/**
* Returns a list of symbols that corresponds to all the symbols
* that tag transitions of the given list.
*/
symbol_t* symbols_from_transs(Transition* list) {
symbol_t res;
symbol_t* tmp;
res.next=NULL;
symbol_t* end=&res;
while (list!=NULL) {
tmp=list->label;
concat_symbols(end,dup_symbols(tmp),&end);
list=list->next;
}
return res.next;
}
/**
* This function returns a symbol list that matches
* everything but the symbols matched by the given
* transition list, or NULL if the transition list
* matches everything.
*/
symbol_t* LEXIC_minus_transitions(language_t* language,Transition* trans) {
#ifdef NO_C99_VARIABLE_LENGTH_ARRAY
symbol_t** POS=(symbol_t**)malloc(sizeof(symbol_t*)*(language->POSs->size));
#else
symbol_t* POS[language->POSs->size];
#endif
int i;
/* First we build an array containing a full symbol for each POS.
* For instance, we could have POS[0]=<A>, POS[1]=<V>, etc. */
for (i=0;i<language->POSs->size;i++) {
POS[i]=new_symbol_POS((POS_t*)language->POSs->value[i],-1);
}
symbol_t* tmp;
while (trans!=NULL) {
tmp=(symbol_t*)trans->label;
if (tmp->type==S_LEXIC) {
/* If a transition matches everything, then we can stop
* and return NULL */
for (i=0;i<language->POSs->size;i++) {
free_symbols(POS[i]);
}
#ifdef NO_C99_VARIABLE_LENGTH_ARRAY
free(POS);
#endif
return NULL;
}
/* If we have a transition tagged by <A:s>, we have to replace
* the POS array cell #z that corresponds to <A> by POS[z]-<A:s>,
* that may give something like POS[z]=<A:p> */
symbol_t* minus=symbols_minus_symbol(language,POS[tmp->POS->index],tmp);
free_symbols(POS[tmp->POS->index]);
POS[tmp->POS->index]=minus;
trans=trans->next;
}
/* Finally, we concatenate all the symbols we have computed into
* one symbol list */
symbol_t res;
res.next=NULL;
symbol_t* end=&res;
for (i=0;i<language->POSs->size;i++) {
concat_symbols(end,POS[i],NULL);
}
#ifdef NO_C99_VARIABLE_LENGTH_ARRAY
free(POS);
#endif
return res.next;
}
