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69 lines
1.7 KiB
C++
69 lines
1.7 KiB
C++
/* re2c lesson 001_upn_calculator, calc_002, (c) M. Boerger 2006 - 2007 */
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/*!ignore:re2c
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- making use of YYFILL
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. Here we modified the scanner to not require strlen() on the call. Instead
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we compute limit on the fly. That is whenever more input is needed we
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search for the terminating \0 in the next n chars the scanner needs.
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. If there is not enough input we quit the scanner.
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. Note that in lesson_001 YYLIMIT was a character pointer computed only once.
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Here is of course also of type YYCTYPE but a variable that gets reevaluated
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by YYFILL().
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. To make the code smaller we take advantage of the fact that our loop has no
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break so far. This allows us to use break here and have the code that is
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used for YYFILL() not contain the printf in every occurence. That way the
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generated code gets smaller.
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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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int fill(char *p, int n, char **l)
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{
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while (*++p && n--) ;
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* l = p;
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return n <= 0;
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}
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int scan(char *s)
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{
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char *p = s;
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char *l = s;
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char *q = 0;
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#define YYCTYPE char
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#define YYCURSOR p
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#define YYLIMIT l
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#define YYMARKER q
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#define YYFILL(n) { if (!fill(p, n, &l)) break; }
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for(;;)
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{
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/*!re2c
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re2c:indent:top = 2;
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"0"[0-9]+ { printf("Oct\n"); continue; }
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[1-9][0-9]* { printf("Num\n"); continue; }
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"0" { printf("Num\n"); 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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printf("OOD\n"); return 2;
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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]);
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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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