On Tue, Jan 7, 2020 at 10:39 AM Tom Payne <twpa...@gmail.com> wrote:
>
> Thank you :) Is this worth adding to the regexp/syntax documentation? I'd
> happily contribute a patch.
I think so, if it can be described precisely and tersely. Thanks.
Ian
> 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> 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
>
> --
> You received this message because you are subscribed to the Google Groups
> "golang-nuts" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to golang-nuts+unsubscr...@googlegroups.com.
> To view this discussion on the web visit
> https://groups.google.com/d/msgid/golang-nuts/a22421cc-becb-496e-8d32-b41506536a54%40googlegroups.com.
--
You received this message because you are subscribed to the Google Groups
"golang-nuts" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to golang-nuts+unsubscr...@googlegroups.com.
To view this discussion on the web visit
https://groups.google.com/d/msgid/golang-nuts/CAOyqgcWZan2r3FX_UcE6XNT7vanDLUBi3QjFhyuO0%3DEZ-yG0pA%40mail.gmail.com.
