+ (substitute-chars-strings string '((#\& . "&") (#\< . "<"))))
+
+(defun make-usb8-array (len)
+ (make-array len :element-type '(unsigned-byte 8)))
+
+(defun usb8-array-to-string (vec)
+ (declare (type (simple-array (unsigned-byte 8) (*)) vec))
+ (let* ((len (length vec))
+ (str (make-string len)))
+ (declare (fixnum len)
+ (simple-string str)
+ (optimize (speed 3)))
+ (do ((i 0 (1+ i)))
+ ((= i len) str)
+ (declare (fixnum i))
+ (setf (schar str i) (code-char (aref vec i))))))
+
+(defun string-to-usb8-array (str)
+ (declare (simple-string str))
+ (let* ((len (length str))
+ (vec (make-usb8-array len)))
+ (declare (fixnum len)
+ (type (simple-array (unsigned-byte 8) (*)) vec)
+ (optimize (speed 3)))
+ (do ((i 0 (1+ i)))
+ ((= i len) vec)
+ (declare (fixnum i))
+ (setf (aref vec i) (char-code (schar str i))))))
+
+(defun concat-separated-strings (separator &rest lists)
+ (format nil (concatenate 'string "~{~A~^" (string separator) "~}")
+ (append-sublists lists)))
+
+(defun only-null-list-elements-p (lst)
+ (or (null lst) (every #'null lst)))
+
+(defun print-separated-strings (strm separator &rest lists)
+ (declare (optimize (speed 3) (safety 0) (space 0) (debug 0)
+ (compilation-speed 0)))
+ (do* ((rest-lists lists (cdr rest-lists))
+ (list (car rest-lists) (car rest-lists))
+ (last-list (only-null-list-elements-p (cdr rest-lists))
+ (only-null-list-elements-p (cdr rest-lists))))
+ ((null rest-lists) strm)
+ (do* ((lst list (cdr lst))
+ (elem (car lst) (car lst))
+ (last-elem (null (cdr lst)) (null (cdr lst))))
+ ((null lst))
+ (write-string elem strm)
+ (unless (and last-elem last-list)
+ (write-string separator strm)))))
+
+(defun prefixed-fixnum-string (num pchar len)
+ "Outputs a string of LEN digit with an optional initial character PCHAR.
+Leading zeros are present."
+ (declare (optimize (speed 3) (safety 0) (space 0))
+ (type fixnum num len))
+ (when pchar
+ (incf len))
+ (do* ((zero-code (char-code #\0))
+ (result (make-string len :initial-element #\0))
+ (minus? (minusp num))
+ (val (if minus? (- num) num)
+ (nth-value 0 (floor val 10)))
+ (pos (1- len) (1- pos))
+ (mod (mod val 10) (mod val 10)))
+ ((or (zerop val) (minusp pos))
+ (when pchar
+ (setf (schar result 0) pchar))
+ (when minus? (setf (schar result (if pchar 1 0)) #\-))
+ result)
+ (declare (fixnum val mod zero-code pos) (simple-string result))
+ (setf (schar result pos) (code-char (+ zero-code mod)))))
+
+(defun integer-string (num len)
+ "Outputs a string of LEN digit with an optional initial character PCHAR.
+Leading zeros are present."
+ (declare (optimize (speed 3) (safety 0) (space 0))
+ (type fixnum len)
+ (type integer num))
+ (do* ((zero-code (char-code #\0))
+ (result (make-string len :initial-element #\0))
+ (minus? (minusp num))
+ (val (if minus? (- 0 num) num)
+ (nth-value 0 (floor val 10)))
+ (pos (1- len) (1- pos))
+ (mod (mod val 10) (mod val 10)))
+ ((or (zerop val) (minusp pos))
+ (when minus? (setf (schar result 0) #\-))
+ result)
+ (declare (fixnum mod zero-code pos) (simple-string result) (integer val))
+ (setf (schar result pos) (code-char (+ zero-code mod)))))
+
+(defun fast-string-search (substr str substr-length startpos endpos)
+ "Optimized search for a substring in a simple-string"
+ (declare (simple-string substr str)
+ (fixnum substr-length startpos endpos)
+ (optimize (speed 3) (space 0) (safety 0)))
+ (do* ((pos startpos (1+ pos))
+ (lastpos (- endpos substr-length)))
+ ((> pos lastpos) nil)
+ (declare (fixnum pos lastpos))
+ (do ((i 0 (1+ i)))
+ ((= i substr-length)
+ (return-from fast-string-search pos))
+ (declare (fixnum i))
+ (unless (char= (schar str (+ i pos)) (schar substr i))
+ (return nil)))))
+
+(defun string-delimited-string-to-list (str substr)
+ "splits a string delimited by substr into a list of strings"
+ (declare (simple-string str substr)
+ (optimize (speed 3) (safety 0) (space 0) (compilation-speed 0)
+ (debug 0)))
+ (do* ((substr-len (length substr))
+ (strlen (length str))
+ (output '())
+ (pos 0)
+ (end (fast-string-search substr str substr-len pos strlen)
+ (fast-string-search substr str substr-len pos strlen)))
+ ((null end)
+ (when (< pos strlen)
+ (push (subseq str pos) output))
+ (nreverse output))
+ (declare (fixnum strlen substr-len pos)
+ (type (or fixnum null) end))
+ (push (subseq str pos end) output)
+ (setq pos (+ end substr-len))))
+
+(defun string-to-list-skip-delimiter (str &optional (delim #\space))
+ "Return a list of strings, delimited by spaces, skipping spaces."
+ (declare (simple-string str)
+ (optimize (speed 0) (space 0) (safety 0)))
+ (do* ((results '())
+ (end (length str))
+ (i (position-not-char delim str 0 end)
+ (position-not-char delim str j end))
+ (j (when i (position-char delim str i end))
+ (when i (position-char delim str i end))))
+ ((or (null i) (null j))
+ (when (and i (< i end))
+ (push (subseq str i end) results))
+ (nreverse results))
+ (declare (fixnum end)
+ (type (or fixnum null) i j))
+ (push (subseq str i j) results)))
+
+(defun string-starts-with (start str)
+ (and (>= (length str) (length start))
+ (string-equal start str :end2 (length start))))
+
+(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))
+
+(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)))))
+
+(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 (+ +code-char-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)))))