With regards to a minifier, I see no reason it couldn't compact it to the regex we have today. After all, the only changes are the addition of whitespace and comments.
I can't speak as to parse time, though in production that would large be removed by the aforementioned minification. String concatenation certainly works, but then any escapes have to be doubly so, else you use `String.raw` on template literals in every situation, quickly cluttering things back up. On Tue, Jun 4, 2019, 00:36 kai zhu <[email protected]> wrote: > 1. is this minifier-friendly? > 2. is parsing-impact minimal enough to not affect load-times? > regexp-detection/bounding is among the most expensive/complex part of > javascript-parsing. > > those 2 nits aside, i'm on the fence. regexp-spaghetti is a valid > painpoint, and jslint's author has expressed desire for multiline regexp > [1]. otoh, there is a good-enough solution by falling-back to > constructor-form to improve readability: > > ```js > // real-world spaghetti-regexp code in jslint.js > const rx_token = > /^((\s+)|([a-zA-Z_$][a-zA-Z0-9_$]*)|[(){}\[\],:;'"~`]|\?\.?|=(?:==?|>)?|\.+|[*\/][*\/=]?|\+[=+]?|-[=\-]?|[\^%]=?|&[&=]?|\|[|=]?|>{1,3}=?|<<?=?|!(?:!|==?)?|(0|[1-9][0-9]*))(.*)$/; > > // vs > > /* > * break JSON.stringify(rx_token.source) > * into multiline constructor-form for readability > */ > const rx_token = new RegExp( > "^(" > + "(\\s+)" > + "|([a-zA-Z_$][a-zA-Z0-9_$]*)" > + "|[(){}\\[\\],:;'\"~`]" > + "|\\?\\.?" > + "|=(?:==?|>)?" > + "|\\.+" > + "|[*\\/][*\\/=]?" > + "|\\+[=+]?" > + "|-[=\\-]?" > + "|[\\^%]=?" > + "|&[&=]?" > + "|\\|[|=]?" > + "|>{1,3}=?" > + "|<<?=?" > + "|!(?:!|==?)?" > + "|(0|[1-9][0-9]*)" > + ")(.*)$" > ); > ``` > > [1] github jslint-issue #231 - ignore long regexp's (and comments) > https://github.com/douglascrockford/JSLint/pull/231#issuecomment-421881426 > > > > > On Mon, Jun 3, 2019 at 10:27 PM Jacob Pratt <[email protected]> wrote: > >> Even if this flag were restricted to constructors instead of both >> constructors and literals, it could be worthwhile. >> >> On Mon, Jun 3, 2019, 23:19 Isiah Meadows <[email protected]> wrote: >> >>> Let me clarify that previous message: I mean "newline restriction" in >>> the sense that newlines are not permitted in regexp literals. A `/x` >>> flag would make removing it practically required for it to have any >>> utility. >>> >>> ----- >>> >>> Isiah Meadows >>> [email protected] >>> www.isiahmeadows.com >>> >>> On Mon, Jun 3, 2019 at 11:14 PM Isiah Meadows <[email protected]> >>> wrote: >>> > >>> > I would personally love this (as well as interpolations in regexp >>> > literals). I do have a concern about whether removing the newline >>> > restriction creates ambiguities with division, but I suspect this is >>> > *not* the case. >>> > >>> > ----- >>> > >>> > Isiah Meadows >>> > [email protected] >>> > www.isiahmeadows.com >>> > >>> > On Mon, Jun 3, 2019 at 10:03 PM Jacob Pratt <[email protected]> >>> wrote: >>> > > >>> > > Has there been any previous discussion of adding the `x` flag to JS? >>> It exists in other languages, and can make relatively complicated regex >>> _much_ easier to read. It also allows for comments, which are incredibly >>> helpful when trying to understand some regexes. >>> > > >>> > > For prior art, XRegExp has this flag (though I've no idea to figure >>> out how frequently it's used), as do a few other languages. >>> > > >>> > > Quick overview: >>> https://www.regular-expressions.info/freespacing.html >>> > > >>> > > Language references: >>> > > Python: https://docs.python.org/3/library/re.html#re.X >>> > > Rust: https://docs.rs/regex/1.1.6/regex/ >>> > > XRegExp: http://xregexp.com/xregexp/flags/#extended >>> > > .NET: >>> https://docs.microsoft.com/en-us/dotnet/standard/base-types/regular-expression-language-quick-reference#regular-expression-options >>> > > >>> > > Jacob Pratt >>> > > _______________________________________________ >>> > > es-discuss mailing list >>> > > [email protected] >>> > > https://mail.mozilla.org/listinfo/es-discuss >>> >> _______________________________________________ >> es-discuss mailing list >> [email protected] >> https://mail.mozilla.org/listinfo/es-discuss >> >
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