Update fastest CL implementation

Author: renatoathaydes

src/lisp/build.lisp

@@ -0,0 +1,5 @@
+(load "main.lisp")
+
+(sb-ext:save-lisp-and-die "lisp-phone-encoder"
+                          :toplevel 'main-with-options
+                          :executable t)

src/lisp/main.lisp

@@ -4,10 +4,36 @@
 ;; each phone number can be expressed as a list of words.
 ;; Run: (main "word-list-file-name" "phone-number-file-name")
 
-(defvar *dict* nil
+(declaim (optimize (speed 3) (debug 0) (safety 0)))
+(declaim (inline nth-digit char->digit update-key update-key-fast))
+
+(defglobal *dict* nil
   "A hash table mapping a phone number (integer) to a list of words from the
   input dictionary that produce that number.")
 
+(declaim (ftype (function (simple-string (integer 0 50)) (integer 48 57)) nth-digit))
+(defun nth-digit (digits i)
+  "The i-th element of a character string of digits, as an integer 0 to 9."
+  (- (char-code (char digits i)) #.(char-code #\0)))
+
+(declaim (ftype (function (base-char) (integer 0 9)) char->digit))
+(defun char->digit (ch)
+  "Convert a character to a digit according to the phone number rules."
+  (ecase (char-downcase ch)
+    ((#\e) 0)
+    ((#\j #\n #\q) 1)
+    ((#\r #\w #\x) 2)
+    ((#\d #\s #\y) 3)
+    ((#\f #\t) 4)
+    ((#\a #\m) 5)
+    ((#\c #\i #\v) 6)
+    ((#\b #\k #\u) 7)
+    ((#\l #\o #\p) 8)
+    ((#\g #\h #\z) 9)))
+
+(deftype handler-fn () `(function (simple-string list) null))
+
+(declaim (ftype (function (simple-string) handler-fn) choose-handler))
 (defun choose-handler (print-or-count)
   "Chooses a solution handler function.
    When a numbers file is fully consumed, call the function with nil words to signal EOF."
@@ -17,26 +43,25 @@
          (when words (format t "~a:~{ ~a~}~%" num (reverse words)))))
     ((string= print-or-count "count")
      (let ((count 0))
+       (declare (type fixnum count))
        #'(lambda (num words)
+           (declare (ignore num))
            (if words
                (incf count)
                (progn ;; no words is the EOF signal
                  (format t "~a~%" count)
                  (setf count 0)))))) ;; reset count for the next file
     (t (error "Unknown option: ~a" print-or-count))))
-    
 
-(defun main (&optional print-or-count (dict "tests/words.txt") (nums "tests/numbers.txt") (dict-size 100))
-  "Read the input file ¨DICT and load it into *dict*.  Then for each line in
-  NUMS, print all the translations of the number into a sequence of words,
-  according to the rules of translation."
-  (let ((handler (choose-handler print-or-count)))
-    (setf *dict* (load-dictionary dict dict-size))
-    (with-open-file (in nums)
-      (loop for num = (read-line in nil) while num do
-        (find-translations handler num (remove-if-not #'digit-char-p num))))
-    (funcall handler "" nil)))
+(defun update-key-fast (n digit)
+  (logand #.(1- (ash 1 (integer-length most-positive-fixnum)))
+	  (+ (* 10 n) digit)))
 
+(defun update-key (n digit)
+  (+ (* 10 n) digit))
+
+(declaim (ftype (function (handler-fn simple-string simple-string &optional
+                                      (integer 0 50) list) null) find-translations))
 (defun find-translations (handler num digits &optional (start 0) (words nil))
   "Print each possible translation of NUM into a string of words.  DIGITS
   must be WORD with non-digits removed.  On recursive calls, START is the
@@ -57,17 +82,31 @@
   becomes 12 and ER becomes 102."
   (if (>= start (length digits))
       (funcall handler num words)
-      (let ((found-word nil)
-            (n 1)) ; leading zero problem
-        (loop for i from start below (length digits) do
-              (setf n (+ (* 10 n) (nth-digit digits i)))
-              (loop for word in (gethash n *dict*) do
-                 (setf found-word t)
-                 (find-translations handler num digits (+ 1 i) (cons word words))))
-        (when (and (not found-word) (not (numberp (first words))))
-           (find-translations handler num digits (+ start 1)
-                              (cons (nth-digit digits start) words))))))
+      (loop with found-word = nil
+            with n = 1 ; leading zero problem
+            with len = (length digits)
+            with update-n = (if (< (+ start len) 19) #'update-key-fast #'update-key)
+            for i from start below len
+            do (setf n (funcall update-n n (nth-digit digits i)))
+               (loop for word in (gethash n *dict*)
+		     do (setf found-word t)
+			(find-translations handler num digits (1+ i) (cons word words)))
+            finally (return (when (and (not found-word) (not (numberp (first words))))
+                              (find-translations handler num digits (1+ start)
+                                                 (cons (nth-digit digits start) words)))))))
+
+(declaim (ftype (function (simple-string) integer) word->number))
+(defun word->number (word)
+  "Translate a word (string) into a phone number, according to the rules."
+  (let ((update-n (if (< (length word) 19) #'update-key-fast #'update-key)))
+    (loop with n = 1 ; leading zero problem
+          for i from 0 below (length word)
+          for ch of-type base-char = (char word i)
+          do (when (alpha-char-p ch)
+	       (setf n (funcall update-n n (char->digit ch))))
+          finally (return n))))
 
+(declaim (ftype (function (simple-string (integer 0))) load-dictionary))
 (defun load-dictionary (file size)
   "Create a hashtable from the file of words (one per line).  Takes a hint
   for the initial hashtable size.  Each key is the phone number for a word;
@@ -78,30 +117,16 @@
         (push word (gethash (word->number word) table))))
     table))
 
-(defun word->number (word)
-  "Translate a word (string) into a phone number, according to the rules."
-  (let ((n 1)) ; leading zero problem
-    (loop for i from 0 below (length word)
-          for ch = (char word i) do
-          (when (alpha-char-p ch) (setf n (+ (* 10 n) (char->digit ch)))))
-    n))
-
-(defun nth-digit (digits i)
-  "The i-th element of a character string of digits, as an integer 0 to 9."
-  (- (char-code (char digits i)) #.(char-code #\0)))
-
-(defun char->digit (ch)
-  "Convert a character to a digit according to the phone number rules."
-  (ecase (char-downcase ch)
-    ((#\e) 0)
-    ((#\j #\n #\q) 1)
-    ((#\r #\w #\x) 2)
-    ((#\d #\s #\y) 3)
-    ((#\f #\t) 4)
-    ((#\a #\m) 5)
-    ((#\c #\i #\v) 6)
-    ((#\b #\k #\u) 7)
-    ((#\l #\o #\p) 8)
-    ((#\g #\h #\z) 9)))
+(defun main (&optional print-or-count (dict "tests/words.txt") (nums "tests/numbers.txt") (dict-size 100))
+  "Read the input file ¨DICT and load it into *dict*.  Then for each line in
+  NUMS, print all the translations of the number into a sequence of words,
+  according to the rules of translation."
+  (let ((handler (choose-handler print-or-count)))
+    (setf *dict* (load-dictionary dict dict-size))
+    (with-open-file (in nums)
+      (loop for num = (read-line in nil) while num do
+        (find-translations handler num (remove-if-not #'digit-char-p num))))
+    (funcall handler "" nil)))
 
-(apply #'main (cdr sb-ext:*posix-argv*))
+(defun main-with-options ()
+  (apply #'main (cdr sb-ext:*posix-argv*)))