/*
* 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;
/**
* SparseIntArrays map integers to integers. Unlike a normal array of integers,
* there can be gaps in the indices. It is intended to be more efficient
* than using a HashMap to map Integers to Integers.
*/
public class SparseIntArray {
/**
* Creates a new SparseIntArray containing no mappings.
*/
public SparseIntArray() {
this(10);
}
/**
* Creates a new SparseIntArray containing no mappings that will not
* require any additional memory allocation to store the specified
* number of mappings.
*/
public SparseIntArray(int initialCapacity) {
initialCapacity = ArrayUtils.idealIntArraySize(initialCapacity);
mKeys = new int[initialCapacity];
mValues = new int[initialCapacity];
mSize = 0;
}
/**
* Gets the int mapped from the specified key, or <code>0</code>
* if no such mapping has been made.
*/
public int get(int key) {
return get(key, 0);
}
/**
* Gets the int mapped from the specified key, or the specified value
* if no such mapping has been made.
*/
public int get(int key, int valueIfKeyNotFound) {
int i = binarySearch(mKeys, 0, mSize, key);
if (i < 0) {
return valueIfKeyNotFound;
} else {
return 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) {
removeAt(i);
}
}
/**
* Removes the mapping at the given index.
*/
public void removeAt(int index) {
System.arraycopy(mKeys, index + 1, mKeys, index, mSize - (index + 1));
System.arraycopy(mValues, index + 1, mValues, index, mSize - (index + 1));
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, int value) {
int i = binarySearch(mKeys, 0, mSize, key);
if (i >= 0) {
mValues[i] = value;
} else {
i = ~i;
if (mSize >= mKeys.length) {
int n = ArrayUtils.idealIntArraySize(mSize + 1);
int[] nkeys = new int[n];
int[] nvalues = new int[n];
// Log.e("SparseIntArray", "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("SparseIntArray", "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 SparseIntArray
* currently stores.
*/
public int size() {
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
* SparseIntArray stores.
*/
public int keyAt(int index) {
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
* SparseIntArray stores.
*/
public int valueAt(int index) {
return mValues[index];
}
/**
* 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) {
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(int value) {
for (int i = 0; i < mSize; i++)
if (mValues[i] == value)
return i;
return -1;
}
/**
* Removes all key-value mappings from this SparseIntArray.
*/
public void clear() {
mSize = 0;
}
/**
* 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, int value) {
if (mSize != 0 && key <= mKeys[mSize - 1]) {
put(key, value);
return;
}
int pos = mSize;
if (pos >= mKeys.length) {
int n = ArrayUtils.idealIntArraySize(pos + 1);
int[] nkeys = new int[n];
int[] nvalues = new int[n];
// Log.e("SparseIntArray", "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 int[] mValues;
private int mSize;
}
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