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
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