Regular expression quirk?

[Ammar Ali]

Hello,

AFAIK, there are no possessive quantifiers in 1.9, so I expected a
syntax error from this:
=> /cats?+/

It worked and it works, but the + is meaningless it seems:
=> #<MatchData "cats">

Interestingly, the + is "preserved":
=> "cats?+"

Does this make sense to anyone?

Thanks,
Ammar

 

[Robert Klemme]

AFAIK, there are no possessive quantifiers in 1.9,

You are misinformed. Where did you get that information? Please see:

http://www.geocities.jp/kosako3/oniguruma/doc/RE.txt

Kind regards

robert

 

[Ammar Ali]

You are misinformed. =C2=A0Where did you get that information? =C2=A0Plea= se see:

http://www.geocities.jp/kosako3/oniguruma/doc/RE.txt

I don't recall how I ended up with that "fact". I was probably looking
at a very old version of that file, or confused by ({n,m}+, {n,}+,
{n}+ are possessive op. in ONIG_SYNTAX_JAVA only).

It makes perfect sense now, and quite a relief for my work.

Thanks,
Ammar

 

[Ammar Ali]

One more thing, Read Ruby
(http://ruby.runpaint.org/regexps#quantifiers) doesn't even mention
possessive quantifiers. Hmmm.

Not everything in Oniguruma is supported in ruby. I guess I need to
verify this further.

Thanks,
Ammar

 

[Robert Klemme]

One more thing, Read Ruby
(http://ruby.runpaint.org/regexps#quantifiers) doesn't even mention
possessive quantifiers. Hmmm.

Not everything in Oniguruma is supported in ruby. I guess I need to
verify this further.

irb(main):001:0> /a+a/ =3D~ "aaa"
=3D> 0
irb(main):002:0> /a++a/ =3D~ "aaa"
=3D> nil

What else do you need to verify?

Cheers

robert


--=20
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/

 

[Ammar Ali]

On Wed, Oct 27, 2010 at 1:47 PM, Robert Klemme

irb(main):001:0> /a+a/ =3D~ "aaa"
=3D> 0
irb(main):002:0> /a++a/ =3D~ "aaa"
=3D> nil

What else do you need to verify?

I ran similar tests and they work as expected from possessives, so I'm
sure they are supported. I would like to see it clearly stated in ruby
documentation. I logged an issue about it for Read Ruby
http://github.com/runpaint/read-ruby/issues#issue/74

Thanks again,
Ammar