    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 *     https://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.configuration2.builder;
    018
    019import java.util.ArrayList;
    020import java.util.Collection;
    021import java.util.HashMap;
    022import java.util.Map;
    023
    024import org.apache.commons.configuration2.ConfigurationDecoder;
    025import org.apache.commons.configuration2.beanutils.BeanHelper;
    026import org.apache.commons.configuration2.convert.ConversionHandler;
    027import org.apache.commons.configuration2.convert.ListDelimiterHandler;
    028import org.apache.commons.configuration2.interpol.ConfigurationInterpolator;
    029import org.apache.commons.configuration2.interpol.InterpolatorSpecification;
    030import org.apache.commons.configuration2.interpol.Lookup;
    031import org.apache.commons.configuration2.io.ConfigurationLogger;
    032import org.apache.commons.configuration2.sync.Synchronizer;
    033
    034/**
    035 * <p>
    036 * An implementation of {@code BuilderParameters} which handles the parameters of a {@link ConfigurationBuilder} common
    037 * to all concrete {@code Configuration} implementations.
    038 * </p>
    039 * <p>
    040 * This class provides methods for setting standard properties supported by the {@code AbstractConfiguration} base
    041 * class. A fluent interface can be used to set property values.
    042 * </p>
    043 * <p>
    044 * This class is not thread-safe. It is intended that an instance is constructed and initialized by a single thread
    045 * during configuration of a {@code ConfigurationBuilder}.
    046 * </p>
    047 *
    048 * @since 2.0
    049 */
    050public class BasicBuilderParameters implements Cloneable, BuilderParameters, BasicBuilderProperties<BasicBuilderParameters> {
    051    /** The key of the <em>throwExceptionOnMissing</em> property. */
    052    private static final String PROP_THROW_EXCEPTION_ON_MISSING = "throwExceptionOnMissing";
    053
    054    /** The key of the <em>listDelimiterHandler</em> property. */
    055    private static final String PROP_LIST_DELIMITER_HANDLER = "listDelimiterHandler";
    056
    057    /** The key of the <em>logger</em> property. */
    058    private static final String PROP_LOGGER = "logger";
    059
    060    /** The key for the <em>interpolator</em> property. */
    061    private static final String PROP_INTERPOLATOR = "interpolator";
    062
    063    /** The key for the <em>prefixLookups</em> property. */
    064    private static final String PROP_PREFIX_LOOKUPS = "prefixLookups";
    065
    066    /** The key for the <em>defaultLookups</em> property. */
    067    private static final String PROP_DEFAULT_LOOKUPS = "defaultLookups";
    068
    069    /** The key for the <em>parentInterpolator</em> property. */
    070    private static final String PROP_PARENT_INTERPOLATOR = "parentInterpolator";
    071
    072    /** The key for the <em>synchronizer</em> property. */
    073    private static final String PROP_SYNCHRONIZER = "synchronizer";
    074
    075    /** The key for the <em>conversionHandler</em> property. */
    076    private static final String PROP_CONVERSION_HANDLER = "conversionHandler";
    077
    078    /** The key for the <em>configurationDecoder</em> property. */
    079    private static final String PROP_CONFIGURATION_DECODER = "configurationDecoder";
    080
    081    /** The key for the {@code BeanHelper}. */
    082    private static final String PROP_BEAN_HELPER = RESERVED_PARAMETER_PREFIX + "BeanHelper";
    083
    084    /**
    085     * Checks whether a map with parameters is present. Throws an exception if not.
    086     *
    087     * @param params the map with parameters to check
    088     * @throws IllegalArgumentException if the map is <strong>null</strong>
    089     */
    090    private static void checkParameters(final Map<String, Object> params) {
    091        if (params == null) {
    092            throw new IllegalArgumentException("Parameters map must not be null!");
    093        }
    094    }
    095
    096    /**
    097     * Creates defensive copies for collection structures when constructing the map with parameters. It should not be
    098     * possible to modify this object's internal state when having access to the parameters map.
    099     *
    100     * @param params the map with parameters to be passed to the caller
    101     */
    102    private static void createDefensiveCopies(final HashMap<String, Object> params) {
    103        final Map<String, ? extends Lookup> prefixLookups = fetchPrefixLookups(params);
    104        if (prefixLookups != null) {
    105            params.put(PROP_PREFIX_LOOKUPS, new HashMap<>(prefixLookups));
    106        }
    107        final Collection<? extends Lookup> defLookups = fetchDefaultLookups(params);
    108        if (defLookups != null) {
    109            params.put(PROP_DEFAULT_LOOKUPS, new ArrayList<>(defLookups));
    110        }
    111    }
    112
    113    /**
    114     * Tests whether the passed in map with parameters contains a valid collection with default lookups. This method works
    115     * like {@link #fetchAndCheckPrefixLookups(Map)}, but tests the default lookups collection.
    116     *
    117     * @param params the map with parameters
    118     * @return the collection with default lookups (may be <strong>null</strong>)
    119     * @throws IllegalArgumentException if invalid data is found
    120     */
    121    private static Collection<? extends Lookup> fetchAndCheckDefaultLookups(final Map<String, Object> params) {
    122        final Collection<?> col = fetchParameter(params, PROP_DEFAULT_LOOKUPS, Collection.class);
    123        if (col == null) {
    124            return null;
    125        }
    126
    127        if (col.stream().noneMatch(Lookup.class::isInstance)) {
    128            throw new IllegalArgumentException("Collection with default lookups contains invalid data: " + col);
    129        }
    130        return fetchDefaultLookups(params);
    131    }
    132
    133    /**
    134     * Tests whether the passed in map with parameters contains a map with prefix lookups. This method is used if the
    135     * parameters map is from an insecure source and we cannot be sure that it contains valid data. Therefore, we have to
    136     * map that the key for the prefix lookups actually points to a map containing keys and values of expected data types.
    137     *
    138     * @param params the parameters map
    139     * @return the obtained map with prefix lookups
    140     * @throws IllegalArgumentException if the map contains invalid data
    141     */
    142    private static Map<String, ? extends Lookup> fetchAndCheckPrefixLookups(final Map<String, Object> params) {
    143        final Map<?, ?> prefixes = fetchParameter(params, PROP_PREFIX_LOOKUPS, Map.class);
    144        if (prefixes == null) {
    145            return null;
    146        }
    147        prefixes.forEach((k, v) -> {
    148            if (!(k instanceof String) || !(v instanceof Lookup)) {
    149                throw new IllegalArgumentException("Map with prefix lookups contains invalid data: " + prefixes);
    150            }
    151        });
    152        return fetchPrefixLookups(params);
    153    }
    154
    155    /**
    156     * Obtains the {@code BeanHelper} object from the specified map with parameters. This method can be used to obtain an
    157     * instance from a parameters map that has been set via the {@code setBeanHelper()} method. If no such instance is
    158     * found, result is <strong>null</strong>.
    159     *
    160     * @param params the map with parameters (must not be <strong>null</strong>)
    161     * @return the {@code BeanHelper} stored in this map or <strong>null</strong>
    162     * @throws IllegalArgumentException if the map is <strong>null</strong>
    163     */
    164    public static BeanHelper fetchBeanHelper(final Map<String, Object> params) {
    165        checkParameters(params);
    166        return (BeanHelper) params.get(PROP_BEAN_HELPER);
    167    }
    168
    169    /**
    170     * Obtains the collection with default lookups from the parameters map.
    171     *
    172     * @param params the map with parameters
    173     * @return the collection with default lookups (may be <strong>null</strong>)
    174     */
    175    private static Collection<? extends Lookup> fetchDefaultLookups(final Map<String, Object> params) {
    176        // This is safe to cast because we either have full control over the map
    177        // and thus know the types of the contained values or have checked
    178        // the content before
    179        @SuppressWarnings("unchecked")
    180        final Collection<? extends Lookup> defLookups = (Collection<? extends Lookup>) params.get(PROP_DEFAULT_LOOKUPS);
    181        return defLookups;
    182    }
    183
    184    /**
    185     * Obtains a specification for a {@link ConfigurationInterpolator} from the specified map with parameters. All
    186     * properties related to interpolation are evaluated and added to the specification object.
    187     *
    188     * @param params the map with parameters (must not be <strong>null</strong>)
    189     * @return an {@code InterpolatorSpecification} object constructed with data from the map
    190     * @throws IllegalArgumentException if the map is <strong>null</strong> or contains invalid data
    191     */
    192    public static InterpolatorSpecification fetchInterpolatorSpecification(final Map<String, Object> params) {
    193        checkParameters(params);
    194        return new InterpolatorSpecification.Builder().withInterpolator(fetchParameter(params, PROP_INTERPOLATOR, ConfigurationInterpolator.class))
    195            .withParentInterpolator(fetchParameter(params, PROP_PARENT_INTERPOLATOR, ConfigurationInterpolator.class))
    196            .withPrefixLookups(fetchAndCheckPrefixLookups(params)).withDefaultLookups(fetchAndCheckDefaultLookups(params)).create();
    197    }
    198
    199    /**
    200     * Obtains a parameter from a map and performs a type check.
    201     *
    202     * @param params the map with parameters
    203     * @param key the key of the parameter
    204     * @param expClass the expected class of the parameter value
    205     * @param <T> the parameter type
    206     * @return the value of the parameter in the correct data type
    207     * @throws IllegalArgumentException if the parameter is not of the expected type
    208     */
    209    private static <T> T fetchParameter(final Map<String, Object> params, final String key, final Class<T> expClass) {
    210        final Object value = params.get(key);
    211        if (value == null) {
    212            return null;
    213        }
    214        if (!expClass.isInstance(value)) {
    215            throw new IllegalArgumentException(String.format("Parameter %s is not of type %s!", key, expClass.getSimpleName()));
    216        }
    217        return expClass.cast(value);
    218    }
    219
    220    /**
    221     * Obtains the map with prefix lookups from the parameters map.
    222     *
    223     * @param params the map with parameters
    224     * @return the map with prefix lookups (may be <strong>null</strong>)
    225     */
    226    private static Map<String, ? extends Lookup> fetchPrefixLookups(final Map<String, Object> params) {
    227        // This is safe to cast because we either have full control over the map
    228        // and thus know the types of the contained values or have checked
    229        // the content before
    230        @SuppressWarnings("unchecked")
    231        final Map<String, ? extends Lookup> prefixLookups = (Map<String, ? extends Lookup>) params.get(PROP_PREFIX_LOOKUPS);
    232        return prefixLookups;
    233    }
    234
    235    /** The map for storing the current property values. */
    236    private Map<String, Object> properties;
    237
    238    /**
    239     * Creates a new instance of {@code BasicBuilderParameters}.
    240     */
    241    public BasicBuilderParameters() {
    242        properties = new HashMap<>();
    243    }
    244
    245    /**
    246     * Clones this object. This is useful because multiple builder instances may use a similar set of parameters. However,
    247     * single instances of parameter objects must not assigned to multiple builders. Therefore, cloning a parameters object
    248     * provides a solution for this use case. This method creates a new parameters object with the same content as this one.
    249     * The internal map storing the parameter values is cloned, too, also collection structures contained in this map.
    250     * However, no a full deep clone operation is performed. Objects like a {@code ConfigurationInterpolator} or
    251     * {@code Lookup}s are shared between this and the newly created instance.
    252     *
    253     * @return a clone of this object
    254     */
    255    @Override
    256    public BasicBuilderParameters clone() {
    257        try {
    258            final BasicBuilderParameters copy = (BasicBuilderParameters) super.clone();
    259            copy.properties = getParameters();
    260            return copy;
    261        } catch (final CloneNotSupportedException cnex) {
    262            // should not happen
    263            throw new AssertionError(cnex);
    264        }
    265    }
    266
    267    /**
    268     * Copies a number of properties from the given map into this object. Properties are only copied if they are defined in
    269     * the source map.
    270     *
    271     * @param source the source map
    272     * @param keys the keys to be copied
    273     */
    274    protected void copyPropertiesFrom(final Map<String, ?> source, final String... keys) {
    275        for (final String key : keys) {
    276            final Object value = source.get(key);
    277            if (value != null) {
    278                storeProperty(key, value);
    279            }
    280        }
    281    }
    282
    283    /**
    284     * Obtains the value of the specified property from the internal map. This method can be used by derived classes if a
    285     * specific property is to be accessed. If the given key is not found, result is <strong>null</strong>.
    286     *
    287     * @param key the key of the property in question
    288     * @return the value of the property with this key or <strong>null</strong>
    289     */
    290    protected Object fetchProperty(final String key) {
    291        return properties.get(key);
    292    }
    293
    294    /**
    295     * {@inheritDoc} This implementation returns a copy of the internal parameters map with the values set so far.
    296     * Collection structures (for example for lookup objects) are stored as defensive copies, so the original data cannot be
    297     * modified.
    298     */
    299    @Override
    300    public Map<String, Object> getParameters() {
    301        final HashMap<String, Object> result = new HashMap<>(properties);
    302        if (result.containsKey(PROP_INTERPOLATOR)) {
    303            // A custom ConfigurationInterpolator overrides lookups
    304            result.remove(PROP_PREFIX_LOOKUPS);
    305            result.remove(PROP_DEFAULT_LOOKUPS);
    306            result.remove(PROP_PARENT_INTERPOLATOR);
    307        }
    308
    309        createDefensiveCopies(result);
    310        return result;
    311    }
    312
    313    /**
    314     * Inherits properties from the specified map. This can be used for instance to reuse parameters from one builder in
    315     * another builder - also in parent-child relations in which a parent builder creates child builders. The purpose of
    316     * this method is to let a concrete implementation decide which properties can be inherited. Because parameters are
    317     * basically organized as a map it would be possible to simply copy over all properties from the source object. However,
    318     * this is not appropriate in all cases. For instance, some properties - like a {@code ConfigurationInterpolator} - are
    319     * tightly connected to a configuration and cannot be reused in a different context. For other properties, for example a file
    320     * name, it does not make sense to copy it. Therefore, an implementation has to be explicit in the properties it wants
    321     * to take over.
    322     *
    323     * @param source the source properties to inherit from
    324     * @throws IllegalArgumentException if the source map is <strong>null</strong>
    325     */
    326    public void inheritFrom(final Map<String, ?> source) {
    327        if (source == null) {
    328            throw new IllegalArgumentException("Source properties must not be null!");
    329        }
    330        copyPropertiesFrom(source, PROP_BEAN_HELPER, PROP_CONFIGURATION_DECODER, PROP_CONVERSION_HANDLER, PROP_LIST_DELIMITER_HANDLER, PROP_LOGGER,
    331            PROP_SYNCHRONIZER, PROP_THROW_EXCEPTION_ON_MISSING);
    332    }
    333
    334    /**
    335     * Merges this object with the given parameters object. This method adds all property values defined by the passed in
    336     * parameters object to the internal storage which are not already in. So properties already defined in this object take
    337     * precedence. Property names starting with the reserved parameter prefix are ignored.
    338     *
    339     * @param p the object whose properties should be merged (must not be <strong>null</strong>)
    340     * @throws IllegalArgumentException if the passed in object is <strong>null</strong>
    341     */
    342    public void merge(final BuilderParameters p) {
    343        if (p == null) {
    344            throw new IllegalArgumentException("Parameters to merge must not be null!");
    345        }
    346        p.getParameters().forEach((k, v) -> {
    347            if (!properties.containsKey(k) && !k.startsWith(RESERVED_PARAMETER_PREFIX)) {
    348                storeProperty(k, v);
    349            }
    350        });
    351    }
    352
    353    /**
    354     * {@inheritDoc} This implementation stores the passed in {@code BeanHelper} object in the internal parameters map, but
    355     * uses a reserved key, so that it is not used for the initialization of properties of the managed configuration object.
    356     * The {@code fetchBeanHelper()} method can be used to obtain the {@code BeanHelper} instance from a parameters map.
    357     */
    358    @Override
    359    public BasicBuilderParameters setBeanHelper(final BeanHelper beanHelper) {
    360        return setProperty(PROP_BEAN_HELPER, beanHelper);
    361    }
    362
    363    /**
    364     * {@inheritDoc} This implementation stores the passed in {@code ConfigurationDecoder} object in the internal parameters
    365     * map.
    366     */
    367    @Override
    368    public BasicBuilderParameters setConfigurationDecoder(final ConfigurationDecoder decoder) {
    369        return setProperty(PROP_CONFIGURATION_DECODER, decoder);
    370    }
    371
    372    /**
    373     * {@inheritDoc} This implementation stores the passed in {@code ConversionHandler} object in the internal parameters
    374     * map.
    375     */
    376    @Override
    377    public BasicBuilderParameters setConversionHandler(final ConversionHandler handler) {
    378        return setProperty(PROP_CONVERSION_HANDLER, handler);
    379    }
    380
    381    /**
    382     * {@inheritDoc} A defensive copy of the passed in collection is created. A <strong>null</strong> argument causes all default
    383     * lookups to be removed from the internal parameters map.
    384     */
    385    @Override
    386    public BasicBuilderParameters setDefaultLookups(final Collection<? extends Lookup> lookups) {
    387        if (lookups == null) {
    388            properties.remove(PROP_DEFAULT_LOOKUPS);
    389            return this;
    390        }
    391        return setProperty(PROP_DEFAULT_LOOKUPS, new ArrayList<>(lookups));
    392    }
    393
    394    /**
    395     * {@inheritDoc} The passed in {@code ConfigurationInterpolator} is set without modifications.
    396     */
    397    @Override
    398    public BasicBuilderParameters setInterpolator(final ConfigurationInterpolator ci) {
    399        return setProperty(PROP_INTERPOLATOR, ci);
    400    }
    401
    402    /**
    403     * Sets the value of the <em>listDelimiterHandler</em> property. This property defines the object responsible for
    404     * dealing with list delimiter and escaping characters. Note:
    405     * {@link org.apache.commons.configuration2.AbstractConfiguration AbstractConfiguration} does not allow setting this
    406     * property to <strong>null</strong>. If the default {@code ListDelimiterHandler} is to be used, do not call this method.
    407     *
    408     * @param handler the {@code ListDelimiterHandler}
    409     * @return a reference to this object for method chaining
    410     */
    411    @Override
    412    public BasicBuilderParameters setListDelimiterHandler(final ListDelimiterHandler handler) {
    413        return setProperty(PROP_LIST_DELIMITER_HANDLER, handler);
    414    }
    415
    416    /**
    417     * Sets the <em>logger</em> property. With this property a concrete {@code Log} object can be set for the configuration.
    418     * Thus logging behavior can be controlled.
    419     *
    420     * @param log the {@code Log} for the configuration produced by this builder
    421     * @return a reference to this object for method chaining
    422     */
    423    @Override
    424    public BasicBuilderParameters setLogger(final ConfigurationLogger log) {
    425        return setProperty(PROP_LOGGER, log);
    426    }
    427
    428    /**
    429     * {@inheritDoc} This implementation stores the passed in {@code ConfigurationInterpolator} object in the internal
    430     * parameters map.
    431     */
    432    @Override
    433    public BasicBuilderParameters setParentInterpolator(final ConfigurationInterpolator parent) {
    434        return setProperty(PROP_PARENT_INTERPOLATOR, parent);
    435    }
    436
    437    /**
    438     * {@inheritDoc} A defensive copy of the passed in map is created. A <strong>null</strong> argument causes all prefix lookups to
    439     * be removed from the internal parameters map.
    440     */
    441    @Override
    442    public BasicBuilderParameters setPrefixLookups(final Map<String, ? extends Lookup> lookups) {
    443        if (lookups == null) {
    444            properties.remove(PROP_PREFIX_LOOKUPS);
    445            return this;
    446        }
    447        return setProperty(PROP_PREFIX_LOOKUPS, new HashMap<>(lookups));
    448    }
    449
    450    /**
    451     * Helper method for setting a property value.
    452     *
    453     * @param key the key of the property
    454     * @param value the value of the property
    455     * @return a reference to this object
    456     */
    457    private BasicBuilderParameters setProperty(final String key, final Object value) {
    458        storeProperty(key, value);
    459        return this;
    460    }
    461
    462    /**
    463     * {@inheritDoc} This implementation stores the passed in {@code Synchronizer} object in the internal parameters map.
    464     */
    465    @Override
    466    public BasicBuilderParameters setSynchronizer(final Synchronizer sync) {
    467        return setProperty(PROP_SYNCHRONIZER, sync);
    468    }
    469
    470    /**
    471     * Sets the value of the <em>throwExceptionOnMissing</em> property. This property controls the configuration's behavior
    472     * if missing properties are queried: a value of <strong>true</strong> causes the configuration to throw an exception, for a value
    473     * of <strong>false</strong> it will return <strong>null</strong> values. (Note: Methods returning a primitive data type will always throw
    474     * an exception if the property is not defined.)
    475     *
    476     * @param b the value of the property
    477     * @return a reference to this object for method chaining
    478     */
    479    @Override
    480    public BasicBuilderParameters setThrowExceptionOnMissing(final boolean b) {
    481        return setProperty(PROP_THROW_EXCEPTION_ON_MISSING, Boolean.valueOf(b));
    482    }
    483
    484    /**
    485     * Sets a property for this parameters object. Properties are stored in an internal map. With this method a new entry
    486     * can be added to this map. If the value is <strong>null</strong>, the key is removed from the internal map. This method can be
    487     * used by sub classes which also store properties in a map.
    488     *
    489     * @param key the key of the property
    490     * @param value the value of the property
    491     */
    492    protected void storeProperty(final String key, final Object value) {
    493        if (value == null) {
    494            properties.remove(key);
    495        } else {
    496            properties.put(key, value);
    497        }
    498    }
    499}