Recently, I had a need to do some replacements in a string. Basically, that meant repeatedly calling replace-regexp-in-string. I strongly disliked the idea of nesting these calls, so I set out to write a simple tool to help with that. Here is the result:
(defun replace-regexen-in-string (replacements string &optional fixedcase literal) "Call `replace-regexp-in-string' on STRING multiple times. REPLACEMENTS is an alist of pairs (regex . replacement). FIXEDCASE and LITERAL are passed to `replace-regexp-in-string'." (let ((result string)) (mapc (lambda (replacement) (setq result (replace-regexp-in-string (car replacement) (cdr replacement) result fixedcase literal))) replacements) result))
It’s probably not the optimal/most beautiful way to do it. In particular, it is rather imperative and not very functional – I am pretty sure that it could be done more elegantly with reduce, or by a macro which would generate the recursive calls. Maybe some day I will write all three versions, and then measure their performance (I suspect my one should be rather a faster one). But it is optimal in terms of programmer time – I hacked it together in a few minutes, and much of that time was looking up replace-regexp-in-string syntax (and then checking whether the last two optional arguments work fine). Feel free to use it if you need to.