Re: c-mode syntax strings and regexp word boundaries

[Andreas Röhler]

Am 06.09.2013 07:14, schrieb Jon Dufresne:
> Hi,
>
> I am trying to modify a major mode derived from c-mode. I am adding support
> for an alternative string syntax (PHP heredoc). To do this I am using
> "syntax-propertize-function" and
> "syntax-propertize-extend-region-functions". (As an aside I am not sure
> this is the best approach, but it is best I have come up with so far.)
>
> When trying to extend the propertize region, a regexp fails, but I am not
> clear as to why. I have isolated the problem with the following test case.
>
> ---
> (with-temp-buffer
>    (c-mode)
>    (insert "END;\n")
>    (goto-char (point-min))
>    (message "Search forward first time")
>    (re-search-forward "^END\\b")
>    (put-text-property (1- (point)) (point)
>                       'syntax-table (string-to-syntax "|"))
>    (goto-char (point-min))
>    (message "Search forward second time")
>    (re-search-forward "^END\\b"))
> ---
>
> Running this give me the output:
>
> Search forward first time
> Search forward second time
> Search failed: "^END\\b"
>
> I do not understand why the second regexp fails. I suppose it has to do
> with the text property string boundary. What is the correct way to look for
> the boundary in this case?
>
> Thanks for any help.

For me it's strange too.

Second

(re-search-forward "^END\\s.")

matches that way.

Can't see why the word-boundary isn't recognised any more.

Andreas