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Merge "Add ObjectId getByte for random access"

This commit is contained in:
Chris Aniszczyk 2010-11-10 18:00:36 -05:00 committed by Code Review
parent 453b620e62 b22a4e8488
commit 9e28cf2fa3
2 changed files with 63 additions and 3 deletions
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16
org.eclipse.jgit.test/tst/org/eclipse/jgit/lib/T0001_ObjectId.java → org.eclipse.jgit.test/tst/org/eclipse/jgit/lib/ObjectIdTest.java
View File

@ -47,7 +47,7 @@
import junit.framework.TestCase;
public class T0001_ObjectId extends TestCase {
public class ObjectIdTest extends TestCase {
public void test001_toString() {
final String x = "def4c620bc3713bb1bb26b808ec9312548e73946";
final ObjectId oid = ObjectId.fromString(x);
@ -108,4 +108,18 @@ public void test011_toString() {
final ObjectId oid = ObjectId.fromString(x);
assertEquals(x.toLowerCase(), oid.name());
}
public void testGetByte() {
byte[] raw = new byte[20];
for (int i = 0; i < 20; i++)
raw[i] = (byte) (0xa0 + i);
ObjectId id = ObjectId.fromRaw(raw);
assertEquals(raw[0] & 0xff, id.getFirstByte());
assertEquals(raw[0] & 0xff, id.getByte(0));
assertEquals(raw[1] & 0xff, id.getByte(1));
for (int i = 2; i < 20; i++)
assertEquals("index " + i, raw[i] & 0xff, id.getByte(i));
}
}

50
org.eclipse.jgit/src/org/eclipse/jgit/lib/AnyObjectId.java
View File

@ -97,14 +97,60 @@ public static boolean equals(final AnyObjectId firstObjectId,
int w5;
/**
* For ObjectIdMap
* Get the first 8 bits of the ObjectId.
*
* @return a discriminator usable for a fan-out style map
* This is a faster version of {@code getByte(0)}.
*
* @return a discriminator usable for a fan-out style map. Returned values
* are unsigned and thus are in the range [0,255] rather than the
* signed byte range of [-128, 127].
*/
public final int getFirstByte() {
return w1 >>> 24;
}
/**
* Get any byte from the ObjectId.
*
* Callers hard-coding {@code getByte(0)} should instead use the much faster
* special case variant {@link #getFirstByte()}.
*
* @param index
* index of the byte to obtain from the raw form of the ObjectId.
* Must be in range [0, {@link Constants#OBJECT_ID_LENGTH}).
* @return the value of the requested byte at {@code index}. Returned values
* are unsigned and thus are in the range [0,255] rather than the
* signed byte range of [-128, 127].
* @throws ArrayIndexOutOfBoundsException
* {@code index} is less than 0, equal to
* {@link Constants#OBJECT_ID_LENGTH}, or greater than
* {@link Constants#OBJECT_ID_LENGTH}.
*/
public final int getByte(int index) {
int w;
switch (index >> 2) {
case 0:
w = w1;
break;
case 1:
w = w2;
break;
case 2:
w = w3;
break;
case 3:
w = w4;
break;
case 4:
w = w5;
break;
default:
throw new ArrayIndexOutOfBoundsException(index);
}
return (w >>> (8 * (3 - (index & 3)))) & 0xff;
}
/**
* Compare this ObjectId to another and obtain a sort ordering.
*