+ #+sbcl
+ (sb-kernel:shrink-vector str size)
+ #+scl
+ (common-lisp::shrink-vector str size)
+ #-(or allegro cmu lispworks sbcl scl)
+ (setq str (subseq str 0 size))
+ str)
+
+(defun lex-string (string &key (whitespace '(#\space #\newline)))
+ "Separates a string at whitespace and returns a list of strings"
+ (flet ((is-sep (char) (member char whitespace :test #'char=)))
+ (let ((tokens nil))
+ (do* ((token-start
+ (position-if-not #'is-sep string)
+ (when token-end
+ (position-if-not #'is-sep string :start (1+ token-end))))
+ (token-end
+ (when token-start
+ (position-if #'is-sep string :start token-start))
+ (when token-start
+ (position-if #'is-sep string :start token-start))))
+ ((null token-start) (nreverse tokens))
+ (push (subseq string token-start token-end) tokens)))))
+
+(defun split-alphanumeric-string (string)
+ "Separates a string at any non-alphanumeric chararacter"
+ (flet ((is-sep (char) (non-alphanumericp char)))
+ (let ((tokens nil))
+ (do* ((token-start
+ (position-if-not #'is-sep string)
+ (when token-end
+ (position-if-not #'is-sep string :start (1+ token-end))))
+ (token-end
+ (when token-start
+ (position-if #'is-sep string :start token-start))
+ (when token-start
+ (position-if #'is-sep string :start token-start))))
+ ((null token-start) (nreverse tokens))
+ (push (subseq string token-start token-end) tokens)))))
+
+
+
+(defun collapse-whitespace (s)
+ "Convert multiple whitespace characters to a single space character."
+ (declare (simple-string s)
+ (optimize (speed 3) (safety 0)))
+ (with-output-to-string (stream)
+ (do ((pos 0 (1+ pos))
+ (in-white nil)
+ (len (length s)))
+ ((= pos len))
+ (declare (fixnum pos len))
+ (let ((c (schar s pos)))
+ (declare (character c))
+ (cond
+ ((kl:is-char-whitespace c)
+ (unless in-white
+ (write-char #\space stream))
+ (setq in-white t))
+ (t
+ (setq in-white nil)
+ (write-char c stream)))))))