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* Documentation for uri.scm finished (except for resolve-uri-procedure as I can't figure out what this procedure is intended to do; someone out there who want to let me know?) 

* new simplify-uri-path written (as the old one did not seem to work correctly)
This commit is contained in:
interp 2001-05-20 18:57:31 +00:00
parent 5a15d24738
commit 812784c6bf
1 changed files with 32 additions and 30 deletions
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62
uri.scm
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@ -103,7 +103,7 @@
; length of the
; unescaped
; string
(ns (make-string nlen))) ; the result
(ns (make-string nlen))) ; stores the result
(let lp ((i start) (j 0)) ; sweap over the string
(if (< j nlen)
@ -258,33 +258,35 @@
(join-strings plist "/")) ; Insert slashes between elts of PLIST.
;;; Remove . and foo/.. elts from path. After simplification, there are no
;;; . elements, and the only .. elements occur at the beginning of the path
;;; (i.e., they attempt to back up past root). One could argue that this is
;;; illegal, and we should error out in this case, reporting an unresolvable
;;; URL. The URI "spec" is not even slightly clear on this issue.
;;;
;;; URI's are pathetic. The case of /a/b//../c is ambiguous. Do we
;;; 1) not simplify across multi-slashes?
;;; 2) Flush the "empty" dir, giving /a/b//c
;;; 3) Flush across multi-slashes, giving /a/c
;;; What is the meaning of //../a ? /../b ? /../../c ?
;;; Remove . and <segment>/.. elements from path. The result is a
;;; (maybe empty) list representing a path that does not contain "."
;;; and ".." elements neither at the beginning nor somewhere else. I
;;; tried to follow RFC2396 here. The procedure returns #f if the path
;;; tries to back up past root (like "//.." or "/foo/../.."). "//" may
;;; occur somewhere in the path but not being backed up. Usually,
;;; relative paths are intended to be used with a base
;;; url. Accordingly to RFC2396 (as I hope) relative paths are
;;; considered not to start with "/". They are appended to a base
;;; URL-path and then simplified. So before you start to simplify a
;;; URL try to find out if it is a relative path (i.e. it does not
;;; start with a "/").
(define (simplify-uri-path p) ; P must be non-null.
(reverse (let lp ((path-list p)
(ans '()))
(let ((elt (car path-list))
(path-list (cdr path-list)))
(? ((pair? path-list)
(? ((string=? "." elt) ; Kill .
(lp path-list ans))
((string=? ".." elt)
(if (pair? ans)
(lp path-list (cddr ans))
(lp path-list (cons elt ans))))
(else
(lp path-list (cons elt ans)))))
;; Last element of list.
((string=? ".." elt)
(if (null? ans) '("..") (cddr ans)))
(else (cons elt ans)))))))
(define (simplify-uri-path p)
(if (null? p) #f ; P must be non-null
(let lp ((path-list (cdr p))
(stack (list (car p))))
(if (null? path-list) ; we're done
(reverse stack)
(cond
((string=? (car path-list) "..") ; back up
; neither the empty path nor root
(if (not (or (null? stack) (string=? (car stack) "")))
(lp (cdr path-list) (cdr stack))
#f))
((string=? (car path-list) ".") ; leave this
(lp (cdr path-list) stack))
((string=? (car path-list) "") ; back to root
(lp (cdr path-list) '("")))
(else ; usual segment
(lp (cdr path-list) (cons (car path-list) stack))))))))