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1b101522 LC |
1 | ;;; test-lr-associativity-02.scm -- |
2 | ;; | |
3 | ;;Show how to use left and right associativity. Notice that the | |
4 | ;;terminal M is declared as left associative; this influences the | |
5 | ;;binding of values to the $n symbols in the semantic clauses. The | |
6 | ;;semantic clause in the rule: | |
7 | ;; | |
8 | ;; (E M E M E) : (list $1 $2 (list $3 $4 $5)) | |
9 | ;; | |
10 | ;;looks like it is right-associated, but the result is left-associated | |
11 | ;;because we have declared M as "left:". | |
12 | ;; | |
13 | ||
14 | (load "common-test.scm") | |
15 | ||
16 | (define (doit . tokens) | |
17 | (let ((parser (lalr-parser | |
18 | (expect: 0) | |
19 | (N (left: A) | |
20 | (left: M) | |
21 | (nonassoc: U)) | |
22 | (E (N) : $1 | |
23 | (E A E) : (list $1 $2 $3) | |
24 | (E M E) : (list $1 $2 $3) | |
25 | (E M E M E) : (list $1 $2 (list $3 $4 $5)) | |
26 | (A E (prec: U)) : (list '- $2))))) | |
27 | (parser (make-lexer tokens) error-handler))) | |
28 | ||
29 | ;;; -------------------------------------------------------------------- | |
30 | ;;; Single operator. | |
31 | ||
32 | (check | |
33 | (doit (make-lexical-token 'N #f 1)) | |
34 | => 1) | |
35 | ||
36 | (check | |
37 | (doit (make-lexical-token 'N #f 1) | |
38 | (make-lexical-token 'A #f '+) | |
39 | (make-lexical-token 'N #f 2)) | |
40 | => '(1 + 2)) | |
41 | ||
42 | (check | |
43 | (doit (make-lexical-token 'N #f 1) | |
44 | (make-lexical-token 'M #f '*) | |
45 | (make-lexical-token 'N #f 2)) | |
46 | => '(1 * 2)) | |
47 | ||
48 | (check | |
49 | (doit (make-lexical-token 'A #f '-) | |
50 | (make-lexical-token 'N #f 1)) | |
51 | => '(- 1)) | |
52 | ||
53 | ;;; -------------------------------------------------------------------- | |
54 | ;;; Precedence. | |
55 | ||
56 | (check | |
57 | (doit (make-lexical-token 'N #f 1) | |
58 | (make-lexical-token 'A #f '+) | |
59 | (make-lexical-token 'N #f 2) | |
60 | (make-lexical-token 'M #f '*) | |
61 | (make-lexical-token 'N #f 3)) | |
62 | => '(1 + (2 * 3))) | |
63 | ||
64 | (check | |
65 | (doit (make-lexical-token 'N #f 1) | |
66 | (make-lexical-token 'M #f '*) | |
67 | (make-lexical-token 'N #f 2) | |
68 | (make-lexical-token 'A #f '+) | |
69 | (make-lexical-token 'N #f 3)) | |
70 | => '((1 * 2) + 3)) | |
71 | ||
72 | ;;; -------------------------------------------------------------------- | |
73 | ;;; Associativity. | |
74 | ||
75 | (check | |
76 | (doit (make-lexical-token 'N #f 1) | |
77 | (make-lexical-token 'A #f '+) | |
78 | (make-lexical-token 'N #f 2) | |
79 | (make-lexical-token 'A #f '+) | |
80 | (make-lexical-token 'N #f 3)) | |
81 | => '((1 + 2) + 3)) | |
82 | ||
83 | (check | |
84 | (doit (make-lexical-token 'N #f 1) | |
85 | (make-lexical-token 'M #f '*) | |
86 | (make-lexical-token 'N #f 2) | |
87 | (make-lexical-token 'M #f '*) | |
88 | (make-lexical-token 'N #f 3)) | |
89 | => '((1 * 2) * 3)) | |
90 | ||
91 | ;;; end of file |