+
+(defun count-string-char (s c)
+ "Return a count of the number of times a character appears in a string"
+ (declare (simple-string s)
+ (character c)
+ (optimize (speed 3) (safety 0)))
+ (do ((len (length s))
+ (i 0 (1+ i))
+ (count 0))
+ ((= i len) count)
+ (declare (fixnum i len count))
+ (when (char= (schar s i) c)
+ (incf count))))
+
+(defun count-string-char-if (pred s)
+ "Return a count of the number of times a predicate is true
+for characters in a string"
+ (declare (simple-string s)
+ (type (or function symbol) pred)
+ (optimize (speed 3) (safety 0) (space 0)))
+ (do ((len (length s))
+ (i 0 (1+ i))
+ (count 0))
+ ((= i len) count)
+ (declare (fixnum i len count))
+ (when (funcall pred (schar s i))
+ (incf count))))
+
+
+;;; URL Encoding
+
+(defun non-alphanumericp (ch)
+ (not (alphanumericp ch)))
+
+(defvar +hex-chars+ "0123456789ABCDEF")
+(declaim (type simple-string +hex-chars+))
+
+(defun hexchar (n)
+ (declare (type (integer 0 15) n))
+ (schar +hex-chars+ n))
+
+(defconstant +char-code-0+ (char-code #\0))
+(defconstant +char-code-upper-a+ (char-code #\A))
+(declaim (type fixnum +char-code-0+ +char-code-upper-a+))
+
+(defun charhex (ch)
+ "convert hex character to decimal"
+ (let ((code (char-code (char-upcase ch))))
+ (declare (fixnum ch))
+ (if (>= code +char-code-upper-a+)
+ (+ 10 (- code +char-code-upper-a+))
+ (- code +char-code-0+))))
+
+(defun escape-uri-field (query)
+ "Escape non-alphanumeric characters for URI fields"
+ (declare (simple-string query)
+ (optimize (speed 3) (safety 0) (space 0)))
+ (do* ((count (count-string-char-if #'non-alphanumericp query))
+ (len (length query))
+ (new-len (+ len (* 2 count)))
+ (str (make-string new-len))
+ (spos 0 (1+ spos))
+ (dpos 0 (1+ dpos)))
+ ((= spos len) str)
+ (declare (fixnum count len new-len spos dpos)
+ (simple-string str))
+ (let ((ch (schar query spos)))
+ (if (non-alphanumericp ch)
+ (let ((c (char-code ch)))
+ (setf (schar str dpos) #\%)
+ (incf dpos)
+ (setf (schar str dpos) (hexchar (logand (ash c -4) 15)))
+ (incf dpos)
+ (setf (schar str dpos) (hexchar (logand c 15))))
+ (setf (schar str dpos) ch)))))
+
+(defun unescape-uri-field (query)
+ "Unescape non-alphanumeric characters for URI fields"
+ (declare (simple-string query)
+ (optimize (speed 3) (safety 0) (space 0)))
+ (do* ((count (count-string-char query #\%))
+ (len (length query))
+ (new-len (- len (* 2 count)))
+ (str (make-string new-len))
+ (spos 0 (1+ spos))
+ (dpos 0 (1+ dpos)))
+ ((= spos len) str)
+ (declare (fixnum count len new-len spos dpos)
+ (simple-string str))
+ (let ((ch (schar query spos)))
+ (if (char= #\% ch)
+ (let ((c1 (charhex (schar query (1+ spos))))
+ (c2 (charhex (schar query (+ spos 2)))))
+ (declare (fixnum c1 c2))
+ (setf (schar str dpos)
+ (code-char (logior c2 (ash c1 4))))
+ (incf spos 2))
+ (setf (schar str dpos) ch)))))
+
+
+(defconstant +char-code-a+ (char-code #\a))
+
+(defun random-string (&optional (len 10))
+ "Returns a random lower-case string."
+ (declare (optimize (speed 3)))
+ (let ((s (make-string len)))
+ (declare (simple-string s))
+ (dotimes (i len s)
+ (setf (schar s i)
+ (code-char (+ +char-code-a+ (random 26)))))))
+
+
+(defun first-char (s)
+ (declare (simple-string s))
+ (when (and (stringp s) (plusp (length s)))
+ (schar s 0)))
+
+(defun last-char (s)
+ (declare (simple-string s))
+ (when (stringp s)
+ (let ((len (length s)))
+ (when (plusp len))
+ (schar s (1- len)))))
+
+(defun ensure-string (v)
+ (typecase v
+ (string v)
+ (character (string v))
+ (symbol (symbol-name v))
+ (otherwise (write-to-string v))))
+
+(defun string-right-trim-one-char (char str)
+ (declare (simple-string str))
+ (let* ((len (length str))
+ (last (1- len)))
+ (declare (fixnum len last))
+ (if (char= char (schar str last))
+ (subseq str 0 last)
+ str)))
+
+