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. */
Exp * n;
if (is_equal(dict, L'(')) {
if (!advance(dict)) {
return NULL;
}
n = in_parens(dict);
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;
}
n = in_parens(dict);
if (!is_equal(dict, L'}')) {
dict_error(dict, L"Expecting a \"}\".");
return NULL;
}
if (!advance(dict)) {
return NULL;
}
n = make_optional_node(dict, n);
} else if (is_equal(dict, L'[')) {
if (!advance(dict)) {
return NULL;
}
n = in_parens(dict);
if (!is_equal(dict, L']')) {
dict_error(dict, L"Expecting a \"]\".");
return NULL;
}
if (!advance(dict)) {
return NULL;
}
n->cost += 1;
} else if (!dict->is_special) {
n = connector(dict);
if (n == NULL) {
return NULL;
}
} else if (is_equal(dict, L')') || is_equal(dict, L']')) {
/* allows "()" or "[]" */
n = make_zeroary_node(dict);
} else {
dict_error(dict, L"Connector, \"(\", \"[\", or \"{\" expected.");
return NULL;
}
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.
*/
Exp * expression(Dictionary dict)
{
Exp * n;
if (is_equal(dict, '(')) {
if (!link_advance(dict)) {
return NULL;
}
n = in_parens(dict);
if (!is_equal(dict, ')')) {
dict_error(dict, "Expecting a \")\".");
return NULL;
}
if (!link_advance(dict)) {
return NULL;
}
} else if (is_equal(dict, '{')) {
if (!link_advance(dict)) {
return NULL;
}
n = in_parens(dict);
if (!is_equal(dict, '}')) {
dict_error(dict, "Expecting a \"}\".");
return NULL;
}
if (!link_advance(dict)) {
return NULL;
}
n = make_optional_node(dict, n);
} else if (is_equal(dict, '[')) {
if (!link_advance(dict)) {
return NULL;
}
n = in_parens(dict);
if (!is_equal(dict, ']')) {
dict_error(dict, "Expecting a \"]\".");
return NULL;
}
if (!link_advance(dict)) {
return NULL;
}
n->cost += 1.0f;
} else if (!dict->is_special) {
n = connector(dict);
if (n == NULL) {
return NULL;
}
} else if (is_equal(dict, ')') || is_equal(dict, ']')) {
/* allows "()" or "[]" */
n = make_zeroary_node(dict);
} else {
dict_error(dict, "Connector, \"(\", \"[\", or \"{\" expected.");
return NULL;
}
return n;
}
