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* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* 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
* with the License. You may obtain a copy of the License at
*
* http://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
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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($paramKey)...#end - e.g. #chunk($a)A = $a#end
* </pre>
* <p>
* If context contains paramKey and it's value isn't null, chunk is included in the
* chain, and if it is not the first chunk, it is prefixed with chain join (OR/AND).
* If context doesn't contain paramKey or it's value is null, chunk is skipped.
* @since 1.1
*/
public class ChunkDirective extends Directive {
@Override
public String getName() {
return "chunk";
}
@Override
public int getType() {
return BLOCK;
}
@Override
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).value(context) == null) {
// skip this chunk
return false;
}
// BLOCK is the last child
Node block = node.jjtGetChild(node.jjtGetNumChildren() - 1);
block.render(context, writer);
return true;
}
}