1 (define
false #f)
2 (define
true #t)
3
4 (define (make-
table)
5 (let ((local-table (list
'*table*)))
6
7 (define (assoc key records)
8 (cond ((
null? records)
false)
9 ((equal?
(caar records) key) (car records))
10 (
else (assoc key (cdr records)))))
11
12 (define (lookup keys)
13 (define (lookup-
helper keys table)
14 (let ((subtable (assoc (car keys) (cdr table))))
15 (
if subtable
16 (
if (
null?
(cdr keys))
17 (cdr subtable)
18 (lookup-
helper (cdr keys) subtable))
19 false)))
20 (lookup-helper keys local-
table))
21
22 (define (insert!
keys value)
23 (define (insert-helper!
keys table)
24 (
if (
null?
table)
25 (
if (
null?
(cdr keys))
26 (cons (car keys) value)
27 (list (car keys) (insert-helper! (cdr keys)
'())))
28 (let ((sub (assoc (car keys) (cdr table))))
29 (
if sub
30 (
if (
null?
(cdr keys))
31 (
set-cdr!
sub value)
32 (insert-helper!
(cdr keys) sub))
33 (
if (
null?
(cdr keys))
34 (
set-cdr!
table (cons (cons (car keys) value) (cdr table)))
35 (
set-cdr!
table (cons
36 (list (car keys)(insert-helper! (cdr keys)
'()))
37 (cdr table))))))))
38 (insert-helper! keys local-
table)
39 'ok)
40
41 (define (dispatch m)
42 (cond ((eq? m
'lookup-proc) lookup)
43 ((eq? m
'insert-proc) insert!)
44 (
else (error
"Unknow operation --TABLE" m))))
45
46 dispatch))
47
48 (define t1 (make-
table))
49
50 ((t1
'insert-proc) '(key1 key2 key4)
5)
51
52 ((t1
'lookup-proc) '(key1 key2 key4))
转载于:https://www.cnblogs.com/tclan126/p/6822909.html
相关资源：数据结构—成绩单生成器
