EnumProperty.java

package de.take_weiland.mods.commons.meta;

import com.google.common.collect.ImmutableSet;
import de.take_weiland.mods.commons.util.JavaUtils;

import java.util.EnumMap;
import java.util.EnumSet;
import java.util.Map;
import java.util.Set;

/**
 * @author diesieben07
 */
final class EnumProperty<T extends Enum<T>> extends GenericProperty<T> {

	private final int shift;
	private final int mask;
	private final Class<T> clazz;
	private final ImmutableSet<T> values;

	EnumProperty(int shift, Class<T> clazz) {
		this.shift = shift;
		this.clazz = clazz;
		this.values = ImmutableSet.copyOf(EnumSet.allOf(clazz));
		// values.size - 1 is largest ordinal ever used
		// highestOneBit of that << 1 is bit right above the MSB of the largest ordinal value
		// that - 1 gives a mask for all values
		this.mask = (Integer.highestOneBit(values.size() - 1) << 1) - 1;
	}

	@Override
	public T value(int metadata) {
		return JavaUtils.byOrdinal(clazz, (metadata >>> shift) & mask);
	}

	@Override
	public int toMeta(T value, int previousMeta) {
		return previousMeta | value.ordinal() << shift;
	}

	@Override
	public boolean hasDistinctValues() {
		return true;
	}

	@Override
	public Set<T> values() {
		return values;
	}

	@Override
	public <V> Map<T, V> createMap() {
		return new EnumMap<>(clazz);
	}
}