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 */
017
018package org.apache.commons.configuration2;
019
020import java.io.IOException;
021import java.io.InputStream;
022import java.io.Reader;
023import java.io.Writer;
024import java.util.Map;
025
026import org.apache.commons.configuration2.ex.ConfigurationException;
027import org.apache.commons.configuration2.io.InputStreamSupport;
028import org.apache.commons.configuration2.tree.ImmutableNode;
029import org.yaml.snakeyaml.DumperOptions;
030import org.yaml.snakeyaml.LoaderOptions;
031import org.yaml.snakeyaml.Yaml;
032import org.yaml.snakeyaml.constructor.SafeConstructor;
033import org.yaml.snakeyaml.representer.Representer;
034
035/**
036 * <p>
037 * A specialized hierarchical configuration class that is able to parse YAML documents.
038 * </p>
039 *
040 * @since 2.2
041 */
042public class YAMLConfiguration extends AbstractYAMLBasedConfiguration implements FileBasedConfiguration, InputStreamSupport {
043    /**
044     * Creates a {@code Yaml} object for reading a Yaml file. The object is configured with some default settings.
045     *
046     * @param options options for loading the file
047     * @return the {@code Yaml} instance for loading a file
048     */
049    private static Yaml createYamlForReading(final LoaderOptions options) {
050        return new Yaml(new SafeConstructor(options), new Representer(new DumperOptions()), new DumperOptions(), options);
051    }
052
053    /**
054     * Creates a new instance of {@code YAMLConfiguration}.
055     */
056    public YAMLConfiguration() {
057    }
058
059    /**
060     * Creates a new instance of {@code YAMLConfiguration} as a copy of the specified configuration.
061     *
062     * @param c the configuration to be copied
063     */
064    public YAMLConfiguration(final HierarchicalConfiguration<ImmutableNode> c) {
065        super(c);
066    }
067
068    public void dump(final Writer out, final DumperOptions options)
069            throws ConfigurationException, IOException {
070        final Yaml yaml = new Yaml(options);
071        yaml.dump(constructMap(getNodeModel().getNodeHandler().getRootNode()), out);
072    }
073
074    /**
075     * Loads the configuration from the given input stream.
076     *
077     * @param in the input stream
078     * @throws ConfigurationException if an error occurs
079     */
080    @Override
081    public void read(final InputStream in) throws ConfigurationException {
082        try {
083            final Yaml yaml = createYamlForReading(new LoaderOptions());
084            final Map<String, Object> map = yaml.load(in);
085            load(map);
086        } catch (final Exception e) {
087            rethrowException(e);
088        }
089    }
090
091    public void read(final InputStream in, final LoaderOptions options) throws ConfigurationException {
092        try {
093            final Yaml yaml = createYamlForReading(options);
094            final Map<String, Object> map = yaml.load(in);
095            load(map);
096        } catch (final Exception e) {
097            rethrowException(e);
098        }
099    }
100
101    @Override
102    public void read(final Reader in) throws ConfigurationException {
103        try {
104            final Yaml yaml = createYamlForReading(new LoaderOptions());
105            final Map<String, Object> map = yaml.load(in);
106            load(map);
107        } catch (final Exception e) {
108            rethrowException(e);
109        }
110    }
111
112    public void read(final Reader in, final LoaderOptions options) throws ConfigurationException {
113        try {
114            final Yaml yaml = createYamlForReading(options);
115            final Map<String, Object> map = yaml.load(in);
116            load(map);
117        } catch (final Exception e) {
118            rethrowException(e);
119        }
120    }
121
122    @Override
123    public void write(final Writer out) throws ConfigurationException, IOException {
124        final DumperOptions options = new DumperOptions();
125        options.setDefaultFlowStyle(DumperOptions.FlowStyle.BLOCK);
126        dump(out, options);
127    }
128
129}