| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, |
| * software distributed under the License is distributed on an |
| * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| * KIND, either express or implied. See the License for the |
| * specific language governing permissions and limitations |
| * under the License. |
| */ |
| package org.apache.openjpa.kernel.exps; |
| |
| import java.util.Collection; |
| import java.util.Collections; |
| import java.util.HashSet; |
| |
| import org.apache.openjpa.kernel.StoreContext; |
| |
| /** |
| * A distinct set of the specified values. |
| * |
| * @author Marc Prud'hommeaux |
| */ |
| class Distinct |
| extends Val { |
| |
| private final Val _val; |
| |
| /** |
| * Constructor. Supply value to aggregate. |
| */ |
| public Distinct(Val val) { |
| _val = val; |
| } |
| |
| public Class getType() { |
| return Collection.class; |
| } |
| |
| public void setImplicitType(Class type) { |
| } |
| |
| protected Object eval(Object candidate, Object orig, |
| StoreContext ctx, Object[] params) { |
| if (candidate == null) |
| candidate = Collections.EMPTY_LIST; |
| Collection arg = candidate instanceof Collection |
| ? (Collection) candidate : Collections.singleton(candidate); |
| return eval(arg, orig, ctx, params).iterator().next(); |
| } |
| |
| protected Collection eval(Collection candidates, Object orig, |
| StoreContext ctx, Object[] params) { |
| Collection args = _val.eval(candidates, orig, ctx, params); |
| return new HashSet(args); |
| } |
| |
| public void acceptVisit(ExpressionVisitor visitor) { |
| visitor.enter(this); |
| _val.acceptVisit(visitor); |
| visitor.exit(this); |
| } |
| } |
| |