    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    @Override
    052    public synchronized void clear() {
    053        orderedKeys.clear();
    054        super.clear();
    055    }
    056
    057    @Override
    058    public synchronized Object compute(final Object key, final BiFunction<? super Object, ? super Object, ? extends Object> remappingFunction) {
    059        final Object compute = super.compute(key, remappingFunction);
    060        if (compute != null) {
    061            orderedKeys.add(key);
    062        }
    063        return compute;
    064    }
    065
    066    @Override
    067    public synchronized Object computeIfAbsent(final Object key, final Function<? super Object, ? extends Object> mappingFunction) {
    068        final Object computeIfAbsent = super.computeIfAbsent(key, mappingFunction);
    069        if (computeIfAbsent != null) {
    070            orderedKeys.add(key);
    071        }
    072        return computeIfAbsent;
    073    }
    074
    075    @Override
    076    public Set<Map.Entry<Object, Object>> entrySet() {
    077        return orderedKeys.stream().map(k -> new SimpleEntry<>(k, get(k))).collect(Collectors.toCollection(LinkedHashSet::new));
    078    }
    079
    080    @Override
    081    public synchronized void forEach(final BiConsumer<? super Object, ? super Object> action) {
    082        Objects.requireNonNull(action);
    083        orderedKeys.forEach(k -> action.accept(k, get(k)));
    084    }
    085
    086    @Override
    087    public synchronized Enumeration<Object> keys() {
    088        return Collections.enumeration(orderedKeys);
    089    }
    090
    091    @Override
    092    public Set<Object> keySet() {
    093        return orderedKeys;
    094    }
    095
    096    @Override
    097    public synchronized Object merge(final Object key, final Object value,
    098            final BiFunction<? super Object, ? super Object, ? extends Object> remappingFunction) {
    099        orderedKeys.add(key);
    100        return super.merge(key, value, remappingFunction);
    101    }
    102
    103    @Override
    104    public Enumeration<?> propertyNames() {
    105        return Collections.enumeration(orderedKeys);
    106    }
    107
    108    @Override
    109    public synchronized Object put(final Object key, final Object value) {
    110        final Object put = super.put(key, value);
    111        if (put == null) {
    112            orderedKeys.add(key);
    113        }
    114        return put;
    115    }
    116
    117    @Override
    118    public synchronized void putAll(final Map<? extends Object, ? extends Object> t) {
    119        orderedKeys.addAll(t.keySet());
    120        super.putAll(t);
    121    }
    122
    123    @Override
    124    public synchronized Object putIfAbsent(final Object key, final Object value) {
    125        final Object putIfAbsent = super.putIfAbsent(key, value);
    126        if (putIfAbsent == null) {
    127            orderedKeys.add(key);
    128        }
    129        return putIfAbsent;
    130    }
    131
    132    @Override
    133    public synchronized Object remove(final Object key) {
    134        final Object remove = super.remove(key);
    135        if (remove != null) {
    136            orderedKeys.remove(key);
    137        }
    138        return remove;
    139    }
    140
    141    @Override
    142    public synchronized boolean remove(final Object key, final Object value) {
    143        final boolean remove = super.remove(key, value);
    144        if (remove) {
    145            orderedKeys.remove(key);
    146        }
    147        return remove;
    148    }
    149
    150    @Override
    151    public synchronized String toString() {
    152        // Must override for Java 17 to maintain order since the implementation is based on a map
    153        final int max = size() - 1;
    154        if (max == -1) {
    155            return "{}";
    156        }
    157        final StringBuilder sb = new StringBuilder();
    158        final Iterator<Map.Entry<Object, Object>> it = entrySet().iterator();
    159        sb.append('{');
    160        for (int i = 0;; i++) {
    161            final Map.Entry<Object, Object> e = it.next();
    162            final Object key = e.getKey();
    163            final Object value = e.getValue();
    164            sb.append(key == this ? "(this Map)" : key.toString());
    165            sb.append('=');
    166            sb.append(value == this ? "(this Map)" : value.toString());
    167            if (i == max) {
    168                return sb.append('}').toString();
    169            }
    170            sb.append(", ");
    171        }
    172    }
    173}