Exp * expression(Dictionary dict) {
/* Build (and return the root of) the tree for the expression beginning */
/* with the current token. At the end, the token is the first one not */
/* part of this expression. */
return restricted_expression(dict, TRUE,TRUE);
}
Exp * restricted_expression(Dictionary dict, int and_ok, int or_ok) {
Exp * nl=NULL, * nr, * n;
E_list *ell, *elr;
if (is_equal(dict, L'(')) {
if (!advance(dict)) {
return NULL;
}
nl = expression(dict);
if (nl == NULL) {
return NULL;
}
if (!is_equal(dict, L')')) {
dict_error(dict, L"Expecting a \")\".");
return NULL;
}
if (!advance(dict)) {
return NULL;
}
} else if (is_equal(dict, L'{')) {
if (!advance(dict)) {
return NULL;
}
nl = expression(dict);
if (nl == NULL) {
return NULL;
}
if (!is_equal(dict, L'}')) {
dict_error(dict, L"Expecting a \"}\".");
return NULL;
}
if (!advance(dict)) {
return NULL;
}
nl = make_optional_node(dict, nl);
} else if (is_equal(dict, L'[')) {
if (!advance(dict)) {
return NULL;
}
nl = expression(dict);
if (nl == NULL) {
return NULL;
}
if (!is_equal(dict, L']')) {
dict_error(dict, L"Expecting a \"]\".");
return NULL;
}
if (!advance(dict)) {
return NULL;
}
nl->cost += 1;
} else if (!dict->is_special) {
nl = connector(dict);
if (nl == NULL) {
return NULL;
}
} else if (is_equal(dict, L')') || is_equal(dict, L']')) {
/* allows "()" or "[]" */
nl = make_zeroary_node(dict);
} else {
dict_error(dict, L"Connector, \"(\", \"[\", or \"{\" expected.");
return NULL;
}
if (is_equal(dict, L'&') || (wcscmp(dict->token, L"and")==0)) {
if (!and_ok) {
warning(dict, L"\"and\" and \"or\" at the same level in an expression");
}
if (!advance(dict)) {
return NULL;
}
nr = restricted_expression(dict, TRUE,FALSE);
if (nr == NULL) {
return NULL;
}
n = Exp_create(dict);
n->u.l = ell = (E_list *) xalloc(sizeof(E_list));
ell->next = elr = (E_list *) xalloc(sizeof(E_list));
elr->next = NULL;
ell->e = nl;
elr->e = nr;
n->type = AND_type;
n->cost = 0;
} else if (is_equal(dict, L'|') || (wcscmp(dict->token, L"or")==0)) {
if (!or_ok) {
warning(dict, L"\"and\" and \"or\" at the same level in an expression");
}
if (!advance(dict)) {
return NULL;
}
nr = restricted_expression(dict, FALSE,TRUE);
if (nr == NULL) {
return NULL;
}
n = Exp_create(dict);
n->u.l = ell = (E_list *) xalloc(sizeof(E_list));
ell->next = elr = (E_list *) xalloc(sizeof(E_list));
elr->next = NULL;
ell->e = nl;
elr->e = nr;
n->type = OR_type;
n->cost = 0;
} else return nl;
return n;
}
/**
* Build (and return the root of) the tree for the expression beginning
* with the current token. At the end, the token is the first one not
* part of this expression.
*/
static Exp * expression(Dictionary dict)
{
return restricted_expression(dict, TRUE, TRUE);
}
