source:
liacs/coco/assignment1/calc.y@
19
Last change on this file since 19 was 2, checked in by , 15 years ago | |
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File size: 2.3 KB |
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1 | /* C declarations */ |
2 | /* vi: set et ts=4: */ |
3 | |
4 | %{ |
5 | |
6 | #include <stdio.h> |
7 | #include <math.h> |
8 | |
9 | int base = 10; |
10 | |
11 | /* Prototypes */ |
12 | static void yyerror(const char *); |
13 | static int fac(int x); |
14 | |
15 | /* import from spascal.l */ |
16 | extern int lineno; |
17 | extern int yylex(void); |
18 | |
19 | %} |
20 | |
21 | |
22 | /* Start symbol */ |
23 | %start line |
24 | |
25 | /* Tokens */ |
26 | %token DIGIT |
27 | %token PI |
28 | %token OPEN_PAREN CLOSE_PAREN |
29 | %token '|' |
30 | |
31 | /* Tokens with precedence assigned */ |
32 | /* The sooner the operator is defined, the lower its precedence */ |
33 | %left '-' '+' |
34 | %left '*' '/' '%' |
35 | %left UMINUS |
36 | %left '!' |
37 | %right EXPONENT |
38 | |
39 | |
40 | |
41 | /* Rules */ |
42 | %% |
43 | |
44 | line: |
45 | | |
46 | |
47 | line stmt '\n' |
48 | |
49 | | |
50 | |
51 | line error '\n' |
52 | { |
53 | yyerrok; |
54 | } |
55 | ; |
56 | |
57 | |
58 | stmt: |
59 | expr |
60 | { |
61 | printf("%d\n",$1); |
62 | } |
63 | ; |
64 | |
65 | |
66 | expr: |
67 | OPEN_PAREN expr CLOSE_PAREN |
68 | { |
69 | $$ = $2; |
70 | } |
71 | |
72 | | |
73 | |
74 | '|' expr '|' |
75 | { |
76 | $$ = (int)fabs((double)$2); |
77 | } |
78 | |
79 | | |
80 | |
81 | expr '*' expr |
82 | { |
83 | $$ = $1 * $3; |
84 | } |
85 | |
86 | | |
87 | |
88 | expr '/' expr |
89 | { |
90 | $$ = $1 / $3; |
91 | } |
92 | |
93 | | |
94 | |
95 | expr '%' expr |
96 | { |
97 | $$ = $1 % $3; |
98 | } |
99 | |
100 | | |
101 | |
102 | expr '-' expr |
103 | { |
104 | $$ = $1 - $3; |
105 | } |
106 | |
107 | | |
108 | |
109 | expr '+' expr |
110 | { |
111 | $$ = $1 + $3; |
112 | } |
113 | |
114 | | |
115 | |
116 | expr '!' |
117 | { |
118 | if ($1 < 0) { |
119 | fprintf(stderr, "Negative values for faculty are undefined.\n"); |
120 | YYERROR; |
121 | } |
122 | $$ = fac($1); |
123 | } |
124 | |
125 | | |
126 | |
127 | expr EXPONENT expr |
128 | { |
129 | $$ = (int)pow((double)$1, (double)$3); |
130 | } |
131 | |
132 | | |
133 | |
134 | '-' expr %prec UMINUS |
135 | { |
136 | $$ = -$2; |
137 | } |
138 | |
139 | | |
140 | |
141 | number |
142 | ; |
143 | |
144 | |
145 | number: |
146 | PI |
147 | { |
148 | $$ = 3; |
149 | } |
150 | |
151 | | |
152 | |
153 | DIGIT |
154 | { |
155 | $$ = $1; |
156 | } |
157 | |
158 | | |
159 | |
160 | number DIGIT |
161 | { |
162 | $$ = base * $1 + $2; |
163 | } |
164 | ; |
165 | %% |
166 | /* End of rules, more C code will follow now */ |
167 | |
168 | |
169 | int main() |
170 | { |
171 | return yyparse(); |
172 | } |
173 | |
174 | static void yyerror(const char *s) |
175 | { |
176 | fprintf(stderr, "%s\n",s); |
177 | } |
178 | |
179 | int yywrap() |
180 | { |
181 | return(1); |
182 | } |
183 | |
184 | int fac(int x) |
185 | { |
186 | return (x > 1) ? x*fac(x-1) : 1; |
187 | } |
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