Revert "[SIC] Make non-const the QRegExp methods that modify the internals"

This reverts commit 75a0c7f9b5. The
source-incompatible change proved to be more trouble than it's
worth. Too much intrusion into the porting effort of applications for
no appreciable gain, especially considering that we have a replacement
class.

Change-Id: Ia99a2360390a2062a8ddb6e12c8f2099287a2704
Discussed-on: http://lists.qt-project.org/pipermail/development/2012-May/003562.html
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>

dist/changes-5.0.0

@@ -353,13 +353,6 @@ QtCore
   QRegularExpressionMatchIterator. They aim to replace QRegExp with a more
   powerful and flexible regular expression engine.
 
-* Certain methods in QRegExp that modified the object's internals are no longer marked
-  const. They were accidentally marked const in Qt 4 but the problem could not be
-  fixed. The following are suggestions to adapt code to this change:
-   - make sure the QRegExp object is not const in the given context
-   - create a copy of the QRegExp object before using it
-   - invert the operation and use QString. E.g., rx.indexIn(string) becomes string.indexOf(rx)
-
 * QEvent::AccessibilityPrepare, AccessibilityHelp and AccessibilityDescription removed:
   * The enum values simply didn't make sense in the first place and should simply be dropped.
 

src/corelib/tools/qregexp.cpp

@@ -4204,6 +4204,7 @@ void QRegExp::setMinimal(bool minimal)
     priv->minimal = minimal;
 }
 
+// ### Qt 5: make non-const
 /*!
     Returns true if \a str is matched exactly by this regular
     expression; otherwise returns false. You can determine how much of
@@ -4219,9 +4220,12 @@ void QRegExp::setMinimal(bool minimal)
     bluebell, \c blutak and \c lightblue, exactMatch() returns false
     and matchedLength() will return 4, 3 and 0 respectively.
 
+    Although const, this function sets matchedLength(),
+    capturedTexts(), and pos().
+
     \sa indexIn(), lastIndexIn()
 */
-bool QRegExp::exactMatch(const QString &str)
+bool QRegExp::exactMatch(const QString &str) const
 {
     prepareEngineForMatch(priv, str);
     priv->matchState.match(str.unicode(), str.length(), 0, priv->minimal, true, 0);
@@ -4234,6 +4238,7 @@ bool QRegExp::exactMatch(const QString &str)
     }
 }
 
+// ### Qt 5: make non-const
 /*!
     Attempts to find a match in \a str from position \a offset (0 by
     default). If \a offset is -1, the search starts at the last
@@ -4252,6 +4257,9 @@ bool QRegExp::exactMatch(const QString &str)
     Example:
     \snippet code/src_corelib_tools_qregexp.cpp 13
 
+    Although const, this function sets matchedLength(),
+    capturedTexts() and pos().
+
     If the QRegExp is a wildcard expression (see setPatternSyntax())
     and want to test a string against the whole wildcard expression,
     use exactMatch() instead of this function.
@@ -4259,7 +4267,7 @@ bool QRegExp::exactMatch(const QString &str)
     \sa lastIndexIn(), exactMatch()
 */
 
-int QRegExp::indexIn(const QString &str, int offset, CaretMode caretMode)
+int QRegExp::indexIn(const QString &str, int offset, CaretMode caretMode) const
 {
     prepareEngineForMatch(priv, str);
     if (offset < 0)
@@ -4269,6 +4277,7 @@ int QRegExp::indexIn(const QString &str, int offset, CaretMode caretMode)
     return priv->matchState.captured[0];
 }
 
+// ### Qt 5: make non-const
 /*!
     Attempts to find a match backwards in \a str from position \a
     offset. If \a offset is -1 (the default), the search starts at the
@@ -4280,13 +4289,16 @@ int QRegExp::indexIn(const QString &str, int offset, CaretMode caretMode)
     The \a caretMode parameter can be used to instruct whether \b{^}
     should match at index 0 or at \a offset.
 
+    Although const, this function sets matchedLength(),
+    capturedTexts() and pos().
+
     \warning Searching backwards is much slower than searching
     forwards.
 
     \sa indexIn(), exactMatch()
 */
 
-int QRegExp::lastIndexIn(const QString &str, int offset, CaretMode caretMode)
+int QRegExp::lastIndexIn(const QString &str, int offset, CaretMode caretMode) const
 {
     prepareEngineForMatch(priv, str);
     if (offset < 0)

src/corelib/tools/qregexp.h

@@ -93,10 +93,10 @@ public:
     bool isMinimal() const;
     void setMinimal(bool minimal);
 
-    bool exactMatch(const QString &str);
+    bool exactMatch(const QString &str) const;
 
-    int indexIn(const QString &str, int offset = 0, CaretMode caretMode = CaretAtZero);
-    int lastIndexIn(const QString &str, int offset = -1, CaretMode caretMode = CaretAtZero);
+    int indexIn(const QString &str, int offset = 0, CaretMode caretMode = CaretAtZero) const;
+    int lastIndexIn(const QString &str, int offset = -1, CaretMode caretMode = CaretAtZero) const;
     int matchedLength() const;
 #ifndef QT_NO_REGEXP_CAPTURE
     int captureCount() const;