/*
* Copyright 2015, The Querydsl Team (http://www.querydsl.com/team)
*
* Licensed 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 com.querydsl.sql;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import javax.annotation.Nullable;
import com.google.common.collect.ImmutableList;
import com.querydsl.core.types.*;
import com.querydsl.core.types.dsl.ComparableExpressionBase;
import com.querydsl.core.types.dsl.Expressions;
import com.querydsl.core.types.dsl.SimpleExpression;
import com.querydsl.core.types.dsl.SimpleOperation;
/**
* {@code WithinGroup} is a builder for {@code WITHIN GROUP} constructs
*
* @param <T> expression type
*
* @author tiwe
*/
public class WithinGroup<T> extends SimpleOperation<T> {
private static final long serialVersionUID = 464583892898579544L;
private static Expression<?> merge(Expression<?>... args) {
if (args.length == 1) {
return args[0];
} else {
return ExpressionUtils.list(Object.class, args);
}
}
/**
* Intermediate step
*/
public class OrderBy extends MutableExpressionBase<T> {
private static final long serialVersionUID = -4936481493030913621L;
private static final String ORDER_BY = "order by ";
@Nullable
private transient volatile SimpleExpression<T> value;
private final List<OrderSpecifier<?>> orderBy = new ArrayList<OrderSpecifier<?>>();
public OrderBy() {
super(WithinGroup.this.getType());
}
@SuppressWarnings("unchecked")
public SimpleExpression<T> getValue() {
if (value == null) {
int size = 0;
ImmutableList.Builder<Expression<?>> args = ImmutableList.builder();
StringBuilder builder = new StringBuilder();
builder.append("{0} within group (");
args.add(WithinGroup.this);
size++;
if (!orderBy.isEmpty()) {
builder.append(ORDER_BY);
builder.append("{" + size + "}");
args.add(ExpressionUtils.orderBy(orderBy));
}
builder.append(")");
value = Expressions.template((Class) WithinGroup.this.getType(), builder.toString(), args.build());
}
return value;
}
@Override
public <R, C> R accept(Visitor<R, C> v, C context) {
return getValue().accept(v, context);
}
public OrderBy orderBy(ComparableExpressionBase<?> orderBy) {
value = null;
this.orderBy.add(orderBy.asc());
return this;
}
public OrderBy orderBy(ComparableExpressionBase<?>... orderBy) {
value = null;
for (ComparableExpressionBase<?> e : orderBy) {
this.orderBy.add(e.asc());
}
return this;
}
public OrderBy orderBy(OrderSpecifier<?> orderBy) {
value = null;
this.orderBy.add(orderBy);
return this;
}
public OrderBy orderBy(OrderSpecifier<?>... orderBy) {
value = null;
Collections.addAll(this.orderBy, orderBy);
return this;
}
}
public WithinGroup(Class<? extends T> type, Operator op) {
super(type, op, ImmutableList.<Expression<?>>of());
}
public WithinGroup(Class<? extends T> type, Operator op, Expression<?> arg) {
super(type, op, ImmutableList.<Expression<?>>of(arg));
}
public WithinGroup(Class<? extends T> type, Operator op, Expression<?> arg1, Expression<?> arg2) {
super(type, op, ImmutableList.of(arg1, arg2));
}
public WithinGroup(Class<? extends T> type, Operator op, Expression<?>... args) {
super(type, op, merge(args));
}
public OrderBy withinGroup() {
return new OrderBy();
}
}