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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 org.apache.drill.common.expression;
import java.util.List;
import org.apache.drill.common.expression.fn.FuncHolder;
import org.apache.drill.common.expression.visitors.ExprVisitor;
import org.apache.drill.shaded.guava.com.google.common.collect.ImmutableList;
import org.apache.drill.shaded.guava.com.google.common.collect.Lists;
public abstract class FunctionHolderExpression extends LogicalExpressionBase {
public final ImmutableList<LogicalExpression> args;
public final String nameUsed;
/**
* A field reference identifies the output field and
* is used to reference that field in the generated classes.
*/
private FieldReference fieldReference;
public FunctionHolderExpression(String nameUsed, ExpressionPosition pos, List<LogicalExpression> args) {
super(pos);
if (args == null) {
args = Lists.newArrayList();
}
if (!(args instanceof ImmutableList)) {
args = ImmutableList.copyOf(args);
}
this.args = (ImmutableList<LogicalExpression>) args;
this.nameUsed = nameUsed;
}
@Override
public <T, V, E extends Exception> T accept(ExprVisitor<T, V, E> visitor, V value) throws E {
return visitor.visitFunctionHolderExpression(this, value);
}
/**
* A function can have multiple names, it returns the function name used in the query.
* @return The function name used in the query.
*/
public String getName() {
return nameUsed;
}
/**
* constant input expected for i'th argument?
* @param i
* @return True if a constant input is expected for the i'th argument. False otherwise.
*/
public abstract boolean argConstantOnly(int i);
/**
* @return aggregating function or not
*/
public abstract boolean isAggregating();
/**
* is the function output non-deterministic?
*/
public abstract boolean isRandom();
/**
* @ return a copy of FunctionHolderExpression, with passed in argument list.
*/
public abstract FunctionHolderExpression copy(List<LogicalExpression> args);
/** Return the underlying function implementation holder. */
public abstract FuncHolder getHolder();
public FieldReference getFieldReference() {
return fieldReference;
}
/**
* Set the FieldReference to be used during generating code.
*
* @param fieldReference FieldReference to set.
*/
public void getFieldReference(FieldReference fieldReference) {
this.fieldReference = fieldReference;
}
}
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