brooklyn.util.yaml.Yamls.java Source code

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Here is the source code for brooklyn.util.yaml.Yamls.java

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/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF 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 brooklyn.util.yaml;

import java.io.Reader;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.google.common.collect.Iterables;

public class Yamls {

    private static final Logger log = LoggerFactory.getLogger(Yamls.class);

    /** returns the given yaml object (map or list or primitive) as the given yaml-supperted type 
     * (map or list or primitive e.g. string, number, boolean).
     * <p>
     * if the object is an iterable containing a single element, and the type is not an iterable,
     * this will attempt to unwrap it.
     * 
     * @throws IllegalArgumentException if the input is an iterable not containing a single element,
     *   and the cast is requested to a non-iterable type 
     * @throws ClassCastException if cannot be casted */
    @SuppressWarnings({ "unchecked", "rawtypes" })
    public static <T> T getAs(Object x, Class<T> type) {
        if (x == null)
            return null;
        if (x instanceof Iterable || x instanceof Iterator) {
            List result = new ArrayList();
            Iterator xi;
            if (Iterator.class.isAssignableFrom(x.getClass())) {
                xi = (Iterator) x;
            } else {
                xi = ((Iterable) x).iterator();
            }
            while (xi.hasNext()) {
                result.add(xi.next());
            }
            if (type.isAssignableFrom(Iterable.class))
                return (T) result;
            if (type.isAssignableFrom(Iterator.class))
                return (T) result.iterator();
            if (type.isAssignableFrom(List.class))
                return (T) result;
            x = Iterables.getOnlyElement(result);
        }
        return (T) x;
    }

    @SuppressWarnings("rawtypes")
    public static void dump(int depth, Object r) {
        if (r instanceof Iterable) {
            for (Object ri : ((Iterable) r))
                dump(depth + 1, ri);
        } else if (r instanceof Map) {
            for (Object re : ((Map) r).entrySet()) {
                for (int i = 0; i < depth; i++)
                    System.out.print(" ");
                System.out.println(((Entry) re).getKey() + ":");
                dump(depth + 1, ((Entry) re).getValue());
            }
        } else {
            for (int i = 0; i < depth; i++)
                System.out.print(" ");
            if (r == null)
                System.out.println("<null>");
            else
                System.out.println("<" + r.getClass().getSimpleName() + ">" + " " + r);
        }
    }

    /** simplifies new Yaml().loadAll, and converts to list to prevent single-use iterable bug in yaml */
    @SuppressWarnings("unchecked")
    public static Iterable<Object> parseAll(String yaml) {
        Iterable<Object> result = new org.yaml.snakeyaml.Yaml().loadAll(yaml);
        return (List<Object>) getAs(result, List.class);
    }

    /** as {@link #parseAll(String)} */
    @SuppressWarnings("unchecked")
    public static Iterable<Object> parseAll(Reader yaml) {
        Iterable<Object> result = new org.yaml.snakeyaml.Yaml().loadAll(yaml);
        return (List<Object>) getAs(result, List.class);
    }

    public static Object removeMultinameAttribute(Map<String, Object> obj, String... equivalentNames) {
        Object result = null;
        for (String name : equivalentNames) {
            Object candidate = obj.remove(name);
            if (candidate != null) {
                if (result == null)
                    result = candidate;
                else if (!result.equals(candidate)) {
                    log.warn("Different values for attributes " + Arrays.toString(equivalentNames) + "; "
                            + "preferring '" + result + "' to '" + candidate + "'");
                }
            }
        }
        return result;
    }

    public static Object getMultinameAttribute(Map<String, Object> obj, String... equivalentNames) {
        Object result = null;
        for (String name : equivalentNames) {
            Object candidate = obj.get(name);
            if (candidate != null) {
                if (result == null)
                    result = candidate;
                else if (!result.equals(candidate)) {
                    log.warn("Different values for attributes " + Arrays.toString(equivalentNames) + "; "
                            + "preferring '" + result + "' to '" + candidate + "'");
                }
            }
        }
        return result;
    }
}