Method union

basex-core/src/main/java/org/basex/query/QueryParser.java:1855–1861

Parses the "UnionExpr" rule. @return query expression or null @throws QueryException query exception

()

   * @throws QueryException query exception
   */
  private Expr union() throws QueryException {
    final Expr expr = intersect();
    if(expr == null || !isUnion()) return expr;
    final ExprList el = new ExprList().add(expr);
    do add(el, intersect()); while(isUnion());
    return new Union(info(), el.finish());
  }

  /**
   * Checks if a union operator is found.