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15 package org.mortbay.util;
16 import java.io.Serializable;
17 import java.lang.reflect.Array;
18 import java.util.ArrayList;
19 import java.util.Arrays;
20 import java.util.Collection;
21 import java.util.Collections;
22 import java.util.Iterator;
23 import java.util.List;
24 import java.util.ListIterator;
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57 public class LazyList
58 implements Cloneable, Serializable
59 {
60 private static final String[] __EMTPY_STRING_ARRAY = new String[0];
61
62
63 private LazyList()
64 {}
65
66
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70
71
72 @SuppressWarnings("unchecked")
73 public static<E> Object add(Object list, E item)
74 {
75 if (list==null)
76 {
77 if (item instanceof List || item==null)
78 {
79 List<Object> l = new ArrayList<Object>();
80 l.add(item);
81 return l;
82 }
83
84 return item;
85 }
86
87 if (list instanceof List)
88 {
89 ((List<Object>)list).add(item);
90 return list;
91 }
92
93 List<Object> l=new ArrayList<Object>();
94 l.add(list);
95 l.add(item);
96 return l;
97 }
98
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105
106 @SuppressWarnings("unchecked")
107 public static Object add(Object list, int index, Object item)
108 {
109 if (list==null)
110 {
111 if (index>0 || item instanceof List || item==null)
112 {
113 List<Object> l = new ArrayList<Object>();
114 l.add(index,item);
115 return l;
116 }
117 return item;
118 }
119
120 if (list instanceof List)
121 {
122 ((List<Object>)list).add(index,item);
123 return list;
124 }
125
126 List<Object> l=new ArrayList<Object>();
127 l.add(list);
128 l.add(index,item);
129 return l;
130 }
131
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133
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135
136
137
138 public static Object addCollection(Object list, Collection<?> collection)
139 {
140 Iterator<?> i=collection.iterator();
141 while(i.hasNext())
142 list=LazyList.add(list,i.next());
143 return list;
144 }
145
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150
151
152 public static Object addArray(Object list, Object[] array)
153 {
154 for(int i=0;array!=null && i<array.length;i++)
155 list=LazyList.add(list,array[i]);
156 return list;
157 }
158
159
160
161
162
163 public static Object ensureSize(Object list, int initialSize)
164 {
165 if (list==null)
166 return new ArrayList<Object>(initialSize);
167 if (list instanceof ArrayList)
168 {
169 ArrayList<?> ol=(ArrayList<?>)list;
170 if (ol.size()>initialSize)
171 return ol;
172 ArrayList<Object> nl = new ArrayList<Object>(initialSize);
173 nl.addAll(ol);
174 return nl;
175 }
176 List<Object> l= new ArrayList<Object>(initialSize);
177 l.add(list);
178 return l;
179 }
180
181
182 public static Object remove(Object list, Object o)
183 {
184 if (list==null)
185 return null;
186
187 if (list instanceof List)
188 {
189 List<?> l = (List<?>)list;
190 l.remove(o);
191 if (l.size()==0)
192 return null;
193 return list;
194 }
195
196 if (list.equals(o))
197 return null;
198 return list;
199 }
200
201
202 public static Object remove(Object list, int i)
203 {
204 if (list==null)
205 return null;
206
207 if (list instanceof List)
208 {
209 List<?> l = (List<?>)list;
210 l.remove(i);
211 if (l.size()==0)
212 return null;
213 return list;
214 }
215
216 if (i==0)
217 return null;
218 return list;
219 }
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230 public static<E> List<E> getList(Object list)
231 {
232 return getList(list,false);
233 }
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245 @SuppressWarnings("unchecked")
246 public static<E> List<E> getList(Object list, boolean nullForEmpty)
247 {
248 if (list==null)
249 {
250 if (nullForEmpty)
251 return null;
252 return Collections.emptyList();
253 }
254 if (list instanceof List)
255 return (List<E>)list;
256
257 return (List<E>)Collections.singletonList(list);
258 }
259
260
261
262 public static String[] toStringArray(Object list)
263 {
264 if (list==null)
265 return __EMTPY_STRING_ARRAY;
266
267 if (list instanceof List)
268 {
269 List<?> l = (List<?>)list;
270 String[] a = new String[l.size()];
271 for (int i=l.size();i-->0;)
272 {
273 Object o=l.get(i);
274 if (o!=null)
275 a[i]=o.toString();
276 }
277 return a;
278 }
279
280 return new String[] {list.toString()};
281 }
282
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288
289 public static Object toArray(Object list,Class<?> aClass)
290 {
291 if (list==null)
292 return (Object[])Array.newInstance(aClass,0);
293
294 if (list instanceof List)
295 {
296 List<?> l = (List<?>)list;
297 if (aClass.isPrimitive())
298 {
299 Object a = Array.newInstance(aClass,l.size());
300 for (int i=0;i<l.size();i++)
301 Array.set(a,i,l.get(i));
302 return a;
303 }
304 return l.toArray((Object[])Array.newInstance(aClass,l.size()));
305
306 }
307
308 Object a = Array.newInstance(aClass,1);
309 Array.set(a,0,list);
310 return (Object[])a;
311 }
312
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316
317
318 public static int size(Object list)
319 {
320 if (list==null)
321 return 0;
322 if (list instanceof List)
323 return ((List<?>)list).size();
324 return 1;
325 }
326
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332
333 @SuppressWarnings("unchecked")
334 public static <E> E get(Object list, int i)
335 {
336 if (list==null)
337 throw new IndexOutOfBoundsException();
338
339 if (list instanceof List)
340 return (E)((List<?>)list).get(i);
341
342 if (i==0)
343 return (E)list;
344
345 throw new IndexOutOfBoundsException();
346 }
347
348
349 public static boolean contains(Object list,Object item)
350 {
351 if (list==null)
352 return false;
353
354 if (list instanceof List)
355 return ((List<?>)list).contains(item);
356
357 return list.equals(item);
358 }
359
360
361
362 public static Object clone(Object list)
363 {
364 if (list==null)
365 return null;
366 if (list instanceof List)
367 return new ArrayList<Object>((List<?>)list);
368 return list;
369 }
370
371
372 public static String toString(Object list)
373 {
374 if (list==null)
375 return "[]";
376 if (list instanceof List)
377 return list.toString();
378 return "["+list+"]";
379 }
380
381
382 @SuppressWarnings("unchecked")
383 public static<E> Iterator<E> iterator(Object list)
384 {
385 if (list==null)
386 {
387 List<E> empty=Collections.emptyList();
388 return empty.iterator();
389 }
390 if (list instanceof List)
391 {
392 return ((List<E>)list).iterator();
393 }
394 List<E> l=getList(list);
395 return l.iterator();
396 }
397
398
399 @SuppressWarnings("unchecked")
400 public static<E> ListIterator<E> listIterator(Object list)
401 {
402 if (list==null)
403 {
404 List<E> empty=Collections.emptyList();
405 return empty.listIterator();
406 }
407 if (list instanceof List)
408 return ((List<E>)list).listIterator();
409
410 List<E> l=getList(list);
411 return l.listIterator();
412 }
413
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419 public static<E> List<E> array2List(E[] array)
420 {
421 if (array==null || array.length==0)
422 return new ArrayList<E>();
423 return new ArrayList<E>(Arrays.asList(array));
424 }
425
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432
433 @SuppressWarnings("unchecked")
434 public static Object[] addToArray(Object[] array, Object item, Class<?> type)
435 {
436 if (array==null)
437 {
438 if (type==null && item!=null)
439 type= (Class<Object>)item.getClass();
440 Object[] na = (Object[])Array.newInstance(type, 1);
441 na[0]=item;
442 return na;
443 }
444 else
445 {
446 Class<?> c = array.getClass().getComponentType();
447 Object[] na = (Object[])Array.newInstance(c, Array.getLength(array)+1);
448 System.arraycopy(array, 0, na, 0, array.length);
449 na[array.length]=item;
450 return na;
451 }
452 }
453
454
455 @SuppressWarnings("unchecked")
456 public static Object removeFromArray(Object[] array, Object item)
457 {
458 if (item==null || array==null)
459 return array;
460 for (int i=array.length;i-->0;)
461 {
462 if (item.equals(array[i]))
463 {
464 Class<?> c = array==null?item.getClass():array.getClass().getComponentType();
465 Object[] na = (Object[])Array.newInstance(c, Array.getLength(array)-1);
466 if (i>0)
467 System.arraycopy(array, 0, na, 0, i);
468 if (i+1<array.length)
469 System.arraycopy(array, i+1, na, i, array.length-(i+1));
470 return na;
471 }
472 }
473 return array;
474 }
475
476 }
477