The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2006 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | package android.util; |
| 18 | |
| 19 | import com.android.internal.util.ArrayUtils; |
| 20 | |
| 21 | /** |
| 22 | * SparseBooleanArrays map integers to booleans. |
| 23 | * Unlike a normal array of booleans |
| 24 | * there can be gaps in the indices. It is intended to be more efficient |
| 25 | * than using a HashMap to map Integers to Booleans. |
| 26 | */ |
Svetoslav Ganov | 35bfede | 2011-07-14 17:57:06 -0700 | [diff] [blame] | 27 | public class SparseBooleanArray implements Cloneable { |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 28 | /** |
| 29 | * Creates a new SparseBooleanArray containing no mappings. |
| 30 | */ |
| 31 | public SparseBooleanArray() { |
| 32 | this(10); |
| 33 | } |
| 34 | |
| 35 | /** |
| 36 | * Creates a new SparseBooleanArray containing no mappings that will not |
| 37 | * require any additional memory allocation to store the specified |
| 38 | * number of mappings. |
| 39 | */ |
| 40 | public SparseBooleanArray(int initialCapacity) { |
| 41 | initialCapacity = ArrayUtils.idealIntArraySize(initialCapacity); |
| 42 | |
| 43 | mKeys = new int[initialCapacity]; |
| 44 | mValues = new boolean[initialCapacity]; |
| 45 | mSize = 0; |
| 46 | } |
| 47 | |
Svetoslav Ganov | 35bfede | 2011-07-14 17:57:06 -0700 | [diff] [blame] | 48 | @Override |
| 49 | public SparseBooleanArray clone() { |
| 50 | SparseBooleanArray clone = null; |
| 51 | try { |
| 52 | clone = (SparseBooleanArray) super.clone(); |
| 53 | clone.mKeys = mKeys.clone(); |
| 54 | clone.mValues = mValues.clone(); |
| 55 | } catch (CloneNotSupportedException cnse) { |
| 56 | /* ignore */ |
| 57 | } |
| 58 | return clone; |
| 59 | } |
| 60 | |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 61 | /** |
| 62 | * Gets the boolean mapped from the specified key, or <code>false</code> |
| 63 | * if no such mapping has been made. |
| 64 | */ |
| 65 | public boolean get(int key) { |
| 66 | return get(key, false); |
| 67 | } |
| 68 | |
| 69 | /** |
| 70 | * Gets the boolean mapped from the specified key, or the specified value |
| 71 | * if no such mapping has been made. |
| 72 | */ |
| 73 | public boolean get(int key, boolean valueIfKeyNotFound) { |
| 74 | int i = binarySearch(mKeys, 0, mSize, key); |
| 75 | |
| 76 | if (i < 0) { |
| 77 | return valueIfKeyNotFound; |
| 78 | } else { |
| 79 | return mValues[i]; |
| 80 | } |
| 81 | } |
| 82 | |
| 83 | /** |
| 84 | * Removes the mapping from the specified key, if there was any. |
| 85 | */ |
| 86 | public void delete(int key) { |
| 87 | int i = binarySearch(mKeys, 0, mSize, key); |
| 88 | |
| 89 | if (i >= 0) { |
| 90 | System.arraycopy(mKeys, i + 1, mKeys, i, mSize - (i + 1)); |
| 91 | System.arraycopy(mValues, i + 1, mValues, i, mSize - (i + 1)); |
| 92 | mSize--; |
| 93 | } |
| 94 | } |
| 95 | |
| 96 | /** |
| 97 | * Adds a mapping from the specified key to the specified value, |
| 98 | * replacing the previous mapping from the specified key if there |
| 99 | * was one. |
| 100 | */ |
| 101 | public void put(int key, boolean value) { |
| 102 | int i = binarySearch(mKeys, 0, mSize, key); |
| 103 | |
| 104 | if (i >= 0) { |
| 105 | mValues[i] = value; |
| 106 | } else { |
| 107 | i = ~i; |
| 108 | |
| 109 | if (mSize >= mKeys.length) { |
| 110 | int n = ArrayUtils.idealIntArraySize(mSize + 1); |
| 111 | |
| 112 | int[] nkeys = new int[n]; |
| 113 | boolean[] nvalues = new boolean[n]; |
| 114 | |
| 115 | // Log.e("SparseBooleanArray", "grow " + mKeys.length + " to " + n); |
| 116 | System.arraycopy(mKeys, 0, nkeys, 0, mKeys.length); |
| 117 | System.arraycopy(mValues, 0, nvalues, 0, mValues.length); |
| 118 | |
| 119 | mKeys = nkeys; |
| 120 | mValues = nvalues; |
| 121 | } |
| 122 | |
| 123 | if (mSize - i != 0) { |
| 124 | // Log.e("SparseBooleanArray", "move " + (mSize - i)); |
| 125 | System.arraycopy(mKeys, i, mKeys, i + 1, mSize - i); |
| 126 | System.arraycopy(mValues, i, mValues, i + 1, mSize - i); |
| 127 | } |
| 128 | |
| 129 | mKeys[i] = key; |
| 130 | mValues[i] = value; |
| 131 | mSize++; |
| 132 | } |
| 133 | } |
| 134 | |
| 135 | /** |
| 136 | * Returns the number of key-value mappings that this SparseBooleanArray |
| 137 | * currently stores. |
| 138 | */ |
| 139 | public int size() { |
| 140 | return mSize; |
| 141 | } |
| 142 | |
| 143 | /** |
| 144 | * Given an index in the range <code>0...size()-1</code>, returns |
| 145 | * the key from the <code>index</code>th key-value mapping that this |
| 146 | * SparseBooleanArray stores. |
| 147 | */ |
| 148 | public int keyAt(int index) { |
| 149 | return mKeys[index]; |
| 150 | } |
| 151 | |
| 152 | /** |
| 153 | * Given an index in the range <code>0...size()-1</code>, returns |
| 154 | * the value from the <code>index</code>th key-value mapping that this |
| 155 | * SparseBooleanArray stores. |
| 156 | */ |
| 157 | public boolean valueAt(int index) { |
| 158 | return mValues[index]; |
| 159 | } |
| 160 | |
| 161 | /** |
| 162 | * Returns the index for which {@link #keyAt} would return the |
| 163 | * specified key, or a negative number if the specified |
| 164 | * key is not mapped. |
| 165 | */ |
| 166 | public int indexOfKey(int key) { |
| 167 | return binarySearch(mKeys, 0, mSize, key); |
| 168 | } |
| 169 | |
| 170 | /** |
| 171 | * Returns an index for which {@link #valueAt} would return the |
| 172 | * specified key, or a negative number if no keys map to the |
| 173 | * specified value. |
| 174 | * Beware that this is a linear search, unlike lookups by key, |
| 175 | * and that multiple keys can map to the same value and this will |
| 176 | * find only one of them. |
| 177 | */ |
| 178 | public int indexOfValue(boolean value) { |
| 179 | for (int i = 0; i < mSize; i++) |
| 180 | if (mValues[i] == value) |
| 181 | return i; |
| 182 | |
| 183 | return -1; |
| 184 | } |
| 185 | |
| 186 | /** |
| 187 | * Removes all key-value mappings from this SparseBooleanArray. |
| 188 | */ |
| 189 | public void clear() { |
| 190 | mSize = 0; |
| 191 | } |
| 192 | |
| 193 | /** |
| 194 | * Puts a key/value pair into the array, optimizing for the case where |
| 195 | * the key is greater than all existing keys in the array. |
| 196 | */ |
| 197 | public void append(int key, boolean value) { |
| 198 | if (mSize != 0 && key <= mKeys[mSize - 1]) { |
| 199 | put(key, value); |
| 200 | return; |
| 201 | } |
| 202 | |
| 203 | int pos = mSize; |
| 204 | if (pos >= mKeys.length) { |
| 205 | int n = ArrayUtils.idealIntArraySize(pos + 1); |
| 206 | |
| 207 | int[] nkeys = new int[n]; |
| 208 | boolean[] nvalues = new boolean[n]; |
| 209 | |
| 210 | // Log.e("SparseBooleanArray", "grow " + mKeys.length + " to " + n); |
| 211 | System.arraycopy(mKeys, 0, nkeys, 0, mKeys.length); |
| 212 | System.arraycopy(mValues, 0, nvalues, 0, mValues.length); |
| 213 | |
| 214 | mKeys = nkeys; |
| 215 | mValues = nvalues; |
| 216 | } |
| 217 | |
| 218 | mKeys[pos] = key; |
| 219 | mValues[pos] = value; |
| 220 | mSize = pos + 1; |
| 221 | } |
| 222 | |
| 223 | private static int binarySearch(int[] a, int start, int len, int key) { |
| 224 | int high = start + len, low = start - 1, guess; |
| 225 | |
| 226 | while (high - low > 1) { |
| 227 | guess = (high + low) / 2; |
| 228 | |
| 229 | if (a[guess] < key) |
| 230 | low = guess; |
| 231 | else |
| 232 | high = guess; |
| 233 | } |
| 234 | |
| 235 | if (high == start + len) |
| 236 | return ~(start + len); |
| 237 | else if (a[high] == key) |
| 238 | return high; |
| 239 | else |
| 240 | return ~high; |
| 241 | } |
| 242 | |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 243 | private int[] mKeys; |
| 244 | private boolean[] mValues; |
| 245 | private int mSize; |
| 246 | } |