public static Expr parse(Tokens tokens) {
int pos = tokens.getPosition();
Expr firstExpr = MultiplyExpr.parse(tokens);
if (firstExpr == null) {
tokens.setPosition(pos);
return null;
}
List<Expr> multiplyExprs = new LinkedList<Expr>();
multiplyExprs.add(firstExpr);
BitSet operators = new BitSet();
for (int i = 0; tokens.hasNext(); i++) {
char operator = tokens.nextChar();
if (operator == '+' || operator == '-') {
Expr nextExpr = MultiplyExpr.parse(tokens);
if (nextExpr == null) {
throw new QuerySyntaxException(tokens);
}
multiplyExprs.add(nextExpr);
if (operator == '+') {
operators.set(i);
}
} else {
tokens.pushback();
break;
}
}
return multiplyExprs.size() == 1 ? firstExpr : new AdditiveExpr(multiplyExprs, operators);
}
AdditiveExpr(List<Expr> multiplyExprs, BitSet operators) {
this.multiplyExprs = multiplyExprs.toArray(new Expr[multiplyExprs.size()]);
this.operators = operators;
}