Method: count()

1: /*
2: * *************************************************************************************************************************************************************
3: *
4: * TheseFoolishThings: Miscellaneous utilities
5: * http://tidalwave.it/projects/thesefoolishthings
6: *
7: * Copyright (C) 2009 - 2025 by Tidalwave s.a.s. (http://tidalwave.it)
8: *
9: * *************************************************************************************************************************************************************
10: *
11: * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License.
12: * You may obtain a copy of the License at
13: *
14: * http://www.apache.org/licenses/LICENSE-2.0
15: *
16: * 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
17: * CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.
18: *
19: * *************************************************************************************************************************************************************
20: *
21: * git clone https://bitbucket.org/tidalwave/thesefoolishthings-src
22: * git clone https://github.com/tidalwave-it/thesefoolishthings-src
23: *
24: * *************************************************************************************************************************************************************
25: */
26: package it.tidalwave.util.spi;
27:
28: import java.lang.reflect.Constructor;
29: // import javax.annotation.Nonnegative;
30: import jakarta.annotation.Nonnull;
31: import java.util.ArrayList;
32: import java.util.Collections;
33: import java.util.List;
34: import java.util.concurrent.CopyOnWriteArrayList;
35: import it.tidalwave.util.Finder;
36: import lombok.AccessLevel;
37: import lombok.AllArgsConstructor;
38: import lombok.Getter;
39: import lombok.RequiredArgsConstructor;
40: import lombok.ToString;
41: import lombok.extern.slf4j.Slf4j;
42: import static it.tidalwave.util.CollectionUtils.concat;
43:
44: /***************************************************************************************************************************************************************
45: *
46: * A support class for implementing a {@link Finder}. Subclasses only need to implement the {@link #computeResults()}
47: * method where <i>raw</i> results are retrieved (with raw we mean that they shouldn't be filtered or sorted, as
48: * post-processing will be performed by this class) and a clone constructor.
49: *
50: * If you don't need to extend the {@link Finder} with extra methods, please use the simplified
51: * {@link SimpleFinderSupport}.
52: *
53: * @author Fabrizio Giudici
54: * @it.tidalwave.javadoc.draft
55: *
56: **************************************************************************************************************************************************************/
57: @Slf4j @AllArgsConstructor(access = AccessLevel.PRIVATE) @ToString
58: public class HierarchicFinderSupport<T, F extends Finder<T>> implements Finder<T>
59: {
60: private static final long serialVersionUID = 2467809593956684L;
61:
62: @RequiredArgsConstructor
63: static class Sorter<U>
64: {
65: @Nonnull
66: private final InMemorySortCriterion<U> sortCriterion;
67:
68: @Nonnull
69: private final SortDirection sortDirection;
70:
71: public void sort (@Nonnull final List<? extends U> results)
72: {
73: sortCriterion.sort(results, sortDirection);
74: }
75: }
76:
77: private static final String MESSAGE =
78: "Since version 2.0, Implementations of Finder must have a clone constructor such as "
79: + "MyFinder(MyFinder other, Object override). This means that they can't be implemented by anonymous or inner, "
80: + "non static classes. See the javadoc for further information. Could not find constructor: ";
81:
82: @Nonnull
83: private final String name;
84:
85: /* @Nonnegative */
86: protected final int firstResult;
87:
88: /* @Nonnegative */
89: protected final int maxResults;
90:
91: @Nonnull @Getter(AccessLevel.PROTECTED)
92: private final List<Object> contexts;
93:
94: @Nonnull
95: private final List<Sorter<T>> sorters;
96:
97: private static final int DEFAULT_MAX_RESULTS = Integer.MAX_VALUE;
98:
99: /***********************************************************************************************************************************************************
100: * Creates an instance with the given name (that will be used for diagnostics).
101: *
102: * @param name the name
103: **********************************************************************************************************************************************************/
104: protected HierarchicFinderSupport (@Nonnull final String name)
105: {
106: this.name = name;
107: this.firstResult = 0;
108: this.maxResults = DEFAULT_MAX_RESULTS;
109: this.sorters = new ArrayList<>();
110: this.contexts = Collections.emptyList();
111: checkSubClass();
112: }
113:
114: /***********************************************************************************************************************************************************
115: * Default constructor.
116: **********************************************************************************************************************************************************/
117: protected HierarchicFinderSupport()
118: {
119: this.name = getClass().getName();
120: this.firstResult = 0;
121: this.maxResults = DEFAULT_MAX_RESULTS;
122: this.sorters = new ArrayList<>();
123: this.contexts = Collections.emptyList();
124: checkSubClass();
125: }
126:
127: /***********************************************************************************************************************************************************
128: * Clone constructor for subclasses.
129: *
130: * @param other the other instance to clone
131: * @param holder the holder object
132: **********************************************************************************************************************************************************/
133: protected HierarchicFinderSupport (@Nonnull final HierarchicFinderSupport<T, F> other, @Nonnull final Object holder)
134: {
135: log.trace("HierarchicFinderSupport({}, {})", other, holder);
136: final var source = getSource(HierarchicFinderSupport.class, other, holder);
137: this.name = source.name;
138: this.firstResult = source.firstResult;
139: this.maxResults = source.maxResults;
140: this.sorters = source.sorters;
141: this.contexts = source.contexts; // it's always unmodifiable
142: }
143:
144: /***********************************************************************************************************************************************************
145: * This method throws an exception since a {@code Finder} extending this class must be cloned with
146: * {@link #clonedWith(Object)}.
147: *
148: * @see #clonedWith(Object)
149: * @deprecated
150: **********************************************************************************************************************************************************/
151: @Override @Nonnull
152: public final HierarchicFinderSupport<T, F> clone()
153: {
154: throw new UnsupportedOperationException("\"HierarchicFinderSupport.clone() no more supported");
155: }
156:
157: /***********************************************************************************************************************************************************
158: * Create a clone of this object calling the special copy constructor by reflection.
159: *
160: * @param override the override object
161: * @return the clone
162: **********************************************************************************************************************************************************/
163: @Nonnull
164: protected F clonedWith (@Nonnull final Object override)
165: {
166: try
167: {
168: final var constructor = getCloneConstructor();
169: constructor.setAccessible(true);
170: return (F)constructor.newInstance(this, override);
171: }
172: catch (Exception e)
173: {
174: throw new RuntimeException(e);
175: }
176: }
177:
178: /***********************************************************************************************************************************************************
179: * Create a clone of this object calling the special clone constructor by reflection.
180: *
181: * @param override the override object
182: * @return the clone
183: * @deprecated Use {@link #clonedWith(Object)} instead.
184: **********************************************************************************************************************************************************/
185: @Nonnull @Deprecated
186: protected F clone (@Nonnull final Object override)
187: {
188: return clonedWith(override);
189: }
190:
191: /***********************************************************************************************************************************************************
192: * {@inheritDoc}
193: **********************************************************************************************************************************************************/
194: @Override @Nonnull
195: public F from (/* @Nonnegative */ final int firstResult)
196: {
197: return clonedWith(new HierarchicFinderSupport<T, F>(name, firstResult, maxResults, contexts, sorters));
198: }
199:
200: /***********************************************************************************************************************************************************
201: * {@inheritDoc}
202: **********************************************************************************************************************************************************/
203: @Override @Nonnull
204: public F max (/* @Nonnegative */ final int maxResults)
205: {
206: return clonedWith(new HierarchicFinderSupport<T, F>(name, firstResult, maxResults, contexts, sorters));
207: }
208:
209: /***********************************************************************************************************************************************************
210: * {@inheritDoc}
211: **********************************************************************************************************************************************************/
212: @Override @Nonnull
213: public F withContext (@Nonnull final Object context)
214: {
215: final var contexts = concat(this.contexts, context);
216: return clonedWith(new HierarchicFinderSupport<T, F>(name, firstResult, maxResults, contexts, sorters));
217: }
218:
219: /***********************************************************************************************************************************************************
220: * {@inheritDoc}
221: **********************************************************************************************************************************************************/
222: @Override @Nonnull
223: public <U> Finder<U> ofType (@Nonnull final Class<U> type)
224: {
225: throw new UnsupportedOperationException("Must be eventually implemented by subclasses.");
226: }
227:
228: /***********************************************************************************************************************************************************
229: * {@inheritDoc}
230: **********************************************************************************************************************************************************/
231: @Override @Nonnull
232: public F sort (@Nonnull final SortCriterion criterion, @Nonnull final SortDirection direction)
233: {
234: if (criterion instanceof Finder.InMemorySortCriterion)
235: {
236: @SuppressWarnings("unchecked")
237: final var sorters = concat(this.sorters, new Sorter<>((InMemorySortCriterion<T>)criterion, direction));
238: return clonedWith(new HierarchicFinderSupport<T, F>(name, firstResult, maxResults, contexts, sorters));
239: }
240:
241: final var template = "%s does not implement %s - you need to subclass Finder and override sort()";
242: final var message = String.format(template, criterion, InMemorySortCriterion.class);
243: throw new UnsupportedOperationException(message);
244: }
245:
246: /***********************************************************************************************************************************************************
247: * {@inheritDoc}
248: **********************************************************************************************************************************************************/
249: @Override @Nonnull
250: public final F sort (@Nonnull final SortCriterion criterion)
251: {
252: return sort(criterion, SortDirection.ASCENDING);
253: }
254:
255: /***********************************************************************************************************************************************************
256: * {@inheritDoc}
257: **********************************************************************************************************************************************************/
258: @Override @Nonnull
259: public List<T> results()
260: {
261: return computeNeededResults();
262: }
263:
264: /***********************************************************************************************************************************************************
265: * {@inheritDoc}
266: **********************************************************************************************************************************************************/
267: @Override /* @Nonnegative */
268: public int count()
269: {
270: return computeNeededResults().size();
271: }
272:
273: /***********************************************************************************************************************************************************
274: * Subclasses can implement this method where *all* the raw results must be actually retrieved.
275: *
276: * @return the unprocessed results
277: **********************************************************************************************************************************************************/
278: // START SNIPPET: computeResults
279: @Nonnull
280: protected List<T> computeResults()
281: // END SNIPPET: computeResults
282: {
283: throw new UnsupportedOperationException("You must implement me!");
284: }
285:
286: /***********************************************************************************************************************************************************
287: * Subclasses can implement this method where *only the requested* raw results must be retrieved.
288: *
289: * @return the unprocessed results
290: **********************************************************************************************************************************************************/
291: // START SNIPPET: computeNeededResults
292: @Nonnull
293: protected List<T> computeNeededResults()
294: // END SNIPPET: computeNeededResults
295: {
296: log.trace("computeNeededResults() - {}", this);
297: var results = computeResults();
298:
299: // First sort and then extract the sublist
300: for (final var sorter : sorters)
301: {
302: log.trace(">>>> sorting with {}...", sorter);
303: sorter.sort(results);
304: }
305:
306: final var toIndex = (int)Math.min(results.size(), (long)firstResult + (long)maxResults);
307:
308: if (firstResult > toIndex)
309: {
310: return new CopyOnWriteArrayList<>();
311: }
312:
313: results = results.subList(firstResult, toIndex);
314:
315: return results;
316: }
317:
318: /***********************************************************************************************************************************************************
319: * A utility method used by the copy constructor (see general documentation). If the override object is strictly
320: * of the specified type, it is returned; otherwise the other object is returned.
321: *
322: * @param <U> the static type of the source
323: * @param type the dynamic type of the source
324: * @param other the other finder
325: * @param override the holder object
326: * @return the override or other
327: **********************************************************************************************************************************************************/
328: @Nonnull
329: protected static <U> U getSource (@Nonnull final Class<? extends U> type,
330: @Nonnull final U other,
331: @Nonnull final Object override)
332: {
333: return override.getClass().equals(type) ? type.cast(override) : other;
334: }
335:
336: /***********************************************************************************************************************************************************
337: **********************************************************************************************************************************************************/
338: @Nonnull @SuppressWarnings("unchecked")
339: private Constructor<HierarchicFinderSupport<T, F>> getCloneConstructor()
340: throws SecurityException, NoSuchMethodException
341: {
342: return (Constructor<HierarchicFinderSupport<T, F>>)getClass().getConstructor(getClass(), Object.class);
343: }
344:
345: /***********************************************************************************************************************************************************
346: **********************************************************************************************************************************************************/
347: private void checkSubClass ()
348: {
349: try
350: {
351: getCloneConstructor();
352: }
353: catch (SecurityException | NoSuchMethodException e)
354: {
355: throw new ExceptionInInitializerError(MESSAGE + e.getMessage());
356: }
357: }
358: }