DoubleArrayDictionary.java
/* Copyright 2002-2022 CS GROUP
* Licensed to CS GROUP (CS) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* CS licenses this file to You 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 org.orekit.utils;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
/** String → double[] mapping, for small number of keys.
* <p>
* This class is a low overhead for a very small number of keys.
* It is based on simple array and string comparison. It plays
* the same role a {@code Map<String, double[]>} but with reduced
* features and not intended for large number of keys. For such
* needs the regular {@code Map<String, double[]>} should be preferred.
* </p>
* @since 11.1
*/
public class DoubleArrayDictionary implements Serializable {
/** Serializable UID. */
private static final long serialVersionUID = 20211121L;
/** Default capacity. */
private static final int DEFAULT_INITIAL_CAPACITY = 4;
/** Data container. */
private final List<Entry> data;
/** Constructor with {@link #DEFAULT_INITIAL_CAPACITY default initial capacity}.
*/
public DoubleArrayDictionary() {
this(DEFAULT_INITIAL_CAPACITY);
}
/** Constructor with specified capacity.
* @param initialCapacity initial capacity
*/
public DoubleArrayDictionary(final int initialCapacity) {
data = new ArrayList<>(initialCapacity);
}
/** Constructor from another dictionary.
* @param dictionary dictionary to use for initializing entries
*/
public DoubleArrayDictionary(final DoubleArrayDictionary dictionary) {
// take care to call dictionary.getData() and not use dictionary.data,
// otherwise we get an empty dictionary when using a DoubleArrayDictionary.view
this(DEFAULT_INITIAL_CAPACITY + dictionary.getData().size());
for (final Entry entry : dictionary.getData()) {
// we don't call put(key, value) to avoid the overhead of the unneeded call to remove(key)
data.add(new Entry(entry.getKey(), entry.getValue()));
}
}
/** Constructor from a map.
* @param map map to use for initializing entries
*/
public DoubleArrayDictionary(final Map<String, double[]> map) {
this(map.size());
for (final Map.Entry<String, double[]> entry : map.entrySet()) {
// we don't call put(key, value) to avoid the overhead of the unneeded call to remove(key)
data.add(new Entry(entry.getKey(), entry.getValue()));
}
}
/** Get an unmodifiable view of the dictionary entries.
* @return unmodifiable view of the dictionary entries
*/
public List<Entry> getData() {
return Collections.unmodifiableList(data);
}
/** Get the number of dictionary entries.
* @return number of dictionary entries
*/
public int size() {
return data.size();
}
/** Create a map from the instance.
* <p>
* The map contains a copy of the instance data
* </p>
* @return copy of the dictionary, as an independent map
*/
public Map<String, double[]> toMap() {
final Map<String, double[]> map = new HashMap<>(data.size());
for (final Entry entry : data) {
map.put(entry.getKey(), entry.getValue());
}
return map;
}
/** Remove all entries.
*/
public void clear() {
data.clear();
}
/** Add an entry.
* <p>
* If an entry with the same key already exists, it will be removed first.
* </p>
* <p>
* The new entry is always put at the end.
* </p>
* @param key entry key
* @param value entry value
*/
public void put(final String key, final double[] value) {
remove(key);
data.add(new Entry(key, value));
}
/** Put all the entries from the map in the dictionary.
* @param map map to copy into the instance
*/
public void putAll(final Map<String, double[]> map) {
for (final Map.Entry<String, double[]> entry : map.entrySet()) {
put(entry.getKey(), entry.getValue());
}
}
/** Put all the entries from another dictionary.
* @param dictionary dictionary to copy into the instance
*/
public void putAll(final DoubleArrayDictionary dictionary) {
for (final Entry entry : dictionary.data) {
put(entry.getKey(), entry.getValue());
}
}
/** Get the value corresponding to a key.
* @param key entry key
* @return copy of the value corresponding to the key or null if key not present
*/
public double[] get(final String key) {
final Entry entry = getEntry(key);
return entry == null ? null : entry.getValue();
}
/** Get a complete entry.
* @param key entry key
* @return entry with key if it exists, null otherwise
*/
public Entry getEntry(final String key) {
for (final Entry entry : data) {
if (entry.getKey().equals(key)) {
return entry;
}
}
return null;
}
/** Remove an entry.
* @param key key of the entry to remove
* @return true if an entry has been removed, false if the key was not present
*/
public boolean remove(final String key) {
final Iterator<Entry> iterator = data.iterator();
while (iterator.hasNext()) {
if (iterator.next().getKey().equals(key)) {
iterator.remove();
return true;
}
}
return false;
}
/** Get an unmodifiable view of the dictionary.
* <p>
* The return dictionary is backed by the original instance and offers {@code read-only}
* access to it, but all operations that modify it throw an {@link UnsupportedOperationException}.
* </p>
* @return unmodifiable view of the dictionary
*/
public DoubleArrayDictionary unmodifiableView() {
return new View();
}
/** Get a string representation of the dictionary.
* <p>
* This string representation is intended for improving displays in debuggers only.
* </p>
* @return string representation of the dictionary
*/
@Override
public String toString() {
final StringBuilder builder = new StringBuilder();
builder.append('{');
for (int i = 0; i < data.size(); ++i) {
if (i > 0) {
builder.append(", ");
}
builder.append(data.get(i).getKey());
builder.append('[');
builder.append(data.get(i).getValue().length);
builder.append(']');
}
builder.append('}');
return builder.toString();
}
/** Entry in a dictionary. */
public static class Entry implements Serializable {
/** Serializable UID. */
private static final long serialVersionUID = 20211121L;
/** Key. */
private final String key;
/** Value. */
private final double[] value;
/** Simple constructor.
* @param key key
* @param value value
*/
Entry(final String key, final double[] value) {
this.key = key;
this.value = value.clone();
}
/** Get the entry key.
* @return entry key
*/
public String getKey() {
return key;
}
/** Get the value.
* @return a copy of the value (independent from internal array)
*/
public double[] getValue() {
return value.clone();
}
/** Get the size of the value array.
* @return size of the value array
*/
public int size() {
return value.length;
}
/** Increment the value.
* <p>
* For the sake of performance, no checks are done on argument.
* </p>
* @param increment increment to apply to the entry value
*/
public void increment(final double[] increment) {
for (int i = 0; i < increment.length; ++i) {
value[i] += increment[i];
}
}
/** Reset the value to zero.
*/
public void zero() {
Arrays.fill(value, 0.0);
}
}
/** Unmodifiable view of the dictionary. */
private class View extends DoubleArrayDictionary {
/** {@link Serializable} UID. */
private static final long serialVersionUID = 20211121L;
/** {@inheritDoc} */
@Override
public List<Entry> getData() {
return DoubleArrayDictionary.this.getData();
}
/** {@inheritDoc} */
@Override
public int size() {
return DoubleArrayDictionary.this.size();
}
/** {@inheritDoc} */
@Override
public Map<String, double[]> toMap() {
return DoubleArrayDictionary.this.toMap();
}
/** {@inheritDoc} */
@Override
public void clear() {
throw new UnsupportedOperationException();
}
/** {@inheritDoc} */
@Override
public void put(final String key, final double[] value) {
throw new UnsupportedOperationException();
}
/** {@inheritDoc} */
@Override
public void putAll(final Map<String, double[]> map) {
throw new UnsupportedOperationException();
}
/** {@inheritDoc} */
@Override
public void putAll(final DoubleArrayDictionary dictionary) {
throw new UnsupportedOperationException();
}
/** {@inheritDoc} */
@Override
public double[] get(final String key) {
return DoubleArrayDictionary.this.get(key);
}
/** {@inheritDoc} */
@Override
public Entry getEntry(final String key) {
return DoubleArrayDictionary.this.getEntry(key);
}
/** {@inheritDoc} */
@Override
public boolean remove(final String key) {
throw new UnsupportedOperationException();
}
}
}