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Spring Data Relational support
/*
* Copyright 2019-2023 the original author or authors.
*
* 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
*
* https://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.springframework.data.relational.core.sql;
import java.util.HashSet;
import java.util.Set;
import org.springframework.lang.Nullable;
/**
* Validator for statements to import columns.
*
* @author Mark Paluch
* @since 1.1
*/
abstract class AbstractImportValidator implements Visitor {
Set requiredByWhere = new HashSet<>();
Set from = new HashSet<>();
@Nullable Visitable parent;
/*
* (non-Javadoc)
* @see org.springframework.data.relational.core.sql.Visitor#enter(org.springframework.data.relational.core.sql.Visitable)
*/
@Override
public void enter(Visitable segment) {
if (segment instanceof Table && parent instanceof From) {
from.add((Table) segment);
}
if (segment instanceof Where) {
segment.visit(new SubselectFilteringWhereVisitor());
}
if (segment instanceof Join || segment instanceof OrderByField || segment instanceof From
|| segment instanceof Select || segment instanceof Where || segment instanceof SimpleFunction) {
parent = segment;
}
}
/*
* (non-Javadoc)
* @see org.springframework.data.relational.core.sql.Visitor#leave(org.springframework.data.relational.core.sql.Visitable)
*/
@Override
public void leave(Visitable segment) {}
/**
* {@link Visitor} that skips sub-{@link Select} and collects columns within a {@link Where} clause.
*/
class SubselectFilteringWhereVisitor implements Visitor {
private @Nullable Select selectFilter;
/*
* (non-Javadoc)
* @see org.springframework.data.relational.core.sql.Visitor#enter(org.springframework.data.relational.core.sql.Visitable)
*/
@Override
public void enter(Visitable segment) {
if (selectFilter != null) {
return;
}
if (segment instanceof Select) {
this.selectFilter = (Select) segment;
return;
}
if (segment instanceof Table) {
requiredByWhere.add((Table) segment);
}
}
/*
* (non-Javadoc)
* @see org.springframework.data.relational.core.sql.Visitor#leave(org.springframework.data.relational.core.sql.Visitable)
*/
@Override
public void leave(Visitable segment) {
if (this.selectFilter == segment) {
this.selectFilter = null;
}
}
}
}
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