org.springframework.data.relational.core.sql.render.SelectListVisitor Maven / Gradle / Ivy
/*
* Copyright 2019-2022 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 org.springframework.data.relational.core.sql.Aliased;
import org.springframework.data.relational.core.sql.Expression;
import org.springframework.data.relational.core.sql.SelectList;
import org.springframework.data.relational.core.sql.Visitable;
/**
* {@link PartRenderer} for {@link SelectList}s.
*
* @author Mark Paluch
* @author Jens Schauder
* @since 1.1
*/
class SelectListVisitor extends TypedSubtreeVisitor implements PartRenderer {
private final RenderContext context;
private final StringBuilder builder = new StringBuilder();
private final RenderTarget target;
private boolean requiresComma = false;
private boolean insideFunction = false; // this is hackery and should be fix with a proper visitor for
private ExpressionVisitor expressionVisitor;
// subelements.
SelectListVisitor(RenderContext context, RenderTarget target) {
this.context = context;
this.target = target;
this.expressionVisitor = new ExpressionVisitor(context, ExpressionVisitor.AliasHandling.IGNORE);
}
/*
* (non-Javadoc)
* @see org.springframework.data.relational.core.sql.render.TypedSubtreeVisitor#enterNested(org.springframework.data.relational.core.sql.Visitable)
*/
@Override
Delegation enterNested(Visitable segment) {
if (requiresComma) {
builder.append(", ");
requiresComma = false;
}
if (segment instanceof Expression) {
return Delegation.delegateTo(expressionVisitor);
}
return super.enterNested(segment);
}
/*
* (non-Javadoc)
* @see org.springframework.data.relational.core.sql.render.TypedSubtreeVisitor#leaveMatched(org.springframework.data.relational.core.sql.Visitable)
*/
@Override
Delegation leaveMatched(SelectList segment) {
target.onRendered(builder);
return super.leaveMatched(segment);
}
/*
* (non-Javadoc)
* @see org.springframework.data.relational.core.sql.render.TypedSubtreeVisitor#leaveNested(org.springframework.data.relational.core.sql.Visitable)
*/
@Override
Delegation leaveNested(Visitable segment) {
if (segment instanceof Expression) {
builder.append(expressionVisitor.getRenderedPart());
requiresComma = true;
}
if (segment instanceof Aliased && !insideFunction) {
builder.append(" AS ").append(NameRenderer.render(context, (Aliased) segment));
}
return super.leaveNested(segment);
}
/*
* (non-Javadoc)
* @see org.springframework.data.relational.core.sql.render.PartRenderer#getRenderedPart()
*/
@Override
public CharSequence getRenderedPart() {
return builder;
}
}