Unicode line breaking: Implement rules LB15a and LB15b

The new rules were added in Unicode 15.1 (TR #14, revision 51).

The rules read:

    LB15a: (sot | BK | CR | LF | NL | OP | QU | GL | SP | ZW)
           [\p{Pi}&QU] SP* ×
    LB15b: × [\p{Pf}&QU] (SP | GL | WJ | CL | QU | CP | EX
           | IS | SY | BK | CR | LF | NL | ZW | eot)

Add two new line breaking classes LineBreak_QU_Pi and _QU_Pf to
represent quotation characters with context that matches left
side of LB15a and right side of LB15b respectively. This way
it is still possible to use the line breaking classes table.

Also add a coment about the original source of the line
break table.

Task-number: QTBUG-121529
Change-Id: Ib35f400e39e76819cd1c3299691f7b040ea37178
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

1 files changed, 93 insertions, 34 deletions

diff --git a/src/corelib/text/qunicodetools.cpp b/src/corelib/text/qunicodetools.cpp
index 59cf6f7634..f381923854 100644
--- a/src/corelib/text/qunicodetools.cpp
+++ b/src/corelib/text/qunicodetools.cpp
@@ -559,45 +559,49 @@ enum Action {
     IndirectBreakIfNarrow, IN = IndirectBreakIfNarrow, // For LB30
 };
 
+// See https://www.unicode.org/reports/tr14/tr14-37.html for the information
+// about the table. It was removed in the later versions of the standard.
 static const uchar breakTable[QUnicodeTables::LineBreak_ZWJ][QUnicodeTables::LineBreak_ZWJ] = {
-/*         OP  CL  CP  QU  GL  NS  EX  SY  IS  PR  PO  NU  AL  HL  ID  IN  HY  BA  BB  B2  ZW  CM  WJ  H2  H3  JL  JV  JT  RI  CB  EB  EM*/
-/* OP */ { PB, PB, PB, PB, PB, PB, PB, PB, PB, PB, PB, PB, PB, PB, PB, PB, PB, PB, PB, PB, PB, CP, PB, PB, PB, PB, PB, PB, PB, PB, PB, PB },
-/* CL */ { DB, PB, PB, IB, IB, PB, PB, PB, PB, DB, DB, DB, DB, DB, DB, IB, IB, IB, DB, DB, PB, CI, PB, DB, DB, DB, DB, DB, DB, DB, DB, DB },
-/* CP */ { DB, PB, PB, IB, IB, PB, PB, PB, PB, DB, DB, IB, IB, IB, DB, IB, IB, IB, DB, DB, PB, CI, PB, DB, DB, DB, DB, DB, DB, DB, DB, DB },
-/* QU */ { PB, PB, PB, IB, IB, IB, PB, PB, PB, IB, IB, IB, IB, IB, IB, IB, IB, IB, IB, IB, PB, CI, PB, IB, IB, IB, IB, IB, IB, IB, IB, IB },
-/* GL */ { IB, PB, PB, IB, IB, IB, PB, PB, PB, IB, IB, IB, IB, IB, IB, IB, IB, IB, IB, IB, PB, CI, PB, IB, IB, IB, IB, IB, IB, IB, IB, IB },
-/* NS */ { DB, PB, PB, IB, IB, IB, PB, PB, PB, DB, DB, DB, DB, DB, DB, IB, IB, IB, DB, DB, PB, CI, PB, DB, DB, DB, DB, DB, DB, DB, DB, DB },
-/* EX */ { DB, PB, PB, IB, IB, IB, PB, PB, PB, DB, DB, DB, DB, DB, DB, IB, IB, IB, DB, DB, PB, CI, PB, DB, DB, DB, DB, DB, DB, DB, DB, DB },
-/* SY */ { DB, PB, PB, IB, IB, IB, PB, PB, PB, DB, DB, DB, DB, IB, DB, IB, IB, IB, DB, DB, PB, CI, PB, DB, DB, DB, DB, DB, DB, DB, DB, DB },
-/* IS */ { DB, PB, PB, IB, IB, IB, PB, PB, PB, DB, DB, DB, IB, IB, DB, IB, IB, IB, DB, DB, PB, CI, PB, DB, DB, DB, DB, DB, DB, DB, DB, DB },
-/* PR */ { DB, PB, PB, IB, IB, IB, PB, PB, PB, DB, DB, IB, IB, IB, IB, IB, IB, IB, DB, DB, PB, CI, PB, IB, IB, IB, IB, IB, DB, DB, IB, IB },
-/* PO */ { DB, PB, PB, IB, IB, IB, PB, PB, PB, DB, DB, IB, IB, IB, DB, IB, IB, IB, DB, DB, PB, CI, PB, DB, DB, DB, DB, DB, DB, DB, DB, DB },
-/* NU */ { IN, PB, PB, IB, IB, IB, PB, PB, PB, IB, IB, IB, IB, IB, DB, IB, IB, IB, DB, DB, PB, CI, PB, DB, DB, DB, DB, DB, DB, DB, DB, DB },
-/* AL */ { IN, PB, PB, IB, IB, IB, PB, PB, PB, IB, IB, IB, IB, IB, DB, IB, IB, IB, DB, DB, PB, CI, PB, DB, DB, DB, DB, DB, DB, DB, DB, DB },
-/* HL */ { IN, PB, PB, IB, IB, IB, PB, PB, PB, IB, IB, IB, IB, IB, DB, IB, CI, CI, DB, DB, PB, CI, PB, DB, DB, DB, DB, DB, DB, DB, DB, DB },
-/* ID */ { DB, PB, PB, IB, IB, IB, PB, PB, PB, DB, IB, DB, DB, DB, DB, IB, IB, IB, DB, DB, PB, CI, PB, DB, DB, DB, DB, DB, DB, DB, DB, DB },
-/* IN */ { DB, PB, PB, IB, IB, IB, PB, PB, PB, DB, DB, DB, DB, DB, DB, IB, IB, IB, DB, DB, PB, CI, PB, DB, DB, DB, DB, DB, DB, DB, DB, DB },
-/* HY */ { HH, PB, PB, IB, HH, IB, PB, PB, PB, HH, HH, IB, HH, HH, HH, IB, IB, IB, HH, HH, PB, CI, PB, HH, HH, HH, HH, HH, HH, DB, DB, DB },
-/* BA */ { HH, PB, PB, IB, HH, IB, PB, PB, PB, HH, HH, HH, HH, HH, HH, IB, IB, IB, HH, HH, PB, CI, PB, HH, HH, HH, HH, HH, HH, DB, DB, DB },
-/* BB */ { IB, PB, PB, IB, IB, IB, PB, PB, PB, IB, IB, IB, IB, IB, IB, IB, IB, IB, IB, IB, PB, CI, PB, IB, IB, IB, IB, IB, IB, DB, IB, IB },
-/* B2 */ { DB, PB, PB, IB, IB, IB, PB, PB, PB, DB, DB, DB, DB, DB, DB, IB, IB, IB, DB, PB, PB, CI, PB, DB, DB, DB, DB, DB, DB, DB, DB, DB },
-/* ZW */ { DB, DB, DB, DB, DB, DB, DB, DB, DB, DB, DB, DB, DB, DB, DB, DB, DB, DB, DB, DB, PB, DB, DB, DB, DB, DB, DB, DB, DB, DB, DB, DB },
-/* CM */ { IB, PB, PB, IB, IB, IB, PB, PB, PB, DB, DB, IB, IB, IB, DB, IB, IB, IB, DB, DB, PB, CI, PB, DB, DB, DB, DB, DB, DB, DB, DB, DB },
-/* WJ */ { IB, PB, PB, IB, IB, IB, PB, PB, PB, IB, IB, IB, IB, IB, IB, IB, IB, IB, IB, IB, PB, CI, PB, IB, IB, IB, IB, IB, IB, IB, IB, IB },
-/* H2 */ { DB, PB, PB, IB, IB, IB, PB, PB, PB, DB, IB, DB, DB, DB, DB, IB, IB, IB, DB, DB, PB, CI, PB, DB, DB, DB, IB, IB, DB, DB, DB, DB },
-/* H3 */ { DB, PB, PB, IB, IB, IB, PB, PB, PB, DB, IB, DB, DB, DB, DB, IB, IB, IB, DB, DB, PB, CI, PB, DB, DB, DB, DB, IB, DB, DB, DB, DB },
-/* JL */ { DB, PB, PB, IB, IB, IB, PB, PB, PB, DB, IB, DB, DB, DB, DB, IB, IB, IB, DB, DB, PB, CI, PB, IB, IB, IB, IB, DB, DB, DB, DB, DB },
-/* JV */ { DB, PB, PB, IB, IB, IB, PB, PB, PB, DB, IB, DB, DB, DB, DB, IB, IB, IB, DB, DB, PB, CI, PB, DB, DB, DB, IB, IB, DB, DB, DB, DB },
-/* JT */ { DB, PB, PB, IB, IB, IB, PB, PB, PB, DB, IB, DB, DB, DB, DB, IB, IB, IB, DB, DB, PB, CI, PB, DB, DB, DB, DB, IB, DB, DB, DB, DB },
-/* RI */ { DB, PB, PB, IB, IB, IB, PB, PB, PB, DB, DB, DB, DB, DB, DB, IB, IB, IB, DB, DB, PB, CI, PB, DB, DB, DB, DB, DB, IB, DB, DB, DB },
-/* CB */ { DB, PB, PB, IB, IB, DB, PB, PB, PB, DB, DB, DB, DB, DB, DB, DB, DB, DB, DB, DB, PB, CI, PB, DB, DB, DB, DB, DB, DB, DB, DB, DB },
-/* EB */ { DB, PB, PB, IB, IB, IB, PB, PB, PB, DB, IB, DB, DB, DB, DB, IB, IB, IB, DB, DB, PB, CI, PB, DB, DB, DB, DB, DB, DB, DB, DB, IB },
-/* EM */ { DB, PB, PB, IB, IB, IB, PB, PB, PB, DB, IB, DB, DB, DB, DB, IB, IB, IB, DB, DB, PB, CI, PB, DB, DB, DB, DB, DB, DB, DB, DB, DB },
+/* 1↓ 2→   OP  CL  CP  QU  +Pi +Pf GL  NS  EX  SY  IS  PR  PO  NU  AL  HL  ID  IN  HY  BA  BB  B2  ZW  CM  WJ  H2  H3  JL  JV  JT  RI  CB  EB  EM*/
+/* OP */ { PB, PB, PB, PB, PB, PB, PB, PB, PB, PB, PB, PB, PB, PB, PB, PB, PB, PB, PB, PB, PB, PB, PB, CP, PB, PB, PB, PB, PB, PB, PB, PB, PB, PB },
+/* CL */ { DB, PB, PB, IB, IB, PB, IB, PB, PB, PB, PB, DB, DB, DB, DB, DB, DB, IB, IB, IB, DB, DB, PB, CI, PB, DB, DB, DB, DB, DB, DB, DB, DB, DB },
+/* CP */ { DB, PB, PB, IB, IB, PB, IB, PB, PB, PB, PB, DB, DB, IB, IB, IB, DB, IB, IB, IB, DB, DB, PB, CI, PB, DB, DB, DB, DB, DB, DB, DB, DB, DB },
+/* QU */ { IB, PB, PB, IB, IB, PB, IB, IB, PB, PB, PB, IB, IB, IB, IB, IB, IB, IB, IB, IB, IB, IB, PB, CI, PB, IB, IB, IB, IB, IB, IB, IB, IB, IB },
+/* +Pi*/ { PB, PB, PB, PB, PB, PB, PB, PB, PB, PB, PB, PB, PB, PB, PB, PB, PB, PB, PB, PB, PB, PB, PB, CP, PB, PB, PB, PB, PB, PB, PB, PB, PB, PB },
+/* +Pf*/ { IB, PB, PB, IB, IB, PB, IB, IB, PB, PB, PB, IB, IB, IB, IB, IB, IB, IB, IB, IB, IB, IB, PB, CI, PB, IB, IB, IB, IB, IB, IB, IB, IB, IB },
+/* GL */ { IB, PB, PB, IB, IB, PB, IB, IB, PB, PB, PB, IB, IB, IB, IB, IB, IB, IB, IB, IB, IB, IB, PB, CI, PB, IB, IB, IB, IB, IB, IB, IB, IB, IB },
+/* NS */ { DB, PB, PB, IB, IB, PB, IB, IB, PB, PB, PB, DB, DB, DB, DB, DB, DB, IB, IB, IB, DB, DB, PB, CI, PB, DB, DB, DB, DB, DB, DB, DB, DB, DB },
+/* EX */ { DB, PB, PB, IB, IB, PB, IB, IB, PB, PB, PB, DB, DB, DB, DB, DB, DB, IB, IB, IB, DB, DB, PB, CI, PB, DB, DB, DB, DB, DB, DB, DB, DB, DB },
+/* SY */ { DB, PB, PB, IB, IB, PB, IB, IB, PB, PB, PB, DB, DB, DB, DB, IB, DB, IB, IB, IB, DB, DB, PB, CI, PB, DB, DB, DB, DB, DB, DB, DB, DB, DB },
+/* IS */ { DB, PB, PB, IB, IB, PB, IB, IB, PB, PB, PB, DB, DB, DB, IB, IB, DB, IB, IB, IB, DB, DB, PB, CI, PB, DB, DB, DB, DB, DB, DB, DB, DB, DB },
+/* PR */ { DB, PB, PB, IB, IB, PB, IB, IB, PB, PB, PB, DB, DB, IB, IB, IB, IB, IB, IB, IB, DB, DB, PB, CI, PB, IB, IB, IB, IB, IB, DB, DB, IB, IB },
+/* PO */ { DB, PB, PB, IB, IB, PB, IB, IB, PB, PB, PB, DB, DB, IB, IB, IB, DB, IB, IB, IB, DB, DB, PB, CI, PB, DB, DB, DB, DB, DB, DB, DB, DB, DB },
+/* NU */ { IN, PB, PB, IB, IB, PB, IB, IB, PB, PB, PB, IB, IB, IB, IB, IB, DB, IB, IB, IB, DB, DB, PB, CI, PB, DB, DB, DB, DB, DB, DB, DB, DB, DB },
+/* AL */ { IN, PB, PB, IB, IB, PB, IB, IB, PB, PB, PB, IB, IB, IB, IB, IB, DB, IB, IB, IB, DB, DB, PB, CI, PB, DB, DB, DB, DB, DB, DB, DB, DB, DB },
+/* HL */ { IN, PB, PB, IB, IB, PB, IB, IB, PB, PB, PB, IB, IB, IB, IB, IB, DB, IB, CI, CI, DB, DB, PB, CI, PB, DB, DB, DB, DB, DB, DB, DB, DB, DB },
+/* ID */ { DB, PB, PB, IB, IB, PB, IB, IB, PB, PB, PB, DB, IB, DB, DB, DB, DB, IB, IB, IB, DB, DB, PB, CI, PB, DB, DB, DB, DB, DB, DB, DB, DB, DB },
+/* IN */ { DB, PB, PB, IB, IB, PB, IB, IB, PB, PB, PB, DB, DB, DB, DB, DB, DB, IB, IB, IB, DB, DB, PB, CI, PB, DB, DB, DB, DB, DB, DB, DB, DB, DB },
+/* HY */ { HH, PB, PB, IB, IB, PB, HH, IB, PB, PB, PB, HH, HH, IB, HH, HH, HH, IB, IB, IB, HH, HH, PB, CI, PB, HH, HH, HH, HH, HH, HH, DB, DB, DB },
+/* BA */ { HH, PB, PB, IB, IB, PB, HH, IB, PB, PB, PB, HH, HH, HH, HH, HH, HH, IB, IB, IB, HH, HH, PB, CI, PB, HH, HH, HH, HH, HH, HH, DB, DB, DB },
+/* BB */ { IB, PB, PB, IB, IB, PB, IB, IB, PB, PB, PB, IB, IB, IB, IB, IB, IB, IB, IB, IB, IB, IB, PB, CI, PB, IB, IB, IB, IB, IB, IB, DB, IB, IB },
+/* B2 */ { DB, PB, PB, IB, IB, PB, IB, IB, PB, PB, PB, DB, DB, DB, DB, DB, DB, IB, IB, IB, DB, PB, PB, CI, PB, DB, DB, DB, DB, DB, DB, DB, DB, DB },
+/* ZW */ { DB, DB, DB, DB, DB, DB, DB, DB, DB, DB, DB, DB, DB, DB, DB, DB, DB, DB, DB, DB, DB, DB, PB, DB, DB, DB, DB, DB, DB, DB, DB, DB, DB, DB },
+/* CM */ { IB, PB, PB, IB, IB, PB, IB, IB, PB, PB, PB, DB, DB, IB, IB, IB, DB, IB, IB, IB, DB, DB, PB, CI, PB, DB, DB, DB, DB, DB, DB, DB, DB, DB },
+/* WJ */ { IB, PB, PB, IB, IB, PB, IB, IB, PB, PB, PB, IB, IB, IB, IB, IB, IB, IB, IB, IB, IB, IB, PB, CI, PB, IB, IB, IB, IB, IB, IB, IB, IB, IB },
+/* H2 */ { DB, PB, PB, IB, IB, PB, IB, IB, PB, PB, PB, DB, IB, DB, DB, DB, DB, IB, IB, IB, DB, DB, PB, CI, PB, DB, DB, DB, IB, IB, DB, DB, DB, DB },
+/* H3 */ { DB, PB, PB, IB, IB, PB, IB, IB, PB, PB, PB, DB, IB, DB, DB, DB, DB, IB, IB, IB, DB, DB, PB, CI, PB, DB, DB, DB, DB, IB, DB, DB, DB, DB },
+/* JL */ { DB, PB, PB, IB, IB, PB, IB, IB, PB, PB, PB, DB, IB, DB, DB, DB, DB, IB, IB, IB, DB, DB, PB, CI, PB, IB, IB, IB, IB, DB, DB, DB, DB, DB },
+/* JV */ { DB, PB, PB, IB, IB, PB, IB, IB, PB, PB, PB, DB, IB, DB, DB, DB, DB, IB, IB, IB, DB, DB, PB, CI, PB, DB, DB, DB, IB, IB, DB, DB, DB, DB },
+/* JT */ { DB, PB, PB, IB, IB, PB, IB, IB, PB, PB, PB, DB, IB, DB, DB, DB, DB, IB, IB, IB, DB, DB, PB, CI, PB, DB, DB, DB, DB, IB, DB, DB, DB, DB },
+/* RI */ { DB, PB, PB, IB, IB, PB, IB, IB, PB, PB, PB, DB, DB, DB, DB, DB, DB, IB, IB, IB, DB, DB, PB, CI, PB, DB, DB, DB, DB, DB, IB, DB, DB, DB },
+/* CB */ { DB, PB, PB, IB, IB, PB, IB, DB, PB, PB, PB, DB, DB, DB, DB, DB, DB, DB, DB, DB, DB, DB, PB, CI, PB, DB, DB, DB, DB, DB, DB, DB, DB, DB },
+/* EB */ { DB, PB, PB, IB, IB, PB, IB, IB, PB, PB, PB, DB, IB, DB, DB, DB, DB, IB, IB, IB, DB, DB, PB, CI, PB, DB, DB, DB, DB, DB, DB, DB, DB, IB },
+/* EM */ { DB, PB, PB, IB, IB, PB, IB, IB, PB, PB, PB, DB, IB, DB, DB, DB, DB, IB, IB, IB, DB, DB, PB, CI, PB, DB, DB, DB, DB, DB, DB, DB, DB, DB },
 };
 
 // The following line break classes are not treated by the pair table
 // and must be resolved outside:
-//  AI, BK, CB, CJ, CR, LF, NL, ZWJ, SA, SG, SP, XX
+//  AI, AK, AP, AS, BK, CB, CJ, CR, LF, NL, SA, SG, SP, VF, VI, XX, ZWJ
 
 } // namespace LB
 
@@ -657,6 +661,61 @@ static void getLineBreaks(const char16_t *string, qsizetype len, QCharAttributes
                 ncls = QUnicodeTables::LineBreak_CM;
         }
 
+        if (Q_UNLIKELY(ncls == QUnicodeTables::LineBreak_QU)) {
+            if (prop->category == QChar::Punctuation_InitialQuote) {
+                // LB15a: Do not break after an unresolved initial punctuation
+                // that lies at the start of the line, after a space, after
+                // opening punctuation, or after an unresolved quotation mark,
+                // even after spaces.
+                //   (sot | BK | CR | LF | NL | OP | QU | GL | SP | ZW)
+                //     [\p{Pi}&QU] SP* ×
+                // Note: sot is treated as LF here due to initial loop setup.
+                constexpr QUnicodeTables::LineBreakClass lb15a[] = {
+                        QUnicodeTables::LineBreak_BK,    QUnicodeTables::LineBreak_CR,
+                        QUnicodeTables::LineBreak_LF,    QUnicodeTables::LineBreak_OP,
+                        QUnicodeTables::LineBreak_QU,    QUnicodeTables::LineBreak_QU_Pi,
+                        QUnicodeTables::LineBreak_QU_Pf, QUnicodeTables::LineBreak_GL,
+                        QUnicodeTables::LineBreak_SP,    QUnicodeTables::LineBreak_ZW};
+                if (std::any_of(std::begin(lb15a), std::end(lb15a),
+                                [lcls](auto x) { return x == lcls; })) {
+                    ncls = QUnicodeTables::LineBreak_QU_Pi;
+                }
+            } else if (prop->category == QChar::Punctuation_FinalQuote) {
+                // LB15b: Do not break before an unresolved final punctuation
+                // that lies at the end of the line, before a space, before
+                // a prohibited break, or before an unresolved quotation mark,
+                // even after spaces.
+                //   × [\p{Pf}&QU] ( SP | GL | WJ | CL | QU | CP | EX | IS
+                //     | SY | BK | CR | LF | NL | ZW | eot)
+                auto nncls = QUnicodeTables::LineBreak_LF;
+
+                if (i + 1 < len) {
+                    char32_t c = string[i + 1];
+                    if (QChar::isHighSurrogate(c) && i + 2 != len) {
+                        ushort low = string[i + 2];
+                        if (QChar::isLowSurrogate(low))
+                            c = QChar::surrogateToUcs4(c, low);
+                    }
+                    nncls = QUnicodeTables::LineBreakClass(
+                            QUnicodeTables::properties(c)->lineBreakClass);
+                }
+
+                constexpr QUnicodeTables::LineBreakClass lb15b[] = {
+                        QUnicodeTables::LineBreak_SP,    QUnicodeTables::LineBreak_GL,
+                        QUnicodeTables::LineBreak_WJ,    QUnicodeTables::LineBreak_CL,
+                        QUnicodeTables::LineBreak_QU,    QUnicodeTables::LineBreak_QU_Pi,
+                        QUnicodeTables::LineBreak_QU_Pf, QUnicodeTables::LineBreak_CP,
+                        QUnicodeTables::LineBreak_EX,    QUnicodeTables::LineBreak_IS,
+                        QUnicodeTables::LineBreak_SY,    QUnicodeTables::LineBreak_BK,
+                        QUnicodeTables::LineBreak_CR,    QUnicodeTables::LineBreak_LF,
+                        QUnicodeTables::LineBreak_ZW};
+                if (std::any_of(std::begin(lb15b), std::end(lb15b),
+                                [nncls](auto x) { return x == nncls; })) {
+                    ncls = QUnicodeTables::LineBreak_QU_Pf;
+                }
+            }
+        }
+
         if (Q_UNLIKELY(lcls >= QUnicodeTables::LineBreak_CR)) {
             // LB4: BK!, LB5: (CRxLF|CR|LF|NL)!
             if (lcls > QUnicodeTables::LineBreak_CR || ncls != QUnicodeTables::LineBreak_LF)