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Spring Data Relational support
/*
* 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.Assignment;
import org.springframework.data.relational.core.sql.Column;
import org.springframework.data.relational.core.sql.Expression;
import org.springframework.data.relational.core.sql.Visitable;
/**
* {@link org.springframework.data.relational.core.sql.Visitor} rendering {@link Assignment}. Uses a
* {@link RenderTarget} to call back for render results.
*
* @author Mark Paluch
* @since 1.1
* @see Assignment
*/
class AssignmentVisitor extends TypedSubtreeVisitor {
private final ColumnVisitor columnVisitor;
private final ExpressionVisitor expressionVisitor;
private final RenderTarget target;
private final StringBuilder part = new StringBuilder();
AssignmentVisitor(RenderContext context, RenderTarget target) {
this.columnVisitor = new ColumnVisitor(context, false, part::append);
this.expressionVisitor = new ExpressionVisitor(context);
this.target = target;
}
/*
* (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 Column) {
return Delegation.delegateTo(columnVisitor);
}
if (segment instanceof Expression) {
return Delegation.delegateTo(expressionVisitor);
}
throw new IllegalStateException("Cannot provide visitor for " + segment);
}
/*
* (non-Javadoc)
* @see org.springframework.data.relational.core.sql.render.FilteredSubtreeVisitor#leaveNested(org.springframework.data.relational.core.sql.Visitable)
*/
@Override
Delegation leaveNested(Visitable segment) {
if (segment instanceof Column) {
if (part.length() != 0) {
part.append(" = ");
}
return super.leaveNested(segment);
}
if (segment instanceof Expression) {
part.append(expressionVisitor.getRenderedPart());
}
return super.leaveNested(segment);
}
/*
* (non-Javadoc)
* @see org.springframework.data.relational.core.sql.render.FilteredSubtreeVisitor#leaveMatched(org.springframework.data.relational.core.sql.Visitable)
*/
@Override
Delegation leaveMatched(Assignment segment) {
target.onRendered(new StringBuilder(part));
part.setLength(0);
return super.leaveMatched(segment);
}
}