does emacs regular expression support (?!expression)

does emacs regular expression support (?!expression)

[土星五号]

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does emacs regular expression support (?!expression)  ?

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Re: does emacs regular expression support (?!expression)

[Tassilo Horn]

土星五号 <laf163@gmail.com> writes:

> does emacs regular expression support (?!expression) ?

It would be more helpful if you'd tell us what (?!expression) would
match, preferably with some examples.  Syntactically, emacs regexp's shy
groups look similar.  The regular expression

  "\\(:?foo\\|bar\\)\\([0-9]+\\)"

matches "foo19" or "bar23", but doesn't capture foo or bar, so that
(match-string 1) is the number.

Bye,
Tassilo

Re: does emacs regular expression support (?!expression)

[Tim Landscheidt]

Tassilo Horn <tassilo@member.fsf.org> wrote:

>> does emacs regular expression support (?!expression) ?

> It would be more helpful if you'd tell us what (?!expression) would
> match, preferably with some examples.  Syntactically, emacs regexp's shy
> groups look similar.  The regular expression

>   "\\(:?foo\\|bar\\)\\([0-9]+\\)"

> matches "foo19" or "bar23", but doesn't capture foo or bar, so that
> (match-string 1) is the number.

In Perl, "(?!pattern)" is a zero-width negative look-ahead
assertion.  Emacs does not support these AFAIK.

Tim

Re: does emacs regular expression support (?!expression)

[Tassilo Horn]

Tim Landscheidt <tim@tim-landscheidt.de> writes:

Hi Tim,

>> It would be more helpful if you'd tell us what (?!expression) would
>> match, preferably with some examples.  Syntactically, emacs regexp's shy
>> groups look similar.  The regular expression
>
>>   "\\(:?foo\\|bar\\)\\([0-9]+\\)"

BTW, that should have been (?:...).

>> matches "foo19" or "bar23", but doesn't capture foo or bar, so that
>> (match-string 1) is the number.
>
> In Perl, "(?!pattern)" is a zero-width negative look-ahead
> assertion.  Emacs does not support these AFAIK.

I see.  So when you do /foo(?!bar)/ in Perl, you'd need to do
"foo\\(?:[^b][^a][^r]\\)" in elisp.

Bye,
Tassilo

Re: does emacs regular expression support (?!expression)

[Tim Landscheidt]

Tassilo Horn <tassilo@member.fsf.org> wrote:

> [...]

>>> matches "foo19" or "bar23", but doesn't capture foo or bar, so that
>>> (match-string 1) is the number.

>> In Perl, "(?!pattern)" is a zero-width negative look-ahead
>> assertion.  Emacs does not support these AFAIK.

> I see.  So when you do /foo(?!bar)/ in Perl, you'd need to do
> "foo\\(?:[^b][^a][^r]\\)" in elisp.

You have to account for possible end-of-buffer as well so
usually it's "easier" to use two matches ('(while (and
(search-forward-regexp "foo") (not (looking-at "bar"))))'
(untested)) - that's why I (still :-)) think these features
should be implemented in Emacs as well.

Tim

Re: does emacs regular expression support (?!expression)

[Tim Landscheidt]

I wrote:

>> [...]

>>>> matches "foo19" or "bar23", but doesn't capture foo or bar, so that
>>>> (match-string 1) is the number.

>>> In Perl, "(?!pattern)" is a zero-width negative look-ahead
>>> assertion.  Emacs does not support these AFAIK.

>> I see.  So when you do /foo(?!bar)/ in Perl, you'd need to do
>> "foo\\(?:[^b][^a][^r]\\)" in elisp.

> You have to account for possible end-of-buffer as well so
> usually it's "easier" to use two matches ('(while (and
> (search-forward-regexp "foo") (not (looking-at "bar"))))'
> (untested)) - [...]

Eh, yes, there is an "(untested)", but still the logic is
obviously plain wrong.  But you get the idea.

Tim

Re: does emacs regular expression support (?!expression)

[Kevin Rodgers]

On 2/2/12 2:45 PM, Tassilo Horn wrote:
> Tim Landscheidt<tim@tim-landscheidt.de>  writes:

>> In Perl, "(?!pattern)" is a zero-width negative look-ahead
>> assertion.  Emacs does not support these AFAIK.
>
> I see.  So when you do /foo(?!bar)/ in Perl, you'd need to do
> "foo\\(?:[^b][^a][^r]\\)" in elisp.

IIUC, the Perl regex would successfully match "foo" if it were followed by
"far", but the Emacs regexp would not.

Maybe \(?:[^b][^a][^r]\) should be \(?:[^b]\|b[^a]\|ba[^r]\)

-- 
Kevin Rodgers
Denver, Colorado, USA

Re: does emacs regular expression support (?!expression)

[土星五号]

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I would like match Err in any words(e.g. LastError), but not ErrorMode.
(defvar txt-mode-font-lock-keywords
  `(
    ;; 文件名
    ("\\\\\\(\\w+\\.exe\\)" 1 font-lock-keyword-face)
    ;; IP和版本

("[^0-9]\\([0-9]\\{1,3\\}\\.[0-9]\\{1,3\\}\\.[0-9]\\{1,3\\}\\.[0-9]\\{1,3\\}\\)"
1 font-lock-keyword-face)
    ;; Error
    ("\\<\\([Dd][Bb][Ee][Rr][Rr][Oo][Rr]\\)\\>" 1 font-lock-warning-face)
    ("\\<\\([Dd][Bb][Ee][Rr][Rr]\\)\\>" 1 font-lock-warning-face)
    ("\\<\\([Ee][Rr][Rr][Oo][Rr]\\)\\>" 1 font-lock-warning-face)
    ("\\([Ee][Rr][Rr]\\)\\(?!orMode\\)" 1 font-lock-warning-face)
    ("\\(错误\\)" 1 font-lock-warning-face)
    ("\\(失败\\)" 1 font-lock-warning-face)
    ("\\(严重\\)" 1 font-lock-warning-face)
    ("\\<\\([Ff][Aa][Ii][Ll][Ee][Dd]\\)\\>" 1 font-lock-warning-face)
    ("\\<\\([Ff][Aa][Ii][Ll]\\)\\>" 1 font-lock-warning-face)
    ("\\<\\([Cc][Aa][Nn]\\s+[Nn][Oo][Tt]\\)\\>" 1 font-lock-warning-face)
    ("\\<\\([Cc][Aa][Nn]'[Tt]\\)\\>" 1 font-lock-warning-face)
    ("\\<\\([Ww][Rr][Oo][Nn][Gg]\\)\\>" 1 font-lock-warning-face)
    ;; Warning
    ("\\<\\([Ww][Aa][Rr][Nn][Ii][Nn][Gg]\\)\\>" 1 font-lock-warning-face)
    ("\\<\\([Ww][Aa][Rr][Nn]\\)\\>" 1 font-lock-warning-face)
    ("\\(警告\\)" 1 font-lock-warning-face)
    ;; Exception
    ("\\<\\([Ee][Xx][Cc][Ee][Pp][Tt][Ii][Oo][Nn]\\)\\>" 1
font-lock-warning-face)
    ("\\<\\([Ee][Xx][Cc][Ee][Pp][Tt]\\)\\>" 1 font-lock-warning-face)
    ("\\(异常\\)" 1 font-lock-warning-face)
    )
  "Basic font lock keywords for txt mode.  Highlights keywords.")

2012/2/3 Kevin Rodgers <kevin.d.rodgers@gmail.com>

> On 2/2/12 2:45 PM, Tassilo Horn wrote:
>
>> Tim Landscheidt<tim@tim-**landscheidt.de <tim@tim-landscheidt.de>>
>>  writes:
>>
>
>  In Perl, "(?!pattern)" is a zero-width negative look-ahead
>>> assertion.  Emacs does not support these AFAIK.
>>>
>>
>> I see.  So when you do /foo(?!bar)/ in Perl, you'd need to do
>> "foo\\(?:[^b][^a][^r]\\)" in elisp.
>>
>
> IIUC, the Perl regex would successfully match "foo" if it were followed by
> "far", but the Emacs regexp would not.
>
> Maybe \(?:[^b][^a][^r]\) should be \(?:[^b]\|b[^a]\|ba[^r]\)
>
> --
> Kevin Rodgers
> Denver, Colorado, USA
>
>
>

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Re: does emacs regular expression support (?!expression)

[Thien-Thi Nguyen]

() 土星五号 <laf163@gmail.com>
() Fri, 3 Feb 2012 10:12:27 +0800

   I would like match Err in any words(e.g. LastError), but not ErrorMode.

       ("\\([Ee][Rr][Rr]\\)\\(?!orMode\\)" 1 font-lock-warning-face)

You can add a spec for ‘ErrorMode’, with default face, prior to this one.

Re: does emacs regular expression support (?!expression)

[Tim Landscheidt]

Thien-Thi Nguyen <ttn@gnuvola.org> wrote:

>    I would like match Err in any words(e.g. LastError), but not ErrorMode.

>        ("\\([Ee][Rr][Rr]\\)\\(?!orMode\\)" 1 font-lock-warning-face)

> You can add a spec for ‘ErrorMode’, with default face, prior to this one.

Which Emacs version does support that?

Tim

Re: does emacs regular expression support (?!expression)

[Thien-Thi Nguyen]

() Tim Landscheidt <tim@tim-landscheidt.de>
() Fri, 03 Feb 2012 11:17:25 +0000

   > You can add a spec for ‘ErrorMode’, with default face, prior to this one.

   Which Emacs version does support that?

Any that processes these specs in the given order, with
"masking semantics", i suppose.  (I haven't tried.)

Re: does emacs regular expression support (?!expression)

[Tim Landscheidt]

Thien-Thi Nguyen <ttn@gnuvola.org> wrote:

>    > You can add a spec for ‘ErrorMode’, with default face, prior to this one.

>    Which Emacs version does support that?

> Any that processes these specs in the given order, with
> "masking semantics", i suppose.  (I haven't tried.)

What does:

| (search-forward-regexp "\\([Ee][Rr][Rr]\\)\\(?!orMode\\)")

give on your Emacs?

Tim

Re: does emacs regular expression support (?!expression)

[土星五号]

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No, i put it in txt-mode-load.el.

 .emacs:
(require 'txt-mode-load)



2012/2/4 Tim Landscheidt <tim@tim-landscheidt.de>

> Thien-Thi Nguyen <ttn@gnuvola.org> wrote:
>
> >    > You can add a spec for ‘ErrorMode’, with default face, prior to
> this one.
>
> >    Which Emacs version does support that?
>
> > Any that processes these specs in the given order, with
> > "masking semantics", i suppose.  (I haven't tried.)
>
> What does:
>
> | (search-forward-regexp "\\([Ee][Rr][Rr]\\)\\(?!orMode\\)")
>
> give on your Emacs?
>
> Tim
>
>
>

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Re: does emacs regular expression support (?!expression)

[Thien-Thi Nguyen]

() Tim Landscheidt <tim@tim-landscheidt.de>
() Sat, 04 Feb 2012 10:12:33 +0000

   Thien-Thi Nguyen <ttn@gnuvola.org> wrote:

   >    > You can add a spec for ‘ErrorMode’, with default face, prior to this one.

   >    Which Emacs version does support that?

   > Any that processes these specs in the given order, with
   > "masking semantics", i suppose.  (I haven't tried.)

   What does:

   | (search-forward-regexp "\\([Ee][Rr][Rr]\\)\\(?!orMode\\)")

   give on your Emacs?

It throws an error "Invalid regular expression".
Sorry for being unclear.  Here is a reformulation:

"Presuming that Emacs processes the user-specified font-lock specs
in the order given and that once a piece of text is marked as 
fontified, it no longer qualifies for further processing,
one way to "not match ErrorMode but match "Err" is to specify first
"ErrorMode" with the default face (thus simulating "not matching"
and simultaneously making that text unavailable for...), and second
the "Err" with the warning face."

That is, two entries in the list, neither of which use ‘?:’.

So, instead of asking Emacs to look ahead on "Err" and decline to
match if the trailing text is "orMode", you ask Emacs to explicitly
find "ErrorMode" and (quietly) exclude it from future hits when
looking for "Err".  This is like sweeping the path with a glue gun.

Re: does emacs regular expression support (?!expression)

[Tim Landscheidt]

Thien-Thi Nguyen <ttn@gnuvola.org> wrote:

> [...]
> It throws an error "Invalid regular expression".
> Sorry for being unclear.  [...]

Thanks.

Tim

Re: does emacs regular expression support (?!expression)

[Glenn Morris]

Tim Landscheidt wrote:

> In Perl, "(?!pattern)" is a zero-width negative look-ahead
> assertion.  Emacs does not support these AFAIK.

http://debbugs.gnu.org/cgi/bugreport.cgi?bug=5393
(to date, not applied)

See also the linked
http://lists.gnu.org/archive/html/emacs-devel/2012-01/msg00732.html