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Spring Data Relational support
/*
* Copyright 2021-2022 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.StringJoiner;
import org.springframework.data.relational.core.sql.Cast;
import org.springframework.data.relational.core.sql.Visitable;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
/**
* Renders a CAST expression, by delegating to an {@link ExpressionVisitor} and building the expression out of the
* rendered parts.
*
* @author Jens Schauder
* @since 2.3
*/
class CastVisitor extends TypedSubtreeVisitor implements PartRenderer {
private final RenderContext context;
@Nullable private StringJoiner joiner;
@Nullable private ExpressionVisitor expressionVisitor;
CastVisitor(RenderContext context) {
this.context = context;
}
@Override
Delegation enterMatched(Cast cast) {
joiner = new StringJoiner(", ", "CAST(", " AS " + cast.getTargetType() + ")");
return super.enterMatched(cast);
}
@Override
Delegation enterNested(Visitable segment) {
expressionVisitor = new ExpressionVisitor(context, ExpressionVisitor.AliasHandling.IGNORE);
return Delegation.delegateTo(expressionVisitor);
}
@Override
Delegation leaveNested(Visitable segment) {
Assert.state(joiner != null, "Joiner must not be null.");
Assert.state(expressionVisitor != null, "ExpressionVisitor must not be null.");
joiner.add(expressionVisitor.getRenderedPart());
return super.leaveNested(segment);
}
@Override
public CharSequence getRenderedPart() {
if (joiner == null) {
throw new IllegalStateException("Joiner must not be null.");
}
return joiner.toString();
}
}