core/java/android/util/LongSparseArray.java - platform/frameworks/base - Git at Google

 /*
  * Copyright (C) 2009 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;

 /**
  * SparseArray mapping longs to Objects.  Unlike a normal array of Objects,
  * there can be gaps in the indices.  It is intended to be more memory efficient
  * than using a HashMap to map Longs to Objects, both because it avoids
  * auto-boxing keys 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>To help with performance, the container includes an optimization when removing
  * keys: instead of compacting its array immediately, it leaves the removed entry marked
  * as deleted.  The entry can then be re-used for the same key, or compacted later in
  * a single garbage collection step of all removed entries.  This garbage collection will
  * need to be performed at any time the array needs to be grown or the the map size or
  * entry values are retrieved.</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 LongSparseArray<E> implements Cloneable {
     private static final Object DELETED = new Object();
     private boolean mGarbage = false;

     private long[] mKeys;
     private Object[] mValues;
     private int mSize;

     /**
      * Creates a new LongSparseArray containing no mappings.
      */
     public LongSparseArray() {
         this(10);
     }

     /**
      * Creates a new LongSparseArray 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 LongSparseArray(int initialCapacity) {
         if (initialCapacity == 0) {
             mKeys = EmptyArray.LONG;
             mValues = EmptyArray.OBJECT;
         } else {
             mKeys = ArrayUtils.newUnpaddedLongArray(initialCapacity);
             mValues = ArrayUtils.newUnpaddedObjectArray(initialCapacity);
         }
         mSize = 0;
     }

     @Override
     @SuppressWarnings("unchecked")
     public LongSparseArray<E> clone() {
         LongSparseArray<E> clone = null;
         try {
             clone = (LongSparseArray<E>) super.clone();
             clone.mKeys = mKeys.clone();
             clone.mValues = mValues.clone();
         } catch (CloneNotSupportedException cnse) {
             /* ignore */
         }
         return clone;
     }

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

     /**
      * Gets the Object mapped from the specified key, or the specified Object
      * if no such mapping has been made.
      */
     @SuppressWarnings("unchecked")
     public E get(long key, E valueIfKeyNotFound) {
         int i = ContainerHelpers.binarySearch(mKeys, 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(long key) {
         int i = ContainerHelpers.binarySearch(mKeys, mSize, key);

         if (i >= 0) {
             if (mValues[i] != DELETED) {
                 mValues[i] = DELETED;
                 mGarbage = true;
             }
         }
     }

     /**
      * Alias for {@link #delete(long)}.
      */
     public void remove(long key) {
         delete(key);
     }

     /**
      * Removes the mapping at the specified index.
      */
     public void removeAt(int index) {
         if (mValues[index] != DELETED) {
             mValues[index] = DELETED;
             mGarbage = true;
         }
     }

     private void gc() {
         // Log.e("SparseArray", "gc start with " + mSize);

         int n = mSize;
         int o = 0;
         long[] 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;
                     values[i] = null;
                 }

                 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(long key, E value) {
         int i = ContainerHelpers.binarySearch(mKeys, 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 = ~ContainerHelpers.binarySearch(mKeys, mSize, key);
             }

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

     /**
      * Returns the number of key-value mappings that this LongSparseArray
      * 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
      * LongSparseArray 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) {
         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
      * LongSparseArray 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>
      */
     @SuppressWarnings("unchecked")
     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
      * LongSparseArray 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(long key) {
         if (mGarbage) {
             gc();
         }

         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(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 LongSparseArray.
      */
     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(long key, E value) {
         if (mSize != 0 && key <= mKeys[mSize - 1]) {
             put(key, value);
             return;
         }

         if (mGarbage && mSize >= mKeys.length) {
             gc();
         }

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

     /**
      * {@inheritDoc}
      *
      * <p>This implementation composes a string by iterating over its mappings. If
      * this map contains itself as a value, the string "(this Map)"
      * will appear in its place.
      */
     @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('=');
             Object value = valueAt(i);
             if (value != this) {
                 buffer.append(value);
             } else {
                 buffer.append("(this Map)");
             }
         }
         buffer.append('}');
         return buffer.toString();
     }
 }
	/*
	* Copyright (C) 2009 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;

	/**
	* SparseArray mapping longs to Objects. Unlike a normal array of Objects,
	* there can be gaps in the indices. It is intended to be more memory efficient
	* than using a HashMap to map Longs to Objects, both because it avoids
	* auto-boxing keys 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>To help with performance, the container includes an optimization when removing
	* keys: instead of compacting its array immediately, it leaves the removed entry marked
	* as deleted. The entry can then be re-used for the same key, or compacted later in
	* a single garbage collection step of all removed entries. This garbage collection will
	* need to be performed at any time the array needs to be grown or the the map size or
	* entry values are retrieved.</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 LongSparseArray<E> implements Cloneable {
	private static final Object DELETED = new Object();
	private boolean mGarbage = false;

	private long[] mKeys;
	private Object[] mValues;
	private int mSize;

	/**
	* Creates a new LongSparseArray containing no mappings.
	*/
	public LongSparseArray() {
	this(10);
	}

	/**
	* Creates a new LongSparseArray 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 LongSparseArray(int initialCapacity) {
	if (initialCapacity == 0) {
	mKeys = EmptyArray.LONG;
	mValues = EmptyArray.OBJECT;
	} else {
	mKeys = ArrayUtils.newUnpaddedLongArray(initialCapacity);
	mValues = ArrayUtils.newUnpaddedObjectArray(initialCapacity);
	}
	mSize = 0;
	}

	@Override
	@SuppressWarnings("unchecked")
	public LongSparseArray<E> clone() {
	LongSparseArray<E> clone = null;
	try {
	clone = (LongSparseArray<E>) super.clone();
	clone.mKeys = mKeys.clone();
	clone.mValues = mValues.clone();
	} catch (CloneNotSupportedException cnse) {
	/* ignore */
	}
	return clone;
	}

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

	/**
	* Gets the Object mapped from the specified key, or the specified Object
	* if no such mapping has been made.
	*/
	@SuppressWarnings("unchecked")
	public E get(long key, E valueIfKeyNotFound) {
	int i = ContainerHelpers.binarySearch(mKeys, 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(long key) {
	int i = ContainerHelpers.binarySearch(mKeys, mSize, key);

	if (i >= 0) {
	if (mValues[i] != DELETED) {
	mValues[i] = DELETED;
	mGarbage = true;
	}
	}
	}

	/**
	* Alias for {@link #delete(long)}.
	*/
	public void remove(long key) {
	delete(key);
	}

	/**
	* Removes the mapping at the specified index.
	*/
	public void removeAt(int index) {
	if (mValues[index] != DELETED) {
	mValues[index] = DELETED;
	mGarbage = true;
	}
	}

	private void gc() {
	// Log.e("SparseArray", "gc start with " + mSize);

	int n = mSize;
	int o = 0;
	long[] 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;
	values[i] = null;
	}

	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(long key, E value) {
	int i = ContainerHelpers.binarySearch(mKeys, 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 = ~ContainerHelpers.binarySearch(mKeys, mSize, key);
	}

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

	/**
	* Returns the number of key-value mappings that this LongSparseArray
	* 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
	* LongSparseArray 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) {
	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
	* LongSparseArray 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>
	*/
	@SuppressWarnings("unchecked")
	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
	* LongSparseArray 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(long key) {
	if (mGarbage) {
	gc();
	}

	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(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 LongSparseArray.
	*/
	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(long key, E value) {
	if (mSize != 0 && key <= mKeys[mSize - 1]) {
	put(key, value);
	return;
	}

	if (mGarbage && mSize >= mKeys.length) {
	gc();
	}

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

	/**
	* {@inheritDoc}
	*
	* <p>This implementation composes a string by iterating over its mappings. If
	* this map contains itself as a value, the string "(this Map)"
	* will appear in its place.
	*/
	@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('=');
	Object value = valueAt(i);
	if (value != this) {
	buffer.append(value);
	} else {
	buffer.append("(this Map)");
	}
	}
	buffer.append('}');
	return buffer.toString();
	}
	}