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package org.codehaus.plexus.util.xml;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
/*
* Copyright The Codehaus Foundation.
*
* 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
*
* 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 org.codehaus.plexus.util.xml.pull.XmlSerializer;
/** @author Jason van Zyl */
public class Xpp3DomUtils
{
public static final String CHILDREN_COMBINATION_MODE_ATTRIBUTE = "combine.children";
public static final String CHILDREN_COMBINATION_MERGE = "merge";
public static final String CHILDREN_COMBINATION_APPEND = "append";
/**
* This default mode for combining children DOMs during merge means that where element names match, the process will
* try to merge the element data, rather than putting the dominant and recessive elements (which share the same
* element name) as siblings in the resulting DOM.
*/
public static final String DEFAULT_CHILDREN_COMBINATION_MODE = CHILDREN_COMBINATION_MERGE;
public static final String SELF_COMBINATION_MODE_ATTRIBUTE = "combine.self";
public static final String SELF_COMBINATION_OVERRIDE = "override";
public static final String SELF_COMBINATION_MERGE = "merge";
/**
* In case of complex XML structures, combining can be done based on id.
*
* @since 3.0.22
*/
public static final String ID_COMBINATION_MODE_ATTRIBUTE = "combine.id";
/**
* In case of complex XML structures, combining can be done based on keys.
* This is a comma separated list of attribute names.
*
* @since 3.4.0
*/
public static final String KEYS_COMBINATION_MODE_ATTRIBUTE = "combine.keys";
/**
* This default mode for combining a DOM node during merge means that where element names match, the process will
* try to merge the element attributes and values, rather than overriding the recessive element completely with the
* dominant one. This means that wherever the dominant element doesn't provide the value or a particular attribute,
* that value or attribute will be set from the recessive DOM node.
*/
public static final String DEFAULT_SELF_COMBINATION_MODE = SELF_COMBINATION_MERGE;
public void writeToSerializer( String namespace, XmlSerializer serializer, Xpp3Dom dom )
throws IOException
{
// TODO: WARNING! Later versions of plexus-utils psit out an header due to thinking this is a new
// document - not the desired behaviour!
SerializerXMLWriter xmlWriter = new SerializerXMLWriter( namespace, serializer );
Xpp3DomWriter.write( xmlWriter, dom );
if ( xmlWriter.getExceptions().size() > 0 )
{
throw (IOException) xmlWriter.getExceptions().get( 0 );
}
}
/**
* Merges one DOM into another, given a specific algorithm and possible override points for that algorithm.
* The algorithm is as follows:
*
* - if the recessive DOM is null, there is nothing to do... return.
* - Determine whether the dominant node will suppress the recessive one (flag=mergeSelf).
*
* - retrieve the 'combine.self' attribute on the dominant node, and try to match against 'override'...
* if it matches 'override', then set mergeSelf == false...the dominant node suppresses the recessive one
* completely.
* - otherwise, use the default value for mergeSelf, which is true...this is the same as specifying
* 'combine.self' == 'merge' as an attribute of the dominant root node.
*
* - If mergeSelf == true
*
* - Determine whether children from the recessive DOM will be merged or appended to the dominant DOM as
* siblings (flag=mergeChildren).
*
* - if childMergeOverride is set (non-null), use that value (true/false)
* - retrieve the 'combine.children' attribute on the dominant node, and try to match against
* 'append'...
* - if it matches 'append', then set mergeChildren == false...the recessive children will be appended as
* siblings of the dominant children.
* - otherwise, use the default value for mergeChildren, which is true...this is the same as specifying
* 'combine.children' == 'merge' as an attribute on the dominant root node.
*
* - Iterate through the recessive children, and:
*
* - if 'combine.id' is set and there is a corresponding dominant child (matched by value of 'combine.id'),
* merge the two.
* - if 'combine.keys' is set and there is a corresponding dominant child (matched by value of key elements),
* merge the two.
* - if mergeChildren == true and there is a corresponding dominant child (matched by element name),
* merge the two.
* - otherwise, add the recessive child as a new child on the dominant root node.
*
*
*
*/
private static void mergeIntoXpp3Dom( Xpp3Dom dominant, Xpp3Dom recessive, Boolean childMergeOverride )
{
// TODO: share this as some sort of assembler, implement a walk interface?
if ( recessive == null )
{
return;
}
boolean mergeSelf = true;
String selfMergeMode = dominant.getAttribute( SELF_COMBINATION_MODE_ATTRIBUTE );
if ( isNotEmpty( selfMergeMode ) && SELF_COMBINATION_OVERRIDE.equals( selfMergeMode ) )
{
mergeSelf = false;
}
if ( mergeSelf )
{
String[] recessiveAttrs = recessive.getAttributeNames();
for ( String attr : recessiveAttrs )
{
if ( isEmpty( dominant.getAttribute( attr ) ) )
{
dominant.setAttribute( attr, recessive.getAttribute( attr ) );
}
}
boolean mergeChildren = true;
if ( childMergeOverride != null )
{
mergeChildren = childMergeOverride;
}
else
{
String childMergeMode = dominant.getAttribute( CHILDREN_COMBINATION_MODE_ATTRIBUTE );
if ( isNotEmpty( childMergeMode ) && CHILDREN_COMBINATION_APPEND.equals( childMergeMode ) )
{
mergeChildren = false;
}
}
final String keysValue = recessive.getAttribute( KEYS_COMBINATION_MODE_ATTRIBUTE );
Xpp3Dom[] children = recessive.getChildren();
for ( Xpp3Dom recessiveChild : children )
{
String idValue = recessiveChild.getAttribute( ID_COMBINATION_MODE_ATTRIBUTE );
Xpp3Dom childDom = null;
if ( isNotEmpty( idValue ) )
{
for ( Xpp3Dom dominantChild : dominant.getChildren() )
{
if ( idValue.equals( dominantChild.getAttribute( ID_COMBINATION_MODE_ATTRIBUTE ) ) )
{
childDom = dominantChild;
// we have a match, so don't append but merge
mergeChildren = true;
}
}
}
else if ( isNotEmpty( keysValue ) )
{
String[] keys = keysValue.split( "," );
Map recessiveKeyValues = new HashMap<>( keys.length );
for ( String key : keys )
{
recessiveKeyValues.put( key, recessiveChild.getAttribute( key ) );
}
for ( Xpp3Dom dominantChild : dominant.getChildren() )
{
Map dominantKeyValues = new HashMap<>( keys.length );
for ( String key : keys )
{
dominantKeyValues.put( key, dominantChild.getAttribute( key ) );
}
if ( recessiveKeyValues.equals( dominantKeyValues ) )
{
childDom = dominantChild;
// we have a match, so don't append but merge
mergeChildren = true;
}
}
}
else
{
childDom = dominant.getChild( recessiveChild.getName() );
}
if ( mergeChildren && childDom != null )
{
mergeIntoXpp3Dom( childDom, recessiveChild, childMergeOverride );
}
else
{
dominant.addChild( new Xpp3Dom( recessiveChild ) );
}
}
}
}
/**
* Merge two DOMs, with one having dominance in the case of collision.
*
* @see #CHILDREN_COMBINATION_MODE_ATTRIBUTE
* @see #SELF_COMBINATION_MODE_ATTRIBUTE
* @param dominant The dominant DOM into which the recessive value/attributes/children will be merged
* @param recessive The recessive DOM, which will be merged into the dominant DOM
* @param childMergeOverride Overrides attribute flags to force merging or appending of child elements into the
* dominant DOM
* @return merged DOM
*/
public static Xpp3Dom mergeXpp3Dom( Xpp3Dom dominant, Xpp3Dom recessive, Boolean childMergeOverride )
{
if ( dominant != null )
{
mergeIntoXpp3Dom( dominant, recessive, childMergeOverride );
return dominant;
}
return recessive;
}
/**
* Merge two DOMs, with one having dominance in the case of collision. Merge mechanisms (vs. override for nodes, or
* vs. append for children) is determined by attributes of the dominant root node.
*
* @see #CHILDREN_COMBINATION_MODE_ATTRIBUTE
* @see #SELF_COMBINATION_MODE_ATTRIBUTE
* @param dominant The dominant DOM into which the recessive value/attributes/children will be merged
* @param recessive The recessive DOM, which will be merged into the dominant DOM
* @return merged DOM
*/
public static Xpp3Dom mergeXpp3Dom( Xpp3Dom dominant, Xpp3Dom recessive )
{
if ( dominant != null )
{
mergeIntoXpp3Dom( dominant, recessive, null );
return dominant;
}
return recessive;
}
/**
* @deprecated Use {@link org.codehaus.plexus.util.StringUtils#isNotEmpty(String)} instead
*/
@Deprecated
public static boolean isNotEmpty( String str )
{
return ( str != null && str.length() > 0 );
}
/**
* @deprecated Use {@link org.codehaus.plexus.util.StringUtils#isEmpty(String)} instead
*/
@Deprecated
public static boolean isEmpty( String str )
{
return ( str == null || str.length() == 0 );
}
}