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78 lines
1.9 KiB
C++
78 lines
1.9 KiB
C++
/* re2c lesson 001_upn_calculator, calc_004, (c) M. Boerger 2006 - 2007 */
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/*!ignore:re2c
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- making use of definitions
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. We provide complex rules as definitions. We can even have definitions made
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up from other definitions. And we could also use definitions as part of
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rules and not only as full rules as shown in this lesson.
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- showing the tokens
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. re2c does not store the beginning of a token on its own but we can easily
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do this by providing variable, in our case t, that is set to YYCURSOR on
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every loop. If we were not using a loop here the token, we could have used
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s instead of a new variable instead.
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. As we use the token for an output function that requires a terminating zero
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we copy the token. Alternatively we could store the end of the token, then
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replace it with a zero character and replace it after the token has been
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used. However that approach is not always acceptable.
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*/
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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char * tokendup(const char *t, const char *l)
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{
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size_t n = l -t + 1;
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char *r = (char*)malloc(n);
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memmove(r, t, n-1);
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r[n] = '\0';
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return r;
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}
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int scan(char *s, int l)
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{
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char *p = s;
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char *q = 0;
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char *t;
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#define YYCTYPE char
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#define YYCURSOR p
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#define YYLIMIT (s+l+2)
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#define YYMARKER q
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#define YYFILL(n) { printf("OOD\n"); return 2; }
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for(;;)
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{
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t = p;
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/*!re2c
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re2c:indent:top = 2;
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DIGIT = [0-9] ;
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OCT = "0" DIGIT+ ;
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INT = "0" | ( [1-9] DIGIT* ) ;
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OCT { t = tokendup(t, p); printf("Oct: %s\n", t); free(t); continue; }
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INT { t = tokendup(t, p); printf("Num: %s\n", t); free(t); continue; }
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"+" { printf("+\n"); continue; }
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"-" { printf("+\n"); continue; }
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"\000" { printf("EOF\n"); return 0; }
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[^] { printf("ERR\n"); return 1; }
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*/
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}
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return 0;
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}
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int main(int argc, char **argv)
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{
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if (argc > 1)
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{
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return scan(argv[1], strlen(argv[1]));
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}
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else
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{
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fprintf(stderr, "%s <expr>\n", argv[0]);
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return 0;
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}
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}
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