QRegularExpression 类

QRegularExpression 类提供以正则表达式进行模式匹配。 更多...

头: #include <QRegularExpression>
qmake: QT += core
Since: Qt 5.0

该类在 Qt 5.0 引入。

注意: 此类的所有函数 可重入 .

公共类型

enum MatchOption { NoMatchOption, AnchoredMatchOption, DontCheckSubjectStringMatchOption }
flags MatchOptions
enum MatchType { NormalMatch, PartialPreferCompleteMatch, PartialPreferFirstMatch, NoMatch }
enum PatternOption { NoPatternOption, CaseInsensitiveOption, DotMatchesEverythingOption, MultilineOption, ExtendedPatternSyntaxOption, …, DontAutomaticallyOptimizeOption }
flags PatternOptions

公共函数

QRegularExpression (const QRegularExpression & re )
QRegularExpression (const QString & pattern , QRegularExpression::PatternOptions options = NoPatternOption)
QRegularExpression ()
QRegularExpression & operator= (QRegularExpression && re )
QRegularExpression & operator= (const QRegularExpression & re )
~QRegularExpression ()
int captureCount () const
QString errorString () const
QRegularExpressionMatchIterator globalMatch (const QString & subject , int offset = 0, QRegularExpression::MatchType matchType = NormalMatch, QRegularExpression::MatchOptions matchOptions = NoMatchOption) const
QRegularExpressionMatchIterator globalMatch (const QStringRef & subjectRef , int offset = 0, QRegularExpression::MatchType matchType = NormalMatch, QRegularExpression::MatchOptions matchOptions = NoMatchOption) const
QRegularExpressionMatchIterator globalMatch (QStringView subject , int offset = 0, QRegularExpression::MatchType matchType = NormalMatch, QRegularExpression::MatchOptions matchOptions = NoMatchOption) const
bool isValid () const
QRegularExpressionMatch match (const QString & subject , int offset = 0, QRegularExpression::MatchType matchType = NormalMatch, QRegularExpression::MatchOptions matchOptions = NoMatchOption) const
QRegularExpressionMatch match (const QStringRef & subjectRef , int offset = 0, QRegularExpression::MatchType matchType = NormalMatch, QRegularExpression::MatchOptions matchOptions = NoMatchOption) const
QRegularExpressionMatch match (QStringView subject , int offset = 0, QRegularExpression::MatchType matchType = NormalMatch, QRegularExpression::MatchOptions matchOptions = NoMatchOption) const
QStringList namedCaptureGroups () const
void optimize () const
QString pattern () const
int patternErrorOffset () const
QRegularExpression::PatternOptions patternOptions () const
void setPattern (const QString & pattern )
void setPatternOptions (QRegularExpression::PatternOptions options )
void swap (QRegularExpression & other )
bool operator!= (const QRegularExpression & re ) const
bool operator== (const QRegularExpression & re ) const

静态公共成员

QString anchoredPattern (QStringView 表达式 )
QString anchoredPattern (const QString & 表达式 )
QString escape (QStringView str )
QString escape (const QString & str )
QString wildcardToRegularExpression (QStringView pattern )
QString wildcardToRegularExpression (const QString & pattern )
uint qHash (const QRegularExpression & key , uint seed = 0)
QDataStream & operator<< (QDataStream & out , const QRegularExpression & re )
QDebug operator<< (QDebug debug , const QRegularExpression & re )
QDebug operator<< (QDebug debug , QRegularExpression::PatternOptions patternOptions )
QDataStream & operator>> (QDataStream & in , QRegularExpression & re )

详细描述

正则表达式,或 regexps , are a very powerful tool to handle strings and texts. This is useful in many contexts, e.g.,

验证 A regexp can test whether a substring meets some criteria, e.g. is an integer or contains no whitespace.
搜索 A regexp provides more powerful pattern matching than simple substring matching, e.g., match one of the words mail , letter or correspondence , but none of the words email , mailman , mailer , letterbox ,等。
搜索和替换 A regexp can replace all occurrences of a substring with a different substring, e.g., replace all occurrences of & with & except where the & is already followed by an amp; .
字符串分割 A regexp can be used to identify where a string should be split apart, e.g. splitting tab-delimited strings.

This document is by no means a complete reference to pattern matching using regular expressions, and the following parts will require the reader to have some basic knowledge about Perl-like regular expressions and their pattern syntax.

有关正则表达式的参考资料,包括:

介绍

QRegularExpression implements Perl-compatible regular expressions. It fully supports Unicode. For an overview of the regular expression syntax supported by QRegularExpression, please refer to the aforementioned pcrepattern(3) man page. A regular expression is made up of two things: a pattern string and a set of pattern options that change the meaning of the pattern string.

You can set the pattern string by passing a string to the QRegularExpression constructor:

QRegularExpression re("a pattern");
					

这将模式字符串设为 a pattern 。还可以使用 setPattern () function to set a pattern on an existing QRegularExpression object:

QRegularExpression re;
re.setPattern("another pattern");
					

Note that due to C++ literal strings rules, you must escape all backslashes inside the pattern string with another backslash:

// matches two digits followed by a space and a word
QRegularExpression re("\\d\\d \\w+");
// matches a backslash
QRegularExpression re2("\\\\");
					

The pattern () function returns the pattern that is currently set for a QRegularExpression object:

QRegularExpression re("a third pattern");
QString pattern = re.pattern(); // pattern == "a third pattern"
					
					

模式选项

The meaning of the pattern string can be modified by setting one or more pattern options . For instance, it is possible to set a pattern to match case insensitively by setting the QRegularExpression::CaseInsensitiveOption .

You can set the options by passing them to the QRegularExpression constructor, as in:

// matches "Qt rocks", but also "QT rocks", "QT ROCKS", "qT rOcKs", etc.
QRegularExpression re("Qt rocks", QRegularExpression::CaseInsensitiveOption);
					

Alternatively, you can use the setPatternOptions () function on an existing QRegularExpressionObject:

QRegularExpression re("^\\d+$");
re.setPatternOptions(QRegularExpression::MultilineOption);
// re matches any line in the subject string that contains only digits (but at least one)
					

It is possible to get the pattern options currently set on a QRegularExpression object by using the patternOptions () 函数:

QRegularExpression re = QRegularExpression("^two.*words$", QRegularExpression::MultilineOption
                                                           | QRegularExpression::DotMatchesEverythingOption);
QRegularExpression::PatternOptions options = re.patternOptions();
// options == QRegularExpression::MultilineOption | QRegularExpression::DotMatchesEverythingOption
					

请参考 QRegularExpression::PatternOption enum documentation for more information about each pattern option.

匹配类型和匹配选项

The last two arguments of the match () 和 globalMatch () functions set the match type and the match options. The match type is a value of the QRegularExpression::MatchType enum; the "traditional" matching algorithm is chosen by using the NormalMatch match type (the default). It is also possible to enable partial matching of the regular expression against a subject string: see the 局部匹配 章节了解更多细节。

The match options are a set of one or more QRegularExpression::MatchOption values. They change the way a specific match of a regular expression against a subject string is done. Please refer to the QRegularExpression::MatchOption enum documentation for more details.

正常匹配

为履行匹配,只需援引 match () function passing a string to match against. We refer to this string as the subject string . The result of the match () function is a QRegularExpressionMatch object that can be used to inspect the results of the match. For instance:

// match two digits followed by a space and a word
QRegularExpression re("\\d\\d \\w+");
QRegularExpressionMatch match = re.match("abc123 def");
bool hasMatch = match.hasMatch(); // true
					

If a match is successful, the (implicit) capturing group number 0 can be used to retrieve the substring matched by the entire pattern (see also the section about extracting captured substrings ):

QRegularExpression re("\\d\\d \\w+");
QRegularExpressionMatch match = re.match("abc123 def");
if (match.hasMatch()) {
    QString matched = match.captured(0); // matched == "23 def"
    // ...
}
					

It's also possible to start a match at an arbitrary offset inside the subject string by passing the offset as an argument of the match () function. In the following example "12 abc" is not matched because the match is started at offset 1:

QRegularExpression re("\\d\\d \\w+");
QRegularExpressionMatch match = re.match("12 abc 45 def", 1);
if (match.hasMatch()) {
    QString matched = match.captured(0); // matched == "45 def"
    // ...
}
					
					
					

提取捕获的子字符串

The QRegularExpressionMatch object contains also information about the substrings captured by the capturing groups in the pattern string. The captured() function will return the string captured by the n-th capturing group:

QRegularExpression re("^(\\d\\d)/(\\d\\d)/(\\d\\d\\d\\d)$");
QRegularExpressionMatch match = re.match("08/12/1985");
if (match.hasMatch()) {
    QString day = match.captured(1); // day == "08"
    QString month = match.captured(2); // month == "12"
    QString year = match.captured(3); // year == "1985"
    // ...
}
					

Capturing groups in the pattern are numbered starting from 1, and the implicit capturing group 0 is used to capture the substring that matched the entire pattern.

It's also possible to retrieve the starting and the ending offsets (inside the subject string) of each captured substring, by using the capturedStart() capturedEnd() functions:

QRegularExpression re("abc(\\d+)def");
QRegularExpressionMatch match = re.match("XYZabc123defXYZ");
if (match.hasMatch()) {
    int startOffset = match.capturedStart(1); // startOffset == 6
    int endOffset = match.capturedEnd(1); // endOffset == 9
    // ...
}
					

All of these functions have an overload taking a QString as a parameter in order to extract 命名 captured substrings. For instance:

QRegularExpression re("^(?<date>\\d\\d)/(?<month>\\d\\d)/(?<year>\\d\\d\\d\\d)$");
QRegularExpressionMatch match = re.match("08/12/1985");
if (match.hasMatch()) {
    QString date = match.captured("date"); // date == "08"
    QString month = match.captured("month"); // month == "12"
    QString year = match.captured("year"); // year == 1985
}
					
					
					

全局匹配

全局匹配 is useful to find all the occurrences of a given regular expression inside a subject string. Suppose that we want to extract all the words from a given string, where a word is a substring matching the pattern \w+ .

QRegularExpression::globalMatch 返回 QRegularExpressionMatchIterator , which is a Java-like forward iterator that can be used to iterate over the results. For instance:

QRegularExpression re("(\\w+)");
QRegularExpressionMatchIterator i = re.globalMatch("the quick fox");
					

由于它是像 Java 迭代器, QRegularExpressionMatchIterator will point immediately before the first result. Every result is returned as a QRegularExpressionMatch 对象。 hasNext() function will return true if there's at least one more result, and next() will return the next result and advance the iterator. Continuing from the previous example:

QStringList words;
while (i.hasNext()) {
    QRegularExpressionMatch match = i.next();
    QString word = match.captured(1);
    words << word;
}
// words contains "the", "quick", "fox"
					

还可以使用 peekNext() to get the next result without advancing the iterator.

It is possible to pass a starting offset and one or more match options to the globalMatch () function, exactly like normal matching with match ().

部分匹配

A partial match is obtained when the end of the subject string is reached, but more characters are needed to successfully complete the match. Note that a partial match is usually much more inefficient than a normal match because many optimizations of the matching algorithm cannot be employed.

A partial match must be explicitly requested by specifying a match type of PartialPreferCompleteMatch or PartialPreferFirstMatch 当调用 QRegularExpression::match or QRegularExpression::globalMatch . If a partial match is found, then calling the hasMatch() function on the QRegularExpressionMatch object returned by match () 会返回 false ,但 hasPartialMatch() 将返回 true .

When a partial match is found, no captured substrings are returned, and the (implicit) capturing group 0 corresponding to the whole match captures the partially matched substring of the subject string.

Note that asking for a partial match can still lead to a complete match, if one is found; in this case, hasMatch() 将返回 true and hasPartialMatch() false . It never happens that a QRegularExpressionMatch reports both a partial and a complete match.

Partial matching is mainly useful in two scenarios: validating user input in real time and incremental/multi-segment matching.

Validating user input

Suppose that we would like the user to input a date in a specific format, for instance "MMM dd, yyyy". We can check the input validity with a pattern like:

^(Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec) \d\d?, \d\d\d\d$

(This pattern doesn't catch invalid days, but let's keep it for the example's purposes).

We would like to validate the input with this regular expression while the user is typing it, so that we can report an error in the input as soon as it is committed (for instance, the user typed the wrong key). In order to do so we must distinguish three cases:

  • the input cannot possibly match the regular expression;
  • the input does match the regular expression;
  • the input does not match the regular expression right now, but it will if more characters will be added to it.

Note that these three cases represent exactly the possible states of a QValidator (see the QValidator::State enum).

In particular, in the last case we want the regular expression engine to report a partial match: we are successfully matching the pattern against the subject string but the matching cannot continue because the end of the subject is encountered. Notice, however, that the matching algorithm should continue and try all possibilities, and in case a complete (non-partial) match is found, then this one should be reported, and the input string accepted as fully valid.

This behavior is implemented by the PartialPreferCompleteMatch match type. For instance:

QString pattern("^(Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec) \\d\\d?, \\d\\d\\d\\d$");
QRegularExpression re(pattern);
QString input("Jan 21,");
QRegularExpressionMatch match = re.match(input, 0, QRegularExpression::PartialPreferCompleteMatch);
bool hasMatch = match.hasMatch(); // false
bool hasPartialMatch = match.hasPartialMatch(); // true
					

If matching the same regular expression against the subject string leads to a complete match, it is reported as usual:

QString input("Dec 8, 1985");
QRegularExpressionMatch match = re.match(input, 0, QRegularExpression::PartialPreferCompleteMatch);
bool hasMatch = match.hasMatch(); // true
bool hasPartialMatch = match.hasPartialMatch(); // false
					

Another example with a different pattern, showing the behavior of preferring a complete match over a partial one:

QRegularExpression re("abc\\w+X|def");
QRegularExpressionMatch match = re.match("abcdef", 0, QRegularExpression::PartialPreferCompleteMatch);
bool hasMatch = match.hasMatch(); // true
bool hasPartialMatch = match.hasPartialMatch(); // false
QString captured = match.captured(0); // captured == "def"
					

在此情况下,子模式 abc\\w+X partially matches the subject string; however, the subpattern def matches the subject string completely, and therefore a complete match is reported.

If multiple partial matches are found when matching (but no complete match), then the QRegularExpressionMatch object will report the first one that is found. For instance:

QRegularExpression re("abc\\w+X|defY");
QRegularExpressionMatch match = re.match("abcdef", 0, QRegularExpression::PartialPreferCompleteMatch);
bool hasMatch = match.hasMatch(); // false
bool hasPartialMatch = match.hasPartialMatch(); // true
QString captured = match.captured(0); // captured == "abcdef"
					
					

增量/多段匹配

Incremental matching is another use case of partial matching. Suppose that we want to find the occurrences of a regular expression inside a large text (that is, substrings matching the regular expression). In order to do so we would like to "feed" the large text to the regular expression engines in smaller chunks. The obvious problem is what happens if the substring that matches the regular expression spans across two or more chunks.

In this case, the regular expression engine should report a partial match, so that we can match again adding new data and (eventually) get a complete match. This implies that the regular expression engine may assume that there are other characters beyond the end of the subject string. This is not to be taken literally -- the engine will never try to access any character after the last one in the subject.

QRegularExpression implements this behavior when using the PartialPreferFirstMatch match type. This match type reports a partial match as soon as it is found, and other match alternatives are not tried (even if they could lead to a complete match). For instance:

QRegularExpression re("abc|ab");
QRegularExpressionMatch match = re.match("ab", 0, QRegularExpression::PartialPreferFirstMatch);
bool hasMatch = match.hasMatch(); // false
bool hasPartialMatch = match.hasPartialMatch(); // true
					

This happens because when matching the first branch of the alternation operator a partial match is found, and therefore matching stops, without trying the second branch. Another example:

QRegularExpression re("abc(def)?");
QRegularExpressionMatch match = re.match("abc", 0, QRegularExpression::PartialPreferFirstMatch);
bool hasMatch = match.hasMatch(); // false
bool hasPartialMatch = match.hasPartialMatch(); // true
					

This shows what could seem a counterintuitive behavior of quantifiers: since ? is greedy, then the engine tries first to continue the match after having matched "abc" ; but then the matching reaches the end of the subject string, and therefore a partial match is reported. This is even more surprising in the following example:

QRegularExpression re("(abc)*");
QRegularExpressionMatch match = re.match("abc", 0, QRegularExpression::PartialPreferFirstMatch);
bool hasMatch = match.hasMatch(); // false
bool hasPartialMatch = match.hasPartialMatch(); // true
					

It's easy to understand this behavior if we remember that the engine expects the subject string to be only a substring of the whole text we're looking for a match into (that is, how we said before, that the engine assumes that there are other characters beyond the end of the subject string).

由于 * quantifier is greedy, then reporting a complete match could be an error, because after the current subject "abc" there may be other occurrences of "abc" . For instance, the complete text could have been "abcabcX", and therefore the right match to report (in the complete text) would have been "abcabc" ; by matching only against the leading "abc" we instead get a partial match.

错误处理

It is possible for a QRegularExpression object to be invalid because of syntax errors in the pattern string. The isValid () function will return true if the regular expression is valid, or false otherwise:

QRegularExpression invalidRe("(unmatched|parenthesis");
bool isValid = invalidRe.isValid(); // false
					

You can get more information about the specific error by calling the errorString () 函数;再者, patternErrorOffset () function will return the offset inside the pattern string

QRegularExpression invalidRe("(unmatched|parenthesis");
if (!invalidRe.isValid()) {
    QString errorString = invalidRe.errorString(); // errorString == "missing )"
    int errorOffset = invalidRe.patternErrorOffset(); // errorOffset == 22
    // ...
}
					

If a match is attempted with an invalid QRegularExpression, then the returned QRegularExpressionMatch object will be invalid as well (that is, its isValid() function will return false). The same applies for attempting a global match.

不支持 Perl 兼容正则表达式特征

QRegularExpression does not support all the features available in Perl-compatible regular expressions. The most notable one is the fact that duplicated names for capturing groups are not supported, and using them can lead to undefined behavior.

这在未来 Qt 版本可能改变。

QRegExp 用户注意事项

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 not 被修改当请求匹配时。取而代之, 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 .

其它差异提纲如下。

不同模式句法

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:

  • Curly braces are needed in order to use a hexadecimal escape like \xHHHH with more than 2 digits. A pattern like \x2022 neeeds to be ported to \x{2022} , or it will match a space ( 0x20 ) followed by the string "22" . In general, it is highly recommended to always use curly braces with the \x escape, no matter the amount of digits specified.
  • A 0-to-n quantification like {,n} needs to be ported to {0,n} to preserve semantics. Otherwise, a pattern such as \d{,3} would actually match a digit followed by the exact string "{,3}" .
  • QRegExp by default does Unicode-aware matching, while QRegularExpression requires a separate option; see below for more details.

移植自 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.

移植自 QRegExp 准确匹配

Exact matching indicates whether the regular expression matches the entire subject string. For example, the classes yield on the subject string "abc123" :

QRegExp::exactMatch () QRegularExpressionMatch::hasMatch ()
"\\d+" false true
"[a-z]+\\d+" true true

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 () 函数:

QString p("a .*|pattern");
// re matches exactly the pattern string p
QRegularExpression re(QRegularExpression::anchoredPattern(p));
					
					
Porting from QRegExp's Partial Matching

当使用 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 .

全局匹配

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 "a*" ) are problematic.

QRegularExpression::globalMatch () implements Perl global match correctly, and the returned iterator can be used to examine each result.

Unicode 特性支持

当使用 QRegExp , character classes such as \w , \d , etc. match characters with the corresponding Unicode property: for instance, \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, \d matches exactly a character in the 0-9 ASCII range. It is possible to change this behaviour by using the UseUnicodePropertiesOption 模式选项。

通配符匹配

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.

Other pattern syntaxes

QRegularExpression supports only Perl-compatible regular expressions.

最小匹配

QRegExp::setMinimal () implemented minimal matching by simply reversing the greediness of the quantifiers ( QRegExp did not support lazy quantifiers, like *? , +? , 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).

^ 插入符号模式

The AnchoredMatchOption match option can be used to emulate the QRegExp::CaretAtOffset behaviour. There is no equivalent for the other QRegExp::CaretMode 模式。

使用 QRegularExpression 调试代码

QRegularExpression internally uses a just in time compiler (JIT) to optimize the execution of the matching algorithm. The JIT makes extensive usage of self-modifying code, which can lead debugging tools such as Valgrind to crash. You must enable all checks for self-modifying code if you want to debug programs using QRegularExpression (for instance, Valgrind's --smc-check command line option). The downside of enabling such checks is that your program will run considerably slower.

To avoid that, the JIT is disabled by default if you compile Qt in debug mode. It is possible to override the default and enable or disable the JIT usage (both in debug or release mode) by setting the QT_ENABLE_REGEXP_JIT environment variable to a non-zero or zero value respectively.

另请参阅 QRegularExpressionMatch and QRegularExpressionMatchIterator .

成员类型文档编制

enum QRegularExpression:: MatchOption
flags QRegularExpression:: MatchOptions

常量 描述
QRegularExpression::NoMatchOption 0x0000 No match options are set.
QRegularExpression::AnchoredMatchOption 0x0001 The match is constrained to start exactly at the offset passed to match () in order to be successful, even if the pattern string does not contain any metacharacter that anchors the match at that point.
QRegularExpression::DontCheckSubjectStringMatchOption 0x0002 The subject string is not checked for UTF-16 validity before attempting a match. Use this option with extreme caution, as attempting to match an invalid string may crash the program and/or constitute a security issue. This enum value has been introduced in Qt 5.4.

The MatchOptions type is a typedef for QFlags <MatchOption>. It stores an OR combination of MatchOption values.

enum QRegularExpression:: MatchType

The MatchType enum defines the type of the match that should be attempted against the subject string.

常量 描述
QRegularExpression::NormalMatch 0 正常匹配完成。
QRegularExpression::PartialPreferCompleteMatch 1 The pattern string is matched partially against the subject string. If a partial match is found, then it is recorded, and other matching alternatives are tried as usual. If a complete match is then found, then it's preferred to the partial match; in this case only the complete match is reported. If instead no complete match is found (but only the partial one), then the partial one is reported.
QRegularExpression::PartialPreferFirstMatch 2 The pattern string is matched partially against the subject string. If a partial match is found, then matching stops and the partial match is reported. In this case, other matching alternatives (potentially leading to a complete match) are not tried. Moreover, this match type assumes that the subject string only a substring of a larger text, and that (in this text) there are other characters beyond the end of the subject string. This can lead to surprising results; see the discussion in the 局部匹配 章节了解更多细节。
QRegularExpression::NoMatch 3 No matching is done. This value is returned as the match type by a default constructed QRegularExpressionMatch or QRegularExpressionMatchIterator . Using this match type is not very useful for the user, as no matching ever happens. This enum value has been introduced in Qt 5.1.

enum QRegularExpression:: PatternOption
flags QRegularExpression:: PatternOptions

The PatternOption enum defines modifiers to the way the pattern string should be interpreted, and therefore the way the pattern matches against a subject string.

常量 描述
QRegularExpression::NoPatternOption 0x0000 No pattern options are set.
QRegularExpression::CaseInsensitiveOption 0x0001 The pattern should match against the subject string in a case insensitive way. This option corresponds to the /i modifier in Perl regular expressions.
QRegularExpression::DotMatchesEverythingOption 0x0002 The dot metacharacter ( . ) in the pattern string is allowed to match any character in the subject string, including newlines (normally, the dot does not match newlines). This option corresponds to the /s modifier in Perl regular expressions.
QRegularExpression::MultilineOption 0x0004 The caret ( ^ ) and the dollar ( $ ) metacharacters in the pattern string are allowed to match, respectively, immediately after and immediately before any newline in the subject string, as well as at the very beginning and at the very end of the subject string. This option corresponds to the /m modifier in Perl regular expressions.
QRegularExpression::ExtendedPatternSyntaxOption 0x0008 Any whitespace in the pattern string which is not escaped and outside a character class is ignored. Moreover, an unescaped sharp ( # ) outside a character class causes all the following characters, until the first newline (included), to be ignored. This can be used to increase the readability of a pattern string as well as put comments inside regular expressions; this is particularly useful if the pattern string is loaded from a file or written by the user, because in C++ code it is always possible to use the rules for string literals to put comments outside the pattern string. This option corresponds to the /x modifier in Perl regular expressions.
QRegularExpression::InvertedGreedinessOption 0x0010 The greediness of the quantifiers is inverted: * , + , ? , {m,n} , etc. become lazy, while their lazy versions ( *? , +? , ?? , {m,n}? , etc.) become greedy. There is no equivalent for this option in Perl regular expressions.
QRegularExpression::DontCaptureOption 0x0020 The non-named capturing groups do not capture substrings; named capturing groups still work as intended, as well as the implicit capturing group number 0 corresponding to the entire match. There is no equivalent for this option in Perl regular expressions.
QRegularExpression::UseUnicodePropertiesOption 0x0040 The meaning of the \w , \d , etc., character classes, as well as the meaning of their counterparts ( \W , \D , etc.), is changed from matching ASCII characters only to matching any character with the corresponding Unicode property. For instance, \d is changed to match any character with the Unicode Nd (decimal digit) property; \w to match any character with either the Unicode L (letter) or N (digit) property, plus underscore, and so on. This option corresponds to the /u modifier in Perl regular expressions.
QRegularExpression::OptimizeOnFirstUsageOption 0x0080 This option is ignored. A regular expression is automatically optimized (including JIT compiling) the first time it is used. This enum value was introduced in Qt 5.4.
QRegularExpression::DontAutomaticallyOptimizeOption 0x0100 This option is ignored. A regular expression is automatically optimized (including JIT compiling) the first time it is used. This enum value was introduced in Qt 5.4.

The PatternOptions type is a typedef for QFlags <PatternOption>. It stores an OR combination of PatternOption values.

成员函数文档编制

QRegularExpression:: QRegularExpression (const QRegularExpression & re )

Constructs a QRegularExpression object as a copy of re .

另请参阅 operator= ().

QRegularExpression:: QRegularExpression (const QString & pattern , QRegularExpression::PatternOptions options = NoPatternOption)

Constructs a QRegularExpression object using the given pattern as pattern and the options as the pattern options.

另请参阅 setPattern () 和 setPatternOptions ().

QRegularExpression:: QRegularExpression ()

Constructs a QRegularExpression object with an empty pattern and no pattern options.

另请参阅 setPattern () 和 setPatternOptions ().

QRegularExpression &QRegularExpression:: operator= ( QRegularExpression && re )

Move-assigns the regular expression re to this object, and returns a reference to the copy. Both the pattern and the pattern options are copied.

QRegularExpression &QRegularExpression:: operator= (const QRegularExpression & re )

Assigns the regular expression re to this object, and returns a reference to the copy. Both the pattern and the pattern options are copied.

QRegularExpression:: ~QRegularExpression ()

销毁 QRegularExpression 对象。

[static] QString QRegularExpression:: anchoredPattern ( QStringView 表达式 )

返回 表达式 被包裹介于 \A and \z 锚点 (用于准确匹配)。

该函数在 Qt 5.15 引入。

另请参阅 移植自 QRegExp 准确匹配 .

[static] QString QRegularExpression:: anchoredPattern (const QString & 表达式 )

这是重载函数。

该函数在 Qt 5.12 引入。

int QRegularExpression:: captureCount () const

返回模式字符串内的捕获组数,或 -1 若正则表达式无效。

注意: 隐式捕获组 0 not 包括在返回数中。

另请参阅 isValid ().

QString QRegularExpression:: errorString () const

Returns a textual description of the error found when checking the validity of the regular expression, or "no error" if no error was found.

另请参阅 isValid () 和 patternErrorOffset ().

[static] QString QRegularExpression:: escape ( QStringView str )

Escapes all characters of 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:

QString escaped = QRegularExpression::escape("a(x) = f(x) + g(x)");
// escaped == "a\\(x\\)\\ \\=\\ f\\(x\\)\\ \\+\\ g\\(x\\)"
					

This is very convenient in order to build patterns from arbitrary strings:

QString pattern = "(" + QRegularExpression::escape(name) +
                  "|" + QRegularExpression::escape(nickname) + ")";
QRegularExpression re(pattern);
					

注意: This function implements Perl's quotemeta algorithm and escapes with a backslash all characters in str , except for the characters in the [A-Z] , [a-z] and [0-9] ranges, as well as the underscore ( _ ) character. The only difference with Perl is that a literal NUL inside str is escaped with the sequence "\\0" (backslash + '0' ), instead of "\\\0" (backslash + NUL ).

该函数在 Qt 5.15 引入。

[static] QString QRegularExpression:: escape (const QString & str )

这是重载函数。

QRegularExpressionMatchIterator QRegularExpression:: globalMatch (const QString & subject , int offset = 0, QRegularExpression::MatchType matchType = NormalMatch, QRegularExpression::MatchOptions matchOptions = NoMatchOption) const

试图履行正则表达式全局匹配针对给定 subject 字符串,起始于位置 offset 在主题中,使用匹配类型 matchType 且尊重给定 matchOptions .

返回的 QRegularExpressionMatchIterator 位于第 1 匹配结果 (若有的话) 之前。

另请参阅 QRegularExpressionMatchIterator and 全局匹配 .

QRegularExpressionMatchIterator QRegularExpression:: globalMatch (const QStringRef & subjectRef , int offset = 0, QRegularExpression::MatchType matchType = NormalMatch, QRegularExpression::MatchOptions matchOptions = NoMatchOption) const

这是重载函数。

试图履行正则表达式全局匹配针对给定 subjectRef string reference, starting at the position offset 在主题中,使用匹配类型 matchType 且尊重给定 matchOptions .

返回的 QRegularExpressionMatchIterator 位于第 1 匹配结果 (若有的话) 之前。

该函数在 Qt 5.5 引入。

另请参阅 QRegularExpressionMatchIterator and 全局匹配 .

QRegularExpressionMatchIterator QRegularExpression:: globalMatch ( QStringView subject , int offset = 0, QRegularExpression::MatchType matchType = NormalMatch, QRegularExpression::MatchOptions matchOptions = NoMatchOption) const

这是重载函数。

试图履行正则表达式全局匹配针对给定 subject 字符串,起始于位置 offset 在主题中,使用匹配类型 matchType 且尊重给定 matchOptions .

返回的 QRegularExpressionMatchIterator 位于第 1 匹配结果 (若有的话) 之前。

注意: This overload has been added in 5.15.2 to simplify writing code that is portable between Qt 5.15 and Qt 6. The implementation is not tuned for performance in Qt 5.

This function was introduced in Qt 5.15.2.

另请参阅 QRegularExpressionMatchIterator and 全局匹配 .

bool QRegularExpression:: isValid () const

返回 true if the regular expression is a valid regular expression (that is, it contains no syntax errors, etc.), or false otherwise. Use errorString () to obtain a textual description of the error.

另请参阅 errorString () 和 patternErrorOffset ().

QRegularExpressionMatch QRegularExpression:: match (const QString & subject , int offset = 0, QRegularExpression::MatchType matchType = NormalMatch, QRegularExpression::MatchOptions matchOptions = NoMatchOption) const

试图匹配正则表达式针对给定 subject 字符串,起始于位置 offset 在主题中,使用匹配类型 matchType 且尊重给定 matchOptions .

返回的 QRegularExpressionMatch 对象包含匹配结果。

另请参阅 QRegularExpressionMatch and 正常匹配 .

QRegularExpressionMatch QRegularExpression:: match (const QStringRef & subjectRef , int offset = 0, QRegularExpression::MatchType matchType = NormalMatch, QRegularExpression::MatchOptions matchOptions = NoMatchOption) const

这是重载函数。

试图匹配正则表达式针对给定 subjectRef string reference, starting at the position offset 在主题中,使用匹配类型 matchType 且尊重给定 matchOptions .

返回的 QRegularExpressionMatch 对象包含匹配结果。

该函数在 Qt 5.5 引入。

另请参阅 QRegularExpressionMatch and 正常匹配 .

QRegularExpressionMatch QRegularExpression:: match ( QStringView subject , int offset = 0, QRegularExpression::MatchType matchType = NormalMatch, QRegularExpression::MatchOptions matchOptions = NoMatchOption) const

这是重载函数。

试图匹配正则表达式针对给定 subjectRef string reference, starting at the position offset 在主题中,使用匹配类型 matchType 且尊重给定 matchOptions .

返回的 QRegularExpressionMatch 对象包含匹配结果。

注意: This overload has been added in 5.15.2 to simplify writing code that is portable between Qt 5.15 and Qt 6. The implementation is not tuned for performance in Qt 5.

This function was introduced in Qt 5.15.2.

另请参阅 QRegularExpressionMatch and 正常匹配 .

QStringList QRegularExpression:: namedCaptureGroups () const

Returns a list of captureCount () + 1 elements, containing the names of the named capturing groups in the pattern string. The list is sorted such that the element of the list at position i is the name of the i -th capturing group, if it has a name, or an empty string if that capturing group is unnamed.

For instance, given the regular expression

    (?<day>\d\d)-(?<month>\d\d)-(?<year>\d\d\d\d) (\w+) (?<name>\w+)
					

namedCaptureGroups() will return the following list:

    ("", "day", "month", "year", "", "name")
					

which corresponds to the fact that the capturing group #0 (corresponding to the whole match) has no name, the capturing group #1 has name "day", the capturing group #2 has name "month", etc.

If the regular expression is not valid, returns an empty list.

该函数在 Qt 5.1 引入。

另请参阅 isValid (), QRegularExpressionMatch::captured (),和 QString::isEmpty ().

void QRegularExpression:: optimize () const

Compiles the pattern immediately, including JIT compiling it (if the JIT is enabled) for optimization.

该函数在 Qt 5.4 引入。

另请参阅 isValid () 和 使用 QRegularExpression 调试代码 .

QString QRegularExpression:: pattern () const

返回正则表达式的模式字符串。

另请参阅 setPattern () 和 patternOptions ().

int QRegularExpression:: patternErrorOffset () const

Returns the offset, inside the pattern string, at which an error was found when checking the validity of the regular expression. If no error was found, then -1 is returned.

另请参阅 pattern (), isValid (),和 errorString ().

QRegularExpression::PatternOptions QRegularExpression:: patternOptions () const

Returns the pattern options for the regular expression.

另请参阅 setPatternOptions () 和 pattern ().

void QRegularExpression:: setPattern (const QString & pattern )

Sets the pattern string of the regular expression to pattern . The pattern options are left unchanged.

另请参阅 pattern () 和 setPatternOptions ().

void QRegularExpression:: setPatternOptions ( QRegularExpression::PatternOptions options )

设置给定 options as the pattern options of the regular expression. The pattern string is left unchanged.

另请参阅 patternOptions () 和 setPattern ().

void QRegularExpression:: swap ( QRegularExpression & other )

Swaps the regular expression other with this regular expression. This operation is very fast and never fails.

[static] QString QRegularExpression:: wildcardToRegularExpression ( QStringView pattern )

Returns a regular expression representation of the given glob pattern . The transformation is targeting file path globbing, which means in particular that path separators receive special treatment. This implies that it is not just a basic translation from "*" to ".*".

QString wildcard = QRegularExpression::wildcardToRegularExpression("*.jpeg");
// Will match files with names like:
//    foo.jpeg
//    f_o_o.jpeg
//    föö.jpeg
					

The returned regular expression is already fully anchored. In other words, there is no need of calling anchoredPattern () again on the result.

警告: 不像 QRegExp , this implementation follows closely the definition of wildcard for glob patterns:

c Any character represents itself apart from those mentioned below. Thus c 匹配字符 c .
? Matches any single character. It is the same as . in full regexps.
* Matches zero or more of any characters. It is the same as .* in full regexps.
[abc] Matches one character given in the bracket.
[a-c] Matches one character from the range given in the bracket.
[!abc] Matches one character that is not given in the bracket. It is the same as [^abc] in full regexp.
[!a-c] Matches one character that is not from the range given in the bracket. It is the same as [^a-c] in full regexp.

注意: The backslash (\) character is not an escape char in this context. In order to match one of the special characters, place it in square brackets (for example, [?] ).

More information about the implementation can be found in:

该函数在 Qt 5.15 引入。

另请参阅 escape ().

[static] QString QRegularExpression:: wildcardToRegularExpression (const QString & pattern )

这是重载函数。

该函数在 Qt 5.12 引入。

bool QRegularExpression:: operator!= (const QRegularExpression & re ) const

返回 true 若正则表达式不同于 re ,或 false 否则。

另请参阅 operator== ().

bool QRegularExpression:: operator== (const QRegularExpression & re ) const

返回 true 若正则表达式等于 re ,或 false 否则。两 QRegularExpression objects are equal if they have the same pattern string and the same pattern options.

另请参阅 operator!= ().

相关非成员

uint qHash (const QRegularExpression & key , uint seed = 0)

返回哈希值为 key ,使用 seed 做计算种子。

该函数在 Qt 5.6 引入。

QDataStream & operator<< ( QDataStream & out , const QRegularExpression & re )

写入正则表达式 re 到流 out .

另请参阅 序列化 Qt 数据类型 .

QDebug operator<< ( QDebug debug , const QRegularExpression & re )

写入正则表达式 re 到 debug 对象 debug 为调试目的。

另请参阅 调试技术 .

QDebug operator<< ( QDebug debug , QRegularExpression::PatternOptions patternOptions )

写入模式选项 patternOptions 到 debug 对象 debug 为调试目的。

另请参阅 调试技术 .

QDataStream & operator>> ( QDataStream & in , QRegularExpression & re )

读取正则表达式从流 in into re .

另请参阅 序列化 Qt 数据类型 .