org.apache.flink.table.expressions.ExpressionVisitor Maven / Gradle / Ivy
/*
* 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.flink.table.expressions;
import org.apache.flink.annotation.PublicEvolving;
/**
* The visitor definition of {@link Expression}.
*
* An expression visitor transforms an expression to instances of {@code R}.
*
*
Please note that only {@link ResolvedExpression}s are listed here. Pure API expression are
* handled in {@link #visit(Expression)}.
*/
@PublicEvolving
public interface ExpressionVisitor {
// --------------------------------------------------------------------------------------------
// resolved expressions
// --------------------------------------------------------------------------------------------
R visit(CallExpression call);
R visit(ValueLiteralExpression valueLiteral);
R visit(FieldReferenceExpression fieldReference);
R visit(TypeLiteralExpression typeLiteral);
// --------------------------------------------------------------------------------------------
// other expressions
// --------------------------------------------------------------------------------------------
R visit(Expression other);
}