com.hazelcast.org.apache.calcite.rel.core.Collect Maven / Gradle / Ivy
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* 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 com.hazelcast.org.apache.calcite.rel.core;
import com.hazelcast.org.apache.calcite.plan.Convention;
import com.hazelcast.org.apache.calcite.plan.RelOptCluster;
import com.hazelcast.org.apache.calcite.plan.RelTraitSet;
import com.hazelcast.org.apache.calcite.rel.RelInput;
import com.hazelcast.org.apache.calcite.rel.RelNode;
import com.hazelcast.org.apache.calcite.rel.RelWriter;
import com.hazelcast.org.apache.calcite.rel.SingleRel;
import com.hazelcast.org.apache.calcite.rel.type.RelDataType;
import com.hazelcast.org.apache.calcite.rel.type.RelDataTypeFactory;
import com.hazelcast.org.apache.calcite.sql.type.SqlTypeUtil;
import java.util.List;
/**
* A relational expression that collapses multiple rows into one.
*
* Rules:
*
*
* - {@code net.sf.farrago.fennel.rel.FarragoMultisetSplitterRule}
* creates a Collect from a call to
* {@link com.hazelcast.org.apache.calcite.sql.fun.SqlMultisetValueConstructor} or to
* {@link com.hazelcast.org.apache.calcite.sql.fun.SqlMultisetQueryConstructor}.
*
*/
public class Collect extends SingleRel {
//~ Instance fields --------------------------------------------------------
protected final String fieldName;
//~ Constructors -----------------------------------------------------------
/**
* Creates a Collect.
*
* @param cluster Cluster
* @param child Child relational expression
* @param fieldName Name of the sole output field
*/
public Collect(
RelOptCluster cluster,
RelTraitSet traitSet,
RelNode child,
String fieldName) {
super(cluster, traitSet, child);
this.fieldName = fieldName;
}
/**
* Creates a Collect by parsing serialized output.
*/
public Collect(RelInput input) {
this(input.getCluster(), input.getTraitSet(), input.getInput(),
input.getString("field"));
}
//~ Methods ----------------------------------------------------------------
@Override public final RelNode copy(RelTraitSet traitSet,
List inputs) {
return copy(traitSet, sole(inputs));
}
public RelNode copy(RelTraitSet traitSet, RelNode input) {
assert traitSet.containsIfApplicable(Convention.NONE);
return new Collect(getCluster(), traitSet, input, fieldName);
}
@Override public RelWriter explainTerms(RelWriter pw) {
return super.explainTerms(pw)
.item("field", fieldName);
}
/**
* Returns the name of the sole output field.
*
* @return name of the sole output field
*/
public String getFieldName() {
return fieldName;
}
@Override protected RelDataType deriveRowType() {
return deriveCollectRowType(this, fieldName);
}
/**
* Derives the output type of a collect relational expression.
*
* @param rel relational expression
* @param fieldName name of sole output field
* @return output type of a collect relational expression
*/
public static RelDataType deriveCollectRowType(
SingleRel rel,
String fieldName) {
RelDataType childType = rel.getInput().getRowType();
assert childType.isStruct();
final RelDataTypeFactory typeFactory = rel.getCluster().getTypeFactory();
RelDataType ret =
SqlTypeUtil.createMultisetType(
typeFactory,
childType,
false);
ret = typeFactory.builder().add(fieldName, ret).build();
return typeFactory.createTypeWithNullability(ret, false);
}
}