1 package jalview.ext.android;
4 * Copyright (C) 2006 The Android Open Source Project
6 * Licensed under the Apache License, Version 2.0 (the "License");
7 * you may not use this file except in compliance with the License.
8 * You may obtain a copy of the License at
10 * http://www.apache.org/licenses/LICENSE-2.0
12 * Unless required by applicable law or agreed to in writing, software
13 * distributed under the License is distributed on an "AS IS" BASIS,
14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15 * See the License for the specific language governing permissions and
16 * limitations under the License.
19 * SparseShortArrays map shorts to shorts. Unlike a normal array of shorts,
20 * there can be gaps in the indices. It is intended to be more memory efficient
21 * than using a HashMap to map Shorts to Shorts, both because it avoids
22 * auto-boxing keys and values and its data structure doesn't rely on an extra
23 * entry object for each mapping.
26 * Note that this container keeps its mappings in an array data structure, using
27 * a binary search to find keys. The implementation is not intended to be
28 * appropriate for data structures that may contain large numbers of items. It
29 * is generally slower than a traditional HashMap, since lookups require a
30 * binary search and adds and removes require inserting and deleting entries in
31 * the array. For containers holding up to hundreds of items, the performance
32 * difference is not significant, less than 50%.
36 * It is possible to iterate over the items in this container using
37 * {@link #keyAt(int)} and {@link #valueAt(int)}. Iterating over the keys using
38 * <code>keyAt(int)</code> with ascending values of the index will return the
39 * keys in ascending order, or the values corresponding to the keys in ascending
40 * order in the case of <code>valueAt(int)<code>.
44 * A copy of SparseShortArray designed to store short values (to minimise space
47 * Note that operations append, put, add throw ArithmeticException if the
48 * resulting value overflows the range of a short.
50 public class SparseShortArray implements Cloneable
52 private short[] mKeys;
54 private short[] mValues;
59 * Creates a new SparseShortArray containing no mappings.
61 public SparseShortArray()
67 * Creates a new SparseShortArray containing no mappings that will not require
68 * any additional memory allocation to store the specified number of mappings.
69 * If you supply an initial capacity of 0, the sparse array will be
70 * initialized with a light-weight representation not requiring any additional
73 public SparseShortArray(int initialCapacity)
75 if (initialCapacity == 0)
78 mValues = new short[0];
82 initialCapacity = idealShortArraySize(initialCapacity);
83 mKeys = new short[initialCapacity];
84 mValues = new short[initialCapacity];
90 public SparseShortArray clone()
92 SparseShortArray clone = null;
95 clone = (SparseShortArray) super.clone();
96 clone.mKeys = mKeys.clone();
97 clone.mValues = mValues.clone();
98 } catch (CloneNotSupportedException cnse)
106 * Gets the int mapped from the specified key, or <code>0</code> if no such
107 * mapping has been made.
109 public int get(int key)
115 * Gets the int mapped from the specified key, or the specified value if no
116 * such mapping has been made.
118 * @throws ArithmeticException
119 * if key is outside the range of a short value
121 public int get(int key, int valueIfKeyNotFound)
124 int i = ContainerHelpers.binarySearch(mKeys, mSize, (short) key);
127 return valueIfKeyNotFound;
136 * Removes the mapping from the specified key, if there was any.
138 * @throws ArithmeticException
139 * if key is outside the range of a short value
141 public void delete(int key)
144 int i = ContainerHelpers.binarySearch(mKeys, mSize, (short) key);
152 * Removes the mapping at the given index.
154 public void removeAt(int index)
156 System.arraycopy(mKeys, index + 1, mKeys, index, mSize - (index + 1));
157 System.arraycopy(mValues, index + 1, mValues, index, mSize
163 * Adds a mapping from the specified key to the specified value, replacing the
164 * previous mapping from the specified key if there was one.
166 * @throws ArithmeticException
167 * if either argument is outside the range of a short value
169 public void put(int key, int value)
172 checkOverflow(value);
173 int i = ContainerHelpers.binarySearch(mKeys, mSize, (short) key);
176 mValues[i] = (short) value;
181 if (mSize >= mKeys.length)
183 int n = idealShortArraySize(mSize + 1);
184 short[] nkeys = new short[n];
185 short[] nvalues = new short[n];
186 // Log.e("SparseShortArray", "grow " + mKeys.length + " to " + n);
187 System.arraycopy(mKeys, 0, nkeys, 0, mKeys.length);
188 System.arraycopy(mValues, 0, nvalues, 0, mValues.length);
194 // Log.e("SparseShortArray", "move " + (mSize - i));
195 System.arraycopy(mKeys, i, mKeys, i + 1, mSize - i);
196 System.arraycopy(mValues, i, mValues, i + 1, mSize - i);
198 mKeys[i] = (short) key;
199 mValues[i] = (short) value;
205 * Returns the number of key-value mappings that this SparseShortArray
214 * Given an index in the range <code>0...size()-1</code>, returns the key from
215 * the <code>index</code>th key-value mapping that this SparseShortArray
219 * The keys corresponding to indices in ascending order are guaranteed to be
220 * in ascending order, e.g., <code>keyAt(0)</code> will return the smallest
221 * key and <code>keyAt(size()-1)</code> will return the largest key.
224 public short keyAt(int index)
230 * Given an index in the range <code>0...size()-1</code>, returns the value
231 * from the <code>index</code>th key-value mapping that this SparseShortArray
235 * The values corresponding to indices in ascending order are guaranteed to be
236 * associated with keys in ascending order, e.g., <code>valueAt(0)</code> will
237 * return the value associated with the smallest key and
238 * <code>valueAt(size()-1)</code> will return the value associated with the
242 public short valueAt(int index)
244 return mValues[index];
248 * Returns the index for which {@link #keyAt} would return the specified key,
249 * or a negative number if the specified key is not mapped.
251 * @throws ArithmeticException
252 * if key is outside the range of a short value
254 public int indexOfKey(int key)
257 return ContainerHelpers.binarySearch(mKeys, mSize, (short) key);
261 * Returns an index for which {@link #valueAt} would return the specified key,
262 * or a negative number if no keys map to the specified value. Beware that
263 * this is a linear search, unlike lookups by key, and that multiple keys can
264 * map to the same value and this will find only one of them.
266 public int indexOfValue(int value)
268 for (int i = 0; i < mSize; i++)
270 if (mValues[i] == value)
279 * Removes all key-value mappings from this SparseShortArray.
287 * Puts a key/value pair into the array, optimizing for the case where the key
288 * is greater than all existing keys in the array.
290 public void append(int key, int value)
292 if (mSize != 0 && key <= mKeys[mSize - 1])
298 if (pos >= mKeys.length)
300 int n = idealShortArraySize(pos + 1);
301 short[] nkeys = new short[n];
302 short[] nvalues = new short[n];
303 // Log.e("SparseShortArray", "grow " + mKeys.length + " to " + n);
304 System.arraycopy(mKeys, 0, nkeys, 0, mKeys.length);
305 System.arraycopy(mValues, 0, nvalues, 0, mValues.length);
310 checkOverflow(value);
311 mKeys[pos] = (short) key;
312 mValues[pos] = (short) value;
317 * Throws an exception if the value is outside the range of a short.
320 * @throws ArithmeticException
322 public static void checkOverflow(int value)
324 if (value > Short.MAX_VALUE || value < Short.MIN_VALUE)
326 throw new ArithmeticException(String.valueOf(value));
331 * Inlined here by copying from com.android.internal.util.ArrayUtils
336 public static int idealShortArraySize(int need)
338 return idealByteArraySize(need * 2) / 2;
342 * Inlined here by copying from com.android.internal.util.ArrayUtils
347 public static int idealByteArraySize(int need)
349 for (int i = 4; i < 32; i++)
351 if (need <= (1 << i) - 12)
353 return (1 << i) - 12;
364 * This implementation composes a string by iterating over its mappings.
367 public String toString()
373 StringBuilder buffer = new StringBuilder(mSize * 28);
375 for (int i = 0; i < mSize; i++)
384 int value = valueAt(i);
385 buffer.append(value);
388 return buffer.toString();
392 * Method (copied from put) added for Jalview to efficiently increment a key's
393 * value if present, else add it with the given value. This avoids a double
394 * binary search (once to get the value, again to put the updated value).
398 * @return the new value of the count for the key
399 * @throws ArithmeticException
400 * if key, or result of adding toAdd, is outside the range of a
403 public int add(int key, int toAdd)
405 int newValue = toAdd;
407 int i = ContainerHelpers.binarySearch(mKeys, mSize, (short) key);
410 checkOverflow(toAdd + mValues[i]);
411 mValues[i] += (short) toAdd;
412 newValue = mValues[i];
416 checkOverflow(toAdd);
418 if (mSize >= mKeys.length)
420 int n = idealShortArraySize(mSize + 1);
421 short[] nkeys = new short[n];
422 short[] nvalues = new short[n];
423 System.arraycopy(mKeys, 0, nkeys, 0, mKeys.length);
424 System.arraycopy(mValues, 0, nvalues, 0, mValues.length);
430 System.arraycopy(mKeys, i, mKeys, i + 1, mSize - i);
431 System.arraycopy(mValues, i, mValues, i + 1, mSize - i);
433 mKeys[i] = (short) key;
434 mValues[i] = (short) toAdd;