src_corelib_text_qregularexpression.cpp

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// Copyright (C) 2016 Giuseppe D'Angelo <dangelog@gmail.com>.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
 
#include <QString>
#include <QStringList>
#include <QRegularExpression>
#include <QRegularExpressionMatch>
#include <QRegularExpressionMatchIterator>
 
int main() {
 
{
QRegularExpression re("a pattern");
}
 
{
QRegularExpression re;
re.setPattern("another pattern");
}
 
{
// matches two digits followed by a space and a word
QRegularExpression re("\\d\\d \\w+");
 
// matches a backslash
QRegularExpression re2("\\\\");
}
 
{
QRegularExpression re("a third pattern");
QString pattern = re.pattern(); // pattern == "a third pattern"
}
 
{
// matches "Qt rocks", but also "QT rocks", "QT ROCKS", "qT rOcKs", etc.
QRegularExpression re("Qt rocks", QRegularExpression::CaseInsensitiveOption);
}
 
{
QRegularExpression re("^\\d+$");
re.setPatternOptions(QRegularExpression::MultilineOption);
// re matches any line in the subject string that contains only digits (but at least one)
}
 
{
QRegularExpression re = QRegularExpression("^two.*words$", QRegularExpression::MultilineOption
                                                           | QRegularExpression::DotMatchesEverythingOption);
 
QRegularExpression::PatternOptions options = re.patternOptions();
// options == QRegularExpression::MultilineOption | QRegularExpression::DotMatchesEverythingOption
}
 
{
// 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
}
 
{
QRegularExpression re("\\d\\d \\w+");
QRegularExpressionMatch match = re.match("abc123 def");
if (match.hasMatch()) {
    QString matched = match.captured(0); // matched == "23 def"
    // ...
}
}
 
{
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"
    // ...
}
}
 
{
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"
    // ...
}
}
 
{
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
    // ...
}
}
 
{
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
}
}
 
{
QRegularExpression re("(\\w+)");
QRegularExpressionMatchIterator i = re.globalMatch("the quick fox");
 
QStringList words;
while (i.hasNext()) {
    QRegularExpressionMatch match = i.next();
    QString word = match.captured(1);
    words << word;
}
// words contains "the", "quick", "fox"
}
 
{
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
}
 
{
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("Dec 8, 1985");
QRegularExpressionMatch match = re.match(input, 0, QRegularExpression::PartialPreferCompleteMatch);
bool hasMatch = match.hasMatch(); // true
bool hasPartialMatch = match.hasPartialMatch(); // false
}
 
{
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"
}
 
{
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"
}
 
{
QRegularExpression re("abc|ab");
QRegularExpressionMatch match = re.match("ab", 0, QRegularExpression::PartialPreferFirstMatch);
bool hasMatch = match.hasMatch(); // false
bool hasPartialMatch = match.hasPartialMatch(); // true
}
 
{
QRegularExpression re("abc(def)?");
QRegularExpressionMatch match = re.match("abc", 0, QRegularExpression::PartialPreferFirstMatch);
bool hasMatch = match.hasMatch(); // false
bool hasPartialMatch = match.hasPartialMatch(); // true
}
 
{
QRegularExpression re("(abc)*");
QRegularExpressionMatch match = re.match("abc", 0, QRegularExpression::PartialPreferFirstMatch);
bool hasMatch = match.hasMatch(); // false
bool hasPartialMatch = match.hasPartialMatch(); // true
}
 
{
QRegularExpression invalidRe("(unmatched|parenthesis");
bool isValid = invalidRe.isValid(); // false
}
 
{
QRegularExpression invalidRe("(unmatched|parenthesis");
if (!invalidRe.isValid()) {
    QString errorString = invalidRe.errorString(); // errorString == "missing )"
    int errorOffset = invalidRe.patternErrorOffset(); // errorOffset == 22
    // ...
}
}
 
{
QString escaped = QRegularExpression::escape("a(x) = f(x) + g(x)");
// escaped == "a\\‍(x\\‍)\\ \\=\\ f\\‍(x\\‍)\\ \\+\\ g\\‍(x\\‍)"
}
 
{
QString name;
QString nickname;
QString pattern = "(" + QRegularExpression::escape(name) +
                  "|" + QRegularExpression::escape(nickname) + ")";
QRegularExpression re(pattern);
}
 
{
QString string;
QRegularExpression re;
QRegularExpressionMatch match = re.match(string);
for (int i = 0; i <= match.lastCapturedIndex(); ++i) {
    QString captured = match.captured(i);
    // ...
}
}
 
{
QRegularExpression re("(\\d\\d) (?<name>\\w+)");
QRegularExpressionMatch match = re.match("23 Jordan");
if (match.hasMatch()) {
    QString number = match.captured(1); // first == "23"
    QString name = match.captured("name"); // name == "Jordan"
}
}
 
{
// extracts the words
QRegularExpression re("(\\w+)");
QString subject("the quick fox");
QRegularExpressionMatchIterator i = re.globalMatch(subject);
while (i.hasNext()) {
    QRegularExpressionMatch match = i.next();
    // ...
}
}
 
{
QString wildcard = QRegularExpression::wildcardToRegularExpression("*.jpeg");
// Will match files with names like:
//    foo.jpeg
//    f_o_o.jpeg
//    föö.jpeg
}
 
    (?<day>\d\d)-(?<month>\d\d)-(?<year>\d\d\d\d) (\w+) (?<name>\w+)
 
    ("", "day", "month", "year", "", "name")
 
{
// using a raw string literal, R"(raw_characters)", to be able to use "\w"
// without having to escape the backslash as "\\w"
QRegularExpression re(R"(\w+)");
QString subject("the quick fox");
for (const QRegularExpressionMatch &match : re.globalMatch(subject)) {
    // ...
}
}
 
{
// matches two digits followed by a space and a word
QRegularExpression re(R"(\d\d \w+)");
}
 
{
QRegularExpression re("([a-z]+)|([A-Z]+)");
QRegularExpressionMatch m = re.match("UPPERCASE");
if (m.hasMatch()) {
    qDebug() << m.hasCaptured(0); // true
    qDebug() << m.hasCaptured(1); // false
    qDebug() << m.hasCaptured(2); // true
}
}
 
}