Why does replace-regexp backwards work so differently?
C-u - M-x replace-regexp \w+
The - prefix arg replaces backwards but it hits one char at a time, as if the plus sign weren’t there. The same replacement forwards (without the prefix arg) does hit one word at a time. What’s going on, @emacs@lemmy.ml?
Because once it hits the ultimate character of a word,
\w+matches that (single) character, next time it matches the penultimate character, etc. You’d need\W\w+to make it look far enough back to the beginning of the word.So it’s literally looking at the regexp backwards and forwards at the same time 😵💫
@0v0 @emacs
The regexp itself always looks forward, the BACKWARD argument just determines which direction the point should move after a match.
But what’s so weird is that replace-regexp forwards with \w+ replaces all words, while replace-regexp backwards with \w+ replaces the characters individually.
@0v0 @emacs
Consider the string
abc. From the end, moving backwards, when does it match\w+, and what does it match? When it reachesc, it matchesc. And from the front, moving forwards? When it reachesa, it matchesabc. This is why it acts differently.Yes, I got that, that wasn’t the weird part. The weird part is why the matcher is searching char-by-char backwards in the first place as opposed to skipping match-by-match.
I’ll use “\b\w+”, that seems to work well. \W\w+ was not good since it caught the spaces.
(Thanks for your patient repeated replies, BTW, I don’t mean to come across as ungrateful.)
@0v0 @emacs