org.jclouds.functions.JoinOnComma.java Source code

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Here is the source code for org.jclouds.functions.JoinOnComma.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 org.jclouds.functions;

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;

import java.lang.reflect.Array;

import javax.inject.Singleton;

import com.google.common.base.Function;
import com.google.common.base.Joiner;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableList.Builder;
import com.google.common.collect.Iterables;

/**
 * 
 * @author Adrian Cole
 * 
 */
@Singleton
public class JoinOnComma implements Function<Object, String> {

    public String apply(Object o) {
        checkNotNull(o, "input cannot be null");
        if (o.getClass().isArray()) {
            Builder<Object> builder = ImmutableList.builder();
            for (int i = 0; i < Array.getLength(o); i++)
                builder.add(Array.get(o, i));
            o = builder.build();
        }
        checkArgument(o instanceof Iterable<?>, "you must pass an iterable or array");
        Iterable<?> toJoin = (Iterable<?>) o;
        checkArgument(Iterables.size(toJoin) > 0, "you must pass an iterable or array with elements");
        return Joiner.on(',').join(toJoin);
    }
}