AmiToolsVersion.java

/*
 * Copyright 2008-2012 Amazon Technologies, 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://aws.amazon.com/apache2.0
 *
 * This file 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 com.amazonaws.eclipse.ec2;

import java.text.ParseException;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * Represents the version number of the AMI bundling tools.
 */
public class AmiToolsVersion {
	private final int majorVersion;
	private final int minorVersion;
	private final int patch;

	private static final String regex = "^(\\d+)\\.(\\d+)-(\\d+)\\s*.*";
	private static final Pattern pattern = Pattern.compile(regex, Pattern.DOTALL);

	/**
	 * Constructs a new version object directly from major, minor, and patch
	 * version numbers.
	 * 
	 * @param majorVersion
	 *            The major version for this new version object.
	 * @param minorVersion
	 *            The minor version for this new version object.
	 * @param patch
	 *            The patch version for this new version object.
	 */
	public AmiToolsVersion(int majorVersion, int minorVersion, int patch) {
		this.majorVersion = majorVersion;
		this.minorVersion = minorVersion;
		this.patch = patch;
	}

	/**
	 * Constructs a new version object by parsing a version string, which is
	 * assumed to be of the form:
	 * <major-version>.<minor-version>-<patch-version>
	 * 
	 * @param versionString
	 *            The version string to parse for the major, minor and patch
	 *            version numbers.
	 * 
	 * @throws ParseException
	 *             If the version string parameter was not able to be parsed
	 *             into the expected format.
	 */
	public AmiToolsVersion(String versionString) throws ParseException {
		String parseExceptionMessage = "Version string '" + versionString 
			+ "' does not start with version number in the form " 
			+ "'<major-version>.<minor-version>-<patch-version>'";
	
		Matcher matcher = pattern.matcher(versionString);
		if (! matcher.matches()) {
			throw new ParseException(parseExceptionMessage, -1);
		}

		try {
			majorVersion = Integer.parseInt(matcher.group(1));
			minorVersion = Integer.parseInt(matcher.group(2));
			patch        = Integer.parseInt(matcher.group(3));
		} catch (Throwable t) {
			throw new ParseException(parseExceptionMessage, -1);
		}
	}
	
	/* (non-Javadoc)
	 * @see java.lang.Object#toString()
	 */
	@Override
	public String toString() {
		return majorVersion + "." + minorVersion + "-" + patch;
	}

	/**
	 * Returns true if this version is greater than the specified version.
	 * 
	 * @param other
	 *            The other version to compare against.
	 * 
	 * @return True if this version is greater than the other specified
	 *         version.
	 */
	public boolean isGreaterThan(AmiToolsVersion other) {
		if (this.majorVersion > other.majorVersion) {
			return true;
		} else if (this.majorVersion < other.majorVersion) {
			return false;
		}
		
		if (this.minorVersion > other.minorVersion) {
			return true;
		} else if (this.minorVersion < other.minorVersion) {
			return false;
		}
		
		if (this.patch > other.patch) {
			return true;
		} else if (this.patch < other.patch) {
			return false;
		}
		
		return false;
	}

	/**
	 * Returns the major version component of this version number.
	 * 
	 * @return The major version component of this version number.
	 */
	public int getMajorVersion() {
		return majorVersion;
	}

	/**
	 * Returns the minor version component of this version number.
	 * 
	 * @return The minor version component of this version number.
	 */
	public int getMinorVersion() {
		return minorVersion;
	}

	/**
	 * Returns the patch component of this version number.
	 * 
	 * @return The patch component of this version number.
	 */
	public int getPatch() {
		return patch;
	}
	
}