/*
* Copyright (c) 1999, 2006, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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*/
package com.sun.tools.javac.code;
import com.sun.tools.javac.util.*;
import java.util.Iterator;
/** A scope represents an area of visibility in a Java program. The
* Scope class is a container for symbols which provides
* efficient access to symbols given their names. Scopes are implemented
* as hash tables. Scopes can be nested; the next field of a scope points
* to its next outer scope. Nested scopes can share their hash tables.
*
* <p><b>This is NOT part of any supported API.
* If you write code that depends on this, you do so at your own risk.
* This code and its internal interfaces are subject to change or
* deletion without notice.</b>
*/
public class Scope {
/** The number of scopes that share this scope's hash table.
*/
private int shared;
/** Next enclosing scope (with whom this scope may share a hashtable)
*/
public Scope next;
/** The scope's owner.
*/
public Symbol owner;
/** A hash table for the scope's entries.
*/
public Entry[] table;
/** Mask for hash codes, always equal to (table.length - 1).
*/
int hashMask;
/** A linear list that also contains all entries in
* reverse order of appearance (i.e later entries are pushed on top).
*/
public Entry elems;
/** The number of elements in this scope.
*/
public int nelems = 0;
/** Every hash bucket is a list of Entry's which ends in sentinel.
*/
private static final Entry sentinel = new Entry(null, null, null, null);
/** The hash table's initial size.
*/
private static final int INITIAL_SIZE = 0x10;
/** A value for the empty scope.
*/
public static final Scope emptyScope = new Scope(null, null, new Entry[]{});
/** Construct a new scope, within scope next, with given owner, using
* given table. The table's length must be an exponent of 2.
*/
Scope(Scope next, Symbol owner, Entry[] table) {
this.next = next;
assert emptyScope == null || owner != null;
this.owner = owner;
this.table = table;
this.hashMask = table.length - 1;
this.elems = null;
this.nelems = 0;
this.shared = 0;
}
/** Construct a new scope, within scope next, with given owner,
* using a fresh table of length INITIAL_SIZE.
*/
public Scope(Symbol owner) {
this(null, owner, new Entry[INITIAL_SIZE]);
for (int i = 0; i < INITIAL_SIZE; i++) table[i] = sentinel;
}
/** Construct a fresh scope within this scope, with same owner,
* which shares its table with the outer scope. Used in connection with
* method leave if scope access is stack-like in order to avoid allocation
* of fresh tables.
*/
public Scope dup() {
Scope result = new Scope(this, this.owner, this.table);
shared++;
// System.out.println("====> duping scope " + this.hashCode() + " owned by " + this.owner + " to " + result.hashCode());
// new Error().printStackTrace(System.out);
return result;
}
/** Construct a fresh scope within this scope, with new owner,
* which shares its table with the outer scope. Used in connection with
* method leave if scope access is stack-like in order to avoid allocation
* of fresh tables.
*/
public Scope dup(Symbol newOwner) {
Scope result = new Scope(this, newOwner, this.table);
shared++;
// System.out.println("====> duping scope " + this.hashCode() + " owned by " + newOwner + " to " + result.hashCode());
// new Error().printStackTrace(System.out);
return result;
}
/** Construct a fresh scope within this scope, with same owner,
* with a new hash table, whose contents initially are those of
* the table of its outer scope.
*/
public Scope dupUnshared() {
return new Scope(this, this.owner, this.table.clone());
}
/** Remove all entries of this scope from its table, if shared
* with next.
*/
public Scope leave() {
assert shared == 0;
if (table != next.table) return next;
while (elems != null) {
int hash = elems.sym.name.index & hashMask;
Entry e = table[hash];
assert e == elems : elems.sym;
table[hash] = elems.shadowed;
elems = elems.sibling;
}
assert next.shared > 0;
next.shared--;
// System.out.println("====> leaving scope " + this.hashCode() + " owned by " + this.owner + " to " + next.hashCode());
// new Error().printStackTrace(System.out);
return next;
}
/** Double size of hash table.
*/
private void dble() {
assert shared == 0;
Entry[] oldtable = table;
Entry[] newtable = new Entry[oldtable.length * 2];
for (Scope s = this; s != null; s = s.next) {
if (s.table == oldtable) {
assert s == this || s.shared != 0;
s.table = newtable;
s.hashMask = newtable.length - 1;
}
}
for (int i = 0; i < newtable.length; i++) newtable[i] = sentinel;
for (int i = 0; i < oldtable.length; i++) copy(oldtable[i]);
}
/** Copy the given entry and all entries shadowed by it to table
*/
private void copy(Entry e) {
if (e.sym != null) {
copy(e.shadowed);
int hash = e.sym.name.index & hashMask;
e.shadowed = table[hash];
table[hash] = e;
}
}
/** Enter symbol sym in this scope.
*/
public void enter(Symbol sym) {
assert shared == 0;
enter(sym, this);
}
public void enter(Symbol sym, Scope s) {
enter(sym, s, s);
}
/**
* Enter symbol sym in this scope, but mark that it comes from
* given scope `s' accessed through `origin'. The last two
* arguments are only used in import scopes.
*/
public void enter(Symbol sym, Scope s, Scope origin) {
assert shared == 0;
// Temporarily disabled (bug 6460352):
// if (nelems * 3 >= hashMask * 2) dble();
int hash = sym.name.index & hashMask;
Entry e = makeEntry(sym, table[hash], elems, s, origin);
table[hash] = e;
elems = e;
nelems++;
}
Entry makeEntry(Symbol sym, Entry shadowed, Entry sibling, Scope scope, Scope origin) {
return new Entry(sym, shadowed, sibling, scope);
}
/** Remove symbol from this scope. Used when an inner class
* attribute tells us that the class isn't a package member.
*/
public void remove(Symbol sym) {
assert shared == 0;
Entry e = lookup(sym.name);
while (e.scope == this && e.sym != sym) e = e.next();
if (e.scope == null) return;
// remove e from table and shadowed list;
Entry te = table[sym.name.index & hashMask];
if (te == e)
table[sym.name.index & hashMask] = e.shadowed;
else while (true) {
if (te.shadowed == e) {
te.shadowed = e.shadowed;
break;
}
te = te.shadowed;
}
// remove e from elems and sibling list
te = elems;
if (te == e)
elems = e.sibling;
else while (true) {
if (te.sibling == e) {
te.sibling = e.sibling;
break;
}
te = te.sibling;
}
}
/** Enter symbol sym in this scope if not already there.
*/
public void enterIfAbsent(Symbol sym) {
assert shared == 0;
Entry e = lookup(sym.name);
while (e.scope == this && e.sym.kind != sym.kind) e = e.next();
if (e.scope != this) enter(sym);
}
/** Given a class, is there already a class with same fully
* qualified name in this (import) scope?
*/
public boolean includes(Symbol c) {
for (Scope.Entry e = lookup(c.name);
e.scope == this;
e = e.next()) {
if (e.sym == c) return true;
}
return false;
}
/** Return the entry associated with given name, starting in
* this scope and proceeding outwards. If no entry was found,
* return the sentinel, which is characterized by having a null in
* both its scope and sym fields, whereas both fields are non-null
* for regular entries.
*/
public Entry lookup(Name name) {
Entry e = table[name.index & hashMask];
while (e.scope != null && e.sym.name != name)
e = e.shadowed;
return e;
}
public Iterable<Symbol> getElements() {
return new Iterable<Symbol>() {
public Iterator<Symbol> iterator() {
return new Iterator<Symbol>() {
private Scope currScope = Scope.this;
private Scope.Entry currEntry = elems;
{
update();
}
public boolean hasNext() {
return currEntry != null;
}
public Symbol next() {
Symbol sym = (currEntry == null ? null : currEntry.sym);
currEntry = currEntry.sibling;
update();
return sym;
}
public void remove() {
throw new UnsupportedOperationException();
}
private void update() {
while (currEntry == null && currScope.next != null) {
currScope = currScope.next;
currEntry = currScope.elems;
}
}
};
}
};
}
public String toString() {
StringBuilder result = new StringBuilder();
result.append("Scope[");
for (Scope s = this; s != null ; s = s.next) {
if (s != this) result.append(" | ");
for (Entry e = s.elems; e != null; e = e.sibling) {
if (e != s.elems) result.append(", ");
result.append(e.sym);
}
}
result.append("]");
return result.toString();
}
/** A class for scope entries.
*/
public static class Entry {
/** The referenced symbol.
* sym == null iff this == sentinel
*/
public Symbol sym;
/** An entry with the same hash code, or sentinel.
*/
private Entry shadowed;
/** Next entry in same scope.
*/
public Entry sibling;
/** The entry's scope.
* scope == null iff this == sentinel
* for an entry in an import scope, this is the scope
* where the entry came from (i.e. was imported from).
*/
public Scope scope;
public Entry(Symbol sym, Entry shadowed, Entry sibling, Scope scope) {
this.sym = sym;
this.shadowed = shadowed;
this.sibling = sibling;
this.scope = scope;
}
/** Return next entry with the same name as this entry, proceeding
* outwards if not found in this scope.
*/
public Entry next() {
Entry e = shadowed;
while (e.scope != null && e.sym.name != sym.name)
e = e.shadowed;
return e;
}
public Scope getOrigin() {
// The origin is only recorded for import scopes. For all
// other scope entries, the "enclosing" type is available
// from other sources. See Attr.visitSelect and
// Attr.visitIdent. Rather than throwing an assertion
// error, we return scope which will be the same as origin
// in many cases.
return scope;
}
}
public static class ImportScope extends Scope {
public ImportScope(Symbol owner) {
super(owner);
}
@Override
Entry makeEntry(Symbol sym, Entry shadowed, Entry sibling, Scope scope, Scope origin) {
return new ImportEntry(sym, shadowed, sibling, scope, origin);
}
public Entry lookup(Name name) {
Entry e = table[name.index & hashMask];
while (e.scope != null &&
(e.sym.name != name ||
/* Since an inner class will show up in package and
* import scopes until its inner class attribute has
* been processed, we have to weed it out here. This
* is done by comparing the owners of the entry's
* scope and symbol fields. The scope field's owner
* points to where the class originally was imported
* from. The symbol field's owner points to where the
* class is situated now. This can change when an
* inner class is read (see ClassReader.enterClass).
* By comparing the two fields we make sure that we do
* not accidentally import an inner class that started
* life as a flat class in a package. */
e.sym.owner != e.scope.owner))
e = e.shadowed;
return e;
}
static class ImportEntry extends Entry {
private Scope origin;
ImportEntry(Symbol sym, Entry shadowed, Entry sibling, Scope scope, Scope origin) {
super(sym, shadowed, sibling, scope);
this.origin = origin;
}
public Entry next() {
Entry e = super.shadowed;
while (e.scope != null &&
(e.sym.name != sym.name ||
e.sym.owner != e.scope.owner)) // see lookup()
e = e.shadowed;
return e;
}
@Override
public Scope getOrigin() { return origin; }
}
}
/** An empty scope, into which you can't place anything. Used for
* the scope for a variable initializer.
*/
public static class DelegatedScope extends Scope {
Scope delegatee;
public static final Entry[] emptyTable = new Entry[0];
public DelegatedScope(Scope outer) {
super(outer, outer.owner, emptyTable);
delegatee = outer;
}
public Scope dup() {
return new DelegatedScope(next);
}
public Scope dupUnshared() {
return new DelegatedScope(next);
}
public Scope leave() {
return next;
}
public void enter(Symbol sym) {
// only anonymous classes could be put here
}
public void enter(Symbol sym, Scope s) {
// only anonymous classes could be put here
}
public void remove(Symbol sym) {
throw new AssertionError(sym);
}
public Entry lookup(Name name) {
return delegatee.lookup(name);
}
}
/** An error scope, for which the owner should be an error symbol. */
public static class ErrorScope extends Scope {
ErrorScope(Scope next, Symbol errSymbol, Entry[] table) {
super(next, /*owner=*/errSymbol, table);
}
public ErrorScope(Symbol errSymbol) {
super(errSymbol);
}
public Scope dup() {
return new ErrorScope(this, owner, table);
}
public Scope dupUnshared() {
return new ErrorScope(this, owner, table.clone());
}
public Entry lookup(Name name) {
Entry e = super.lookup(name);
if (e.scope == null)
return new Entry(owner, null, null, null);
else
return e;
}
}
}