/*
 * Copyright (C) 2011 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;
import com.android.internal.util.GrowingArrayUtils;

import libcore.util.EmptyArray;

SparseLongArrays map integers to longs.  Unlike a normal array of longs,
there can be gaps in the indices.  It is intended to be more memory efficient
than using a HashMap to map Integers to Longs, both because it avoids
auto-boxing keys and values and its data structure doesn't rely on an extra entry object
for each mapping.
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%.
It is possible to iterate over the items in this container using keyAt(int) and valueAt(int). Iterating over the keys using keyAt(int) 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 valueAt(int).
/**
 * SparseLongArrays map integers to longs.  Unlike a normal array of longs,
 * there can be gaps in the indices.  It is intended to be more memory efficient
 * than using a HashMap to map Integers to Longs, 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>
 */
public class SparseLongArray implements Cloneable {
    private int[] mKeys;
    private long[] mValues;
    private int mSize;

    
Creates a new SparseLongArray containing no mappings.
/**
     * Creates a new SparseLongArray containing no mappings.
     */
    public SparseLongArray() {
        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.
/**
     * 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 SparseLongArray(int initialCapacity) {
        if (initialCapacity == 0) {
            mKeys = EmptyArray.INT;
            mValues = EmptyArray.LONG;
        } else {
            mValues = ArrayUtils.newUnpaddedLongArray(initialCapacity);
            mKeys = new int[mValues.length];
        }
        mSize = 0;
    }

    @Override
    public SparseLongArray clone() {
        SparseLongArray clone = null;
        try {
            clone = (SparseLongArray) 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 0
if no such mapping has been made.
/**
     * Gets the long mapped from the specified key, or <code>0</code>
     * if no such mapping has been made.
     */
    public long get(int key) {
        return get(key, 0);
    }

    
Gets the long mapped from the specified key, or the specified value
if no such mapping has been made.
/**
     * Gets the long mapped from the specified key, or the specified value
     * if no such mapping has been made.
     */
    public long get(int 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.
/**
     * Removes the mapping from the specified key, if there was any.
     */
    public void delete(int key) {
        int i = ContainerHelpers.binarySearch(mKeys, mSize, key);

        if (i >= 0) {
            removeAt(i);
        }
    }

    
Params:
index – Index to begin at
size – Number of mappings to remove
For indices outside of the range 0...size()-1,
the behavior is undefined.
@hide

Remove a range of mappings as a batch./**
     * @hide
     * Remove a range of mappings as a batch.
     *
     * @param index Index to begin at
     * @param size Number of mappings to remove
     *
     * <p>For indices outside of the range <code>0...size()-1</code>,
     * the behavior is undefined.</p>
     */
    public void removeAtRange(int index, int size) {
        size = Math.min(size, mSize - index);
        System.arraycopy(mKeys, index + size, mKeys, index, mSize - (index + size));
        System.arraycopy(mValues, index + size, mValues, index, mSize - (index + size));
        mSize -= size;
    }

    
Removes the mapping at the given index.
/**
     * 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.
/**
     * 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, long value) {
        int i = ContainerHelpers.binarySearch(mKeys, mSize, key);

        if (i >= 0) {
            mValues[i] = value;
        } else {
            i = ~i;

            mKeys = GrowingArrayUtils.insert(mKeys, mSize, i, key);
            mValues = GrowingArrayUtils.insert(mValues, mSize, i, value);
            mSize++;
        }
    }

    
Returns the number of key-value mappings that this SparseIntArray
currently stores.
/**
     * Returns the number of key-value mappings that this SparseIntArray
     * currently stores.
     */
    public int size() {
        return mSize;
    }

    
Given an index in the range 0...size()-1, returns
the key from the indexth key-value mapping that this
SparseLongArray stores.
The keys corresponding to indices in ascending order are guaranteed to
be in ascending order, e.g., keyAt(0) will return the
smallest key and keyAt(size()-1) will return the largest
key.
/**
     * 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 int keyAt(int index) {
        return mKeys[index];
    }

    
Given an index in the range 0...size()-1, returns
the value from the indexth key-value mapping that this
SparseLongArray stores.
The values corresponding to indices in ascending order are guaranteed
to be associated with keys in ascending order, e.g.,
valueAt(0) will return the value associated with the
smallest key and valueAt(size()-1) will return the value
associated with the largest key.
/**
     * 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 keyAt would return the specified key, or a negative number if the specified key is not mapped. /**
     * 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 ContainerHelpers.binarySearch(mKeys, mSize, key);
    }

    
Returns an index for which 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. /**
     * 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.
/**
     * 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.
/**
     * 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, long value) {
        if (mSize != 0 && key <= mKeys[mSize - 1]) {
            put(key, value);
            return;
        }

        mKeys = GrowingArrayUtils.append(mKeys, mSize, key);
        mValues = GrowingArrayUtils.append(mValues, mSize, value);
        mSize++;
    }

    
{@inheritDoc}
This implementation composes a string by iterating over its mappings.
/**
     * {@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(", ");
            }
            int key = keyAt(i);
            buffer.append(key);
            buffer.append('=');
            long value = valueAt(i);
            buffer.append(value);
        }
        buffer.append('}');
        return buffer.toString();
    }
}