/**
* Append an argument to the list of query operator arguments.
*
* @param q The query argument (query operator) to append.
* @throws IllegalArgumentException q is an invalid argument
*/
public void appendArg(Qry q) throws IllegalArgumentException {
// The query parser and query operator type system are too simple
// to detect some kinds of query syntax errors. appendArg does
// additional syntax checking while creating the query tree. It
// also inserts SCORE operators between QrySop operators and QryIop
// arguments, and propagates field information from QryIop
// children to parents. Basically, it creates a well-formed
// query tree.
if (this instanceof QryIopTerm) {
throw new IllegalArgumentException("The TERM operator has no arguments.");
}
// SCORE operators can have only a single argument of type QryIop.
if (this instanceof QrySopScore) {
if (this.args.size() > 0) {
throw new IllegalArgumentException("Score operators can have only one argument");
} else if (!(q instanceof QryIop)) {
throw new IllegalArgumentException(
"The argument to a SCORE operator must be of type QryIop.");
} else {
this.args.add(q);
return;
}
}
// Check whether it is necessary to insert an implied SCORE
// operator between a QrySop operator and a QryIop argument.
if ((this instanceof QrySop) && (q instanceof QryIop)) {
Qry impliedOp = new QrySopScore();
impliedOp.setDisplayName("#SCORE");
impliedOp.appendArg(q);
this.args.add(impliedOp);
return;
}
// QryIop operators must have QryIop arguments in the same field.
if ((this instanceof QryIop) && (q instanceof QryIop)) {
if (this.args.size() == 0) {
((QryIop) this).field = new String(((QryIop) q).getField());
} else {
if (!((QryIop) this).field.equals(((QryIop) q).getField())) {
throw new IllegalArgumentException(
"Arguments to QryIop operators must be in the same field.");
}
}
this.args.add(q);
return;
}
// QrySop operators and their arguments must be of the same type.
if ((this instanceof QrySop) && (q instanceof QrySop)) {
this.args.add(q);
return;
}
throw new IllegalArgumentException(
"Objects of type "
+ q.getClass().getName()
+ " cannot be an argument to a query operator of type "
+ this.getClass().getName());
}
