/* Return pointer to ST record of lexeme s, or NULL if not found */
STrec *STlookup(char *s)
{
/*Get the hash of s*/
int hash = SThash(s);
/*Check to see if there are any lexemes at the given hash index.
If there were, compare the strings. If theyre not the same, go on to the next STrec.
*/
STrec *recpt = NULL;
if (symtab[hash]!= NULL) {
recpt = symtab[hash];
}
char *lex;
STrec *link;
do {
if (recpt != NULL) {
lex = recpt->lexptr;
link = recpt->hashlink;
if (lex == NULL) {
return NULL;
}
else {
if (strcmp(lex, s) == 0) {
return recpt;
}
else {
recpt = link;
}
}
} else {
return NULL;
}
} while (link != NULL);
/*Looped through without finding anything, so return NULL */
return NULL;
}
/* Insert lexeme s into symbol table and return pointer to new STrec */
STrec *STinsert(char *s)
{
STrec *node;
int hash = SThash(s);
node = (STrec *)malloc(sizeof(STrec));
node->lexptr = (char *)malloc(strlen(s)+1);
strcpy(node->lexptr, s);
node->declstack = NULL; /* NEW HW 4: initially empty stack of decldescs. */
STrec* target = symtab[hash];
/* If there is a clash, then we want to push node to the front
* Do this by temporarily storing the existing node and setting
* the temporary node (target) as the child of the new node
*/
node->hashlink = target;
symtab[hash] = node;
return node;
}
/* Return pointer to ST record of lexeme s, or NULL if not found */
STrec *STlookup(char *s)
{
int hash = SThash(s);
STrec* rec = symtab[hash];
/* Find the corresponding spot in the table to insert
* If rec is null, this means the lexeme has not been inserted
* If there is a hit, we have to iterate through the linked list
* recursively and see if any strec points to the same lexeme
*/
while (rec != NULL) {
if (strcmp(s, rec->lexptr) == 0) {
return rec;
}
else {
// printf("found %s, was looking for %s\n", rec->lexptr, s);
rec = rec->hashlink;
}
}
// printf("failed to find %s\n", s);
return NULL;
}
/* Insert lexeme s into symbol table and return pointer to new STrec */
STrec *STinsert(char *s)
{
STrec *node;
int hash = SThash(s);
node = (STrec *)malloc(sizeof(STrec));
node->lexptr = (char *)malloc(strlen(s)+1);
strcpy(node->lexptr, s);
/* (need to insert 'node' at beginning of linked list at 'symtab[hash]') */
STrec *oldSTrec = NULL;
/* If there was an STrec at that index before, save it then place the pointer in node's hashlink */
if (symtab[hash] != NULL) {
oldSTrec = symtab[hash];
}
symtab[hash] = node;
node->hashlink = oldSTrec;
node->declstack = NULL; /* NEW HW4 */
return node;
}
