.
* It assumes the start of the char sequence at offset {@code off} is a boundary.
*
* See Unicode Standard Annex #29 Unicode Text Segmentation for the specification
* for the extended grapheme cluster boundary rules. The following implementation
* is based on version 12.0 of the annex.
* (http://www.unicode.org/reports/tr29/tr29-35.html)
*
* @param src the {@code CharSequence} to be scanned
* @param off offset to start looking for the next boundary in the src
* @param limit limit offset in the src (exclusive)
* @return the next grapheme boundary
*/
static int nextBoundary(CharSequence src, int off, int limit) {
Objects.checkFromToIndex(off, limit, src.length());
int ch0 = Character.codePointAt(src, off);
int ret = off + Character.charCount(ch0);
// indicates whether gb11 or gb12 is underway
int t0 = getType(ch0);
int riCount = t0 == RI ? 1 : 0;
boolean gb11 = t0 == EXTENDED_PICTOGRAPHIC;
while (ret < limit) {
int ch1 = Character.codePointAt(src, ret);
int t1 = getType(ch1);
if (gb11 && t0 == ZWJ && t1 == EXTENDED_PICTOGRAPHIC) {
// continue for gb11
} else if (riCount % 2 == 1 && t0 == RI && t1 == RI) {
// continue for gb12
} else if (rules[t0][t1]) {
if (ret > off) {
break;
} else {
gb11 = t1 == EXTENDED_PICTOGRAPHIC;
riCount = 0;
}
}
riCount += (t1 == RI) ? 1 : 0;
t0 = t1;
ret += Character.charCount(ch1);
}
return ret;
}
// types
private static final int OTHER = 0;
private static final int CR = 1;
private static final int LF = 2;
private static final int CONTROL = 3;
private static final int EXTEND = 4;
private static final int ZWJ = 5;
private static final int RI = 6;
private static final int PREPEND = 7;
private static final int SPACINGMARK = 8;
private static final int L = 9;
private static final int V = 10;
private static final int T = 11;
private static final int LV = 12;
private static final int LVT = 13;
private static final int EXTENDED_PICTOGRAPHIC = 14;
private static final int FIRST_TYPE = 0;
private static final int LAST_TYPE = 14;
private static boolean[][] rules;
static {
rules = new boolean[LAST_TYPE + 1][LAST_TYPE + 1];
// GB 999 Any + Any -> default
for (int i = FIRST_TYPE; i <= LAST_TYPE; i++)
for (int j = FIRST_TYPE; j <= LAST_TYPE; j++)
rules[i][j] = true;
// GB 6 L x (L | V | LV | VT)
rules[L][L] = false;
rules[L][V] = false;
rules[L][LV] = false;
rules[L][LVT] = false;
// GB 7 (LV | V) x (V | T)
rules[LV][V] = false;
rules[LV][T] = false;
rules[V][V] = false;
rules[V][T] = false;
// GB 8 (LVT | T) x T
rules[LVT][T] = false;
rules[T][T] = false;
// GB 9 x (Extend|ZWJ)
// GB 9a x Spacing Mark
// GB 9b Prepend x
for (int i = FIRST_TYPE; i <= LAST_TYPE; i++) {
rules[i][EXTEND] = false;
rules[i][ZWJ] = false;
rules[i][SPACINGMARK] = false;
rules[PREPEND][i] = false;
}
// GB 4 (Control | CR | LF) +
// GB 5 + (Control | CR | LF)
for (int i = FIRST_TYPE; i <= LAST_TYPE; i++)
for (int j = CR; j <= CONTROL; j++) {
rules[i][j] = true;
rules[j][i] = true;
}
// GB 3 CR x LF
rules[CR][LF] = false;
// GB 11 Exended_Pictographic x (Extend|ZWJ)
rules[EXTENDED_PICTOGRAPHIC][EXTEND] = false;
rules[EXTENDED_PICTOGRAPHIC][ZWJ] = false;
}
// Hangul syllables
private static final int SYLLABLE_BASE = 0xAC00;
private static final int LCOUNT = 19;
private static final int VCOUNT = 21;
private static final int TCOUNT = 28;
private static final int NCOUNT = VCOUNT * TCOUNT; // 588
private static final int SCOUNT = LCOUNT * NCOUNT; // 11172
// #tr29: SpacingMark exceptions: The following (which have
// General_Category = Spacing_Mark and would otherwise be included)
// are specifically excluded
private static boolean isExcludedSpacingMark(int cp) {
return cp == 0x102B || cp == 0x102C || cp == 0x1038 ||
cp >= 0x1062 && cp <= 0x1064 ||
cp >= 0x1062 && cp <= 0x106D ||
cp == 0x1083 ||
cp >= 0x1087 && cp <= 0x108C ||
cp == 0x108F ||
cp >= 0x109A && cp <= 0x109C ||
cp == 0x1A61 || cp == 0x1A63 || cp == 0x1A64 ||
cp == 0xAA7B || cp == 0xAA7D;
}
@SuppressWarnings("fallthrough")
private static int getType(int cp) {
if (cp < 0x007F) { // ASCII
if (cp < 32) { // Control characters
if (cp == 0x000D)
return CR;
if (cp == 0x000A)
return LF;
return CONTROL;
}
return OTHER;
}
if (EmojiData.isExtendedPictographic(cp)) {
return EXTENDED_PICTOGRAPHIC;
}
int type = Character.getType(cp);
switch(type) {
case Character.UNASSIGNED:
// NOTE: #tr29 lists "Unassigned and Default_Ignorable_Code_Point" as Control
// but GraphemeBreakTest.txt lists u+0378/reserved-0378 as "Other"
// so type it as "Other" to make the test happy
if (cp == 0x0378)
return OTHER;
case Character.CONTROL:
case Character.LINE_SEPARATOR:
case Character.PARAGRAPH_SEPARATOR:
case Character.SURROGATE:
return CONTROL;
case Character.FORMAT:
if (cp == 0x200C ||
cp >= 0xE0020 && cp <= 0xE007F)
return EXTEND;
if (cp == 0x200D)
return ZWJ;
if (cp >= 0x0600 && cp <= 0x0605 ||
cp == 0x06DD || cp == 0x070F || cp == 0x08E2 ||
cp == 0x110BD || cp == 0x110CD)
return PREPEND;
return CONTROL;
case Character.NON_SPACING_MARK:
case Character.ENCLOSING_MARK:
// NOTE:
// #tr29 "plus a few General_Category = Spacing_Mark needed for
// canonical equivalence."
// but for "extended grapheme clusters" support, there is no
// need actually to diff "extend" and "spackmark" given GB9, GB9a
return EXTEND;
case Character.COMBINING_SPACING_MARK:
if (isExcludedSpacingMark(cp))
return OTHER;
// NOTE:
// 0x11720 and 0x11721 are mentioned in #tr29 as
// OTHER_LETTER but it appears their category has been updated to
// COMBING_SPACING_MARK already (verified in ver.8)
return SPACINGMARK;
case Character.OTHER_SYMBOL:
if (cp >= 0x1F1E6 && cp <= 0x1F1FF)
return RI;
return OTHER;
case Character.MODIFIER_LETTER:
case Character.MODIFIER_SYMBOL:
// WARNING:
// not mentioned in #tr29 but listed in GraphemeBreakProperty.txt
if (cp == 0xFF9E || cp == 0xFF9F ||
cp >= 0x1F3FB && cp <= 0x1F3FF)
return EXTEND;
return OTHER;
case Character.OTHER_LETTER:
if (cp == 0x0E33 || cp == 0x0EB3)
return SPACINGMARK;
// hangul jamo
if (cp >= 0x1100 && cp <= 0x11FF) {
if (cp <= 0x115F)
return L;
if (cp <= 0x11A7)
return V;
return T;
}
// hangul syllables
int sindex = cp - SYLLABLE_BASE;
if (sindex >= 0 && sindex < SCOUNT) {
if (sindex % TCOUNT == 0)
return LV;
return LVT;
}
// hangul jamo_extended A
if (cp >= 0xA960 && cp <= 0xA97C)
return L;
// hangul jamo_extended B
if (cp >= 0xD7B0 && cp <= 0xD7C6)
return V;
if (cp >= 0xD7CB && cp <= 0xD7FB)
return T;
// Prepend
switch (cp) {
case 0x0D4E:
case 0x111C2:
case 0x111C3:
case 0x1193F:
case 0x11941:
case 0x11A3A:
case 0x11A84:
case 0x11A85:
case 0x11A86:
case 0x11A87:
case 0x11A88:
case 0x11A89:
case 0x11D46:
return PREPEND;
}
}
return OTHER;
}
}