Add qHash(QRegExp) and qHash(QRegularExpression)

QReg*Exp*s can be compared for equality,
so qHash should be overloaded, too.

There was a (poor) private implementation of qHash(QRegExpEngineKey)
already, which has now been replaced with a better one (the old one
didn't take into account all the fields that make up equality,
producing unnecessary collisions).

[ChangeLog][QtCore][QRegExp] Added qHash(QRegExp).
[ChangeLog][QtCore][QRegularExpression] Added qHash(QRegularExpression).

Change-Id: I1d22fbcc0508018a3f94b4c24571b13ba6e07df2
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>

6 files changed, 58 insertions, 5 deletions

diff --git a/src/corelib/tools/qregexp.cpp b/src/corelib/tools/qregexp.cpp
index cd8c393d51..5aa9d54843 100644
--- a/src/corelib/tools/qregexp.cpp
+++ b/src/corelib/tools/qregexp.cpp
@@ -38,6 +38,7 @@
 #include "qcache.h"
 #include "qdatastream.h"
 #include "qdebug.h"
+#include "qhashfunctions.h"
 #include "qlist.h"
 #include "qmap.h"
 #include "qmutex.h"
@@ -882,6 +883,15 @@ static bool operator==(const QRegExpEngineKey &key1, const QRegExpEngineKey &key
            && key1.cs == key2.cs;
 }
 
+static uint qHash(const QRegExpEngineKey &key, uint seed = 0) Q_DECL_NOTHROW
+{
+    QtPrivate::QHashCombine hash;
+    seed = hash(seed, key.pattern);
+    seed = hash(seed, key.patternSyntax);
+    seed = hash(seed, key.cs);
+    return seed;
+}
+
 class QRegExpEngine;
 
 //Q_DECLARE_TYPEINFO(QVector<int>, Q_MOVABLE_TYPE);
@@ -3807,11 +3817,6 @@ struct QRegExpPrivate
 };
 
 #if !defined(QT_NO_REGEXP_OPTIM)
-uint qHash(const QRegExpEngineKey &key, uint seed = 0) Q_DECL_NOTHROW
-{
-    return qHash(key.pattern, seed);
-}
-
 typedef QCache<QRegExpEngineKey, QRegExpEngine> EngineCache;
 Q_GLOBAL_STATIC(EngineCache, globalEngineCache)
 static QBasicMutex globalEngineCacheMutex;
@@ -4033,6 +4038,21 @@ bool QRegExp::operator==(const QRegExp &rx) const
 }
 
 /*!
+    \since 5.6
+    \relates QRegExp
+
+    Returns the hash value for \a key, using
+    \a seed to seed the calculation.
+*/
+uint qHash(const QRegExp &key, uint seed) Q_DECL_NOTHROW
+{
+    QtPrivate::QHashCombine hash;
+    seed = hash(seed, key.priv->engineKey);
+    seed = hash(seed, key.priv->minimal);
+    return seed;
+}
+
+/*!
     \fn bool QRegExp::operator!=(const QRegExp &rx) const
 
     Returns \c true if this regular expression is not equal to \a rx;
diff --git a/src/corelib/tools/qregexp.h b/src/corelib/tools/qregexp.h
index b08a8bd282..f384e6c51f 100644
--- a/src/corelib/tools/qregexp.h
+++ b/src/corelib/tools/qregexp.h
@@ -45,6 +45,9 @@ QT_BEGIN_NAMESPACE
 
 struct QRegExpPrivate;
 class QStringList;
+class QRegExp;
+
+Q_CORE_EXPORT uint qHash(const QRegExp &key, uint seed = 0) Q_DECL_NOTHROW;
 
 class Q_CORE_EXPORT QRegExp
 {
@@ -104,6 +107,8 @@ public:
 
     static QString escape(const QString &str);
 
+    friend Q_CORE_EXPORT uint qHash(const QRegExp &key, uint seed) Q_DECL_NOTHROW;
+
 private:
     QRegExpPrivate *priv;
 };
diff --git a/src/corelib/tools/qregularexpression.cpp b/src/corelib/tools/qregularexpression.cpp
index 9950b90720..18dd2d12c2 100644
--- a/src/corelib/tools/qregularexpression.cpp
+++ b/src/corelib/tools/qregularexpression.cpp
@@ -38,6 +38,7 @@
 #ifndef QT_NO_REGULAREXPRESSION
 
 #include <QtCore/qcoreapplication.h>
+#include <QtCore/qhashfunctions.h>
 #include <QtCore/qmutex.h>
 #include <QtCore/qvector.h>
 #include <QtCore/qstringlist.h>
@@ -1838,6 +1839,21 @@ bool QRegularExpression::operator==(const QRegularExpression &re) const
 */
 
 /*!
+    \since 5.6
+    \relates QRegularExpression
+
+    Returns the hash value for \a key, using
+    \a seed to seed the calculation.
+*/
+uint qHash(const QRegularExpression &key, uint seed) Q_DECL_NOTHROW
+{
+    QtPrivate::QHashCombine hash;
+    seed = hash(seed, key.d->pattern);
+    seed = hash(seed, key.d->patternOptions);
+    return seed;
+}
+
+/*!
     Escapes all characters of \a str so that they no longer have any special
     meaning when used as a regular expression pattern string, and returns
     the escaped string. For instance:
diff --git a/src/corelib/tools/qregularexpression.h b/src/corelib/tools/qregularexpression.h
index d2abfc7701..2bca6a211b 100644
--- a/src/corelib/tools/qregularexpression.h
+++ b/src/corelib/tools/qregularexpression.h
@@ -49,6 +49,9 @@ QT_BEGIN_NAMESPACE
 class QRegularExpressionMatch;
 class QRegularExpressionMatchIterator;
 struct QRegularExpressionPrivate;
+class QRegularExpression;
+
+Q_CORE_EXPORT uint qHash(const QRegularExpression &key, uint seed = 0) Q_DECL_NOTHROW;
 
 class Q_CORE_EXPORT QRegularExpression
 {
@@ -139,6 +142,7 @@ private:
     friend class QRegularExpressionMatch;
     friend struct QRegularExpressionMatchPrivate;
     friend class QRegularExpressionMatchIterator;
+    friend Q_CORE_EXPORT uint qHash(const QRegularExpression &key, uint seed) Q_DECL_NOTHROW;
 
     QRegularExpression(QRegularExpressionPrivate &dd);
     QExplicitlySharedDataPointer<QRegularExpressionPrivate> d;
diff --git a/tests/auto/corelib/tools/qregexp/tst_qregexp.cpp b/tests/auto/corelib/tools/qregexp/tst_qregexp.cpp
index fefdec7496..b9a3fc13c5 100644
--- a/tests/auto/corelib/tools/qregexp/tst_qregexp.cpp
+++ b/tests/auto/corelib/tools/qregexp/tst_qregexp.cpp
@@ -1224,6 +1224,9 @@ void tst_QRegExp::operator_eq()
         for (int j = 0; j < I * J * K * ELL; ++j) {
             QCOMPARE(rxtable[i] == rxtable[j], i / ELL == j / ELL);
             QCOMPARE(rxtable[i] != rxtable[j], i / ELL != j / ELL);
+            // this just happens to have no hash collisions. If at some point
+            // we get collisions, restrict the test to only equal elements:
+            QCOMPARE(qHash(rxtable[i]) == qHash(rxtable[j]), i / ELL == j / ELL);
         }
     }
 }
diff --git a/tests/auto/corelib/tools/qregularexpression/tst_qregularexpression.cpp b/tests/auto/corelib/tools/qregularexpression/tst_qregularexpression.cpp
index 99f6a31267..6b7614b7b9 100644
--- a/tests/auto/corelib/tools/qregularexpression/tst_qregularexpression.cpp
+++ b/tests/auto/corelib/tools/qregularexpression/tst_qregularexpression.cpp
@@ -1424,6 +1424,7 @@ static void verifyEquality(const QRegularExpression &re1, const QRegularExpressi
 {
     QVERIFY(re1 == re2);
     QVERIFY(re2 == re1);
+    QCOMPARE(qHash(re1), qHash(re2));
     QVERIFY(!(re1 != re2));
     QVERIFY(!(re2 != re1));
 
@@ -1431,22 +1432,26 @@ static void verifyEquality(const QRegularExpression &re1, const QRegularExpressi
 
     QVERIFY(re1 == re3);
     QVERIFY(re3 == re1);
+    QCOMPARE(qHash(re1), qHash(re3));
     QVERIFY(!(re1 != re3));
     QVERIFY(!(re3 != re1));
 
     QVERIFY(re2 == re3);
     QVERIFY(re3 == re2);
+    QCOMPARE(qHash(re2), qHash(re3));
     QVERIFY(!(re2 != re3));
     QVERIFY(!(re3 != re2));
 
     re3 = re2;
     QVERIFY(re1 == re3);
     QVERIFY(re3 == re1);
+    QCOMPARE(qHash(re1), qHash(re3));
     QVERIFY(!(re1 != re3));
     QVERIFY(!(re3 != re1));
 
     QVERIFY(re2 == re3);
     QVERIFY(re3 == re2);
+    QCOMPARE(qHash(re2), qHash(re3));
     QVERIFY(!(re2 != re3));
     QVERIFY(!(re3 != re2));
 }