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8315454: Add a way to create an immutable snapshot of a BitSet
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Co-authored-by: Claes Redestad <redestad@openjdk.org>
Reviewed-by: redestad
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minborg and cl4es committed Sep 5, 2023
1 parent 9def453 commit f292268
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Showing 3 changed files with 193 additions and 13 deletions.
29 changes: 16 additions & 13 deletions src/java.base/share/classes/java/net/URLEncoder.java
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Expand Up @@ -32,7 +32,9 @@
import java.nio.charset.UnsupportedCharsetException ;
import java.util.BitSet;
import java.util.Objects;
import java.util.function.IntPredicate;

import jdk.internal.util.ImmutableBitSetPredicate;
import jdk.internal.util.StaticProperty;

/**
Expand Down Expand Up @@ -78,7 +80,7 @@
* @since 1.0
*/
public class URLEncoder {
private static final BitSet DONT_NEED_ENCODING;
private static final IntPredicate DONT_NEED_ENCODING;
private static final int CASE_DIFF = ('a' - 'A');
private static final String DEFAULT_ENCODING_NAME;

Expand Down Expand Up @@ -120,17 +122,18 @@ public class URLEncoder {
*
*/

DONT_NEED_ENCODING = new BitSet(128);

DONT_NEED_ENCODING.set('a', 'z' + 1);
DONT_NEED_ENCODING.set('A', 'Z' + 1);
DONT_NEED_ENCODING.set('0', '9' + 1);
DONT_NEED_ENCODING.set(' '); /* encoding a space to a + is done
var bitSet = new BitSet(128);
bitSet.set('a', 'z' + 1);
bitSet.set('A', 'Z' + 1);
bitSet.set('0', '9' + 1);
bitSet.set(' '); /* encoding a space to a + is done
* in the encode() method */
DONT_NEED_ENCODING.set('-');
DONT_NEED_ENCODING.set('_');
DONT_NEED_ENCODING.set('.');
DONT_NEED_ENCODING.set('*');
bitSet.set('-');
bitSet.set('_');
bitSet.set('.');
bitSet.set('*');

DONT_NEED_ENCODING = ImmutableBitSetPredicate.of(bitSet);

DEFAULT_ENCODING_NAME = StaticProperty.fileEncoding();
}
Expand Down Expand Up @@ -226,7 +229,7 @@ public static String encode(String s, Charset charset) {
for (int i = 0; i < s.length();) {
int c = s.charAt(i);
//System.out.println("Examining character: " + c);
if (DONT_NEED_ENCODING.get(c)) {
if (DONT_NEED_ENCODING.test(c)) {
if (c == ' ') {
c = '+';
needToChange = true;
Expand Down Expand Up @@ -269,7 +272,7 @@ public static String encode(String s, Charset charset) {
}
}
i++;
} while (i < s.length() && !DONT_NEED_ENCODING.get((c = s.charAt(i))));
} while (i < s.length() && !DONT_NEED_ENCODING.test((c = s.charAt(i))));

charArrayWriter.flush();
String str = charArrayWriter.toString();
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Original file line number Diff line number Diff line change
@@ -0,0 +1,85 @@
/*
* Copyright (c) 2023, 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
* or visit www.oracle.com if you need additional information or have any
* questions.
*/

package jdk.internal.util;

import jdk.internal.ValueBased;
import jdk.internal.vm.annotation.Stable;

import java.util.BitSet;
import java.util.function.IntPredicate;

/**
* Class for working with immutable BitSets.
*/
@ValueBased
public class ImmutableBitSetPredicate implements IntPredicate {

@Stable
private final long[] words;

private ImmutableBitSetPredicate(BitSet original) {
// If this class is made public, we need to do
// a defensive array copy as certain BitSet implementations
// may return a shared array. The spec says the array should be _new_ though but
// the consequences might be unspecified for a malicious BitSet.
this.words = original.toLongArray();
}

@Override
public boolean test(int bitIndex) {
if (bitIndex < 0)
throw new IndexOutOfBoundsException("bitIndex < 0: " + bitIndex);

int wordIndex = wordIndex(bitIndex);
return (wordIndex < words.length)
&& ((words[wordIndex] & (1L << bitIndex)) != 0);
}

/**
* Given a bit index, return word index containing it.
*/
private static int wordIndex(int bitIndex) {
return bitIndex >> 6;
}

/**
* {@return a new {@link IntPredicate } representing the {@link BitSet#get(int)} method applied
* on an immutable snapshot of the current state of this BitSet}.
* <p>
* If the returned predicate is invoked with a {@code bitIndex} that is negative, the predicate
* will throw an IndexOutOfBoundsException just as the {@link BitSet#get(int)} method would.
* <p>
* Returned predicates are threadsafe and can be used without external synchronisation.
*
* @implNote The method is free to return a {@link ValueBased} implementation.
*
* @since 22
*/
public static IntPredicate of(BitSet original) {
return new ImmutableBitSetPredicate(original);
}

}
92 changes: 92 additions & 0 deletions test/jdk/java/util/BitSet/ImmutableBitSet.java
Original file line number Diff line number Diff line change
@@ -0,0 +1,92 @@
/*
* Copyright (c) 2023, 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.
*
* 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
* or visit www.oracle.com if you need additional information or have any
* questions.
*/

/**
* @test
* @summary Basic tests of immutable BitSets
* @modules java.base/jdk.internal.util
* @run junit ImmutableBitSet
*/

import jdk.internal.util.ImmutableBitSetPredicate;
import org.junit.jupiter.api.Test;

import java.util.BitSet;
import java.util.Random;
import java.util.function.IntPredicate;

import static org.junit.jupiter.api.Assertions.*;

public class ImmutableBitSet {

@Test
void empty() {
BitSet bs = new BitSet();
IntPredicate ibs = ImmutableBitSetPredicate.of(bs);
test(bs, ibs);
}

@Test
void negativeIndex() {
BitSet bs = new BitSet();
IntPredicate ibs = ImmutableBitSetPredicate.of(bs);
assertThrows(IndexOutOfBoundsException.class, () -> {
ibs.test(-1);
});
}

@Test
void basic() {
BitSet bs = createReference(147);
IntPredicate ibs = ImmutableBitSetPredicate.of(bs);
test(bs, ibs);
}

@Test
void clearedAtTheTail() {
for (int i = Long.BYTES - 1; i < Long.BYTES + 2; i++) {
BitSet bs = createReference(i);
for (int j = bs.length() - 1; j > Long.BYTES - 1; j++) {
bs.clear(j);
}
IntPredicate ibs = ImmutableBitSetPredicate.of(bs);
test(bs, ibs);
}
}

static void test(BitSet expected, IntPredicate actual) {
for (int i = 0; i < expected.length() + 17; i++) {
assertEquals(expected.get(i), actual.test(i), "at index " + i);
}
}

private static BitSet createReference(int length) {
BitSet result = new BitSet();
Random random = new Random(length);
for (int i = 0; i < length; i++) {
result.set(i, random.nextBoolean());
}
return result;
}

}

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