/*
 * 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;
import com.android.internal.util.GrowingArrayUtils;

import libcore.util.EmptyArray;

SparseBooleanArrays map integers to booleans.
Unlike a normal array of booleans
there can be gaps in the indices.  It is intended to be more memory efficient
than using a HashMap to map Integers to Booleans, 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).
/**
 * SparseBooleanArrays map integers to booleans.
 * Unlike a normal array of booleans
 * there can be gaps in the indices.  It is intended to be more memory efficient
 * than using a HashMap to map Integers to Booleans, 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 SparseBooleanArray implements Cloneable {
    
Creates a new SparseBooleanArray containing no mappings.
/**
     * Creates a new SparseBooleanArray containing no mappings.
     */
    public SparseBooleanArray() {
        this(10);
    }

    
Creates a new SparseBooleanArray 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 SparseBooleanArray 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 SparseBooleanArray(int initialCapacity) {
        if (initialCapacity == 0) {
            mKeys = EmptyArray.INT;
            mValues = EmptyArray.BOOLEAN;
        } else {
            mKeys = ArrayUtils.newUnpaddedIntArray(initialCapacity);
            mValues = new boolean[mKeys.length];
        }
        mSize = 0;
    }

    @Override
    public SparseBooleanArray clone() {
        SparseBooleanArray clone = null;
        try {
            clone = (SparseBooleanArray) super.clone();
            clone.mKeys = mKeys.clone();
            clone.mValues = mValues.clone();
        } catch (CloneNotSupportedException cnse) {
            /* ignore */
        }
        return clone;
    }

    
Gets the boolean mapped from the specified key, or false
if no such mapping has been made.
/**
     * Gets the boolean mapped from the specified key, or <code>false</code>
     * if no such mapping has been made.
     */
    public boolean get(int key) {
        return get(key, false);
    }

    
Gets the boolean mapped from the specified key, or the specified value
if no such mapping has been made.
/**
     * Gets the boolean mapped from the specified key, or the specified value
     * if no such mapping has been made.
     */
    public boolean get(int key, boolean 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) {
            System.arraycopy(mKeys, i + 1, mKeys, i, mSize - (i + 1));
            System.arraycopy(mValues, i + 1, mValues, i, mSize - (i + 1));
            mSize--;
        }
    }

    
Removes the mapping at the specified index.
 For indices outside of the range 0...size()-1, the behavior is undefined. /**
     * Removes the mapping at the specified index.
     * <p>
     * For indices outside of the range {@code 0...size()-1}, the behavior is undefined.
     */
    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, boolean 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 SparseBooleanArray
currently stores.
/**
     * Returns the number of key-value mappings that this SparseBooleanArray
     * 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
SparseBooleanArray 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
     * SparseBooleanArray 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
SparseBooleanArray 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
     * SparseBooleanArray 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 boolean valueAt(int index) {
        return mValues[index];
    }

    
@hide
/** @hide */
    public void setValueAt(int index, boolean value) {
        mValues[index] = value;
    }

    
@hide
/** @hide */
    public void setKeyAt(int index, int key) {
        mKeys[index] = key;
    }

    
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(boolean value) {
        for (int i = 0; i < mSize; i++)
            if (mValues[i] == value)
                return i;

        return -1;
    }

    
Removes all key-value mappings from this SparseBooleanArray.
/**
     * Removes all key-value mappings from this SparseBooleanArray.
     */
    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, boolean 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++;
    }

    @Override
    public int hashCode() {
        int hashCode = mSize;
        for (int i = 0; i < mSize; i++) {
            hashCode = 31 * hashCode + mKeys[i] | (mValues[i] ? 1 : 0);
        }
        return hashCode;
    }

    @Override
    public boolean equals(Object that) {
      if (this == that) {
          return true;
      }

      if (!(that instanceof SparseBooleanArray)) {
          return false;
      }

      SparseBooleanArray other = (SparseBooleanArray) that;
      if (mSize != other.mSize) {
          return false;
      }

      for (int i = 0; i < mSize; i++) {
          if (mKeys[i] != other.mKeys[i]) {
              return false;
          }
          if (mValues[i] != other.mValues[i]) {
              return false;
          }
      }
      return true;
    }

    
{@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('=');
            boolean value = valueAt(i);
            buffer.append(value);
        }
        buffer.append('}');
        return buffer.toString();
    }

    private int[] mKeys;
    private boolean[] mValues;
    private int mSize;
}