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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 org.springframework.data.relational.core.sql.Aliased;
import org.springframework.data.relational.core.sql.From;
import org.springframework.data.relational.core.sql.InlineQuery;
import org.springframework.data.relational.core.sql.TableLike;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
/**
* Renderer for {@link TableLike} used within a {@link From} or
* {@link org.springframework.data.relational.core.sql.Join} clause. Uses a {@link RenderTarget} to call back for render
* results.
*
* @author Mark Paluch
* @author Jens Schauder
* @since 1.1
*/
class FromTableVisitor extends TypedSubtreeVisitor {
private final RenderContext context;
private final RenderTarget parent;
@Nullable private SelectStatementVisitor delegate;
@Nullable private StringBuilder builder = null;
FromTableVisitor(RenderContext context, RenderTarget parent) {
super();
this.context = context;
this.parent = parent;
}
/*
* (non-Javadoc)
* @see org.springframework.data.relational.core.sql.render.TypedSubtreeVisitor#enterMatched(org.springframework.data.relational.core.sql.Visitable)
*/
@Override
Delegation enterMatched(TableLike segment) {
builder = new StringBuilder();
if (segment instanceof InlineQuery) {
builder.append("(");
delegate = new SelectStatementVisitor(context);
return Delegation.delegateTo(delegate);
}
return super.enterMatched(segment);
}
@Override
Delegation leaveMatched(TableLike segment) {
Assert.state(builder != null, "Builder must not be null in leaveMatched.");
if (delegate != null) {
builder.append(delegate.getRenderedPart());
builder.append(") ");
delegate = null;
}
builder.append(NameRenderer.render(context, segment));
if (segment instanceof Aliased) {
builder.append(" ").append(NameRenderer.render(context, (Aliased) segment));
}
parent.onRendered(builder);
return super.leaveMatched(segment);
}
}