CommandModuleItem.java

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package org.scijava.command;

import java.lang.reflect.Field;
import java.lang.reflect.Type;
import java.util.ArrayList;
import java.util.List;

import org.scijava.ItemIO;
import org.scijava.ItemVisibility;
import org.scijava.Optional;
import org.scijava.module.AbstractModuleItem;
import org.scijava.module.ModuleInfo;
import org.scijava.module.ModuleItem;
import org.scijava.plugin.Attr;
import org.scijava.plugin.Parameter;
import org.scijava.util.ConversionUtils;
import org.scijava.util.Types;

/**
 * {@link ModuleItem} implementation describing an input or output of a command.
 * 
 * @author Curtis Rueden
 */
public class CommandModuleItem<T> extends AbstractModuleItem<T> {

	private final Field field;

	public CommandModuleItem(final ModuleInfo info, final Field field) {
		super(info);
		this.field = field;
	}

	// -- CommandModuleItem methods --

	public Field getField() {
		return field;
	}

	public Parameter getParameter() {
		return field.getAnnotation(Parameter.class);
	}

	// -- ModuleItem methods --

	@Override
	public Class<T> getType() {
		final Class<?> type = Types.raw(Types.fieldType(field, getDelegateClass()));
		@SuppressWarnings("unchecked")
		final Class<T> typedType = (Class<T>) type;
		return typedType;
	}

	@Override
	public Type getGenericType() {
		return Types.fieldType(field, getDelegateClass());
	}

	@Override
	public ItemIO getIOType() {
		return getParameter().type();
	}

	@Override
	public ItemVisibility getVisibility() {
		return getParameter().visibility();
	}

	@Override
	public boolean isAutoFill() {
		return getParameter().autoFill();
	}

	@Override
	public boolean isRequired() {
		return getParameter().required() &&
			!Optional.class.isAssignableFrom(getType());
	}

	@Override
	public boolean isPersisted() {
		return getParameter().persist();
	}

	@Override
	public String getPersistKey() {
		return getParameter().persistKey();
	}

	@Override
	public String getInitializer() {
		return getParameter().initializer();
	}

	@Override
	public String getValidater() {
		return getParameter().validater();
	}

	@Override
	public String getCallback() {
		return getParameter().callback();
	}

	@Override
	public String getWidgetStyle() {
		return getParameter().style();
	}

	@Override
	public T getMinimumValue() {
		return tValue(getParameter().min());
	}

	@Override
	public T getMaximumValue() {
		return tValue(getParameter().max());
	}

	@Override
	public T getDefaultValue() {
		// NB: The default value for a command is the initial field value.
		// E.g.:
		//
		//   @Parameter
		//   private int weekdays = 5;
		//
		// To obtain this information, we need to instantiate the module, then
		// extract the value of the associated field.
		//
		// Of course, the command might do evil things like:
		//
		//   @Parameter
		//   private long time = System.currentTimeMillis();
		//
		// In which case the default value will vary by instance. But there is
		// nothing we can really do about that. This is only a best effort.

		try {
			final Object dummy = getInfo().loadDelegateClass().newInstance();
			@SuppressWarnings("unchecked")
			final T value = (T) getField().get(dummy);
			return value;
		}
		catch (final InstantiationException | IllegalAccessException
				| ClassNotFoundException exc)
		{
			throw new IllegalStateException(exc);
		}
	}

	@Override
	public Number getStepSize() {
		// FIXME: stepSize should be typed on T, not Number!
		final String value = getParameter().stepSize();
		try {
			final double stepSize = Double.parseDouble(value);
			return stepSize;
		}
		catch (final NumberFormatException exc) {
			return tValue(value, Number.class);
		}
	}

	@Override
	public String getFormat() {
		return getParameter().format();
	}

	@Override
	public int getColumnCount() {
		return getParameter().columns();
	}

	@Override
	public List<T> getChoices() {
		final String[] choices = getParameter().choices();
		if (choices.length == 0) return super.getChoices();

		final ArrayList<T> choiceList = new ArrayList<>();
		for (final String choice : choices) {
			choiceList.add(tValue(choice));
		}
		return choiceList;
	}

	// -- BasicDetails methods --

	@Override
	public String getLabel() {
		return getParameter().label();
	}

	@Override
	public String getDescription() {
		return getParameter().description();
	}

	@Override
	public boolean is(final String key) {
		for (final Attr attr : getParameter().attrs()) {
			if (attr.name().equals(key)) return true;
		}
		return false;
	}

	@Override
	public String get(final String key) {
		for (final Attr attr : getParameter().attrs()) {
			if (attr.name().equals(key)) return attr.value();
		}
		return null;
	}

	// -- Named methods --

	@Override
	public String getName() {
		return field.getName();
	}

	// -- Helper methods --

	private T tValue(final String value) {
		return tValue(value, getType());
	}

	private <D> D tValue(final String value, final Class<D> type) {
		if (value == null || value.isEmpty()) return null;
		final Class<D> saneType = Types.box(type);
		return ConversionUtils.convert(value, saneType);
	}

}