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1
87 package org.codehaus.loom.components.configuration.merger;
88
89 import java.util.ArrayList  ;
90 import java.util.HashSet ;
91 import java.util.List ;
92 import java.util.Set ;
93 import org.codehaus.dna.Configuration;
94 import org.codehaus.dna.ConfigurationException;
95 import org.codehaus.dna.impl.DefaultConfiguration;
96
97
115 public class ConfigurationMerger
116 {
117
125 public static Configuration merge( final Configuration layer,
126 final Configuration base )
127 throws ConfigurationException
128 {
129 final DefaultConfiguration merged =
130 new DefaultConfiguration( base.getName(),
131 base.getPath(),
132 "Merged [layer: " +
133 layer.getLocation()
134 + ", base: " + base.getLocation() + "]" );
135
136 copyAttributes( base, merged );
137 copyAttributes( layer, merged );
138
139 mergeChildren( layer, base, merged );
140
141 final String value = getValue( layer, base );
142 if( null != value )
143 {
144 merged.setValue( value );
145 }
146
147 return merged;
148 }
149
150 private static void mergeChildren( final Configuration layer,
151 final Configuration base,
152 final DefaultConfiguration merged )
153 throws ConfigurationException
154 {
155 final Configuration[] lc = layer.getChildren();
156 final Configuration[] bc = base.getChildren();
157 final Set baseUsed = new HashSet ();
158 final List toMergeUsed = new ArrayList ();
159
160 for( int i = 0; i < lc.length; i++ )
161 {
162 final Configuration mergeWith =
163 getMergePartner( lc[ i ], layer, base );
164
165 if( null == mergeWith )
166 {
167 toMergeUsed.add( lc[ i ] );
168 }
169 else
170 {
171 toMergeUsed.add( merge( lc[ i ], mergeWith ) );
172 baseUsed.add( mergeWith );
173 }
174 }
175
176 for( int i = 0; i < bc.length; i++ )
177 {
178 if( !baseUsed.contains( bc[ i ] ) )
179 {
180 merged.addChild( bc[ i ] );
181 }
182 }
183
184 final int count = toMergeUsed.size();
185 for( int i = 0; i < count; i++ )
186 {
187 merged.addChild( (Configuration)toMergeUsed.get( i ) );
188 }
189 }
190
191 private static Configuration getMergePartner( final Configuration toMerge,
192 final Configuration layer,
193 final Configuration base )
194 throws ConfigurationException
195 {
196 if( toMerge.getAttributeAsBoolean( Constants.MERGE_ATTR, false ) )
197 {
198 final String keyAttribute = toMerge.getAttribute(
199 Constants.KEY_ATTR, null );
200 final String keyvalue =
201 keyAttribute == null ?
202 null :
203 toMerge.getAttribute( keyAttribute );
204
205 final Configuration[] layerKids = match( layer,
206 toMerge.getName(),
207 keyAttribute,
208 keyvalue );
209
210 final Configuration[] baseKids = match( base,
211 toMerge.getName(),
212 keyAttribute,
213 keyvalue );
214
215 if( layerKids.length == 1 && baseKids.length == 1 )
216 {
217 return baseKids[ 0 ];
218 }
219 else
220 {
221 throw new ConfigurationException( "Unable to merge configuration item, "
222 +
223 "multiple matches on child or base [name: "
224 + toMerge.getName() + "]",
225 toMerge.getPath(),
226 toMerge.getLocation() );
227 }
228 }
229
230 return null;
231 }
232
233 private static String getValue( final Configuration layer,
234 final Configuration base )
235 {
236 try
237 {
238 return layer.getValue();
239 }
240 catch( ConfigurationException e )
241 {
242 return base.getValue( null );
243 }
244 }
245
246 private static void copyAttributes( final Configuration source,
247 final DefaultConfiguration dest )
248 throws ConfigurationException
249 {
250 final String [] names = source.getAttributeNames();
251
252 for( int i = 0; i < names.length; i++ )
253 {
254 if( !names[ i ].startsWith( Constants.MERGE_METADATA_PREFIX ) )
255 {
256 dest.setAttribute( names[ i ],
257 source.getAttribute( names[ i ] ) );
258 }
259 }
260 }
261
262
273 public static Configuration[] match( final Configuration config,
274 final String element,
275 final String attribute )
276 {
277 return match( config, element, attribute, null );
278 }
279
280
293 public static Configuration[] match( final Configuration config,
294 final String element,
295 final String attribute,
296 final String value )
297 {
298 final ArrayList list = new ArrayList ();
299 final Configuration[] children = config.getChildren( element );
300
301 for( int i = 0; i < children.length; i++ )
302 {
303 if( null == attribute )
304 {
305 list.add( children[ i ] );
306 }
307 else
308 {
309 final String v =
310 children[ i ].getAttribute( attribute, null );
311
312 if( v != null )
313 {
314 if( (value == null) || v.equals( value ) )
315 {
316 list.add( children[ i ] );
318 }
319 }
320 }
321 }
322
323 return (Configuration[])list.toArray( new Configuration[ list.size() ] );
324 }
325 }
326 |
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