/*
* Copyright (C) 2007 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 tree.love.providers.downloads.util;
/**
* Map of {@code long} to {@code long}. Unlike a normal array of longs, there
* can be gaps in the indices. It is intended to be more memory efficient than
* using a {@code HashMap}, both because it avoids auto-boxing keys and values
* and its data structure doesn't rely on an extra entry object for each
* mapping.
* <p>
* Note that this container keeps its mappings in an array data structure, using
* a binary search to find keys. The implementation is not intended to be
* appropriate for data structures that may contain large numbers of items. It
* is generally slower than a traditional HashMap, since lookups require a
* binary search and adds and removes require inserting and deleting entries in
* the array. For containers holding up to hundreds of items, the performance
* difference is not significant, less than 50%.
* </p>
* <p>
* It is possible to iterate over the items in this container using
* {@link #keyAt(int)} and {@link #valueAt(int)}. Iterating over the keys using
* <code>keyAt(int)</code> with ascending values of the index will return the
* keys in ascending order, or the values corresponding to the keys in ascending
* order in the case of <code>valueAt(int)</code>.
* </p>
*
* @hide
*/
public class LongSparseLongArray implements Cloneable {
private long[] mKeys;
private long[] mValues;
private int mSize;
/**
* Creates a new SparseLongArray containing no mappings.
*/
public LongSparseLongArray() {
this(10);
}
/**
* Creates a new SparseLongArray containing no mappings that will not
* require any additional memory allocation to store the specified number of
* mappings. If you supply an initial capacity of 0, the sparse array will
* be initialized with a light-weight representation not requiring any
* additional array allocations.
*/
public LongSparseLongArray(int initialCapacity) {
if (initialCapacity == 0) {
mKeys = ContainerHelpers.EMPTY_LONGS;
mValues = ContainerHelpers.EMPTY_LONGS;
} else {
initialCapacity = ArrayUtils.idealLongArraySize(initialCapacity);
mKeys = new long[initialCapacity];
mValues = new long[initialCapacity];
}
mSize = 0;
}
@Override
public LongSparseLongArray clone() {
LongSparseLongArray clone = null;
try {
clone = (LongSparseLongArray) super.clone();
clone.mKeys = mKeys.clone();
clone.mValues = mValues.clone();
} catch (CloneNotSupportedException cnse) {
/* ignore */
}
return clone;
}
/**
* Gets the long mapped from the specified key, or <code>0</code> if no such
* mapping has been made.
*/
public long get(long key) {
return get(key, 0);
}
/**
* Gets the long mapped from the specified key, or the specified value if no
* such mapping has been made.
*/
public long get(long key, long valueIfKeyNotFound) {
int i = ContainerHelpers.binarySearch(mKeys, 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(long key) {
int i = ContainerHelpers.binarySearch(mKeys, 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(long key, long value) {
int i = ContainerHelpers.binarySearch(mKeys, mSize, key);
if (i >= 0) {
mValues[i] = value;
} else {
i = ~i;
if (mSize >= mKeys.length) {
growKeyAndValueArrays(mSize + 1);
}
if (mSize - i != 0) {
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 SparseLongArray
* stores.
* <p>
* The keys corresponding to indices in ascending order are guaranteed to be
* in ascending order, e.g., <code>keyAt(0)</code> will return the smallest
* key and <code>keyAt(size()-1)</code> will return the largest key.
* </p>
*/
public long 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 SparseLongArray
* stores.
* <p>
* The values corresponding to indices in ascending order are guaranteed to
* be associated with keys in ascending order, e.g., <code>valueAt(0)</code>
* will return the value associated with the smallest key and
* <code>valueAt(size()-1)</code> will return the value associated with the
* largest key.
* </p>
*/
public long 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(long key) {
return ContainerHelpers.binarySearch(mKeys, 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(long 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(long key, long value) {
if (mSize != 0 && key <= mKeys[mSize - 1]) {
put(key, value);
return;
}
int pos = mSize;
if (pos >= mKeys.length) {
growKeyAndValueArrays(pos + 1);
}
mKeys[pos] = key;
mValues[pos] = value;
mSize = pos + 1;
}
private void growKeyAndValueArrays(int minNeededSize) {
int n = ArrayUtils.idealLongArraySize(minNeededSize);
long[] nkeys = new long[n];
long[] nvalues = new long[n];
System.arraycopy(mKeys, 0, nkeys, 0, mKeys.length);
System.arraycopy(mValues, 0, nvalues, 0, mValues.length);
mKeys = nkeys;
mValues = nvalues;
}
/**
* {@inheritDoc}
* <p>
* This implementation composes a string by iterating over its mappings.
*/
@Override
public String toString() {
if (size() <= 0) {
return "{}";
}
StringBuilder buffer = new StringBuilder(mSize * 28);
buffer.append('{');
for (int i = 0; i < mSize; i++) {
if (i > 0) {
buffer.append(", ");
}
long key = keyAt(i);
buffer.append(key);
buffer.append('=');
long value = valueAt(i);
buffer.append(value);
}
buffer.append('}');
return buffer.toString();
}
}