Mon, 17 Dec 2012 07:47:05 -0800
8004832: Add new doclint package
Reviewed-by: mcimadamore
1 /*
2 * Copyright (c) 1999, 2012, 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 */
26 package com.sun.tools.javac.code;
28 import java.util.Iterator;
30 import com.sun.tools.javac.util.*;
32 /** A scope represents an area of visibility in a Java program. The
33 * Scope class is a container for symbols which provides
34 * efficient access to symbols given their names. Scopes are implemented
35 * as hash tables with "open addressing" and "double hashing".
36 * Scopes can be nested; the next field of a scope points
37 * to its next outer scope. Nested scopes can share their hash tables.
38 *
39 * <p><b>This is NOT part of any supported API.
40 * If you write code that depends on this, you do so at your own risk.
41 * This code and its internal interfaces are subject to change or
42 * deletion without notice.</b>
43 */
44 public class Scope {
46 /** The number of scopes that share this scope's hash table.
47 */
48 private int shared;
50 /** Next enclosing scope (with whom this scope may share a hashtable)
51 */
52 public Scope next;
54 /** The scope's owner.
55 */
56 public Symbol owner;
58 /** A hash table for the scope's entries.
59 */
60 Entry[] table;
62 /** Mask for hash codes, always equal to (table.length - 1).
63 */
64 int hashMask;
66 /** A linear list that also contains all entries in
67 * reverse order of appearance (i.e later entries are pushed on top).
68 */
69 public Entry elems;
71 /** The number of elements in this scope.
72 * This includes deleted elements, whose value is the sentinel.
73 */
74 int nelems = 0;
76 /** A list of scopes to be notified if items are to be removed from this scope.
77 */
78 List<ScopeListener> listeners = List.nil();
80 /** Use as a "not-found" result for lookup.
81 * Also used to mark deleted entries in the table.
82 */
83 private static final Entry sentinel = new Entry(null, null, null, null);
85 /** The hash table's initial size.
86 */
87 private static final int INITIAL_SIZE = 0x10;
89 /** A value for the empty scope.
90 */
91 public static final Scope emptyScope = new Scope(null, null, new Entry[]{});
93 /** Construct a new scope, within scope next, with given owner, using
94 * given table. The table's length must be an exponent of 2.
95 */
96 private Scope(Scope next, Symbol owner, Entry[] table) {
97 this.next = next;
98 Assert.check(emptyScope == null || owner != null);
99 this.owner = owner;
100 this.table = table;
101 this.hashMask = table.length - 1;
102 }
104 /** Convenience constructor used for dup and dupUnshared. */
105 private Scope(Scope next, Symbol owner, Entry[] table, int nelems) {
106 this(next, owner, table);
107 this.nelems = nelems;
108 }
110 /** Construct a new scope, within scope next, with given owner,
111 * using a fresh table of length INITIAL_SIZE.
112 */
113 public Scope(Symbol owner) {
114 this(null, owner, new Entry[INITIAL_SIZE]);
115 }
117 /** Construct a fresh scope within this scope, with same owner,
118 * which shares its table with the outer scope. Used in connection with
119 * method leave if scope access is stack-like in order to avoid allocation
120 * of fresh tables.
121 */
122 public Scope dup() {
123 return dup(this.owner);
124 }
126 /** Construct a fresh scope within this scope, with new owner,
127 * which shares its table with the outer scope. Used in connection with
128 * method leave if scope access is stack-like in order to avoid allocation
129 * of fresh tables.
130 */
131 public Scope dup(Symbol newOwner) {
132 Scope result = new Scope(this, newOwner, this.table, this.nelems);
133 shared++;
134 // System.out.println("====> duping scope " + this.hashCode() + " owned by " + newOwner + " to " + result.hashCode());
135 // new Error().printStackTrace(System.out);
136 return result;
137 }
139 /** Construct a fresh scope within this scope, with same owner,
140 * with a new hash table, whose contents initially are those of
141 * the table of its outer scope.
142 */
143 public Scope dupUnshared() {
144 return new Scope(this, this.owner, this.table.clone(), this.nelems);
145 }
147 /** Remove all entries of this scope from its table, if shared
148 * with next.
149 */
150 public Scope leave() {
151 Assert.check(shared == 0);
152 if (table != next.table) return next;
153 while (elems != null) {
154 int hash = getIndex(elems.sym.name);
155 Entry e = table[hash];
156 Assert.check(e == elems, elems.sym);
157 table[hash] = elems.shadowed;
158 elems = elems.sibling;
159 }
160 Assert.check(next.shared > 0);
161 next.shared--;
162 next.nelems = nelems;
163 // System.out.println("====> leaving scope " + this.hashCode() + " owned by " + this.owner + " to " + next.hashCode());
164 // new Error().printStackTrace(System.out);
165 return next;
166 }
168 /** Double size of hash table.
169 */
170 private void dble() {
171 Assert.check(shared == 0);
172 Entry[] oldtable = table;
173 Entry[] newtable = new Entry[oldtable.length * 2];
174 for (Scope s = this; s != null; s = s.next) {
175 if (s.table == oldtable) {
176 Assert.check(s == this || s.shared != 0);
177 s.table = newtable;
178 s.hashMask = newtable.length - 1;
179 }
180 }
181 int n = 0;
182 for (int i = oldtable.length; --i >= 0; ) {
183 Entry e = oldtable[i];
184 if (e != null && e != sentinel) {
185 table[getIndex(e.sym.name)] = e;
186 n++;
187 }
188 }
189 // We don't need to update nelems for shared inherited scopes,
190 // since that gets handled by leave().
191 nelems = n;
192 }
194 /** Enter symbol sym in this scope.
195 */
196 public void enter(Symbol sym) {
197 Assert.check(shared == 0);
198 enter(sym, this);
199 }
201 public void enter(Symbol sym, Scope s) {
202 enter(sym, s, s);
203 }
205 /**
206 * Enter symbol sym in this scope, but mark that it comes from
207 * given scope `s' accessed through `origin'. The last two
208 * arguments are only used in import scopes.
209 */
210 public void enter(Symbol sym, Scope s, Scope origin) {
211 Assert.check(shared == 0);
212 if (nelems * 3 >= hashMask * 2)
213 dble();
214 int hash = getIndex(sym.name);
215 Entry old = table[hash];
216 if (old == null) {
217 old = sentinel;
218 nelems++;
219 }
220 Entry e = makeEntry(sym, old, elems, s, origin);
221 table[hash] = e;
222 elems = e;
224 //notify listeners
225 for (List<ScopeListener> l = listeners; l.nonEmpty(); l = l.tail) {
226 l.head.symbolAdded(sym, this);
227 }
228 }
230 Entry makeEntry(Symbol sym, Entry shadowed, Entry sibling, Scope scope, Scope origin) {
231 return new Entry(sym, shadowed, sibling, scope);
232 }
235 public interface ScopeListener {
236 public void symbolAdded(Symbol sym, Scope s);
237 public void symbolRemoved(Symbol sym, Scope s);
238 }
240 public void addScopeListener(ScopeListener sl) {
241 listeners = listeners.prepend(sl);
242 }
244 /** Remove symbol from this scope. Used when an inner class
245 * attribute tells us that the class isn't a package member.
246 */
247 public void remove(Symbol sym) {
248 Assert.check(shared == 0);
249 Entry e = lookup(sym.name);
250 if (e.scope == null) return;
252 // remove e from table and shadowed list;
253 int i = getIndex(sym.name);
254 Entry te = table[i];
255 if (te == e)
256 table[i] = e.shadowed;
257 else while (true) {
258 if (te.shadowed == e) {
259 te.shadowed = e.shadowed;
260 break;
261 }
262 te = te.shadowed;
263 }
265 // remove e from elems and sibling list
266 te = elems;
267 if (te == e)
268 elems = e.sibling;
269 else while (true) {
270 if (te.sibling == e) {
271 te.sibling = e.sibling;
272 break;
273 }
274 te = te.sibling;
275 }
277 //notify listeners
278 for (List<ScopeListener> l = listeners; l.nonEmpty(); l = l.tail) {
279 l.head.symbolRemoved(sym, this);
280 }
281 }
283 /** Enter symbol sym in this scope if not already there.
284 */
285 public void enterIfAbsent(Symbol sym) {
286 Assert.check(shared == 0);
287 Entry e = lookup(sym.name);
288 while (e.scope == this && e.sym.kind != sym.kind) e = e.next();
289 if (e.scope != this) enter(sym);
290 }
292 /** Given a class, is there already a class with same fully
293 * qualified name in this (import) scope?
294 */
295 public boolean includes(Symbol c) {
296 for (Scope.Entry e = lookup(c.name);
297 e.scope == this;
298 e = e.next()) {
299 if (e.sym == c) return true;
300 }
301 return false;
302 }
304 static final Filter<Symbol> noFilter = new Filter<Symbol>() {
305 public boolean accepts(Symbol s) {
306 return true;
307 }
308 };
310 /** Return the entry associated with given name, starting in
311 * this scope and proceeding outwards. If no entry was found,
312 * return the sentinel, which is characterized by having a null in
313 * both its scope and sym fields, whereas both fields are non-null
314 * for regular entries.
315 */
316 public Entry lookup(Name name) {
317 return lookup(name, noFilter);
318 }
319 public Entry lookup(Name name, Filter<Symbol> sf) {
320 Entry e = table[getIndex(name)];
321 if (e == null || e == sentinel)
322 return sentinel;
323 while (e.scope != null && (e.sym.name != name || !sf.accepts(e.sym)))
324 e = e.shadowed;
325 return e;
326 }
328 /*void dump (java.io.PrintStream out) {
329 out.println(this);
330 for (int l=0; l < table.length; l++) {
331 Entry le = table[l];
332 out.print("#"+l+": ");
333 if (le==sentinel) out.println("sentinel");
334 else if(le == null) out.println("null");
335 else out.println(""+le+" s:"+le.sym);
336 }
337 }*/
339 /** Look for slot in the table.
340 * We use open addressing with double hashing.
341 */
342 int getIndex (Name name) {
343 int h = name.hashCode();
344 int i = h & hashMask;
345 // The expression below is always odd, so it is guaranteed
346 // to be mutually prime with table.length, a power of 2.
347 int x = hashMask - ((h + (h >> 16)) << 1);
348 int d = -1; // Index of a deleted item.
349 for (;;) {
350 Entry e = table[i];
351 if (e == null)
352 return d >= 0 ? d : i;
353 if (e == sentinel) {
354 // We have to keep searching even if we see a deleted item.
355 // However, remember the index in case we fail to find the name.
356 if (d < 0)
357 d = i;
358 } else if (e.sym.name == name)
359 return i;
360 i = (i + x) & hashMask;
361 }
362 }
364 public Iterable<Symbol> getElements() {
365 return getElements(noFilter);
366 }
368 public Iterable<Symbol> getElements(final Filter<Symbol> sf) {
369 return new Iterable<Symbol>() {
370 public Iterator<Symbol> iterator() {
371 return new Iterator<Symbol>() {
372 private Scope currScope = Scope.this;
373 private Scope.Entry currEntry = elems;
374 {
375 update();
376 }
378 public boolean hasNext() {
379 return currEntry != null;
380 }
382 public Symbol next() {
383 Symbol sym = (currEntry == null ? null : currEntry.sym);
384 if (currEntry != null) {
385 currEntry = currEntry.sibling;
386 }
387 update();
388 return sym;
389 }
391 public void remove() {
392 throw new UnsupportedOperationException();
393 }
395 private void update() {
396 skipToNextMatchingEntry();
397 while (currEntry == null && currScope.next != null) {
398 currScope = currScope.next;
399 currEntry = currScope.elems;
400 skipToNextMatchingEntry();
401 }
402 }
404 void skipToNextMatchingEntry() {
405 while (currEntry != null && !sf.accepts(currEntry.sym)) {
406 currEntry = currEntry.sibling;
407 }
408 }
409 };
410 }
411 };
412 }
414 public Iterable<Symbol> getElementsByName(Name name) {
415 return getElementsByName(name, noFilter);
416 }
418 public Iterable<Symbol> getElementsByName(final Name name, final Filter<Symbol> sf) {
419 return new Iterable<Symbol>() {
420 public Iterator<Symbol> iterator() {
421 return new Iterator<Symbol>() {
422 Scope.Entry currentEntry = lookup(name, sf);
424 public boolean hasNext() {
425 return currentEntry.scope != null;
426 }
427 public Symbol next() {
428 Scope.Entry prevEntry = currentEntry;
429 currentEntry = currentEntry.next(sf);
430 return prevEntry.sym;
431 }
432 public void remove() {
433 throw new UnsupportedOperationException();
434 }
435 };
436 }
437 };
438 }
440 public String toString() {
441 StringBuilder result = new StringBuilder();
442 result.append("Scope[");
443 for (Scope s = this; s != null ; s = s.next) {
444 if (s != this) result.append(" | ");
445 for (Entry e = s.elems; e != null; e = e.sibling) {
446 if (e != s.elems) result.append(", ");
447 result.append(e.sym);
448 }
449 }
450 result.append("]");
451 return result.toString();
452 }
454 /** A class for scope entries.
455 */
456 public static class Entry {
458 /** The referenced symbol.
459 * sym == null iff this == sentinel
460 */
461 public Symbol sym;
463 /** An entry with the same hash code, or sentinel.
464 */
465 private Entry shadowed;
467 /** Next entry in same scope.
468 */
469 public Entry sibling;
471 /** The entry's scope.
472 * scope == null iff this == sentinel
473 * for an entry in an import scope, this is the scope
474 * where the entry came from (i.e. was imported from).
475 */
476 public Scope scope;
478 public Entry(Symbol sym, Entry shadowed, Entry sibling, Scope scope) {
479 this.sym = sym;
480 this.shadowed = shadowed;
481 this.sibling = sibling;
482 this.scope = scope;
483 }
485 /** Return next entry with the same name as this entry, proceeding
486 * outwards if not found in this scope.
487 */
488 public Entry next() {
489 return shadowed;
490 }
492 public Entry next(Filter<Symbol> sf) {
493 if (shadowed.sym == null || sf.accepts(shadowed.sym)) return shadowed;
494 else return shadowed.next(sf);
495 }
497 public Scope getOrigin() {
498 // The origin is only recorded for import scopes. For all
499 // other scope entries, the "enclosing" type is available
500 // from other sources. See Attr.visitSelect and
501 // Attr.visitIdent. Rather than throwing an assertion
502 // error, we return scope which will be the same as origin
503 // in many cases.
504 return scope;
505 }
506 }
508 public static class ImportScope extends Scope {
510 public ImportScope(Symbol owner) {
511 super(owner);
512 }
514 @Override
515 Entry makeEntry(Symbol sym, Entry shadowed, Entry sibling, Scope scope, Scope origin) {
516 return new ImportEntry(sym, shadowed, sibling, scope, origin);
517 }
519 static class ImportEntry extends Entry {
520 private Scope origin;
522 ImportEntry(Symbol sym, Entry shadowed, Entry sibling, Scope scope, Scope origin) {
523 super(sym, shadowed, sibling, scope);
524 this.origin = origin;
525 }
527 @Override
528 public Scope getOrigin() { return origin; }
529 }
530 }
532 public static class StarImportScope extends ImportScope implements ScopeListener {
534 public StarImportScope(Symbol owner) {
535 super(owner);
536 }
538 public void importAll (Scope fromScope) {
539 for (Scope.Entry e = fromScope.elems; e != null; e = e.sibling) {
540 if (e.sym.kind == Kinds.TYP && !includes(e.sym))
541 enter(e.sym, fromScope);
542 }
543 // Register to be notified when imported items are removed
544 fromScope.addScopeListener(this);
545 }
547 public void symbolRemoved(Symbol sym, Scope s) {
548 remove(sym);
549 }
550 public void symbolAdded(Symbol sym, Scope s) { }
551 }
553 /** An empty scope, into which you can't place anything. Used for
554 * the scope for a variable initializer.
555 */
556 public static class DelegatedScope extends Scope {
557 Scope delegatee;
558 public static final Entry[] emptyTable = new Entry[0];
560 public DelegatedScope(Scope outer) {
561 super(outer, outer.owner, emptyTable);
562 delegatee = outer;
563 }
564 public Scope dup() {
565 return new DelegatedScope(next);
566 }
567 public Scope dupUnshared() {
568 return new DelegatedScope(next);
569 }
570 public Scope leave() {
571 return next;
572 }
573 public void enter(Symbol sym) {
574 // only anonymous classes could be put here
575 }
576 public void enter(Symbol sym, Scope s) {
577 // only anonymous classes could be put here
578 }
579 public void remove(Symbol sym) {
580 throw new AssertionError(sym);
581 }
582 public Entry lookup(Name name) {
583 return delegatee.lookup(name);
584 }
585 }
587 /** A class scope adds capabilities to keep track of changes in related
588 * class scopes - this allows client to realize whether a class scope
589 * has changed, either directly (because a new member has been added/removed
590 * to this scope) or indirectly (i.e. because a new member has been
591 * added/removed into a supertype scope)
592 */
593 public static class CompoundScope extends Scope implements ScopeListener {
595 public static final Entry[] emptyTable = new Entry[0];
597 private List<Scope> subScopes = List.nil();
598 private int mark = 0;
600 public CompoundScope(Symbol owner) {
601 super(null, owner, emptyTable);
602 }
604 public void addSubScope(Scope that) {
605 if (that != null) {
606 subScopes = subScopes.prepend(that);
607 that.addScopeListener(this);
608 mark++;
609 for (ScopeListener sl : listeners) {
610 sl.symbolAdded(null, this); //propagate upwards in case of nested CompoundScopes
611 }
612 }
613 }
615 public void symbolAdded(Symbol sym, Scope s) {
616 mark++;
617 for (ScopeListener sl : listeners) {
618 sl.symbolAdded(sym, s);
619 }
620 }
622 public void symbolRemoved(Symbol sym, Scope s) {
623 mark++;
624 for (ScopeListener sl : listeners) {
625 sl.symbolRemoved(sym, s);
626 }
627 }
629 public int getMark() {
630 return mark;
631 }
633 @Override
634 public String toString() {
635 StringBuilder buf = new StringBuilder();
636 buf.append("CompoundScope{");
637 String sep = "";
638 for (Scope s : subScopes) {
639 buf.append(sep);
640 buf.append(s);
641 sep = ",";
642 }
643 buf.append("}");
644 return buf.toString();
645 }
647 @Override
648 public Iterable<Symbol> getElements(final Filter<Symbol> sf) {
649 return new Iterable<Symbol>() {
650 public Iterator<Symbol> iterator() {
651 return new CompoundScopeIterator(subScopes) {
652 Iterator<Symbol> nextIterator(Scope s) {
653 return s.getElements(sf).iterator();
654 }
655 };
656 }
657 };
658 }
660 @Override
661 public Iterable<Symbol> getElementsByName(final Name name, final Filter<Symbol> sf) {
662 return new Iterable<Symbol>() {
663 public Iterator<Symbol> iterator() {
664 return new CompoundScopeIterator(subScopes) {
665 Iterator<Symbol> nextIterator(Scope s) {
666 return s.getElementsByName(name, sf).iterator();
667 }
668 };
669 }
670 };
671 }
673 abstract class CompoundScopeIterator implements Iterator<Symbol> {
675 private Iterator<Symbol> currentIterator;
676 private List<Scope> scopesToScan;
678 public CompoundScopeIterator(List<Scope> scopesToScan) {
679 this.scopesToScan = scopesToScan;
680 update();
681 }
683 abstract Iterator<Symbol> nextIterator(Scope s);
685 public boolean hasNext() {
686 return currentIterator != null;
687 }
689 public Symbol next() {
690 Symbol sym = currentIterator.next();
691 if (!currentIterator.hasNext()) {
692 update();
693 }
694 return sym;
695 }
697 public void remove() {
698 throw new UnsupportedOperationException();
699 }
701 private void update() {
702 while (scopesToScan.nonEmpty()) {
703 currentIterator = nextIterator(scopesToScan.head);
704 scopesToScan = scopesToScan.tail;
705 if (currentIterator.hasNext()) return;
706 }
707 currentIterator = null;
708 }
709 }
711 @Override
712 public Entry lookup(Name name, Filter<Symbol> sf) {
713 throw new UnsupportedOperationException();
714 }
716 @Override
717 public Scope dup(Symbol newOwner) {
718 throw new UnsupportedOperationException();
719 }
721 @Override
722 public void enter(Symbol sym, Scope s, Scope origin) {
723 throw new UnsupportedOperationException();
724 }
726 @Override
727 public void remove(Symbol sym) {
728 throw new UnsupportedOperationException();
729 }
730 }
732 /** An error scope, for which the owner should be an error symbol. */
733 public static class ErrorScope extends Scope {
734 ErrorScope(Scope next, Symbol errSymbol, Entry[] table) {
735 super(next, /*owner=*/errSymbol, table);
736 }
737 public ErrorScope(Symbol errSymbol) {
738 super(errSymbol);
739 }
740 public Scope dup() {
741 return new ErrorScope(this, owner, table);
742 }
743 public Scope dupUnshared() {
744 return new ErrorScope(this, owner, table.clone());
745 }
746 public Entry lookup(Name name) {
747 Entry e = super.lookup(name);
748 if (e.scope == null)
749 return new Entry(owner, null, null, null);
750 else
751 return e;
752 }
753 }
754 }