patternwildcard.cpp

/****************************************************************************
**
** Copyright (C) 2020 Giuseppe D'Angelo <dangelog@gmail.com>.
** Copyright (C) 2020 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
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// Copy of QRegularExpression::wildcardToRegularExpression from Qt 5.15 for use
// with Qt < 5.12

#include "pattern.h"

#if QT_VERSION < QT_VERSION_CHECK(5, 12, 0)
static inline QString anchoredPattern(const QString &expression)
{
    return QLatin1String("\\A(?:")
           + expression
           + QLatin1String(")\\z");
}

QString Pattern::wildcardToRegularExpression(const QString &pattern)
{
    const int wclen = pattern.length();
    QString rx;
    rx.reserve(wclen + wclen / 16);
    int i = 0;
    const QChar *wc = pattern.data();

#ifdef Q_OS_WIN
    const QLatin1Char nativePathSeparator('\\');
    const QLatin1String starEscape("[^/\\\\]*");
    const QLatin1String questionMarkEscape("[^/\\\\]");
#else
    const QLatin1Char nativePathSeparator('/');
    const QLatin1String starEscape("[^/]*");
    const QLatin1String questionMarkEscape("[^/]");
#endif

    while (i < wclen) {
        const QChar c = wc[i++];
        switch (c.unicode()) {
        case '*':
            rx += starEscape;
            break;
        case '?':
            rx += questionMarkEscape;
            break;
        case '\\':
#ifdef Q_OS_WIN
        case '/':
            rx += QLatin1String("[/\\\\]");
            break;
#endif
        case '$':
        case '(':
        case ')':
        case '+':
        case '.':
        case '^':
        case '{':
        case '|':
        case '}':
            rx += QLatin1Char('\\');
            rx += c;
            break;
        case '[':
            rx += c;
            // Support for the [!abc] or [!a-c] syntax
            if (i < wclen) {
                if (wc[i] == QLatin1Char('!')) {
                    rx += QLatin1Char('^');
                    ++i;
                }

                if (i < wclen && wc[i] == QLatin1Char(']'))
                    rx += wc[i++];

                while (i < wclen && wc[i] != QLatin1Char(']')) {
                    // The '/' appearing in a character class invalidates the
                    // regular expression parsing. It also concerns '\\' on
                    // Windows OS types.
                    if (wc[i] == QLatin1Char('/') || wc[i] == nativePathSeparator)
                        return rx;
                    if (wc[i] == QLatin1Char('\\'))
                        rx += QLatin1Char('\\');
                    rx += wc[i++];
                }
            }
            break;
        default:
            rx += c;
            break;
        }
    }

    return anchoredPattern(rx);
}
#endif