I was trying make a function that return the closing bracket of a given opening bracket, I already can do this, but in my first attempt I can't understand where is my error, and I would like know to avoid the same problem in the future, here is my second function, It worked fine (see it working to let lighter what I tried in my first attempt):
(defun properties-without-spaces (s)
(let ((char-list nil)
(char-remove-p nil))
(loop for c across s do
(when (or (char-equal c #\:)
(char-equal c #\;))
(push c char-list)
(setf char-remove-p t))
(when (and char-remove-p
(not (or (char-equal c #\:)
(char-equal c #\;)))
(not (or (char-equal c #\Space)
(char-equal c #\Newline)
(char-equal c #\Tab))))
(setf char-remove-p nil))
(unless char-remove-p
(push c char-list)))
(trim (make-string-from-chars (reverse char-list)))))
(equal (end-bracket-index "div,ul,li:focus {outline:none; margin: 5px 0 0 1px;} body {background-color: blue;}" 16)
51) ;; => T
(equal (end-bracket-index "div,ul,li:focus {outline:none; margin: 5px 0 0 1px;} body {background-color: blue;} @media (min-width: 30em) {div {margin: 3px 0 1px 3px;} body {background-color: blue;}}" 109)
169) ;; => T
(equal (end-bracket-index "div,ul,li:focus {/*By Umaui*/
outline:none; /*something*/
margin: 5px 0 0 1px;
}
body {
background-color: pink;
}
@media (min-width: 30em) {
div {
margin: 3px 0 1px 3px;
}
body {
background-color: blue;
}
}" 154)
236) ;; => T
I know that have other ways to make this, I could use the cl-ppcre, but this is not my question, my question is where is my mistake in the recursive function below:
(defun end-bracket-index (css start-bracket &optional (open-bracket-level 1))
(let* ((css-before-start-bracket (subseq css 0 (+ start-bracket 1)))
(css-after-start-bracket (subseq css (+ start-bracket 1)))
(next-start-bracket
(search "{" css-after-start-bracket))
(next-end-bracket
(search "}" css-after-start-bracket)))
(cond ((and next-start-bracket
next-end-bracket)
(if (< next-start-bracket next-end-bracket)
(incf open-bracket-level)
(decf open-bracket-level)))
((and (null next-start-bracket)
next-end-bracket)
(decf open-bracket-level)))
(when (zerop open-bracket-level)
(return-from end-bracket-index
(+ next-end-bracket
(length css-before-start-bracket))))
(end-bracket-index css
(+ next-start-bracket
(length css-before-start-bracket))
open-bracket-level)))
(equal (end-bracket-index "div,ul,li:focus {outline:none; margin: 5px 0 0 1px;} body {background-color: blue;}" 16)
51) ;; => T
(equal (end-bracket-index "div,ul,li:focus {outline:none; margin: 5px 0 0 1px;} body {background-color: blue;} @media (min-width: 30em) {div {margin: 3px 0 1px 3px;} body {background-color: blue;}}" 109)
169) ;; => NIL because 168 not equal 169
(equal (end-bracket-index "div,ul,li:focus {/*By Umaui*/
outline:none; /*something*/
margin: 5px 0 0 1px;
}
body {
background-color: pink;
}
@media (min-width: 30em) {
div {
margin: 3px 0 1px 3px;
}
body {
background-color: blue;
}
}" 154)
236) ;; NIL because because 234 not equal 236
Main answer
Your not working attempt jumps from one start to the next start but it stays at the same position if no start is following, while
open-bracket-levelis going down.The correct way however is that you jump instead to the
next-start-bracketto thenext-(start|end)-bracket. (Because sometimes onlynext-end-breackets will follow while nonext-start-brackets are appearing any more towards the end). The last recursive call therefore had to be corrected to determine whether to jump to thenext-start-bracketor to thenext-end-bracket.Debugging
Adding a print command before the exit
whencondition helped me a lot to find this all out:Testing
Your tests were wrong for
clisp. So I corrected the tests:Namings
Since the jumping/stepping doesn't happen from one start to next start brackets, I suggest different namings:
Another possibility
More efficient solution
It is easier and much more efficient to scan character for character.