/*
* Copyright (C) 2006 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package android.util;
import com.android.internal.util.ArrayUtils;
/**
* SparseArrays map integers to Objects. Unlike a normal array of Objects,
* there can be gaps in the indices. It is intended to be more efficient
* than using a HashMap to map Integers to Objects.
*/
public class SparseArray<E> {
private static final Object DELETED = new Object();
private boolean mGarbage = false;
/**
* Creates a new SparseArray containing no mappings.
*/
public SparseArray() {
this(10);
}
/**
* Creates a new SparseArray containing no mappings that will not
* require any additional memory allocation to store the specified
* number of mappings.
*/
public SparseArray(int initialCapacity) {
initialCapacity = ArrayUtils.idealIntArraySize(initialCapacity);
mKeys = new int[initialCapacity];
mValues = new Object[initialCapacity];
mSize = 0;
}
/**
* Gets the Object mapped from the specified key, or <code>null</code>
* if no such mapping has been made.
*/
public E get(int key) {
return get(key, null);
}
/**
* Gets the Object mapped from the specified key, or the specified Object
* if no such mapping has been made.
*/
public E get(int key, E valueIfKeyNotFound) {
int i = binarySearch(mKeys, 0, mSize, key);
if (i < 0 || mValues[i] == DELETED) {
return valueIfKeyNotFound;
} else {
return (E) mValues[i];
}
}
/**
* Removes the mapping from the specified key, if there was any.
*/
public void delete(int key) {
int i = binarySearch(mKeys, 0, mSize, key);
if (i >= 0) {
if (mValues[i] != DELETED) {
mValues[i] = DELETED;
mGarbage = true;
}
}
}
/**
* Alias for {@link #delete(int)}.
*/
public void remove(int key) {
delete(key);
}
private void gc() {
// Log.e("SparseArray", "gc start with " + mSize);
int n = mSize;
int o = 0;
int[] keys = mKeys;
Object[] values = mValues;
for (int i = 0; i < n; i++) {
Object val = values[i];
if (val != DELETED) {
if (i != o) {
keys[o] = keys[i];
values[o] = val;
}
o++;
}
}
mGarbage = false;
mSize = o;
// Log.e("SparseArray", "gc end with " + mSize);
}
/**
* Adds a mapping from the specified key to the specified value,
* replacing the previous mapping from the specified key if there
* was one.
*/
public void put(int key, E value) {
int i = binarySearch(mKeys, 0, mSize, key);
if (i >= 0) {
mValues[i] = value;
} else {
i = ~i;
if (i < mSize && mValues[i] == DELETED) {
mKeys[i] = key;
mValues[i] = value;
return;
}
if (mGarbage && mSize >= mKeys.length) {
gc();
// Search again because indices may have changed.
i = ~binarySearch(mKeys, 0, mSize, key);
}
if (mSize >= mKeys.length) {
int n = ArrayUtils.idealIntArraySize(mSize + 1);
int[] nkeys = new int[n];
Object[] nvalues = new Object[n];
// Log.e("SparseArray", "grow " + mKeys.length + " to " + n);
System.arraycopy(mKeys, 0, nkeys, 0, mKeys.length);
System.arraycopy(mValues, 0, nvalues, 0, mValues.length);
mKeys = nkeys;
mValues = nvalues;
}
if (mSize - i != 0) {
// Log.e("SparseArray", "move " + (mSize - i));
System.arraycopy(mKeys, i, mKeys, i + 1, mSize - i);
System.arraycopy(mValues, i, mValues, i + 1, mSize - i);
}
mKeys[i] = key;
mValues[i] = value;
mSize++;
}
}
/**
* Returns the number of key-value mappings that this SparseArray
* currently stores.
*/
public int size() {
if (mGarbage) {
gc();
}
return mSize;
}
/**
* Given an index in the range <code>0...size()-1</code>, returns
* the key from the <code>index</code>th key-value mapping that this
* SparseArray stores.
*/
public int keyAt(int index) {
if (mGarbage) {
gc();
}
return mKeys[index];
}
/**
* Given an index in the range <code>0...size()-1</code>, returns
* the value from the <code>index</code>th key-value mapping that this
* SparseArray stores.
*/
public E valueAt(int index) {
if (mGarbage) {
gc();
}
return (E) mValues[index];
}
/**
* Given an index in the range <code>0...size()-1</code>, sets a new
* value for the <code>index</code>th key-value mapping that this
* SparseArray stores.
*/
public void setValueAt(int index, E value) {
if (mGarbage) {
gc();
}
mValues[index] = value;
}
/**
* Returns the index for which {@link #keyAt} would return the
* specified key, or a negative number if the specified
* key is not mapped.
*/
public int indexOfKey(int key) {
if (mGarbage) {
gc();
}
return binarySearch(mKeys, 0, mSize, key);
}
/**
* Returns an index for which {@link #valueAt} would return the
* specified key, or a negative number if no keys map to the
* specified value.
* Beware that this is a linear search, unlike lookups by key,
* and that multiple keys can map to the same value and this will
* find only one of them.
*/
public int indexOfValue(E value) {
if (mGarbage) {
gc();
}
for (int i = 0; i < mSize; i++)
if (mValues[i] == value)
return i;
return -1;
}
/**
* Removes all key-value mappings from this SparseArray.
*/
public void clear() {
int n = mSize;
Object[] values = mValues;
for (int i = 0; i < n; i++) {
values[i] = null;
}
mSize = 0;
mGarbage = false;
}
/**
* Puts a key/value pair into the array, optimizing for the case where
* the key is greater than all existing keys in the array.
*/
public void append(int key, E value) {
if (mSize != 0 && key <= mKeys[mSize - 1]) {
put(key, value);
return;
}
if (mGarbage && mSize >= mKeys.length) {
gc();
}
int pos = mSize;
if (pos >= mKeys.length) {
int n = ArrayUtils.idealIntArraySize(pos + 1);
int[] nkeys = new int[n];
Object[] nvalues = new Object[n];
// Log.e("SparseArray", "grow " + mKeys.length + " to " + n);
System.arraycopy(mKeys, 0, nkeys, 0, mKeys.length);
System.arraycopy(mValues, 0, nvalues, 0, mValues.length);
mKeys = nkeys;
mValues = nvalues;
}
mKeys[pos] = key;
mValues[pos] = value;
mSize = pos + 1;
}
private static int binarySearch(int[] a, int start, int len, int key) {
int high = start + len, low = start - 1, guess;
while (high - low > 1) {
guess = (high + low) / 2;
if (a[guess] < key)
low = guess;
else
high = guess;
}
if (high == start + len)
return ~(start + len);
else if (a[high] == key)
return high;
else
return ~high;
}
private void checkIntegrity() {
for (int i = 1; i < mSize; i++) {
if (mKeys[i] <= mKeys[i - 1]) {
for (int j = 0; j < mSize; j++) {
Log.e("FAIL", j + ": " + mKeys[j] + " -> " + mValues[j]);
}
throw new RuntimeException();
}
}
}
private int[] mKeys;
private Object[] mValues;
private int mSize;
}
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