net.razorvine.pickle.objects.TimeZoneConstructor Maven / Gradle / Ivy

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This library allows your Java program to interface very easily with the Python world. It uses the Pyro protocol to call methods on remote objects. (See https://pyro5.readthedocs.io/). Pyrolite only implements part of the client side Pyro library, hence its name 'lite'... So if you don't need Pyro's full feature set, Pyrolite may be a good choice to connect java or .NET and python. Version 5.0 changes: support Pyro5 wire protocol. Dropped support of Pyro4 (stick to version 4.xx for that).

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package net.razorvine.pickle.objects;

import net.razorvine.pickle.IObjectConstructor;
import net.razorvine.pickle.PickleException;
import net.razorvine.pickle.objects.Tzinfo;
import java.util.TimeZone;

public class TimeZoneConstructor implements IObjectConstructor {
	public static int UTC = 1;
	public static int PYTZ = 2;
	public static int DATEUTIL_TZUTC = 3;
	public static int DATEUTIL_TZFILE = 4;
	public static int DATEUTIL_GETTZ = 5;
	public static int TZINFO = 6;

	private int pythontype;

	public TimeZoneConstructor(int pythontype) {
		this.pythontype = pythontype;
	}
	
	@Override
	public Object construct(Object[] args) throws PickleException {
	if (this.pythontype == UTC)
		return createUTC();
	if (this.pythontype == PYTZ)
		return createZoneFromPytz(args);
	if (this.pythontype == DATEUTIL_TZUTC)
		return createInfoFromDateutilTzutc(args);
	if (this.pythontype == DATEUTIL_TZFILE)
		return createInfoFromDateutilTzfile(args);
	if (this.pythontype == DATEUTIL_GETTZ)
		return createInfoFromDateutilGettz(args);
	if (this.pythontype == TZINFO)
		return createInfo(args);

	throw new PickleException("invalid object type");
	}

	public Object reconstruct(Object baseConstructor, Object state) {
		if (!(state instanceof Tzinfo))
			throw new PickleException("invalid pickle data for tzinfo reconstruction; expected emtpy tzinfo state class");
		if (!(baseConstructor instanceof TimeZoneConstructor))
			throw new PickleException("invalid pickle data for tzinfo reconstruction; expected a TimeZoneConstructor from a known tzinfo subclass");

		// The subclass (this) is reconstructing the state given the base class and state. If it is known that the
		// subclass is always UTC, ie dateutil.tz.tzutc, then we can just return the timezone we know matches that.
		if (this.pythontype == DATEUTIL_TZUTC) {
			return TimeZone.getTimeZone("UTC");
		} else {
			throw new PickleException("unsupported pickle data for tzinfo reconstruction; support for tzinfo subclasses other than tztuc has not been implemented");
		}
	}

	private Object createInfo(Object[] args) {
		// args is empty, datetime.tzinfo objects are unpickled via setstate, so return an object which is ready to have it's state set
		return new Tzinfo();
	}

	private Object createInfoFromDateutilTzutc(Object[] args) {
		// In the case of the dateutil.tz.tzutc constructor, which is a python subclass of the datetime.tzinfo class, there is no state
		// to set, because the zone is implied by the constructor. Pass the timezone indicated by the constructor here
		return new Tzinfo(TimeZone.getTimeZone("UTC"));
	}

	private Object createInfoFromDateutilTzfile(Object[] args) {
		if (args.length != 1)
			throw new PickleException("invalid pickle data for dateutil tzfile timezone; expected 1 args, got " + args.length);

		// In the case of the dateutil.tz.tzfile constructor, which is a python subclass of the datetime.tzinfo class, we're passed a
		// fully qualified path to a zoneinfo file. Extract the actual identifier as the part after the "zoneinfo" folder in the
		// absolute path.
		String identifier = (String) args[0];
		int index = identifier.indexOf("zoneinfo");
		if (index != -1) {
			identifier = identifier.substring(index + 8 + 1);
		} else {
			throw new PickleException("couldn't parse timezone identifier from zoneinfo path" + identifier);
		}
		return new Tzinfo(TimeZone.getTimeZone(identifier));
	}

	private Object createInfoFromDateutilGettz(Object[] args) {
		if (args.length != 1)
			throw new PickleException("invalid pickle data for dateutil gettz call; expected 1 args, got " + args.length);

		// In the case of the dateutil.tz.gettz function call, we're passed one string identifier of the the timezone.
		String identifier = (String) args[0];
		return new Tzinfo(TimeZone.getTimeZone(identifier));
	}

	private Object createZoneFromPytz(Object[] args) {

		if (args.length != 4 && args.length != 1)
			throw new PickleException("invalid pickle data for pytz timezone; expected 1 or 4 args, got " + args.length);

		// args can be a tuple of 4 values: string timezone identifier, int seconds from utc offset, int seconds for DST, string python timezone name
		// if args came from a pytz.DstTzInfo object
		// Or, args is a tuple of 1 value: string timezone identifier
		// if args came from a pytz.StaticTzInfo object
		// In both cases we can ask the system for a timezone with that identifier and it should find one with that identifier if python did.

		if (!(args[0] instanceof String))
			throw new PickleException("invalid pickle data for pytz timezone; expected string argument as first tuple member");
		return TimeZone.getTimeZone((String) args[0]);
	}

	private Object createUTC() {
		return TimeZone.getTimeZone("UTC");
	}
}