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IdentityHashMap.java (containsKey): Use getHash.

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* java/util/IdentityHashMap.java (containsKey): Use getHash.
	(get): Likewise.
	(put): Likewise.
	(remove): Likewise.
	(getHash): New method.
	(tombstone, emptyslot): Now static final.
	(put): Correctly determine when to rehash, and correctly rehash.
	(containsKey, remove): Test against table length with `>='.

From-SVN: r45841
This commit is contained in:
Tom Tromey 2001-09-27 16:49:13 +00:00 committed by Tom Tromey
parent c9e7a60950
commit 0caade1b54
2 changed files with 29 additions and 11 deletions
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11
libjava/ChangeLog
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@ -1,3 +1,14 @@
2001-09-27 Tom Tromey <tromey@redhat.com>
* java/util/IdentityHashMap.java (containsKey): Use getHash.
(get): Likewise.
(put): Likewise.
(remove): Likewise.
(getHash): New method.
(tombstone, emptyslot): Now static final.
(put): Correctly determine when to rehash, and correctly rehash.
(containsKey, remove): Test against table length with `>='.
2001-09-26 Tom Tromey <tromey@redhat.com> 2001-09-26 Tom Tromey <tromey@redhat.com>
* gnu/classpath/Configuration.java.in (INIT_LOAD_LIBRARY): New * gnu/classpath/Configuration.java.in (INIT_LOAD_LIBRARY): New

29
libjava/java/util/IdentityHashMap.java
View File

@ -103,7 +103,7 @@ public class IdentityHashMap extends AbstractMap
public boolean containsKey (Object key) public boolean containsKey (Object key)
{ {
int h = Math.abs (2 * System.identityHashCode (key) % table.length); int h = getHash (key);
int save = h; int save = h;
while (true) while (true)
{ {
@ -112,7 +112,7 @@ public class IdentityHashMap extends AbstractMap
if (table[h] == emptyslot) if (table[h] == emptyslot)
return false; return false;
h += 2; h += 2;
if (h > table.length) if (h >= table.length)
h = 0; h = 0;
if (h == save) if (h == save)
return false; return false;
@ -174,7 +174,7 @@ public class IdentityHashMap extends AbstractMap
public Object get (Object key) public Object get (Object key)
{ {
int h = Math.abs (2 * System.identityHashCode (key) % table.length); int h = getHash (key);
int save = h; int save = h;
while (true) while (true)
{ {
@ -230,14 +230,15 @@ public class IdentityHashMap extends AbstractMap
public Object put (Object key, Object value) public Object put (Object key, Object value)
{ {
// Rehash is the load factor is too high. // Rehash if the load factor is too high. We use a factor of 1.5
if (size * 3 / 2 > table.length) // -- the division by 2 is implicit on both sides.
if (size * 3 > table.length)
{ {
Object[] old = table; Object[] old = table;
table = new Object[old.length * 2]; table = new Object[old.length * 2];
Arrays.fill (table, emptyslot); Arrays.fill (table, emptyslot);
size = 0; size = 0;
for (int i = 0; i < old.length; ++i) for (int i = 0; i < old.length; i += 2)
{ {
if (old[i] != tombstone && old[i] != emptyslot) if (old[i] != tombstone && old[i] != emptyslot)
{ {
@ -248,7 +249,7 @@ public class IdentityHashMap extends AbstractMap
} }
} }
int h = Math.abs (2 * System.identityHashCode (key) % table.length); int h = getHash (key);
int save = h; int save = h;
int del = -1; int del = -1;
while (true) while (true)
@ -288,7 +289,7 @@ public class IdentityHashMap extends AbstractMap
public Object remove (Object key) public Object remove (Object key)
{ {
int h = Math.abs (2 * System.identityHashCode (key) % table.length); int h = getHash (key);
int save = h; int save = h;
while (true) while (true)
{ {
@ -301,7 +302,7 @@ public class IdentityHashMap extends AbstractMap
return r; return r;
} }
h += 2; h += 2;
if (h > table.length) if (h >= table.length)
h = 0; h = 0;
if (h == save) if (h == save)
break; break;
@ -413,14 +414,20 @@ public class IdentityHashMap extends AbstractMap
} }
} }
// Compute the hash value we will use for an object.
private int getHash (Object o)
{
return 2 * Math.abs (System.identityHashCode (o) % (table.length / 2));
}
// Number of items in hash table. // Number of items in hash table.
private int size; private int size;
// The table itself. // The table itself.
private Object[] table; private Object[] table;
// This object is used to mark deleted items. // This object is used to mark deleted items.
private Object tombstone = new Object (); private static final Object tombstone = new Object ();
// This object is used to mark empty slots. We need this because // This object is used to mark empty slots. We need this because
// using null is ambiguous. // using null is ambiguous.
private Object emptyslot = new Object (); private static final Object emptyslot = new Object ();
} }