package org.apache.velocity.runtime.directive;
/*
* 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
* "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.
*/
import java.io.IOException;
import java.io.StringWriter;
import java.io.Writer;
import org.apache.commons.lang.text.StrBuilder;
import org.apache.velocity.context.InternalContextAdapter;
import org.apache.velocity.exception.TemplateInitException;
import org.apache.velocity.runtime.Renderable;
import org.apache.velocity.runtime.RuntimeServices;
import org.apache.velocity.runtime.log.Log;
import org.apache.velocity.runtime.parser.node.Node;
/**
* Directive that puts an unrendered AST block in the context
* under the specified key, postponing rendering until the
* reference is used and rendered.
*
* @author Andrew Tetlaw
* @author Nathan Bubna
* @author <a href="mailto:[email protected]">Jarkko Viinamaki</a>
* @since 1.7
* @version $Id: Block.java 686842 2008-08-18 18:29:31Z nbubna $
*/
public abstract class Block extends Directive
{
protected Node block;
protected Log log;
protected int maxDepth;
protected String key;
/**
* Return type of this directive.
*/
public int getType()
{
return BLOCK;
}
/**
* simple init - get the key
*/
public void init(RuntimeServices rs, InternalContextAdapter context, Node node)
throws TemplateInitException
{
super.init(rs, context, node);
log = rs.getLog();
/**
* No checking is done. We just grab the last child node and assume
* that it's the block!
*/
block = node.jjtGetChild(node.jjtGetNumChildren() - 1);
}
public boolean render(InternalContextAdapter context, Writer writer)
{
preRender(context);
try
{
return block.render(context, writer);
}
catch (IOException e)
{
String msg = "Failed to render " + id(context) + " to writer "
+ " at " + Log.formatFileString(this);
log.error(msg, e);
throw new RuntimeException(msg, e);
}
catch (StopCommand stop)
{
if (!stop.isFor(this))
{
throw stop;
}
return true;
}
finally
{
postRender(context);
}
}
/**
* Creates a string identifying the source and location of the block
* definition, and the current template being rendered if that is
* different.
*/
protected String id(InternalContextAdapter context)
{
StrBuilder str = new StrBuilder(100)
.append("block $").append(key);
if (!context.getCurrentTemplateName().equals(getTemplateName()))
{
str.append(" used in ").append(context.getCurrentTemplateName());
}
return str.toString();
}
/**
* actual class placed in the context, holds the context
* being used for the render, as well as the parent (which already holds
* everything else we need).
*/
public static class Reference implements Renderable
{
private InternalContextAdapter context;
private Block parent;
private int depth;
public Reference(InternalContextAdapter context, Block parent)
{
this.context = context;
this.parent = parent;
}
/**
* Render the AST of this block into the writer using the context.
*/
public boolean render(InternalContextAdapter context, Writer writer)
{
depth++;
if (depth > parent.maxDepth)
{
/* this is only a debug message, as recursion can
* happen in quasi-innocent situations and is relatively
* harmless due to how we handle it here.
* this is more to help anyone nuts enough to intentionally
* use recursive block definitions and having problems
* pulling it off properly.
*/
parent.log.debug("Max recursion depth reached for " + parent.id(context)
+ " at " + Log.formatFileString(parent));
depth--;
return false;
}
else
{
parent.render(context, writer);
depth--;
return true;
}
}
public String toString()
{
Writer writer = new StringWriter();
if (render(context, writer))
{
return writer.toString();
}
return null;
}
}
}
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