[Interest] Javascript: regex: no /s flag support?

[ivan tkachenko]

Hi,

On Thursday, November 25, 2021 11:47:19 PM MSK Alexander Dyagilev wrote:
> I'm trying to:
> 
> var re = new RegExp('someregex', 's');
> 
> Getting error: SyntaxError: Invalid flags supplied to RegExp constructor.

At least in qtbase/src/corelib/text/qregularexpression.h[1] file there is a 
QRegularExpression::DotMatchesEverythingOption enum constant. Which means it's 
just a matter of checking for QV4 engine implementation of those flags. Here's 
what in qv4regexp{_p.h,cpp} files[2][3], either in the struct RegExp : Base {} 
declaration, or in flagsAsString() method:

    bool global() const;
    bool ignoreCase() const;
    bool multiLine() const;
    bool unicode() const;
    bool sticky() const;

(little bit stripped down for convenience of the reader)

    QString result;
    if (flags & RegExp_Global)
        result += 'g';
    if (flags & RegExp_IgnoreCase)
        result += 'i';
    if (flags & RegExp_Multiline)
        result += 'm';
    if (flags & RegExp_Unicode)
        result += 'u';
    if (flags & RegExp_Sticky)
        result += 'y';
    return result;

If we compare that to the MDN docs[4], we can see that exactly two out of 
seven flags are missing.

> Can anything be done for '.' to match _any_ character?

Not practically, no. But you can contribute upstream, or in the meantime 
create your own wrapper class in C++ that would #include Qt's private headers 
or something.

[1]: https://code.woboq.org/qt5/qtbase/src/corelib/text/
qregularexpression.h.html#QRegularExpression::DotMatchesEverythingOption
[2]: https://code.woboq.org/qt5/qtdeclarative/src/qml/jsruntime/
qv4regexp_p.h.html
[3]: https://code.woboq.org/qt5/qtdeclarative/src/qml/jsruntime/
qv4regexp.cpp.html
[4]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/
Regular_Expressions#advanced_searching_with_flags


-- 
ivan (@ratijas)
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