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1
50
51 package org.apache.excalibur.configuration.merged;
52
53 import java.util.HashSet  ;
54
55 import org.apache.avalon.framework.configuration.Configuration;
56 import org.apache.avalon.framework.configuration.ConfigurationException;
57 import org.apache.avalon.framework.configuration.DefaultConfiguration;
58 import org.apache.excalibur.configuration.ConfigurationUtil;
59
60
70 public class ConfigurationSplitter
71 {
72
86 public static Configuration split( final Configuration merged, final Configuration base )
87 throws ConfigurationException
88 {
89 final DefaultConfiguration layer = doSplit( merged, base, false );
90
91 layer.makeReadOnly();
92
93 return layer;
94 }
95
96 private static DefaultConfiguration doSplit( final Configuration merged,
97 final Configuration base,
98 final boolean isMerged )
99 throws ConfigurationException
100 {
101 final DefaultConfiguration layer =
102 new DefaultConfiguration( base.getName(),
103 "Merged [merged: " + merged.getLocation()
104 + ", base: " + base.getLocation() + "]" );
105
106 copyAttributes( layer, merged, base );
107 copyValue( layer, merged, base );
108 copyChildren( layer, merged, base );
109
110 if( isMerged )
111 {
112 layer.setAttribute( Constants.MERGE_ATTR, "true" );
113 }
114
115 return layer;
116 }
117
118 private static DefaultConfiguration doSplit( final Configuration merged,
119 final Configuration base,
120 final String keyAttr )
121 throws ConfigurationException
122 {
123 final DefaultConfiguration layer = doSplit( merged, base, true );
124
125 if( null != keyAttr )
126 {
127 layer.setAttribute( Constants.KEY_ATTR, keyAttr );
128 }
129
130 return layer;
131 }
132
133 private static void copyChildren( final DefaultConfiguration layer,
134 final Configuration merged,
135 final Configuration base )
136 throws ConfigurationException
137 {
138 final Configuration[] kids = merged.getChildren();
139
140 for( int i = 0; i < kids.length; i++ )
141 {
142 final Configuration mergedChild = kids[ i ];
143 final String name = mergedChild.getName();
144 final Configuration[] mc = merged.getChildren( name );
145 final Configuration[] bc = base.getChildren( name );
146
147 Configuration mergedWith;
148 String keyAttr = null;
149
150 if( bc.length > mc.length )
151 {
152 throw new UnsupportedOperationException ( "Unable to mask children from base "
153 + "in layer" );
154 }
155 else if( bc.length == 0 )
156 {
157 mergedWith = null;
158 }
159 else if( mc.length == 1 && bc.length == 1 )
160 {
161 mergedWith = bc[ 0 ];
162 }
163 else {
165 keyAttr = findUniqueAttributeName( mc );
166
167 final String keyValue = mergedChild.getAttribute( keyAttr );
168 final Configuration[] matches =
169 ConfigurationUtil.match( base, name, keyAttr, keyValue );
170
171 if( matches.length == 1 )
172 {
173 mergedWith = matches[ 0 ];
174 }
175 else
176 {
177 throw new ConfigurationException( "Multiple children in base with name '"
178 + name + "' and attr '" + keyAttr
179 + " = " + keyValue + "'" );
180 }
181 }
182
183 if( null == mergedWith )
184 {
185 layer.addChild( kids[ i ] );
186 }
187 else if( !ConfigurationUtil.equals( kids[ i ], mergedWith ) )
188 {
189 final DefaultConfiguration layerChild = doSplit( kids[ i ], mergedWith, keyAttr );
190
191 layerChild.makeReadOnly();
192
193 layer.addChild( layerChild );
194 }
195 }
196 }
197
198 private static String findUniqueAttributeName( final Configuration[] c )
199 throws ConfigurationException
200 {
201 final HashSet testedAttributes = new HashSet ();
202 String uniqueAttr = null;
203
204 for( int i = 0; i < c.length; i++ )
205 {
206 final String [] attrs = c[ i ].getAttributeNames();
207
208 for( int j = 0; j < attrs.length; j++ )
209 {
210 final String attr = attrs[ j ];
211
212 if( !testedAttributes.contains( attr )
213 && isUniqueAttribute( attr, c[ i ].getAttribute( attr ), i, c ) )
214 {
215 if( null == uniqueAttr )
216 {
217 uniqueAttr = attr;
218 }
219 else
220 {
221 throw new ConfigurationException( "Multiple unique attributes for child "
222 + "[name: " + c[ 0 ].getName()
223 + ", unique1: " + uniqueAttr
224 + ", unique2: " + attr + "]" );
225 }
226 }
227 else
228 {
229 testedAttributes.add( attr );
230 }
231 }
232 }
233
234 if( null == uniqueAttr )
235 {
236 throw new ConfigurationException( "Unable to find unique attribute for "
237 + "children of name: " + c[ 0 ].getName() );
238 }
239
240 return uniqueAttr;
241 }
242
243 private static boolean isUniqueAttribute( final String attr,
244 final String value,
245 final int currentConfig,
246 final Configuration[] c )
247 {
248 for( int i = 0; i < c.length; i++ )
249 {
250 if( i != currentConfig )
251 {
252 try
253 {
254 if( value.equals( c[ i ].getAttribute( attr ) ) )
255 {
256 return false;
257 }
258 }
259 catch( ConfigurationException e )
260 {
261 return false;
262 }
263 }
264 }
265
266 return true;
267 }
268
269 private static void copyValue( final DefaultConfiguration layer,
270 final Configuration merged,
271 final Configuration base )
272 {
273 final String value = merged.getValue( null );
274
275 if( null != value )
276 {
277 try
278 {
279 final String baseValue = base.getValue();
280
281 if( !value.equals( baseValue ) )
282 {
283 layer.setValue( value );
284 }
285 }
286 catch( ConfigurationException e )
287 {
288 layer.setValue( value );
289 }
290 }
291 }
292
293 private static void copyAttributes( final DefaultConfiguration layer,
294 final Configuration merged,
295 final Configuration base )
296 throws ConfigurationException
297 {
298 final String [] mergedAttr = merged.getAttributeNames();
299
300 for( int i = 0; i < mergedAttr.length; i++ )
301 {
302 final String value = merged.getAttribute( mergedAttr[ i ] );
303
304 try
305 {
306 final String baseValue = base.getAttribute( mergedAttr[ i ] );
307
308 if( !value.equals( baseValue ) )
309 {
310 layer.setAttribute( mergedAttr[ i ], value );
311 }
312 }
313 catch( ConfigurationException e )
314 {
315 layer.setAttribute( mergedAttr[ i ], value );
317 }
318 }
319 }
320
321 }
322 |
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