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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.render;
import java.util.function.Predicate;
import org.springframework.data.relational.core.sql.Condition;
import org.springframework.data.relational.core.sql.Expression;
import org.springframework.data.relational.core.sql.Visitable;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
/**
* Support class for {@link FilteredSubtreeVisitor filtering visitors} that want to render a single {@link Condition}
* and delegate nested {@link Expression} and {@link Condition} rendering.
*
* @author Mark Paluch
* @author Jens Schauder
* @since 1.1
*/
abstract class FilteredSingleConditionRenderSupport extends FilteredSubtreeVisitor {
private final RenderContext context;
private @Nullable PartRenderer current;
/**
* Creates a new {@link FilteredSingleConditionRenderSupport} given the filter {@link Predicate}.
*
* @param context
* @param filter filter predicate to identify when to {@link #enterMatched(Visitable)
* enter}/{@link #leaveMatched(Visitable) leave} the {@link Visitable segment} that this visitor is
* responsible for.
*/
FilteredSingleConditionRenderSupport(RenderContext context, Predicate filter) {
super(filter);
this.context = context;
}
/*
* (non-Javadoc)
* @see org.springframework.data.relational.core.sql.render.FilteredSubtreeVisitor#enterNested(org.springframework.data.relational.core.sql.Visitable)
*/
@Override
Delegation enterNested(Visitable segment) {
if (segment instanceof Condition) {
ConditionVisitor visitor = new ConditionVisitor(context);
current = visitor;
return Delegation.delegateTo(visitor);
}
if (segment instanceof Expression) {
ExpressionVisitor visitor = new ExpressionVisitor(context);
current = visitor;
return Delegation.delegateTo(visitor);
}
throw new IllegalStateException("Cannot provide visitor for " + segment);
}
/**
* Returns whether rendering was delegated to a {@link ExpressionVisitor} or {@link ConditionVisitor}.
*
* @return {@literal true} when rendering was delegated to a {@link ExpressionVisitor} or {@link ConditionVisitor}.
*/
protected boolean hasDelegatedRendering() {
return current != null;
}
/**
* Consumes the delegated rendering part. Call {@link #hasDelegatedRendering()} to check whether rendering was
* actually delegated. Consumption releases the delegated rendered.
*
* @return the delegated rendered part.
* @throws IllegalStateException if rendering was not delegate.
*/
protected CharSequence consumeRenderedPart() {
Assert.state(hasDelegatedRendering(), "Rendering not delegated. Cannot consume delegated rendering part.");
PartRenderer current = this.current;
this.current = null;
return current.getRenderedPart();
}
}