Version.java

package aQute.bnd.version;

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

public class Version implements Comparable<Version> {
	private static final String	HIGHESTCHAR	= "\uFFFF";
	final int					major;
	final int					minor;
	final int					micro;
	final String				qualifier;
	final boolean	snapshot;

	public final static String	VERSION_STRING	= "(\\d{1,9})(\\.(\\d{1,9})(\\.(\\d{1,9})(\\.([-_\\da-zA-Z]+))?)?)?";
	public final static Pattern	VERSION			= Pattern.compile(VERSION_STRING);
	public final static Version	LOWEST			= new Version();
	public final static Version	HIGHEST			= new Version(Integer.MAX_VALUE, Integer.MAX_VALUE, Integer.MAX_VALUE,
			HIGHESTCHAR);

	public static final Version	emptyVersion	= LOWEST;
	public static final Version	ONE				= new Version(1, 0, 0);
	public static final Pattern	SNAPSHOT_P		= Pattern.compile("(.*-)?SNAPSHOT$");

	public Version() {
		this(0);
	}

	public Version(int major, int minor, int micro, String qualifier) {
		this.major = major;
		this.minor = minor;
		this.micro = micro;
		this.qualifier = qualifier;
		this.snapshot = isSnapshot(qualifier);
	}

	public Version(int major, int minor, int micro) {
		this(major, minor, micro, null);
	}

	public Version(int major, int minor) {
		this(major, minor, 0, null);
	}

	public Version(int major) {
		this(major, 0, 0, null);
	}

	public Version(String version) {
		version = version.trim();
		Matcher m = VERSION.matcher(version);
		if (!m.matches())
			throw new IllegalArgumentException("Invalid syntax for version: " + version);

		major = Integer.parseInt(m.group(1));
		if (m.group(3) != null)
			minor = Integer.parseInt(m.group(3));
		else
			minor = 0;

		if (m.group(5) != null)
			micro = Integer.parseInt(m.group(5));
		else
			micro = 0;

		qualifier = m.group(7);
		this.snapshot = isSnapshot(qualifier);
	}

	private boolean isSnapshot(String qualifier) {
		return qualifier != null && qualifier != HIGHESTCHAR && SNAPSHOT_P.matcher(qualifier).matches();
	}

	public int getMajor() {
		return major;
	}

	public int getMinor() {
		return minor;
	}

	public int getMicro() {
		return micro;
	}

	public String getQualifier() {
		return qualifier;
	}

	public int compareTo(Version other) {
		if (other == this)
			return 0;

		Version o = other;
		if (major != o.major)
			return major - o.major;

		if (minor != o.minor)
			return minor - o.minor;

		if (micro != o.micro)
			return micro - o.micro;

		int c = 0;
		if (qualifier != null)
			c = 1;
		if (o.qualifier != null)
			c += 2;

		switch (c) {
			case 0 :
				return 0;
			case 1 :
				return 1;
			case 2 :
				return -1;
		}
		return qualifier.compareTo(o.qualifier);
	}

	@Override
	public String toString() {
		StringBuilder sb = new StringBuilder();
		sb.append(major);
		sb.append(".");
		sb.append(minor);
		sb.append(".");
		sb.append(micro);
		if (qualifier != null) {
			sb.append(".");
			sb.append(qualifier);
		}
		return sb.toString();
	}

	@Override
	public boolean equals(Object ot) {
		if (!(ot instanceof Version))
			return false;

		return compareTo((Version) ot) == 0;
	}

	@Override
	public int hashCode() {
		return major * 97 ^ minor * 13 ^ micro + (qualifier == null ? 97 : qualifier.hashCode());
	}

	public int get(int i) {
		switch (i) {
			case 0 :
				return major;
			case 1 :
				return minor;
			case 2 :
				return micro;
			default :
				throw new IllegalArgumentException("Version can only get 0 (major), 1 (minor), or 2 (micro)");
		}
	}

	public static Version parseVersion(String version) {
		if (version == null) {
			return LOWEST;
		}

		version = version.trim();
		if (version.length() == 0) {
			return LOWEST;
		}

		return new Version(version);

	}

	public Version getWithoutQualifier() {
		if (qualifier == null) {
			return this;
		}
		return new Version(major, minor, micro);
	}

	public static boolean isVersion(String version) {
		return version != null && VERSION.matcher(version).matches();
	}

	public boolean isSnapshot() {
		return snapshot;
	}

}