001 /*
002 * Copyright 2006 Stephen J. McConnell.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
013 * implied.
014 *
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018
019 package net.dpml.metro.builder;
020
021 import java.io.IOException;
022 import java.net.URI;
023
024 import net.dpml.component.ActivationPolicy;
025
026 import net.dpml.metro.data.ContextDirective;
027 import net.dpml.metro.data.CategoryDirective;
028 import net.dpml.metro.data.CategoriesDirective;
029 import net.dpml.metro.data.ComponentDirective;
030 import net.dpml.metro.data.ValueDirective;
031 import net.dpml.metro.data.LookupDirective;
032
033 import net.dpml.metro.info.LifestylePolicy;
034 import net.dpml.metro.info.CollectionPolicy;
035 import net.dpml.metro.info.PartReference;
036 import net.dpml.metro.info.Priority;
037
038 import net.dpml.lang.ValueDecoder;
039 import net.dpml.lang.Value;
040
041 import net.dpml.util.Resolver;
042 import net.dpml.util.DOM3DocumentBuilder;
043 import net.dpml.util.ElementHelper;
044 import net.dpml.util.DecodingException;
045 import net.dpml.util.SimpleResolver;
046
047 import org.w3c.dom.Document;
048 import org.w3c.dom.Element;
049
050 /**
051 * Construct a state graph.
052 */
053 public class ComponentDecoder
054 {
055 private static final String STATE_SCHEMA_URN = "link:xsd:dpml/lang/dpml-state#1.0";
056
057 private static final String SCHEMA_URN = "link:xsd:dpml/lang/dpml-component#1.0";
058
059 private static final DOM3DocumentBuilder DOCUMENT_BUILDER = new DOM3DocumentBuilder();
060
061 private static final ComponentTypeDecoder TYPE_DECODER = new ComponentTypeDecoder();
062
063 private static final ValueDecoder VALUE_DECODER = new ValueDecoder();
064
065 /**
066 * Construct a component directive using the supplied uri. The uri
067 * must refer to an XML document containing a root component element
068 * (typically used in component data testcases).
069 *
070 * @param uri the part uri
071 * @return the component directive
072 * @exception IOException if an error occurs during directive creation
073 */
074 public ComponentDirective loadComponentDirective( URI uri ) throws IOException
075 {
076 if( null == uri )
077 {
078 throw new NullPointerException( "uri" );
079 }
080 try
081 {
082 final Document document = DOCUMENT_BUILDER.parse( uri );
083 final Element root = document.getDocumentElement();
084 //Resolver resolver = new SimpleResolver();
085 //return buildComponent( root, resolver );
086 return buildComponent( root, null );
087 }
088 catch( Throwable e )
089 {
090 final String error =
091 "An error while attempting to load a component directive."
092 + "\nURI: " + uri;
093 IOException exception = new IOException( error );
094 exception.initCause( e );
095 throw exception;
096 }
097 }
098
099 /**
100 * Construct a component directive using the supplied DOM element.
101 * @param root the element representing the component directive definition
102 * @param resolver build-time uri resolver
103 * @return the component directive
104 * @exception DecodingException if an error occurs during directive creation
105 */
106 public ComponentDirective buildComponent( Element root, Resolver resolver ) throws DecodingException
107 {
108 if( null == root )
109 {
110 throw new NullPointerException( "root" );
111 }
112 String tag = root.getTagName();
113 if( "component".equals( tag ) )
114 {
115 return createComponentDirective( root, resolver );
116 }
117 else
118 {
119 final String error =
120 "Component directive element name ["
121 + tag
122 + "] is not recognized.";
123 throw new DecodingException( root, error );
124 }
125 }
126
127 private ComponentDirective createComponentDirective(
128 Element element, Resolver resolver ) throws DecodingException
129 {
130 String classname = buildComponentClassname( element, resolver );
131 String name = buildComponentName( element, resolver );
132 ActivationPolicy activation = buildActivationPolicy( element, resolver );
133 CollectionPolicy collection = buildCollectionPolicy( element, resolver );
134 LifestylePolicy lifestyle = buildLifestylePolicy( element, resolver );
135 CategoriesDirective categories = getNestedCategoriesDirective( element, resolver );
136 ContextDirective context = getNestedContextDirective( element, resolver );
137 PartReference[] parts = getNestedParts( element, resolver );
138 URI base = getBaseURI( element, resolver );
139
140 if( null == base )
141 {
142 if( null == classname )
143 {
144 final String error =
145 "Missing component type attribute.";
146 throw new DecodingException( element, error );
147 }
148 }
149 else
150 {
151 if( null != classname )
152 {
153 final String error =
154 "llegal attempt to override a base type in a supertype.";
155 throw new DecodingException( element, error );
156 }
157 }
158
159 try
160 {
161 return new ComponentDirective(
162 name, activation, collection, lifestyle, classname,
163 categories, context, parts, base );
164 }
165 catch( Exception e )
166 {
167 final String error =
168 "Component directive creation error.";
169 throw new DecodingException( element, error, e );
170 }
171 }
172
173 private URI getBaseURI( Element element, Resolver resolver ) throws DecodingException
174 {
175 String base = ElementHelper.getAttribute( element, "uri", null, resolver );
176 if( null == base )
177 {
178 return null;
179 }
180 else
181 {
182 try
183 {
184 return resolver.toURI( base );
185 }
186 catch( Exception e )
187 {
188 final String error =
189 "Error resolving 'uri' attribute value: "
190 + base;
191 throw new DecodingException( element, error, e );
192 }
193 }
194 }
195
196 private String buildComponentClassname( Element element, Resolver resolver ) throws DecodingException
197 {
198 return ElementHelper.getAttribute( element, "type", null, resolver );
199 }
200
201 private ActivationPolicy buildActivationPolicy( Element element, Resolver resolver ) throws DecodingException
202 {
203 String policy = ElementHelper.getAttribute( element, "activation", null, resolver );
204 if( null == policy )
205 {
206 return null;
207 }
208 else
209 {
210 return ActivationPolicy.parse( policy );
211 }
212 }
213
214 private LifestylePolicy buildLifestylePolicy( Element element, Resolver resolver ) throws DecodingException
215 {
216 String policy = ElementHelper.getAttribute( element, "lifestyle", null, resolver );
217 if( null != policy )
218 {
219 return LifestylePolicy.parse( policy );
220 }
221 else
222 {
223 return null;
224 }
225 }
226
227 private CollectionPolicy buildCollectionPolicy( Element element, Resolver resolver ) throws DecodingException
228 {
229 String policy = ElementHelper.getAttribute( element, "collection", null, resolver );
230 if( null != policy )
231 {
232 return CollectionPolicy.parse( policy );
233 }
234 else
235 {
236 return null;
237 }
238 }
239
240 private String buildComponentName( Element element, Resolver resolver )
241 {
242 return ElementHelper.getAttribute( element, "name", null, resolver );
243 }
244
245 private CategoriesDirective getNestedCategoriesDirective( Element root, Resolver resolver )
246 {
247 Element element = ElementHelper.getChild( root, "categories" );
248 if( null == element )
249 {
250 return null;
251 }
252 else
253 {
254 return createCategoriesDirective( element, resolver );
255 }
256 }
257
258 private CategoriesDirective createCategoriesDirective( Element element, Resolver resolver )
259 {
260 if( null == element )
261 {
262 return null;
263 }
264 else
265 {
266 String name = ElementHelper.getAttribute( element, "name", null, resolver );
267 Priority priority = createPriority( element, resolver );
268 String target = ElementHelper.getAttribute( element, "target", null, resolver );
269 CategoryDirective[] categories = createCategoryDirectiveArray( element, resolver );
270 return new CategoriesDirective( name, priority, target, categories );
271 }
272 }
273
274 private CategoryDirective createCategoryDirective( Element element, Resolver resolver )
275 {
276 String name = ElementHelper.getAttribute( element, "name", null, resolver );
277 Priority priority = createPriority( element, resolver);
278 String target = ElementHelper.getAttribute( element, "target", null, resolver );
279 return new CategoryDirective( name, priority, target );
280 }
281
282 private CategoryDirective[] createCategoryDirectiveArray( Element element, Resolver resolver )
283 {
284 Element[] children = ElementHelper.getChildren( element );
285 CategoryDirective[] categories = new CategoryDirective[ children.length ];
286 for( int i=0; i<categories.length; i++ )
287 {
288 Element elem = children[i];
289 if( "category".equals( elem.getTagName() ) )
290 {
291 categories[i] = createCategoryDirective( elem, resolver );
292 }
293 else
294 {
295 categories[i] = createCategoriesDirective( elem, resolver );
296 }
297 }
298 return categories;
299 }
300
301 private Priority createPriority( Element element, Resolver resolver )
302 {
303 String priority = ElementHelper.getAttribute( element, "priority", null, resolver );
304 if( null == priority )
305 {
306 return null;
307 }
308 else
309 {
310 return Priority.parse( priority );
311 }
312 }
313
314 private ContextDirective getNestedContextDirective( Element root, Resolver resolver ) throws DecodingException
315 {
316 Element context = ElementHelper.getChild( root, "context" );
317 if( null == context )
318 {
319 return null;
320 }
321 else
322 {
323 return createContextDirective( context, resolver );
324 }
325 }
326
327 private ContextDirective createContextDirective( Element element, Resolver resolver ) throws DecodingException
328 {
329 String classname = ElementHelper.getAttribute( element, "class", null, resolver );
330 Element[] children = ElementHelper.getChildren( element );
331 PartReference[] entries = new PartReference[ children.length ];
332 for( int i=0; i<children.length; i++ )
333 {
334 Element elem = children[i];
335 entries[i] = createContextEntryPartReference( elem, resolver );
336 }
337 return new ContextDirective( classname, entries );
338 }
339
340 private PartReference createContextEntryPartReference( Element element, Resolver resolver ) throws DecodingException
341 {
342 String key = ElementHelper.getAttribute( element, "key", null, resolver );
343 String spec = ElementHelper.getAttribute( element, "lookup", null, resolver );
344 if( null != spec )
345 {
346 LookupDirective directive = new LookupDirective( spec );
347 return new PartReference( key, directive );
348 }
349 else
350 {
351 String name = element.getTagName();
352 if( "entry".equals( name ) )
353 {
354 ValueDirective directive = buildValueDirective( element, resolver );
355 return new PartReference( key, directive );
356 }
357 else if( "context".equals( name ) )
358 {
359 ContextDirective directive = createContextDirective( element, resolver );
360 return new PartReference( key, directive );
361 }
362 else
363 {
364 final String error =
365 "Context entry element is not recognized.";
366 throw new DecodingException( element, error );
367 }
368 }
369 }
370
371 /**
372 * Build a value directive using a supplied DOM element.
373 * @param element the DOM element
374 * @return the value directive
375 */
376 protected ValueDirective buildValueDirective( Element element, Resolver resolver )
377 {
378 String classname = ElementHelper.getAttribute( element, "class", null, resolver );
379 String method = ElementHelper.getAttribute( element, "method", null, resolver );
380 Element[] elements = ElementHelper.getChildren( element, "param" );
381 if( elements.length > 0 )
382 {
383 Value[] values = VALUE_DECODER.decodeValues( elements, resolver );
384 return new ValueDirective( classname, method, values );
385 }
386 else
387 {
388 String value = ElementHelper.getAttribute( element, "value", null, resolver );
389 return new ValueDirective( classname, method, value );
390 }
391 }
392
393 private PartReference[] getNestedParts( Element root, Resolver resolver ) throws DecodingException
394 {
395 Element parts = ElementHelper.getChild( root, "parts" );
396 if( null == parts )
397 {
398 return null;
399 }
400 else
401 {
402 return createParts( parts, resolver );
403 }
404 }
405
406 private PartReference[] createParts( Element element, Resolver resolver ) throws DecodingException
407 {
408 Element[] children = ElementHelper.getChildren( element );
409 PartReference[] parts = new PartReference[ children.length ];
410 for( int i=0; i<children.length; i++ )
411 {
412 Element elem = children[i];
413 parts[i] = createPartReference( elem, resolver );
414 }
415 return parts;
416 }
417
418 private PartReference createPartReference( Element element, Resolver resolver ) throws DecodingException
419 {
420 String tag = element.getTagName();
421 String key = ElementHelper.getAttribute( element, "key", null, resolver );
422 int priority = getPriority( element, resolver );
423 if( "component".equals( tag ) )
424 {
425 ComponentDirective directive = buildComponent( element, resolver );
426 return new PartReference( key, directive, priority );
427 }
428 else
429 {
430 final String error =
431 "Component part element name ["
432 + tag
433 + "] is not recognized.";
434 throw new DecodingException( element, error );
435 }
436 }
437
438 private int getPriority( Element element, Resolver resolver ) throws DecodingException
439 {
440 String priority = ElementHelper.getAttribute( element, "priority", "0", resolver );
441 try
442 {
443 return Integer.parseInt( priority );
444 }
445 catch( Exception e )
446 {
447 final String error =
448 "Unable to parse priority value.";
449 throw new DecodingException( element, error, e );
450 }
451 }
452
453 /**
454 * Internal utility to get the name of the class without the package name. Used
455 * when constructing a default component name.
456 * @param classname the fully qualified classname
457 * @return the short class name without the package name
458 */
459 private String toName( String classname )
460 {
461 int i = classname.lastIndexOf( "." );
462 if( i == -1 )
463 {
464 return classname.toLowerCase();
465 }
466 else
467 {
468 return classname.substring( i + 1, classname.length() ).toLowerCase();
469 }
470 }
471
472 }