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fifo.c
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fifo.c
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#include <stdio.h>
#define max_tc 20 // MAXIMUM TRANSITION COUNT
#define max_tl 10 // MAXIMUM TRANSITION LENGTH
#define max_nt 10 // MAXIMUM ALLOWED NON TERMINAL
#define max_te 10 // MAXIMUM ALLOWED TERMINAL
char trans[max_tc][max_tl];
int trcnt = -1;
char nonterm[max_nt], term[max_te];
int ntcnt = 0, tecnt;
int res[max_te];
int isNonTerminal(char ch) { return (ch >= 'A' && ch <='Z') ? 1 : 0; }
int mapSymbol(char ch) {
if(isNonTerminal(ch)) {
for(int i = 0; i < ntcnt; i++)
if(nonterm[i] == ch)
return i;
nonterm[ntcnt++] = ch;
return ntcnt - 1;
}
for(int i = 0; i < tecnt; i++)
if(term[i] == ch)
return i;
term[tecnt++] = ch;
return tecnt - 1;
}
void analyze(FILE *fp) {
char s[32], left;
int i;
while(fscanf(fp, "%s", s) != EOF) {
int tlcnt = 0;
mapSymbol(s[0]);
for(i = 1; i < 32 && s[i] != '\0'; i++) {
if(s[i] == '=' || s[i] == '|') {
if(i == '|')
trans[trcnt][tlcnt++] = '\0';
trcnt++; tlcnt = 0;
trans[trcnt][tlcnt++] = s[0];
trans[trcnt][tlcnt++] = '=';
continue;
}
mapSymbol(s[i]);
trans[trcnt][tlcnt++] = s[i];
}
trans[trcnt][tlcnt++] = '\0';
}
trcnt++;
printf("Transitions Read: (%d)\n", trcnt + 1);
for(i = 0; i < trcnt; i++) printf(" %s\n", trans[i]);
printf("Non-Terminals Encountered: (%d)\n ", ntcnt);
for(i = 0; i < ntcnt; i++) printf("%c ", nonterm[i]);
printf("\nTerminals Encountered: (%d)\n ", ntcnt);
for(i = 0; i < tecnt; i++) printf("%c ", term[i]);
fclose(fp); printf("\n\n");
}
int first(char T) {
int i, j, flag = 0;
for(i = 0; i < trcnt; i++) {
if(trans[i][0] == T) {
for(j = 2; j < max_tl && trans[i][j] != T && trans[i][j] != '\0'; j++) {
if(isNonTerminal(trans[i][j])) {
if(!first(trans[i][j])) {
flag = 0;
break;
}
flag = 1;
}
else {
res[mapSymbol(trans[i][j])] = 1;
if(trans[i][j] == '#') flag = 1;
break;
}
}
}
}
return flag;
}
void follow(char T) {
int i, j, k;
for(i = 0; i <= trcnt; i++) {
for(j = 2; j < max_tl && trans[i][j] != '\0'; j++) {
if(trans[i][j] == T) {
for(k = j + 1; k < max_tl && trans[i][k] != '\0'; k++) {
if(isNonTerminal(trans[i][k])) {
if(!first(trans[i][k]))
break;
}
else {
if(trans[i][k] != '#') {
res[mapSymbol(trans[i][k])] = 1;
break;
}
}
}
if(trans[i][k] == '\0' && trans[i][0] != T) follow(trans[i][0]);
}
}
}
}
void main() {
FILE *fp = fopen("gram.txt", "r");
analyze(fp);
int i, j;
for(i = 0; i < ntcnt; i++) {
for(j = 0; j < tecnt; j++) res[j] = 0;
first(nonterm[i]);
printf("First(%c) = { ", nonterm[i]);
for(j = 0; j < tecnt; j++) if(res[j]) printf("%c, ", term[j]);
printf("}\n");
}
sprintf(trans[trcnt], "%c=%c$", trans[0][0], trans[0][0]);
for(i = 0; i < ntcnt; i++) {
for(j = 0; j < tecnt; j++) res[j] = 0;
follow(nonterm[i]);
printf("Follow(%c) = { ", nonterm[i]);
for(j = 0; j < tecnt; j++) if(res[j] && term[j] != '#') printf("%c, ", term[j]);
printf("}\n");
}
}