com.hazelcast.org.apache.calcite.plan.RelOptRuleOperandChildPolicy 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,
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* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.hazelcast.org.apache.calcite.plan;
/**
* Policy by which operands will be matched by relational expressions with
* any number of children.
*/
public enum RelOptRuleOperandChildPolicy {
/**
* Signifies that operand can have any number of children.
*/
ANY,
/**
* Signifies that operand has no children. Therefore it matches a
* leaf node, such as a table scan or VALUES operator.
*
* {@code RelOptRuleOperand(Foo.class, NONE)} is equivalent to
* {@code RelOptRuleOperand(Foo.class)} but we prefer the former because
* it is more explicit.
*/
LEAF,
/**
* Signifies that the operand's children must precisely match its
* child operands, in order.
*/
SOME,
/**
* Signifies that the rule matches any one of its parents' children.
* The parent may have one or more children.
*/
UNORDERED,
}