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  1. ; Count the operators in your DSL
  2. ; ------------------------------
  3. ; The Little Lisper 3rd Edition
  4. ; Chapter 7
  5. ; Exercise 3
  6. ; Common Lisp
  7. ; http://t...content-available-to-author-only...r.com/thelittlelisper
  8. ; http://t...content-available-to-author-only...t.com/2010/06/little-lisper-chapter-7-shadows.html
  9. ; http://t...content-available-to-author-only...t.com/2010/06/little-lisper.html
  10. ; ------------------------------
  11. (setf l1 '())
  12. (setf l2 '(3 + (66 6)))
  13. (setf aexp1 '(1 + (3 * 4)))
  14. (setf aexp2 '((3 ^ 4) + 5))
  15. (setf aexp4 5)
  16. ; ------------------------------
  17.  
  18.  
  19. (defun sub1 (n)
  20.   (- n 1))
  21.  
  22. (defun operator (aexp_)
  23.   (car (cdr aexp_)))
  24.  
  25. (print (operator '(1 + 2)))
  26. ;+
  27.  
  28. (defun isoperator (a)
  29.   (cond
  30.    ((null a) NIL)
  31.    ((eq a '+) t)
  32.    ((eq a '*) t)
  33.    ((eq a '^) t)
  34.    (t NIL)))
  35.  
  36.  
  37. (print (isoperator '^))
  38. ;T
  39.  
  40. (defun 1st-sub-expr (aexp_)
  41.   (car aexp_))
  42.  
  43. (print (1st-sub-expr '(1 + 2)))
  44. ;1
  45.  
  46. (defun 2nd-sub-expr (aexp_)
  47.   (car (cdr (cdr aexp_))))
  48.  
  49. (print (2nd-sub-expr '(1 + 2)))
  50. ;2
  51.  
  52. (defun number_ (n)
  53.   (cond
  54.    ((null n) t)
  55.    (t (and
  56.        (null (car n))
  57.        (number_ (cdr n))))))
  58.  
  59. (defun notatom (lat)
  60.   (not (atom lat)))
  61.  
  62. (defun number__ (n)
  63.   (cond
  64.    ((null n) nil)
  65.    ((notatom n) nil)
  66.   ((= 0 n) t)
  67.    (t (number__ (sub1 n)))))       
  68.  
  69.  
  70. (defun mk+exp (aexp1_ aexp2_)
  71.   (cons aexp1_
  72.         (cons '+
  73.               (cons aexp2_ '()))))
  74.  
  75. (defun mk*exp (aexp1_ aexp2_)
  76.   (cons aexp1_
  77.         (cons '*
  78.               (cons aexp2_ '()))))
  79.  
  80. (setf aexp1 (mk+exp 1 (mk*exp 3 4)))
  81. (setf aexp3 (mk*exp 3 (mk*exp 4 (mk*exp 5 6))))
  82.  
  83. (defun count-op (aexp_)
  84.   (cond
  85.    ((null aexp_) 0)
  86.    ((number__ aexp_) 0)
  87.    ((isoperator (operator aexp_))
  88.     (+ 
  89.     (+ 1 (count-op (1st-sub-expr aexp_)))
  90.     (count-op (2nd-sub-expr aexp_)))
  91.     )
  92.    (t 0)))
  93.  
  94. (print (count-op '(1 + 2)))
  95. ;1
  96.  
  97. (print (count-op aexp1))
  98. ;2
  99.  
  100. (print (count-op aexp3))
  101. ;3
  102.  
  103. (print (count-op aexp4))
  104. ;0
  105.  
  106. (defun countatomplus (a)
  107.   (cond
  108.    ((null a) 0)
  109.    ((eq a '+) 1)
  110.    (t 0)))
  111.  
  112. (print (countatomplus '*))
  113. ;0
  114.  
  115. (print (countatomplus '+))
  116. ;1
  117.  
  118. (defun count+ (aexp_)
  119.   (cond
  120.    ((null aexp_) 0)
  121.    ((number__ aexp_) 0)
  122.    ((isoperator (operator aexp_))
  123.     (+ 
  124.     (+ (countatomplus(operator aexp_)) (count+ (1st-sub-expr aexp_)))
  125.     (count+ (2nd-sub-expr aexp_)))
  126.     )
  127.    (t 0)))
  128.  
  129. (print (count+ aexp1))
  130. ;1
  131.  
  132. (defun countatomtimes (a)
  133.   (cond
  134.    ((null a) 0)
  135.    ((eq a '*) 1)
  136.    (t 0)))
  137.  
  138. (defun count* (aexp_)
  139.   (cond
  140.    ((null aexp_) 0)
  141.    ((number__ aexp_) 0)
  142.    ((isoperator (operator aexp_))
  143.     (+ 
  144.     (+ (countatomtimes(operator aexp_)) (count* (1st-sub-expr aexp_)))
  145.     (count* (2nd-sub-expr aexp_)))
  146.     )
  147.    (t 0)))
  148.  
  149. (print (count* aexp1))
  150. ;1
  151.  
  152.  
  153. (print (count* aexp3))
  154.  
  155. (defun countatomexp (a)
  156.   (cond
  157.    ((null a) 0)
  158.    ((eq a '^) 1)
  159.    (t 0)))
  160.  
  161. (defun count^ (aexp_)
  162.   (cond
  163.    ((null aexp_) 0)
  164.    ((number__ aexp_) 0)
  165.    ((isoperator (operator aexp_))
  166.     (+ 
  167.     (+ (countatomexp(operator aexp_)) (count^ (1st-sub-expr aexp_)))
  168.     (count^ (2nd-sub-expr aexp_)))
  169.     )
  170.    (t 0)))
  171.  
  172. (print (count^ aexp1))
  173. ;0
  174.  
  175.  
Success #stdin #stdout 0.02s 10568KB
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https://ideone.com/7zciw
language:
Common Lisp (clisp 2.49.92)
created:
13 years ago
visibility:
public

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