org.ros.message.MessageDefinition.java Source code

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Here is the source code for org.ros.message.MessageDefinition.java

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/*
 * Copyright (C) 2011 Google Inc.
 * 
 * Licensed 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.ros.message;

import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableMap;

import org.ros.internal.transport.ConnectionHeaderFields;

import java.util.Map;

/**
 * The definition of a ROS message.
 * 
 * @author damonkohler@google.com (Damon Kohler)
 */
public class MessageDefinition {

    private final String type;
    private final String definition;
    private final String md5Checksum;

    public static MessageDefinition newFromHeader(Map<String, String> header) {
        Preconditions.checkArgument(header.containsKey(ConnectionHeaderFields.TYPE));
        Preconditions.checkArgument(header.containsKey(ConnectionHeaderFields.MD5_CHECKSUM));
        return new MessageDefinition(header.get(ConnectionHeaderFields.TYPE), null,
                header.get(ConnectionHeaderFields.MD5_CHECKSUM));
    }

    /**
     * Create a new {@link MessageDefinition}, which consists only of the
     * specified message type.
     * 
     * <p>
     * The {@code definition} and {@code md5checksum} will be {@code null}.
     * 
     * @param type
     * @return a new {@link MessageDefinition}
     */
    public static MessageDefinition newFromTypeName(String type) {
        return new MessageDefinition(type, null, null);
    }

    /**
     * Create a new message definition.
     * 
     * @param type
     *          the type of the message
     * @param definition
     *          the definition of the message, can be {@code null}
     * @param md5Checksum
     *          the MD5 checksum of the message, can be {@code null}
     * @return a new {@link MessageDefinition}
     */
    public static MessageDefinition newFromStrings(String type, String definition, String md5Checksum) {
        // TODO(damonkohler): Change this factory method to calculate the MD5 from
        // the definition.
        return new MessageDefinition(type, definition, md5Checksum);
    }

    private MessageDefinition(String type, String definition, String md5Checksum) {
        Preconditions.checkNotNull(type);
        this.type = type;
        this.definition = definition;
        this.md5Checksum = md5Checksum;
    }

    public String getType() {
        return type;
    }

    public String getDefinition() {
        Preconditions.checkNotNull(definition);
        return definition;
    }

    public String getMd5Checksum() {
        Preconditions.checkNotNull(md5Checksum);
        return md5Checksum;
    }

    public Map<String, String> toHeader() {
        Preconditions.checkNotNull(md5Checksum);
        return new ImmutableMap.Builder<String, String>().put(ConnectionHeaderFields.TYPE, type)
                .put(ConnectionHeaderFields.MD5_CHECKSUM, md5Checksum)
                .put(ConnectionHeaderFields.MESSAGE_DEFINITION, definition).build();
    }

    @Override
    public String toString() {
        return "MessageDefinition<" + type + ", " + md5Checksum + ">";
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + ((md5Checksum == null) ? 0 : md5Checksum.hashCode());
        result = prime * result + ((type == null) ? 0 : type.hashCode());
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        MessageDefinition other = (MessageDefinition) obj;
        if (type == null) {
            if (other.type != null)
                return false;
        } else if (!type.equals(other.type))
            return false;
        if (md5Checksum == null || other.md5Checksum == null) {
            return true;
        } else if (!md5Checksum.equals(other.md5Checksum))
            return false;
        return true;
    }
}