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* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
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*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
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* KIND, either express or implied. See the License for the
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package org.apache.cayenne.access.jdbc;
import java.io.IOException;
import java.io.Writer;
import org.apache.velocity.context.InternalContextAdapter;
import org.apache.velocity.exception.MethodInvocationException;
import org.apache.velocity.exception.ParseErrorException;
import org.apache.velocity.exception.ResourceNotFoundException;
import org.apache.velocity.runtime.directive.Directive;
import org.apache.velocity.runtime.parser.node.Node;
/**
* A custom Velocity directive to describe a conditional chunk of a {@link ChainDirective chain}.
* Usage of chunk is the following:
*
* <pre>
* #chunk()...#end - e.g. #chunk()A = 5#end
* #chunk(condition)...#end - e.g. #chunk($a)A = $a#end</pre>
*
* <p>If condition is evaluated to false, chunk is not included in the chain,
* if it is true, chunk is included, and if it is not the first chunk, it is
* prefixed with chain join.
*
* @since 1.1
* @author Andrei Adamchik
*/
public class ChunkDirective extends Directive {
public String getName() {
return "chunk";
}
public int getType() {
return BLOCK;
}
public boolean render(InternalContextAdapter context, Writer writer, Node node)
throws
IOException,
ResourceNotFoundException,
ParseErrorException,
MethodInvocationException {
// first child is an expression, second is BLOCK
if (node.jjtGetNumChildren() > 1 && !node.jjtGetChild(0).evaluate(context)) {
// return value is really meaningless in Velocity...whatever
return false;
}
// BLOCK is the last child
Node block = node.jjtGetChild(node.jjtGetNumChildren() - 1);
block.render(context, writer);
return true;
}
}