Use more efficient looking-at-p instead of looking-at in most places

[sergv]

Change looking-at calls into looking-at-p. The latter is more efficient as it does not clobber match-data. While the former is redundant in places where match-data is not used after call (through e.g. match-{beginning,end,string,string-no-properties} functions).

[gracjan]

Cool! Let me review this properly.

[gracjan]

Thanks for these changes, efficiency is very important. There are other places in the code that could use similar efficiency changes. Can you do some more?

[sergv]

This was mostly a brief skim through the code base. I made changes whenever I was confident it won't break anything. I'll try to do more in the future.

[gracjan]

So this one didn't go very well, including a hanging emacs session. For example haskell-decl-scan.el is full of code fragments like:

(if (looking-at "[ \t]*\\(\\sw+\\)")
    (progn
      (setq name (match-string-no-properties 1))
      (setq name-pos (match-beginning 1))
      (setq type 'class))))

So this change isn't as obvious as we thought.

[sergv]

Sorry. It seems I missed something, unfortunately.