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ArrayBackedFMap: use linear instead of binary search

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as it's simpler, shorter and JMH shows that it's mostly faster
This commit is contained in:
peter
2017-05-30 13:03:13 +02:00
parent 7eeb47d238
commit 6d85a64361
1 changed files with 28 additions and 33 deletions
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platform/util/src/com/intellij/util/keyFMap/ArrayBackedFMap.java
+28 -33
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@@ -19,8 +19,6 @@ import com.intellij.openapi.util.Key;
import com.intellij.util.ArrayUtil;
import org.jetbrains.annotations.NotNull;
import java.util.Arrays;
public class ArrayBackedFMap implements KeyFMap {
static final int ARRAY_THRESHOLD = 8;
// Invariant: keys are always sorted
@@ -35,9 +33,8 @@ public class ArrayBackedFMap implements KeyFMap {
@NotNull
@Override
public <V> KeyFMap plus(@NotNull Key<V> key, @NotNull V value) {
int oldSize = size();
int keyCode = key.hashCode();
int keyPos = Arrays.binarySearch(keys, keyCode);
int keyPos = indexOf(keyCode);
if (keyPos >= 0) {
if (values[keyPos] == value) {
return this;
@@ -47,7 +44,7 @@ public class ArrayBackedFMap implements KeyFMap {
// Can reuse keys as it is never mutated
return new ArrayBackedFMap(keys, newValues);
}
if (oldSize < ARRAY_THRESHOLD) {
if (size() < ARRAY_THRESHOLD) {
int[] newKeys = ArrayUtil.insert(keys, -keyPos - 1, keyCode);
Object[] newValues = ArrayUtil.insert(values, -keyPos - 1, value);
return new ArrayBackedFMap(newKeys, newValues);
@@ -59,44 +56,42 @@ public class ArrayBackedFMap implements KeyFMap {
return keys.length;
}
private int indexOf(int keyCode) {
for (int i = 0; i < keys.length; i++) {
int key = keys[i];
if (key == keyCode) return i;
if (key > keyCode) return -i-1;
}
return -keys.length - 1;
}
@NotNull
@Override
public KeyFMap minus(@NotNull Key<?> key) {
int oldSize = size();
int keyCode = key.hashCode();
for (int i = 0; i< oldSize; i++) {
int oldKey = keys[i];
if (keyCode == oldKey) {
if (oldSize == 3) {
int i1 = (2-i)/2;
int i2 = 3 - (i+2)/2;
Key<Object> key1 = Key.getKeyByIndex(keys[i1]);
Key<Object> key2 = Key.getKeyByIndex(keys[i2]);
if (key1 == null && key2 == null) return EMPTY_MAP;
if (key1 == null) return new OneElementFMap(key2, values[i2]);
if (key2 == null) return new OneElementFMap(key1, values[i1]);
return new PairElementsFMap(key1, values[i1], key2, values[i2]);
}
int[] newKeys = ArrayUtil.remove(keys, i);
Object[] newValues = ArrayUtil.remove(values, i, ArrayUtil.OBJECT_ARRAY_FACTORY);
return new ArrayBackedFMap(newKeys, newValues);
int i = indexOf(key.hashCode());
if (i >= 0) {
if (size() == 3) {
int i1 = (2-i)/2;
int i2 = 3 - (i+2)/2;
Key<Object> key1 = Key.getKeyByIndex(keys[i1]);
Key<Object> key2 = Key.getKeyByIndex(keys[i2]);
if (key1 == null && key2 == null) return EMPTY_MAP;
if (key1 == null) return new OneElementFMap(key2, values[i2]);
if (key2 == null) return new OneElementFMap(key1, values[i1]);
return new PairElementsFMap(key1, values[i1], key2, values[i2]);
}
int[] newKeys = ArrayUtil.remove(keys, i);
Object[] newValues = ArrayUtil.remove(values, i, ArrayUtil.OBJECT_ARRAY_FACTORY);
return new ArrayBackedFMap(newKeys, newValues);
}
return this;
}
@Override
public <V> V get(@NotNull Key<V> key) {
int oldSize = size();
int keyCode = key.hashCode();
for (int i = 0; i < oldSize; i++) {
int oldKey = keys[i];
if (keyCode == oldKey) {
//noinspection unchecked
return (V)values[i];
}
}
return null;
int i = indexOf(key.hashCode());
//noinspection unchecked
return i < 0 ? null : (V) values[i];
}
@Override