Mercurial > hg > Applications > Grep
annotate c/regexParser/main.cc @ 55:883e3473a9f5
fix
| author | Masataka Kohagura <kohagura@cr.ie.u-ryukyu.ac.jp> |
|---|---|
| date | Mon, 08 Jun 2015 23:40:09 +0900 |
| parents | f540de861cd6 |
| children | 8901bc071d33 |
| rev | line source |
|---|---|
| 55 | 1 /* |
| 2 Very Simple Calculator | |
| 3 $Id$ | |
| 4 */ | |
| 5 | |
| 45 | 6 #include <stdio.h> |
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7 |
| 55 | 8 static char *ptr,*last_ptr; |
| 9 static int value,lvalue; | |
| 10 static int last_token; | |
| 11 static int variable[48]; | |
| 12 | |
| 13 static int expr(); | |
| 14 static int aexpr(); | |
| 15 static int mexpr(); | |
| 16 static int term(); | |
| 17 static int token(); | |
| 18 static void error(char *); | |
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19 |
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20 |
| 55 | 21 static int |
| 22 token() | |
| 23 { | |
| 24 int c,d; | |
| 25 | |
| 26 last_ptr = ptr; /* for error position */ | |
| 27 c= *ptr; | |
| 28 if(!c) { | |
| 29 last_token = EOF; | |
| 30 return last_token; | |
| 31 } | |
| 32 ptr++; | |
| 33 if (c<=' ') { /* comment */ | |
| 34 while(*ptr++); | |
| 35 ptr--; | |
| 36 last_token = EOF; | |
| 37 last_ptr = ptr; | |
| 38 return last_token; | |
| 39 } | |
| 40 | |
| 41 if('0'<=c && c<='9') { /* Decimal */ | |
| 42 d = c-'0'; | |
| 43 while((c= *ptr++)) { | |
| 44 if('0'<=c && c<='9') { | |
| 45 d = d*10 + (c - '0'); | |
| 46 } else { | |
| 47 break; | |
| 48 } | |
| 49 } | |
| 50 c && ptr--; | |
| 51 value = d; | |
| 52 last_token = '0'; | |
| 53 return last_token; | |
| 54 | |
| 55 } else if ('a'<=c && c<='z') { /* variable */ | |
| 56 value = c-'a'; /* return variable reference */ | |
| 57 last_token = 'v'; | |
| 58 return last_token; | |
| 59 } else { | |
| 60 last_token = c; | |
| 61 return last_token; | |
| 62 return c; | |
| 63 } | |
| 64 } | |
| 65 | |
| 66 static int | |
| 67 expr() | |
| 68 { | |
| 69 int d,assign; | |
| 70 | |
| 71 d = aexpr(); | |
| 72 assign = lvalue; | |
| 73 switch(last_token) { | |
| 74 case '>': | |
| 75 d = (d > aexpr()); | |
| 76 return d; | |
| 77 case '=': | |
| 78 if(assign>=0) { | |
| 79 d = expr(); | |
| 80 variable[assign] = d; | |
| 81 return d; | |
| 82 } else { | |
| 83 error("Bad assignment"); | |
| 84 return 0; | |
| 85 } | |
| 86 case ')': | |
| 87 return d; | |
| 88 case EOF: | |
| 89 return d; | |
| 90 default: | |
| 91 error("Bad expression"); | |
| 92 return d; | |
| 93 } | |
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parents:
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94 } |
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parents:
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changeset
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95 |
| 55 | 96 static int |
| 97 aexpr() | |
| 98 { | |
| 99 int d; | |
| 100 | |
| 101 d = mexpr(); | |
| 102 switch(last_token) { | |
| 103 case '-': | |
| 104 d -= aexpr(); | |
| 105 return d; | |
| 106 case '+': | |
| 107 d += aexpr(); | |
| 108 return d; | |
| 109 default: | |
| 110 return d; | |
| 111 } | |
| 112 } | |
| 113 | |
| 114 static int | |
| 115 mexpr() | |
| 116 { | |
| 117 int d; | |
| 118 d = term(); | |
| 119 switch(last_token) { | |
| 120 case '*': | |
| 121 d *= mexpr(); | |
| 122 return d; | |
| 123 case '/': | |
| 124 d /= mexpr(); | |
| 125 return d; | |
| 126 default: | |
| 127 return d; | |
| 128 } | |
| 129 } | |
| 130 | |
| 131 static int | |
| 132 term() | |
| 133 { | |
| 134 int d; | |
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Masataka Kohagura <kohagura@cr.ie.u-ryukyu.ac.jp>
parents:
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diff
changeset
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135 |
| 55 | 136 lvalue= -1; |
| 137 token(); | |
| 138 if(last_token==EOF) { | |
| 139 error("Term expected"); | |
| 140 } | |
| 141 switch(last_token) { | |
| 142 case '0': | |
| 143 d = value; | |
| 144 token(); | |
| 145 return d; | |
| 146 case 'v': | |
| 147 d = lvalue = value; | |
| 148 token(); | |
| 149 return variable[d]; | |
| 150 case '(': | |
| 151 d = expr(); | |
| 152 if(last_token != ')') { | |
| 153 error("Unbalanced parenthsis"); | |
| 154 } | |
| 155 token(); | |
| 156 return d; | |
| 157 default: | |
| 158 token(); | |
| 159 error("Unknown term"); | |
| 160 return 0; | |
| 161 } | |
| 162 } | |
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impl bitGet and bitSet
Masataka Kohagura <kohagura@cr.ie.u-ryukyu.ac.jp>
parents:
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163 |
| 55 | 164 static int lineno = 0; |
| 165 | |
| 166 void | |
| 167 error(char *msg) | |
| 168 { | |
| 169 fprintf(stderr,"%s on line %d\n",msg, lineno); | |
| 170 } | |
| 171 | |
| 172 int | |
| 173 main() | |
| 174 { | |
| 175 int d; | |
| 176 char buf[BUFSIZ]; | |
| 177 | |
| 178 while (fgets(buf,BUFSIZ,stdin)) { | |
| 179 ptr = buf; | |
| 180 d = expr(); | |
| 181 printf("%s = 0x%08x = %d\n",buf,d,d); | |
| 182 fflush(stdout); | |
| 183 lineno++; | |
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49
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implement bitset
Masataka Kohagura <kohagura@cr.ie.u-ryukyu.ac.jp>
parents:
48
diff
changeset
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184 } |
| 45 | 185 return 0; |
| 186 } |