code review 6543068: regexp/syntax: define accepted syntax

regexp/syntax: define accepted syntax

Update issue 3953.

[rsc, 2012-09-24 16:19:08]

Hello golang-dev@googlegroups.com,

I'd like you to review this change to
https://go.googlecode.com/hg/

[rsc, 2012-09-24 16:21:43]

Related: http://codereview.appspot.com/6555056

[bradfitz, 2012-09-24 16:31:43]

LGTM

https://codereview.appspot.com/6543068/diff/5001/src/pkg/regexp/syntax/doc.go
File src/pkg/regexp/syntax/doc.go (right):

https://codereview.appspot.com/6543068/diff/5001/src/pkg/regexp/syntax/doc.go...
src/pkg/regexp/syntax/doc.go:19: .              any character, including newline
(flag s=true)
I know what this does, but the description seems confusing.

I see you use this style below too, but it's not obvious to me at least that
(flag X=true) means the preceding phrase is conditional.

"any character, including newline if (flag s=true)" ?

It's better described in the table at the bottom at least.

https://codereview.appspot.com/6543068/diff/5001/src/pkg/regexp/syntax/doc.go...
src/pkg/regexp/syntax/doc.go:61: U              ungreedy: swap meaning of x* and
x*?, x+ and x+?, etc (default false)
whoa. didn't know about U.

[rsc, 2012-09-24 16:52:38]

http://codereview.appspot.com/6543068/diff/5001/src/pkg/regexp/syntax/doc.go
File src/pkg/regexp/syntax/doc.go (right):

http://codereview.appspot.com/6543068/diff/5001/src/pkg/regexp/syntax/doc.go#...
src/pkg/regexp/syntax/doc.go:19: .              any character, including newline
(flag s=true)
On 2012/09/24 16:31:43, bradfitz wrote:
> I know what this does, but the description seems confusing.
> 
> I see you use this style below too, but it's not obvious to me at least that
> (flag X=true) means the preceding phrase is conditional.
> 
> "any character, including newline if (flag s=true)" ?
> 
> It's better described in the table at the bottom at least.
> 

Done.

[francesc, 2012-09-24 19:12:49]

Just some details, I'm very happy that looking for "group" or "numbered" works
now :-)

http://codereview.appspot.com/6543068/diff/3004/src/pkg/regexp/syntax/doc.go
File src/pkg/regexp/syntax/doc.go (right):

http://codereview.appspot.com/6543068/diff/3004/src/pkg/regexp/syntax/doc.go#...
src/pkg/regexp/syntax/doc.go:14: The regular expression understood by this
package when parsing with the Perl flag is as follows.
I'd use the plural here, but I'm not a native speaker.
s/expression/expressions/
s/is as/are as/

http://codereview.appspot.com/6543068/diff/3004/src/pkg/regexp/syntax/doc.go#...
src/pkg/regexp/syntax/doc.go:39: x{n,m}         n or n+1 or ... or m x, prefer
more
prefer m?

http://codereview.appspot.com/6543068/diff/3004/src/pkg/regexp/syntax/doc.go#...
src/pkg/regexp/syntax/doc.go:42: x*?            zero or more x, prefer fewer
prefer zero?

http://codereview.appspot.com/6543068/diff/3004/src/pkg/regexp/syntax/doc.go#...
src/pkg/regexp/syntax/doc.go:47: x{n}?          exactly n x
Just curious, is there any difference with "x{n}" ?

[rsc, 2012-09-24 19:19:56]

http://codereview.appspot.com/6543068/diff/3004/src/pkg/regexp/syntax/doc.go
File src/pkg/regexp/syntax/doc.go (right):

http://codereview.appspot.com/6543068/diff/3004/src/pkg/regexp/syntax/doc.go#...
src/pkg/regexp/syntax/doc.go:14: The regular expression understood by this
package when parsing with the Perl flag is as follows.
On 2012/09/24 19:12:49, campoy1 wrote:
> I'd use the plural here, but I'm not a native speaker.
> s/expression/expressions/
> s/is as/are as/

In general I try to use the singular form when writing technical documentation,
as it is often more precise. However, this is just a bug: I meant to say
"regular expression syntax". Fixed.

http://codereview.appspot.com/6543068/diff/3004/src/pkg/regexp/syntax/doc.go#...
src/pkg/regexp/syntax/doc.go:39: x{n,m}         n or n+1 or ... or m x, prefer
more
On 2012/09/24 19:12:49, campoy1 wrote:
> prefer m?

No, it's prefer more. Prefer m does not explain what you get if the choice comes
down to n+4 or n+5.

http://codereview.appspot.com/6543068/diff/3004/src/pkg/regexp/syntax/doc.go#...
src/pkg/regexp/syntax/doc.go:42: x*?            zero or more x, prefer fewer
On 2012/09/24 19:12:49, campoy1 wrote:
> prefer zero?

Same.

http://codereview.appspot.com/6543068/diff/3004/src/pkg/regexp/syntax/doc.go#...
src/pkg/regexp/syntax/doc.go:47: x{n}?          exactly n x
On 2012/09/24 19:12:49, campoy1 wrote:
> Just curious, is there any difference with "x{n}" ?

No.

[rsc, 2012-09-24 19:22:01]

PTAL

[francesc, 2012-09-24 19:25:24]

LGTM

[rsc, 2012-09-24 19:34:02]

*** Submitted as http://code.google.com/p/go/source/detail?r=ba5179494219 ***

regexp/syntax: define accepted syntax

Update issue 3953.

R=bradfitz, campoy
CC=golang-dev
http://codereview.appspot.com/6543068