Thank you :) Is this worth adding to the regexp/syntax documentation? I'd
happily contribute a patch.
On Tuesday, January 7, 2020 at 7:36:02 PM UTC+1, Ian Lance Taylor wrote:
>
> On Tue, Jan 7, 2020 at 10:22 AM Tom Payne <twp...@gmail.com <javascript:>>
> wrote:
> >
> > tl;dr How should I use named Unicode character classes in regexps?
> >
> > I'm trying to write a regular expression that matches Go identifiers,
> which start with a Unicode letter or underscore followed by zero or more
> Unicode letters, decimal digits, and/or underscores.
> >
> > Based on the regexp syntax, and the variables in the unicode package
> which mention the classes "Letter" and "Number, decimal digit", I was
> expecting to write something like:
> >
> > identiferRegexp :=
> regexp.MustCompile(`\A[[\p{Letter}]_][[\p{Letter}][\p{Number, decimal
> digit}]_]*\z`)
> >
> > However, this pattern does not compile, giving the error:
> >
> > regexp: Compile(`\A[[\p{Letter}]_][[\p{Letter}][\p{Number, decimal
> digit}]_]*\z`): error parsing regexp: invalid character class range:
> `\p{Letter}`
> >
> > Using the short name for character classes (L for Letter, Nd for Number,
> decimal digit) does work however:
> >
> > identiferRegexp := regexp.MustCompile(`\A[\pL_][\pL\p{Nd}_]*\z`)
> >
> > You can play with these regexps on play.golang.org.
> >
> > Is this simply an oversight that Unicode character classes like "Letter"
> and "Number, decimal digit" are not available for use in regexps, or should
> I be using them differently?
>
> The strings you can use with \p are the ones listed in
> unicode.Categories and unicode.Scripts. So use \pL as you do in the
> second example.
>
> Ian
>
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