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

 /*
  * 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;

 /**
  * SparseArrays map integers to Objects.  Unlike a normal array of Objects,
  * there can be gaps in the indices.  It is intended to be more efficient
  * than using a HashMap to map Integers to Objects.
  */
 public class SparseArray<E> implements Cloneable {
     private static final Object DELETED = new Object();
     private boolean mGarbage = false;

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

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

     /**
      * Creates a new SparseArray containing no mappings that will not
      * require any additional memory allocation to store the specified
      * number of mappings.
      */
     public SparseArray(int initialCapacity) {
         initialCapacity = ArrayUtils.idealIntArraySize(initialCapacity);

         mKeys = new int[initialCapacity];
         mValues = new Object[initialCapacity];
         mSize = 0;
     }

     @Override
     @SuppressWarnings("unchecked")
     public SparseArray<E> clone() {
         SparseArray<E> clone = null;
         try {
             clone = (SparseArray<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(int 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(int key, E valueIfKeyNotFound) {
         int i = binarySearch(mKeys, 0, 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(int key) {
         int i = binarySearch(mKeys, 0, mSize, key);

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

     /**
      * Alias for {@link #delete(int)}.
      */
     public void remove(int 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;
         int[] 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(int key, E value) {
         int i = binarySearch(mKeys, 0, 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 = ~binarySearch(mKeys, 0, mSize, key);
             }

             if (mSize >= mKeys.length) {
                 int n = ArrayUtils.idealIntArraySize(mSize + 1);

                 int[] nkeys = new int[n];
                 Object[] nvalues = new Object[n];

                 // Log.e("SparseArray", "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("SparseArray", "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 SparseArray
      * 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
      * SparseArray stores.
      */
     public int 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
      * SparseArray stores.
      */
     @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
      * SparseArray 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(int key) {
         if (mGarbage) {
             gc();
         }

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

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

         int pos = mSize;
         if (pos >= mKeys.length) {
             int n = ArrayUtils.idealIntArraySize(pos + 1);

             int[] nkeys = new int[n];
             Object[] nvalues = new Object[n];

             // Log.e("SparseArray", "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;
     }
 }
	/*
	* 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;

	/**
	* SparseArrays map integers to Objects. Unlike a normal array of Objects,
	* there can be gaps in the indices. It is intended to be more efficient
	* than using a HashMap to map Integers to Objects.
	*/
	public class SparseArray<E> implements Cloneable {
	private static final Object DELETED = new Object();
	private boolean mGarbage = false;

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

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

	/**
	* Creates a new SparseArray containing no mappings that will not
	* require any additional memory allocation to store the specified
	* number of mappings.
	*/
	public SparseArray(int initialCapacity) {
	initialCapacity = ArrayUtils.idealIntArraySize(initialCapacity);

	mKeys = new int[initialCapacity];
	mValues = new Object[initialCapacity];
	mSize = 0;
	}

	@Override
	@SuppressWarnings("unchecked")
	public SparseArray<E> clone() {
	SparseArray<E> clone = null;
	try {
	clone = (SparseArray<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(int 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(int key, E valueIfKeyNotFound) {
	int i = binarySearch(mKeys, 0, 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(int key) {
	int i = binarySearch(mKeys, 0, mSize, key);

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

	/**
	* Alias for {@link #delete(int)}.
	*/
	public void remove(int 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;
	int[] 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(int key, E value) {
	int i = binarySearch(mKeys, 0, 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 = ~binarySearch(mKeys, 0, mSize, key);
	}

	if (mSize >= mKeys.length) {
	int n = ArrayUtils.idealIntArraySize(mSize + 1);

	int[] nkeys = new int[n];
	Object[] nvalues = new Object[n];

	// Log.e("SparseArray", "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("SparseArray", "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 SparseArray
	* 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
	* SparseArray stores.
	*/
	public int 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
	* SparseArray stores.
	*/
	@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
	* SparseArray 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(int key) {
	if (mGarbage) {
	gc();
	}

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

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

	int pos = mSize;
	if (pos >= mKeys.length) {
	int n = ArrayUtils.idealIntArraySize(pos + 1);

	int[] nkeys = new int[n];
	Object[] nvalues = new Object[n];

	// Log.e("SparseArray", "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;
	}
	}