QRegularExpressionMatch: add a way to know if a capturing group captured

Relying on the fact that a given capturing group captured a null string
doesn't allow users to distinguish whether a capturing group did not
capture anything, or captured a null substring (say, from a null subject
string).

Perl allows for the distinction: the entries in the @- and @+ arrays are
set to values in case there is a capture, but they're undef otherwise.

PCRE2 gives us the information already in the results "ovector", but
it was simply not exposed to QREM users. So, expose it.

[ChangeLog][QtCore][QRegularExpressionMatch] Added the hasCaptured()
family of functions to know if a given capturing group has captured
something.

Change-Id: Ic1320933d4554e2e313c0a680be1b1b9dd95af0b
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

1 files changed, 159 insertions, 79 deletions

diff --git a/tests/auto/corelib/text/qregularexpression/tst_qregularexpression.cpp b/tests/auto/corelib/text/qregularexpression/tst_qregularexpression.cpp
index 48d4de0aa4..684727758c 100644
--- a/tests/auto/corelib/text/qregularexpression/tst_qregularexpression.cpp
+++ b/tests/auto/corelib/text/qregularexpression/tst_qregularexpression.cpp
@@ -37,6 +37,8 @@
 #include <qregularexpression.h>
 #include <qthread.h>
 
+#include <optional>
+
 Q_DECLARE_METATYPE(QRegularExpression::PatternOptions)
 Q_DECLARE_METATYPE(QRegularExpression::MatchType)
 Q_DECLARE_METATYPE(QRegularExpression::MatchOptions)
@@ -92,6 +94,8 @@ private:
     void provideRegularExpressions();
 };
 
+using CapturedList = QVector<std::optional<QString>>;
+
 struct Match
 {
     Match()
@@ -111,8 +115,8 @@ struct Match
     bool isValid;
     bool hasMatch;
     bool hasPartialMatch;
-    QStringList captured;
-    QHash<QString, QString> namedCaptured;
+    CapturedList captured;
+    QHash<QString, std::optional<QString>> namedCaptured;
 };
 QT_BEGIN_NAMESPACE
 Q_DECLARE_TYPEINFO(Match, Q_RELOCATABLE_TYPE);
@@ -129,27 +133,53 @@ bool operator==(const QRegularExpressionMatch &rem, const Match &m)
     if ((rem.hasMatch() != m.hasMatch) || (rem.hasPartialMatch() != m.hasPartialMatch))
         return false;
     if (rem.hasMatch() || rem.hasPartialMatch()) {
+        if (!rem.hasCaptured(0))
+            return false;
         if (rem.lastCapturedIndex() != (m.captured.size() - 1))
             return false;
         for (int i = 0; i <= rem.lastCapturedIndex(); ++i) {
+            auto mMaybeCaptured = m.captured.at(i);
             QString remCaptured = rem.captured(i);
-            QString mCaptured = m.captured.at(i);
-            if (remCaptured != mCaptured
-                || remCaptured.isNull() != mCaptured.isNull()
-                || remCaptured.isEmpty() != mCaptured.isEmpty()) {
-                return false;
+            if (!mMaybeCaptured) {
+                if (rem.hasCaptured(i))
+                    return false;
+                if (!remCaptured.isNull())
+                    return false;
+            } else {
+                if (!rem.hasCaptured(i))
+                    return false;
+                QString mCaptured = *mMaybeCaptured;
+                if (remCaptured != mCaptured
+                    || remCaptured.isNull() != mCaptured.isNull()
+                    || remCaptured.isEmpty() != mCaptured.isEmpty()) {
+                    return false;
+                }
             }
         }
 
         for (auto it = m.namedCaptured.begin(), end = m.namedCaptured.end(); it != end; ++it) {
-            const QString remCaptured = rem.captured(it.key());
-            const QString mCaptured = it.value();
-            if (remCaptured != mCaptured
-                || remCaptured.isNull() != mCaptured.isNull()
-                || remCaptured.isEmpty() != mCaptured.isEmpty()) {
-                return false;
+            const QString capturedGroupName = it.key();
+            const QString remCaptured = rem.captured(capturedGroupName);
+            const auto mMaybeCaptured = it.value();
+            if (!mMaybeCaptured) {
+                if (rem.hasCaptured(capturedGroupName))
+                    return false;
+                if (!remCaptured.isNull())
+                    return false;
+            } else {
+                if (!rem.hasCaptured(capturedGroupName))
+                    return false;
+                const auto mCaptured = *mMaybeCaptured;
+                if (remCaptured != mCaptured
+                    || remCaptured.isNull() != mCaptured.isNull()
+                    || remCaptured.isEmpty() != mCaptured.isEmpty()) {
+                    return false;
+                }
             }
         }
+    } else {
+        if (rem.hasCaptured(0))
+            return false;
     }
 
     return true;
@@ -803,7 +833,7 @@ void tst_QRegularExpression::normalMatch_data()
 
     m.clear();
     m.isValid = true; m.hasMatch = true;
-    m.captured << " string" << QString() << "string";
+    m.captured << " string" << std::nullopt << "string";
     QTest::newRow("match04") << QRegularExpression("(\\w+)? (\\w+)")
                              << " string"
                              << qsizetype(0)
@@ -887,9 +917,9 @@ void tst_QRegularExpression::normalMatch_data()
     m.captured << "a string" << "a" << "string";
     m.namedCaptured["article"] = "a";
     m.namedCaptured["noun"] = "string";
-    m.namedCaptured["nonexisting1"] = QString();
-    m.namedCaptured["nonexisting2"] = QString();
-    m.namedCaptured["nonexisting3"] = QString();
+    m.namedCaptured["nonexisting1"] = std::nullopt;
+    m.namedCaptured["nonexisting2"] = std::nullopt;
+    m.namedCaptured["nonexisting3"] = std::nullopt;
     QTest::newRow("match10") << QRegularExpression("(?<article>\\w+) (?<noun>\\w+)")
                              << "a string"
                              << qsizetype(0)
@@ -900,7 +930,7 @@ void tst_QRegularExpression::normalMatch_data()
     m.isValid = true; m.hasMatch = true;
     m.captured << "" << "";
     m.namedCaptured["digits"] = ""; // empty VS null
-    m.namedCaptured["nonexisting"] = QString();
+    m.namedCaptured["nonexisting"] = std::nullopt;
     QTest::newRow("match11") << QRegularExpression("(?<digits>\\d*)")
                              << "abcde"
                              << qsizetype(0)
@@ -922,6 +952,56 @@ void tst_QRegularExpression::normalMatch_data()
     // ***
 
     m.clear();
+    m.isValid = true; m.hasMatch = true;
+    m.captured << QString() << QString();
+    QTest::newRow("capture-in-null-string")
+            << QRegularExpression("(a*)")
+            << QString()
+            << qsizetype(0)
+            << QRegularExpression::MatchOptions(QRegularExpression::NoMatchOption)
+            << m;
+
+    m.clear();
+    m.isValid = true; m.hasMatch = true;
+    m.captured << QString() << QString() << QString();
+    QTest::newRow("capture-in-null-string-2")
+            << QRegularExpression("(a*)(b*)")
+            << QString()
+            << qsizetype(0)
+            << QRegularExpression::MatchOptions(QRegularExpression::NoMatchOption)
+            << m;
+
+    m.clear();
+    m.isValid = true; m.hasMatch = true;
+    m.captured << QString();
+    QTest::newRow("no-capture-in-null-string")
+            << QRegularExpression("(a+)?")
+            << QString()
+            << qsizetype(0)
+            << QRegularExpression::MatchOptions(QRegularExpression::NoMatchOption)
+            << m;
+
+    m.clear();
+    m.isValid = true; m.hasMatch = true;
+    m.captured << "bb" << QString("") << "bb";
+    QTest::newRow("empty-capture-in-non-null-string")
+            << QRegularExpression("(a*)(b*)")
+            << QString("bbc")
+            << qsizetype(0)
+            << QRegularExpression::MatchOptions(QRegularExpression::NoMatchOption)
+            << m;
+
+    m.clear();
+    m.isValid = true; m.hasMatch = true;
+    m.captured << "bb" << std::nullopt << "bb";
+    QTest::newRow("no-capture-in-non-null-string")
+            << QRegularExpression("(a+)?(b+)?")
+            << QString("bbc")
+            << qsizetype(0)
+            << QRegularExpression::MatchOptions(QRegularExpression::NoMatchOption)
+            << m;
+
+    m.clear();
     m.isValid = true;
     QTest::newRow("nomatch01") << QRegularExpression("\\d+")
                                << "a string"
@@ -1316,11 +1396,11 @@ void tst_QRegularExpression::globalMatch_data()
     matchList.clear();
     m.clear();
     m.isValid = true; m.hasMatch = true;
-    m.captured = QStringList() << "the";
+    m.captured = CapturedList() << "the";
     matchList << m;
-    m.captured = QStringList() << "quick";
+    m.captured = CapturedList() << "quick";
     matchList << m;
-    m.captured = QStringList() << "fox";
+    m.captured = CapturedList() << "fox";
     matchList << m;
     QTest::newRow("globalmatch01") << QRegularExpression("\\w+")
                                    << "the quick fox"
@@ -1332,11 +1412,11 @@ void tst_QRegularExpression::globalMatch_data()
     matchList.clear();
     m.clear();
     m.isValid = true; m.hasMatch = true;
-    m.captured = QStringList() << "the" << "t" << "he";
+    m.captured = CapturedList() << "the" << "t" << "he";
     matchList << m;
-    m.captured = QStringList() << "quick" << "q" << "uick";
+    m.captured = CapturedList() << "quick" << "q" << "uick";
     matchList << m;
-    m.captured = QStringList() << "fox" << "f" << "ox";
+    m.captured = CapturedList() << "fox" << "f" << "ox";
     matchList << m;
     QTest::newRow("globalmatch02") << QRegularExpression("(\\w+?)(\\w+)")
                                    << "the quick fox"
@@ -1348,13 +1428,13 @@ void tst_QRegularExpression::globalMatch_data()
     matchList.clear();
     m.clear();
     m.isValid = true; m.hasMatch = true;
-    m.captured = QStringList() << "ACA""GTG""CGA""AAA";
+    m.captured = CapturedList() << "ACA""GTG""CGA""AAA";
     matchList << m;
-    m.captured = QStringList() << "AAA";
+    m.captured = CapturedList() << "AAA";
     matchList << m;
-    m.captured = QStringList() << "AAG""GAA""AAG""AAA";
+    m.captured = CapturedList() << "AAG""GAA""AAG""AAA";
     matchList << m;
-    m.captured = QStringList() << "AAA";
+    m.captured = CapturedList() << "AAA";
     matchList << m;
     QTest::newRow("globalmatch03") << QRegularExpression("\\G(?:\\w\\w\\w)*?AAA")
                                    << "ACA""GTG""CGA""AAA""AAA""AAG""GAA""AAG""AAA""AAA"
@@ -1373,19 +1453,19 @@ void tst_QRegularExpression::globalMatch_data()
     matchList.clear();
     m.clear();
     m.isValid = true; m.hasMatch = true;
-    m.captured = QStringList() << "";
+    m.captured = CapturedList() << "";
     matchList << m;
-    m.captured = QStringList() << "c";
+    m.captured = CapturedList() << "c";
     matchList << m;
-    m.captured = QStringList() << "";
+    m.captured = CapturedList() << "";
     matchList << m;
-    m.captured = QStringList() << "c";
+    m.captured = CapturedList() << "c";
     matchList << m;
-    m.captured = QStringList() << "aabb";
+    m.captured = CapturedList() << "aabb";
     matchList << m;
-    m.captured = QStringList() << "";
+    m.captured = CapturedList() << "";
     matchList << m;
-    m.captured = QStringList() << "";
+    m.captured = CapturedList() << "";
     matchList << m;
 
     QTest::newRow("globalmatch_emptycaptures01") << QRegularExpression("a*b*|c")
@@ -1398,17 +1478,17 @@ void tst_QRegularExpression::globalMatch_data()
     matchList.clear();
     m.clear();
     m.isValid = true; m.hasMatch = true;
-    m.captured = QStringList() << "the";
+    m.captured = CapturedList() << "the";
     matchList << m;
-    m.captured = QStringList() << "";
+    m.captured = CapturedList() << "";
     matchList << m;
-    m.captured = QStringList() << "quick";
+    m.captured = CapturedList() << "quick";
     matchList << m;
-    m.captured = QStringList() << "";
+    m.captured = CapturedList() << "";
     matchList << m;
-    m.captured = QStringList() << "fox";
+    m.captured = CapturedList() << "fox";
     matchList << m;
-    m.captured = QStringList() << "";
+    m.captured = CapturedList() << "";
     matchList << m;
 
     QTest::newRow("globalmatch_emptycaptures02") << QRegularExpression(".*")
@@ -1421,19 +1501,19 @@ void tst_QRegularExpression::globalMatch_data()
     matchList.clear();
     m.clear();
     m.isValid = true; m.hasMatch = true;
-    m.captured = QStringList() << "the";
+    m.captured = CapturedList() << "the";
     matchList << m;
-    m.captured = QStringList() << "";
+    m.captured = CapturedList() << "";
     matchList << m;
-    m.captured = QStringList() << "quick";
+    m.captured = CapturedList() << "quick";
     matchList << m;
-    m.captured = QStringList() << "";
+    m.captured = CapturedList() << "";
     matchList << m;
-    m.captured = QStringList() << "fox";
+    m.captured = CapturedList() << "fox";
     matchList << m;
-    m.captured = QStringList() << "";
+    m.captured = CapturedList() << "";
     matchList << m;
-    m.captured = QStringList() << "";
+    m.captured = CapturedList() << "";
     matchList << m;
 
     QTest::newRow("globalmatch_emptycaptures03") << QRegularExpression(".*")
@@ -1446,17 +1526,17 @@ void tst_QRegularExpression::globalMatch_data()
     matchList.clear();
     m.clear();
     m.isValid = true; m.hasMatch = true;
-    m.captured = QStringList() << "the";
+    m.captured = CapturedList() << "the";
     matchList << m;
-    m.captured = QStringList() << "";
+    m.captured = CapturedList() << "";
     matchList << m;
-    m.captured = QStringList() << "quick";
+    m.captured = CapturedList() << "quick";
     matchList << m;
-    m.captured = QStringList() << "";
+    m.captured = CapturedList() << "";
     matchList << m;
-    m.captured = QStringList() << "fox";
+    m.captured = CapturedList() << "fox";
     matchList << m;
-    m.captured = QStringList() << "";
+    m.captured = CapturedList() << "";
     matchList << m;
 
     QTest::newRow("globalmatch_emptycaptures04") << QRegularExpression("(*CRLF).*")
@@ -1469,19 +1549,19 @@ void tst_QRegularExpression::globalMatch_data()
     matchList.clear();
     m.clear();
     m.isValid = true; m.hasMatch = true;
-    m.captured = QStringList() << "the";
+    m.captured = CapturedList() << "the";
     matchList << m;
-    m.captured = QStringList() << "";
+    m.captured = CapturedList() << "";
     matchList << m;
-    m.captured = QStringList() << "quick";
+    m.captured = CapturedList() << "quick";
     matchList << m;
-    m.captured = QStringList() << "";
+    m.captured = CapturedList() << "";
     matchList << m;
-    m.captured = QStringList() << "fox";
+    m.captured = CapturedList() << "fox";
     matchList << m;
-    m.captured = QStringList() << "";
+    m.captured = CapturedList() << "";
     matchList << m;
-    m.captured = QStringList() << "";
+    m.captured = CapturedList() << "";
     matchList << m;
 
     QTest::newRow("globalmatch_emptycaptures05") << QRegularExpression("(*CRLF).*")
@@ -1494,21 +1574,21 @@ void tst_QRegularExpression::globalMatch_data()
     matchList.clear();
     m.clear();
     m.isValid = true; m.hasMatch = true;
-    m.captured = QStringList() << "the";
+    m.captured = CapturedList() << "the";
     matchList << m;
-    m.captured = QStringList() << "";
+    m.captured = CapturedList() << "";
     matchList << m;
-    m.captured = QStringList() << "quick";
+    m.captured = CapturedList() << "quick";
     matchList << m;
-    m.captured = QStringList() << "";
+    m.captured = CapturedList() << "";
     matchList << m;
-    m.captured = QStringList() << "fox";
+    m.captured = CapturedList() << "fox";
     matchList << m;
-    m.captured = QStringList() << "";
+    m.captured = CapturedList() << "";
     matchList << m;
-    m.captured = QStringList() << "jumped";
+    m.captured = CapturedList() << "jumped";
     matchList << m;
-    m.captured = QStringList() << "";
+    m.captured = CapturedList() << "";
     matchList << m;
 
     QTest::newRow("globalmatch_emptycaptures06") << QRegularExpression("(*ANYCRLF).*")
@@ -1521,17 +1601,17 @@ void tst_QRegularExpression::globalMatch_data()
     matchList.clear();
     m.clear();
     m.isValid = true; m.hasMatch = true;
-    m.captured = QStringList() << "ABC";
+    m.captured = CapturedList() << "ABC";
     matchList << m;
-    m.captured = QStringList() << "";
+    m.captured = CapturedList() << "";
     matchList << m;
-    m.captured = QStringList() << "DEF";
+    m.captured = CapturedList() << "DEF";
     matchList << m;
-    m.captured = QStringList() << "";
+    m.captured = CapturedList() << "";
     matchList << m;
-    m.captured = QStringList() << "GHI";
+    m.captured = CapturedList() << "GHI";
     matchList << m;
-    m.captured = QStringList() << "";
+    m.captured = CapturedList() << "";
     matchList << m;
     QTest::newRow("globalmatch_emptycaptures07") << QRegularExpression("[\\x{0000}-\\x{FFFF}]*")
                                                  << QString::fromUtf8("ABC""\xf0\x9d\x85\x9d""DEF""\xf0\x9d\x85\x9e""GHI")
@@ -1543,13 +1623,13 @@ void tst_QRegularExpression::globalMatch_data()
     matchList.clear();
     m.clear();
     m.isValid = true; m.hasMatch = true;
-    m.captured = QStringList() << QString::fromUtf8("ABC""\xc3\x80");
+    m.captured = CapturedList() << QString::fromUtf8("ABC""\xc3\x80");
     matchList << m;
-    m.captured = QStringList() << "";
+    m.captured = CapturedList() << "";
     matchList << m;
-    m.captured = QStringList() << QString::fromUtf8("\xc3\x80""DEF""\xc3\x80");
+    m.captured = CapturedList() << QString::fromUtf8("\xc3\x80""DEF""\xc3\x80");
     matchList << m;
-    m.captured = QStringList() << "";
+    m.captured = CapturedList() << "";
     matchList << m;
     QTest::newRow("globalmatch_emptycaptures08") << QRegularExpression("[\\x{0000}-\\x{FFFF}]*")
                                                  << QString::fromUtf8("ABC""\xc3\x80""\xf0\x9d\x85\x9d""\xc3\x80""DEF""\xc3\x80")