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Diffstat (limited to 'src/corelib/text/qregularexpression.cpp')
| -rw-r--r-- | src/corelib/text/qregularexpression.cpp | 130 |
1 files changed, 1 insertions, 129 deletions
diff --git a/src/corelib/text/qregularexpression.cpp b/src/corelib/text/qregularexpression.cpp index cff4c1870c..7ed8618e96 100644 --- a/src/corelib/text/qregularexpression.cpp +++ b/src/corelib/text/qregularexpression.cpp @@ -431,132 +431,6 @@ QT_BEGIN_NAMESPACE This may change in a future version of Qt. - \section1 Notes for QRegExp Users - - The QRegularExpression class introduced in Qt 5 is a big improvement upon - QRegExp, in terms of APIs offered, supported pattern syntax and speed of - execution. The biggest difference is that QRegularExpression simply holds a - regular expression, and it's \e{not} modified when a match is requested. - Instead, a QRegularExpressionMatch object is returned, in order to check - the result of a match and extract the captured substring. The same applies - with global matching and QRegularExpressionMatchIterator. - - Other differences are outlined below. - - \section2 Different pattern syntax - - Porting a regular expression from QRegExp to QRegularExpression may require - changes to the pattern itself. - - In certain scenarios, QRegExp was too lenient and accepted patterns that - are simply invalid when using QRegularExpression. These are somehow easy - to detect, because the QRegularExpression objects built with these patterns - are not valid (cf. isValid()). - - In other cases, a pattern ported from QRegExp to QRegularExpression may - silently change semantics. Therefore, it is necessary to review the - patterns used. The most notable cases of silent incompatibility are: - - \list - - \li Curly braces are needed in order to use a hexadecimal escape like - \c{\xHHHH} with more than 2 digits. A pattern like \c{\x2022} neeeds to - be ported to \c{\x{2022}}, or it will match a space (\c{0x20}) followed - by the string \c{"22"}. In general, it is highly recommended to always use - curly braces with the \c{\x} escape, no matter the amount of digits - specified. - - \li A 0-to-n quantification like \c{{,n}} needs to be ported to \c{{0,n}} to - preserve semantics. Otherwise, a pattern such as \c{\d{,3}} would - actually match a digit followed by the exact string \c{"{,3}"}. - - \li QRegExp by default does Unicode-aware matching, while - QRegularExpression requires a separate option; see below for more details. - - \endlist - - \section2 Porting from QRegExp::exactMatch() - - QRegExp::exactMatch() in Qt 4 served two purposes: it exactly matched - a regular expression against a subject string, and it implemented partial - matching. - - \section3 Porting from QRegExp's Exact Matching - - Exact matching indicates whether the regular expression matches the entire - subject string. For example, the classes yield on the subject string \c{"abc123"}: - - \table - \header \li \li QRegExp::exactMatch() \li QRegularExpressionMatch::hasMatch() - \row \li \c{"\\d+"} \li \b false \li \b true - \row \li \c{"[a-z]+\\d+"} \li \b true \li \b true - \endtable - - Exact matching is not reflected in QRegularExpression. If you want - to be sure that the subject string matches the regular expression - exactly, you can wrap the pattern using the anchoredPattern() - function: - - \snippet code/src_corelib_tools_qregularexpression.cpp 24 - - \section3 Porting from QRegExp's Partial Matching - - When using QRegExp::exactMatch(), if an exact match was not found, one - could still find out how much of the subject string was matched by the - regular expression by calling QRegExp::matchedLength(). If the returned length - was equal to the subject string's length, then one could conclude that a partial - match was found. - - QRegularExpression supports partial matching explicitly by means of the - appropriate MatchType. - - \section2 Global matching - - Due to limitations of the QRegExp API it was impossible to implement global - matching correctly (that is, like Perl does). In particular, patterns that - can match 0 characters (like \c{"a*"}) are problematic. - - QRegularExpression::globalMatch() implements Perl global match correctly, and - the returned iterator can be used to examine each result. - - \section2 Unicode properties support - - When using QRegExp, character classes such as \c{\w}, \c{\d}, etc. match - characters with the corresponding Unicode property: for instance, \c{\d} - matches any character with the Unicode Nd (decimal digit) property. - - Those character classes only match ASCII characters by default when using - QRegularExpression: for instance, \c{\d} matches exactly a character in the - \c{0-9} ASCII range. It is possible to change this behaviour by using the - UseUnicodePropertiesOption pattern option. - - \section2 Wildcard matching - - There is no direct way to do wildcard matching in QRegularExpression. - However, the wildcardToRegularExpression method is provided to translate - glob patterns into a Perl-compatible regular expression that can be used - for that purpose. - - \section2 Other pattern syntaxes - - QRegularExpression supports only Perl-compatible regular expressions. - - \section2 Minimal matching - - QRegExp::setMinimal() implemented minimal matching by simply reversing the - greediness of the quantifiers (QRegExp did not support lazy quantifiers, - like \c{*?}, \c{+?}, etc.). QRegularExpression instead does support greedy, - lazy and possessive quantifiers. The InvertedGreedinessOption - pattern option can be useful to emulate the effects of QRegExp::setMinimal(): - if enabled, it inverts the greediness of quantifiers (greedy ones become - lazy and vice versa). - - \section2 Caret modes - - The AnchorAtOffsetMatchOption match option can be used to emulate the - QRegExp::CaretAtOffset behaviour. There is no equivalent for the other - QRegExp::CaretMode modes. - \section1 Debugging Code that Uses QRegularExpression QRegularExpression internally uses a just in time compiler (JIT) to @@ -1936,7 +1810,7 @@ QString QRegularExpression::escape(QStringView str) result. To get an a regular expression that is not anchored, pass UnanchoredWildcardConversion as the conversion \a option. - \warning Unlike QRegExp, this implementation follows closely the definition + This implementation follows closely the definition of wildcard for glob patterns: \table \row \li \b{c} @@ -2066,8 +1940,6 @@ QString QRegularExpression::wildcardToRegularExpression(QStringView pattern, Wil Returns the \a expression wrapped between the \c{\A} and \c{\z} anchors to be used for exact matching. - - \sa {Porting from QRegExp's Exact Matching} */ QString QRegularExpression::anchoredPattern(QStringView expression) { |