int find_ht(node_type* ptr)
{ /* Auxilliary Function for finding height*/
int htr,htl,ht=-1;
if(ptr!=NULL)
{
htl=find_ht(ptr->left);
htr=find_ht(ptr->right);
if(htl>htr) /* Height of Left Subtree is greater*/
{
ht=htl+1;
}
else /* Height of Right Subtree is greater*/
{
ht=htr+1;
}
}
return ht;
}
DFA read_dfa(const char *filename, Hashtable ht, char symbols[][25], int *num)
{
//reads DFA from specified file, updates info about the terminals
FILE *fp = fopen(filename,"r");
if(fp==NULL){
printf("File %s could not be opened\n",filename);
exit(0);
}
DFA d;
fscanf(fp,"%d\n",&(d.num_states));
fscanf(fp,"%d\n",&(d.start_state));
int i, num_terminals = 1;
for(i=1;i<=d.num_states;i++){
//info about each state
// state_no <space> final?(Y/N) <space> token(if final) <space> backtrack? (Y/N, if final)
int s_no;
char temp[25], tok[25];
fscanf(fp,"%d %s",&s_no,temp);
if(!strcmp(temp,"N")){
d.is_final[s_no] = 0;
}
else d.is_final[s_no] = 1;
if(d.is_final[s_no]){
fscanf(fp, "%s %s",tok,temp);
strcpy(d.tok[s_no],tok);
if(find_ht(ht,tok)==-1){
strcpy(symbols[num_terminals], tok);
insert_ht(ht,tok,num_terminals++);
}
if(!strcmp(temp,"N")){
d.to_backtrack[s_no] = 0;
}
else d.to_backtrack[s_no] = 1;
}
}
memset(d.transitions,-1,sizeof(d.transitions)); //if not specified -> invalid
//info about transitions - one per line till EOF
//from_state <space> to_state <space> range of chars (eg. a z)
char r1[10], r2[10];
int t1, t2;
while(!feof(fp)){
fscanf(fp,"%d %d %s",&t1,&t2,r1);
if(!strcmp(r1,"others")){
int i;
for(i=0;i<128;i++){
if(d.transitions[t1][i] == -1)
d.transitions[t1][i] = t2;
}
}
else{
fscanf(fp,"%s",r2);
if(!strcmp(r1,"sp"))
r1[0] = ' ';
if(!strcmp(r2,"sp"))
r2[0] = ' ';
int i;
for(i=r1[0];i<=r2[0];i++){
d.transitions[t1][i] = t2;
}
}
}
*num = num_terminals;
fclose(fp);
return d;
}