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Tools to assist in the reading of configuration/preferences files in
various formats
/*
* 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.
*/
package org.apache.commons.configuration;
import java.util.Iterator;
import org.apache.commons.collections.Transformer;
import org.apache.commons.collections.iterators.TransformIterator;
import org.apache.commons.configuration.interpol.ConfigurationInterpolator;
/**
* A subset of another configuration. The new Configuration object contains
* every key from the parent Configuration that starts with prefix. The prefix
* is removed from the keys in the subset.
* It is usually not necessary to use this class directly. Instead the
* {@link Configuration#subset(String)} method should be used,
* which will return a correctly initialized instance.
*
* @author Emmanuel Bourg
* @version $Revision: 930693 $, $Date: 2010-04-04 16:02:59 +0200 (So, 04. Apr 2010) $
*/
public class SubsetConfiguration extends AbstractConfiguration
{
/** The parent configuration. */
protected Configuration parent;
/** The prefix used to select the properties. */
protected String prefix;
/** The prefix delimiter */
protected String delimiter;
/**
* Create a subset of the specified configuration
*
* @param parent The parent configuration
* @param prefix The prefix used to select the properties
*/
public SubsetConfiguration(Configuration parent, String prefix)
{
this.parent = parent;
this.prefix = prefix;
}
/**
* Create a subset of the specified configuration
*
* @param parent The parent configuration
* @param prefix The prefix used to select the properties
* @param delimiter The prefix delimiter
*/
public SubsetConfiguration(Configuration parent, String prefix, String delimiter)
{
this.parent = parent;
this.prefix = prefix;
this.delimiter = delimiter;
}
/**
* Return the key in the parent configuration associated to the specified
* key in this subset.
*
* @param key The key in the subset.
* @return the key as to be used by the parent
*/
protected String getParentKey(String key)
{
if ("".equals(key) || key == null)
{
return prefix;
}
else
{
return delimiter == null ? prefix + key : prefix + delimiter + key;
}
}
/**
* Return the key in the subset configuration associated to the specified
* key in the parent configuration.
*
* @param key The key in the parent configuration.
* @return the key in the context of this subset configuration
*/
protected String getChildKey(String key)
{
if (!key.startsWith(prefix))
{
throw new IllegalArgumentException("The parent key '" + key + "' is not in the subset.");
}
else
{
String modifiedKey = null;
if (key.length() == prefix.length())
{
modifiedKey = "";
}
else
{
int i = prefix.length() + (delimiter != null ? delimiter.length() : 0);
modifiedKey = key.substring(i);
}
return modifiedKey;
}
}
/**
* Return the parent configuration for this subset.
*
* @return the parent configuration
*/
public Configuration getParent()
{
return parent;
}
/**
* Return the prefix used to select the properties in the parent configuration.
*
* @return the prefix used by this subset
*/
public String getPrefix()
{
return prefix;
}
/**
* Set the prefix used to select the properties in the parent configuration.
*
* @param prefix the prefix
*/
public void setPrefix(String prefix)
{
this.prefix = prefix;
}
public Configuration subset(String prefix)
{
return parent.subset(getParentKey(prefix));
}
public boolean isEmpty()
{
return !getKeys().hasNext();
}
public boolean containsKey(String key)
{
return parent.containsKey(getParentKey(key));
}
public void addPropertyDirect(String key, Object value)
{
parent.addProperty(getParentKey(key), value);
}
protected void clearPropertyDirect(String key)
{
parent.clearProperty(getParentKey(key));
}
public Object getProperty(String key)
{
return parent.getProperty(getParentKey(key));
}
public Iterator getKeys(String prefix)
{
return new TransformIterator(parent.getKeys(getParentKey(prefix)), new Transformer()
{
public Object transform(Object obj)
{
return getChildKey((String) obj);
}
});
}
public Iterator getKeys()
{
return new TransformIterator(parent.getKeys(prefix), new Transformer()
{
public Object transform(Object obj)
{
return getChildKey((String) obj);
}
});
}
protected Object interpolate(Object base)
{
if (delimiter == null && "".equals(prefix))
{
return super.interpolate(base);
}
else
{
SubsetConfiguration config = new SubsetConfiguration(parent, "");
ConfigurationInterpolator interpolator = config.getInterpolator();
getInterpolator().registerLocalLookups(interpolator);
if (parent instanceof AbstractConfiguration)
{
interpolator.setParentInterpolator(((AbstractConfiguration) parent).getInterpolator());
}
return config.interpolate(base);
}
}
protected String interpolate(String base)
{
return super.interpolate(base);
}
/**
* {@inheritDoc}
*
* Change the behaviour of the parent configuration if it supports this feature.
*/
public void setThrowExceptionOnMissing(boolean throwExceptionOnMissing)
{
if (parent instanceof AbstractConfiguration)
{
((AbstractConfiguration) parent).setThrowExceptionOnMissing(throwExceptionOnMissing);
}
else
{
super.setThrowExceptionOnMissing(throwExceptionOnMissing);
}
}
/**
* {@inheritDoc}
*
* The subset inherits this feature from its parent if it supports this feature.
*/
public boolean isThrowExceptionOnMissing()
{
if (parent instanceof AbstractConfiguration)
{
return ((AbstractConfiguration) parent).isThrowExceptionOnMissing();
}
else
{
return super.isThrowExceptionOnMissing();
}
}
/**
* Returns the list delimiter. This property will be fetched from the parent
* configuration if supported.
*
* @return the list delimiter
* @since 1.4
*/
public char getListDelimiter()
{
return (parent instanceof AbstractConfiguration) ? ((AbstractConfiguration) parent)
.getListDelimiter()
: super.getListDelimiter();
}
/**
* Sets the list delimiter. If the parent configuration supports this
* feature, the delimiter will be set at the parent.
*
* @param delim the new list delimiter
* @since 1.4
*/
public void setListDelimiter(char delim)
{
if (parent instanceof AbstractConfiguration)
{
((AbstractConfiguration) parent).setListDelimiter(delim);
}
else
{
super.setListDelimiter(delim);
}
}
/**
* Returns a flag whether string properties should be checked for list
* delimiter characters. This implementation ensures that this flag is kept
* in sync with the parent configuration if this object supports this
* feature.
*
* @return the delimiter parsing disabled flag
* @since 1.4
*/
public boolean isDelimiterParsingDisabled()
{
return (parent instanceof AbstractConfiguration) ? ((AbstractConfiguration) parent)
.isDelimiterParsingDisabled()
: super.isDelimiterParsingDisabled();
}
/**
* Sets a flag whether list parsing is disabled. This implementation will
* also set the flag at the parent configuration if this object supports
* this feature.
*
* @param delimiterParsingDisabled the delimiter parsing disabled flag
* @since 1.4
*/
public void setDelimiterParsingDisabled(boolean delimiterParsingDisabled)
{
if (parent instanceof AbstractConfiguration)
{
((AbstractConfiguration) parent)
.setDelimiterParsingDisabled(delimiterParsingDisabled);
}
else
{
super.setDelimiterParsingDisabled(delimiterParsingDisabled);
}
}
}