Why does this happen in regexp isearch?

Why does this happen in regexp isearch?

[Deniz Dogan]

I open cus-edit.el.gz in Emacs and do a regexp isearch for:

^  ;;

(Beginning of line, then two spaces, then two semicolons.)

For some reason that I don't understand, it seems to match "beginning
of line, any number of spaces OR tabs, then two semicolons". When I
search for:

^ \{2\};;

...it finds what I'm looking for. Why is this?

-- 
Deniz Dogan

Re: Why does this happen in regexp isearch?

[Andreas Politz]

Deniz Dogan <deniz.a.m.dogan@gmail.com> writes:

> I open cus-edit.el.gz in Emacs and do a regexp isearch for:
>
> ^  ;;
>
> (Beginning of line, then two spaces, then two semicolons.)
>
> For some reason that I don't understand, it seems to match "beginning
> of line, any number of spaces OR tabs, then two semicolons". When I
> search for:
>
> ^ \{2\};;
>
> ...it finds what I'm looking for. Why is this?

(setq search-spaces-regexp nil)

, or read it's documentation.

-ap

Re: Why does this happen in regexp isearch?

[Daniel Pittman]

Deniz Dogan <deniz.a.m.dogan@gmail.com> writes:

> I open cus-edit.el.gz in Emacs and do a regexp isearch for:
>
> ^  ;;
>
> (Beginning of line, then two spaces, then two semicolons.)
>
> For some reason that I don't understand, it seems to match "beginning
> of line, any number of spaces OR tabs, then two semicolons". When I
> search for:
>
> ^ \{2\};;
>
> ...it finds what I'm looking for. Why is this?

(defcustom search-whitespace-regexp (purecopy "\\s-+")
  "If non-nil, regular expression to match a sequence of whitespace chars.
This applies to regular expression incremental search.
When you put a space or spaces in the incremental regexp, it stands for
this, unless it is inside of a regexp construct such as [...] or *, + or ?.
You might want to use something like \"[ \\t\\r\\n]+\" instead.
In the Customization buffer, that is `[' followed by a space,
a tab, a carriage return (control-M), a newline, and `]+'.

When this is nil, each space you type matches literally, against one space."
  :type '(choice (const :tag "Find Spaces Literally" nil)
		 regexp)
  :group 'isearch)

Regards,
        Daniel
-- 
✣ Daniel Pittman            ✉ daniel@rimspace.net            ☎ +61 401 155 707
               ♽ made with 100 percent post-consumer electrons

Re: Why does this happen in regexp isearch?

[Deniz Dogan]

2010/7/3 Daniel Pittman <daniel@rimspace.net>:
> Deniz Dogan <deniz.a.m.dogan@gmail.com> writes:
>
>> I open cus-edit.el.gz in Emacs and do a regexp isearch for:
>>
>> ^  ;;
>>
>> (Beginning of line, then two spaces, then two semicolons.)
>>
>> For some reason that I don't understand, it seems to match "beginning
>> of line, any number of spaces OR tabs, then two semicolons". When I
>> search for:
>>
>> ^ \{2\};;
>>
>> ...it finds what I'm looking for. Why is this?
>
> (defcustom search-whitespace-regexp (purecopy "\\s-+")
>  "If non-nil, regular expression to match a sequence of whitespace chars.
> This applies to regular expression incremental search.
> When you put a space or spaces in the incremental regexp, it stands for
> this, unless it is inside of a regexp construct such as [...] or *, + or ?.
> You might want to use something like \"[ \\t\\r\\n]+\" instead.
> In the Customization buffer, that is `[' followed by a space,
> a tab, a carriage return (control-M), a newline, and `]+'.
>
> When this is nil, each space you type matches literally, against one space."
>  :type '(choice (const :tag "Find Spaces Literally" nil)
>                 regexp)
>  :group 'isearch)
>

Thank you.

-- 
Deniz Dogan