1 /*
2 * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.lang.invoke;
27
28 import java.util.*;
29 import jdk.internal.vm.annotation.Stable;
30
31 import static java.lang.invoke.MethodHandleStatics.rangeCheck1;
32 import static java.lang.invoke.MethodHandleStatics.rangeCheck2;
33
34 /** Utility class for implementing ConstantGroup. */
35 /*non-public*/
36 abstract class AbstractConstantGroup implements ConstantGroup {
37 /** The size of this constant group, set permanently by the constructor. */
38 protected final int size;
39
40 /** The constructor requires the size of the constant group being represented.
41 * @param size the size of this constant group, set permanently by the constructor
42 */
43 AbstractConstantGroup(int size) {
44 this.size = size;
45 }
46
47 @Override public final int size() {
48 return size;
49 }
50
51 public abstract Object get(int index) throws LinkageError;
52
53 public abstract Object get(int index, Object ifNotPresent);
54
55 public abstract boolean isPresent(int index);
56
57 // Do not override equals or hashCode, since this type is stateful.
58
59 /**
60 * Produce a string using the non-resolving list view,
61 * where unresolved elements are presented as asterisks.
62 * @return {@code this.asList("*").toString()}
63 */
64 @Override public String toString() {
65 return asList("*").toString();
66 }
67
68 static class AsIterator implements Iterator<Object> {
69 private final ConstantGroup self;
70 private final int end;
71 private final boolean resolving;
72 private final Object ifNotPresent;
73
74 // Mutable state:
75 private int index;
76
77 private AsIterator(ConstantGroup self, int start, int end,
78 boolean resolving, Object ifNotPresent) {
79 this.self = self;
80 this.end = end;
81 this.index = start;
82 this.resolving = resolving;
83 this.ifNotPresent = ifNotPresent;
84 }
85 AsIterator(ConstantGroup self, int start, int end) {
86 this(self, start, end, true, null);
87 }
88 AsIterator(ConstantGroup self, int start, int end,
89 Object ifNotPresent) {
90 this(self, start, end, false, ifNotPresent);
91 }
92
93 @Override
94 public boolean hasNext() {
95 return index < end;
96 }
97
98 @Override
99 public Object next() {
100 int i = bumpIndex();
101 if (resolving)
102 return self.get(i);
103 else
104 return self.get(i, ifNotPresent);
105 }
106
107 private int bumpIndex() {
108 int i = index;
109 if (i >= end) throw new NoSuchElementException();
110 index = i+1;
111 return i;
112 }
113 }
114
115 static class SubGroup extends AbstractConstantGroup {
116 private final ConstantGroup self; // the real CG
117 private final int offset; // offset within myself
118 SubGroup(ConstantGroup self, int start, int end) {
119 super(end - start);
120 this.self = self;
121 this.offset = start;
122 rangeCheck2(start, end, size);
123 }
124
125 private int mapIndex(int index) {
126 return rangeCheck1(index, size) + offset;
127 }
128
129 @Override
130 public Object get(int index) {
131 return self.get(mapIndex(index));
132 }
133
134 @Override
135 public Object get(int index, Object ifNotPresent) {
136 return self.get(mapIndex(index), ifNotPresent);
137 }
138
139 @Override
140 public boolean isPresent(int index) {
141 return self.isPresent(mapIndex(index));
142 }
143
144 @Override
145 public ConstantGroup subGroup(int start, int end) {
146 rangeCheck2(start, end, size);
147 return new SubGroup(self, offset + start, offset + end);
148 }
149
150 @Override
151 public List<Object> asList() {
152 return new AsList(self, offset, offset + size);
153 }
154
155 @Override
156 public List<Object> asList(Object ifNotPresent) {
157 return new AsList(self, offset, offset + size, ifNotPresent);
158 }
159
160 @Override
161 public int copyConstants(int start, int end,
162 Object[] buf, int pos) throws LinkageError {
163 rangeCheck2(start, end, size);
164 return self.copyConstants(offset + start, offset + end,
165 buf, pos);
166 }
167
168 @Override
169 public int copyConstants(int start, int end,
170 Object[] buf, int pos,
171 Object ifNotPresent) {
172 rangeCheck2(start, end, size);
173 return self.copyConstants(offset + start, offset + end,
174 buf, pos, ifNotPresent);
175 }
176 }
177
178 static class AsList extends AbstractList<Object> {
179 private final ConstantGroup self;
180 private final int size;
181 private final int offset;
182 private final boolean resolving;
183 private final Object ifNotPresent;
184
185 private AsList(ConstantGroup self, int start, int end,
186 boolean resolving, Object ifNotPresent) {
187 this.self = self;
188 this.size = end - start;
189 this.offset = start;
190 this.resolving = resolving;
191 this.ifNotPresent = ifNotPresent;
192 rangeCheck2(start, end, self.size());
193 }
194 AsList(ConstantGroup self, int start, int end) {
195 this(self, start, end, true, null);
196 }
197 AsList(ConstantGroup self, int start, int end,
198 Object ifNotPresent) {
199 this(self, start, end, false, ifNotPresent);
200 }
201
202 private int mapIndex(int index) {
203 return rangeCheck1(index, size) + offset;
204 }
205
206 @Override public final int size() {
207 return size;
208 }
209
210 @Override public Object get(int index) {
211 if (resolving)
212 return self.get(mapIndex(index));
213 else
214 return self.get(mapIndex(index), ifNotPresent);
215 }
216
217 @Override
218 public Iterator<Object> iterator() {
219 if (resolving)
220 return new AsIterator(self, offset, offset + size);
221 else
222 return new AsIterator(self, offset, offset + size, ifNotPresent);
223 }
224
225 @Override public List<Object> subList(int start, int end) {
226 rangeCheck2(start, end, size);
227 return new AsList(self, offset + start, offset + end,
228 resolving, ifNotPresent);
229 }
230
231 @Override public Object[] toArray() {
232 return toArray(new Object[size]);
233 }
234 @Override public <T> T[] toArray(T[] a) {
235 int pad = a.length - size;
236 if (pad < 0) {
237 pad = 0;
238 a = Arrays.copyOf(a, size);
239 }
240 if (resolving)
241 self.copyConstants(offset, offset + size, a, 0);
242 else
243 self.copyConstants(offset, offset + size, a, 0,
244 ifNotPresent);
245 if (pad > 0) a[size] = null;
246 return a;
247 }
248 }
249
250 static abstract
251 class WithCache extends AbstractConstantGroup {
252 @Stable final Object[] cache;
253
254 WithCache(int size) {
255 super(size);
256 // It is caller's responsibility to initialize the cache.
257 // Initial contents are all-null, which means nothing is present.
258 cache = new Object[size];
259 }
260
261 void initializeCache(List<Object> cacheContents, Object ifNotPresent) {
262 // Replace ifNotPresent with NOT_PRESENT,
263 // and null with RESOLVED_TO_NULL.
264 // Then forget about the user-provided ifNotPresent.
265 for (int i = 0; i < cache.length; i++) {
266 Object x = cacheContents.get(i);
267 if (x == ifNotPresent)
268 continue; // leave the null in place
269 if (x == null)
270 x = RESOLVED_TO_NULL;
271 cache[i] = x;
272 }
273 }
274
275 @Override public Object get(int i) {
276 Object x = cache[i];
277 // @Stable array must use null for sentinel
278 if (x == null) x = fillCache(i);
279 return unwrapNull(x);
280 }
281
282 @Override public Object get(int i, Object ifNotAvailable) {
283 Object x = cache[i];
284 // @Stable array must use null for sentinel
285 if (x == null) return ifNotAvailable;
286 return unwrapNull(x);
287 }
288
289 @Override
290 public boolean isPresent(int i) {
291 return cache[i] != null;
292 }
293
294 /** hook for local subclasses */
295 Object fillCache(int i) {
296 throw new NoSuchElementException("constant group does not contain element #"+i);
297 }
298
299 /// routines for mapping between null sentinel and true resolved null
300
301 static Object wrapNull(Object x) {
302 return x == null ? RESOLVED_TO_NULL : x;
303 }
304
305 static Object unwrapNull(Object x) {
306 assert(x != null);
307 return x == RESOLVED_TO_NULL ? null : x;
308 }
309
310 // secret sentinel for an actual null resolved value, in the cache
311 static final Object RESOLVED_TO_NULL = new Object();
312
313 // secret sentinel for a "hole" in the cache:
314 static final Object NOT_PRESENT = new Object();
315
316 }
317
318 /** Skeleton implementation of BootstrapCallInfo. */
319 static
320 class BSCIWithCache<T> extends WithCache implements BootstrapCallInfo<T> {
321 private final MethodHandle bsm;
322 private final String name;
323 private final T type;
324
325 @Override public String toString() {
326 return bsm+"/"+name+":"+type+super.toString();
327 }
328
329 BSCIWithCache(MethodHandle bsm, String name, T type, int size) {
330 super(size);
331 this.type = type;
332 this.bsm = bsm;
333 this.name = name;
334 assert(type instanceof Class || type instanceof MethodType);
335 }
336
337 @Override public MethodHandle bootstrapMethod() { return bsm; }
338 @Override public String invocationName() { return name; }
339 @Override public T invocationType() { return type; }
340 }
341 }