    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017package org.apache.commons.collections4.properties;
    018
    019import java.util.AbstractMap.SimpleEntry;
    020import java.util.Collections;
    021import java.util.Enumeration;
    022import java.util.Iterator;
    023import java.util.LinkedHashSet;
    024import java.util.Map;
    025import java.util.Objects;
    026import java.util.Properties;
    027import java.util.Set;
    028import java.util.function.BiConsumer;
    029import java.util.function.BiFunction;
    030import java.util.function.Function;
    031import java.util.stream.Collectors;
    032
    033/**
    034 * A drop-in replacement for {@link Properties} for ordered keys.
    035 * <p>
    036 * Overrides methods to keep keys in insertion order. Allows other methods in the superclass to work with ordered keys.
    037 * </p>
    038 *
    039 * @see OrderedPropertiesFactory#INSTANCE
    040 * @since 4.5.0-M1
    041 */
    042public class OrderedProperties extends Properties {
    043
    044    private static final long serialVersionUID = 1L;
    045
    046    /**
    047     * Preserves the insertion order.
    048     */
    049    private final LinkedHashSet<Object> orderedKeys = new LinkedHashSet<>();
    050
    051    /**
    052     * Constructs a new instance.
    053     */
    054    public OrderedProperties() {
    055        // empty
    056    }
    057
    058    @Override
    059    public synchronized void clear() {
    060        orderedKeys.clear();
    061        super.clear();
    062    }
    063
    064    @Override
    065    public synchronized Object compute(final Object key, final BiFunction<? super Object, ? super Object, ? extends Object> remappingFunction) {
    066        final Object compute = super.compute(key, remappingFunction);
    067        if (compute != null) {
    068            orderedKeys.add(key);
    069        }
    070        return compute;
    071    }
    072
    073    @Override
    074    public synchronized Object computeIfAbsent(final Object key, final Function<? super Object, ? extends Object> mappingFunction) {
    075        final Object computeIfAbsent = super.computeIfAbsent(key, mappingFunction);
    076        if (computeIfAbsent != null) {
    077            orderedKeys.add(key);
    078        }
    079        return computeIfAbsent;
    080    }
    081
    082    @Override
    083    public Set<Map.Entry<Object, Object>> entrySet() {
    084        return orderedKeys.stream().map(k -> new SimpleEntry<>(k, get(k))).collect(Collectors.toCollection(LinkedHashSet::new));
    085    }
    086
    087    @Override
    088    public synchronized void forEach(final BiConsumer<? super Object, ? super Object> action) {
    089        Objects.requireNonNull(action);
    090        orderedKeys.forEach(k -> action.accept(k, get(k)));
    091    }
    092
    093    @Override
    094    public synchronized Enumeration<Object> keys() {
    095        return Collections.enumeration(orderedKeys);
    096    }
    097
    098    @Override
    099    public Set<Object> keySet() {
    100        return orderedKeys;
    101    }
    102
    103    @Override
    104    public synchronized Object merge(final Object key, final Object value,
    105            final BiFunction<? super Object, ? super Object, ? extends Object> remappingFunction) {
    106        orderedKeys.add(key);
    107        return super.merge(key, value, remappingFunction);
    108    }
    109
    110    @Override
    111    public Enumeration<?> propertyNames() {
    112        return Collections.enumeration(orderedKeys);
    113    }
    114
    115    @Override
    116    public synchronized Object put(final Object key, final Object value) {
    117        final Object put = super.put(key, value);
    118        if (put == null) {
    119            orderedKeys.add(key);
    120        }
    121        return put;
    122    }
    123
    124    @Override
    125    public synchronized void putAll(final Map<? extends Object, ? extends Object> t) {
    126        orderedKeys.addAll(t.keySet());
    127        super.putAll(t);
    128    }
    129
    130    @Override
    131    public synchronized Object putIfAbsent(final Object key, final Object value) {
    132        final Object putIfAbsent = super.putIfAbsent(key, value);
    133        if (putIfAbsent == null) {
    134            orderedKeys.add(key);
    135        }
    136        return putIfAbsent;
    137    }
    138
    139    @Override
    140    public synchronized Object remove(final Object key) {
    141        final Object remove = super.remove(key);
    142        if (remove != null) {
    143            orderedKeys.remove(key);
    144        }
    145        return remove;
    146    }
    147
    148    @Override
    149    public synchronized boolean remove(final Object key, final Object value) {
    150        final boolean remove = super.remove(key, value);
    151        if (remove) {
    152            orderedKeys.remove(key);
    153        }
    154        return remove;
    155    }
    156
    157    @Override
    158    public synchronized String toString() {
    159        // Must override for Java 17 to maintain order since the implementation is based on a map
    160        final int max = size() - 1;
    161        if (max == -1) {
    162            return "{}";
    163        }
    164        final StringBuilder sb = new StringBuilder();
    165        final Iterator<Map.Entry<Object, Object>> it = entrySet().iterator();
    166        sb.append('{');
    167        for (int i = 0;; i++) {
    168            final Map.Entry<Object, Object> e = it.next();
    169            final Object key = e.getKey();
    170            final Object value = e.getValue();
    171            sb.append(key == this ? "(this Map)" : key.toString());
    172            sb.append('=');
    173            sb.append(value == this ? "(this Map)" : value.toString());
    174            if (i == max) {
    175                return sb.append('}').toString();
    176            }
    177            sb.append(", ");
    178        }
    179    }
    180}