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package org.scijava.io.location;

import java.io.IOException;
import java.util.Collections;
import java.util.Set;

/**
 * A {@link Location} that offers methods to browse other locations relative to
 * it.
 *
 * @author Gabriel Einsdorf
 * @author Curtis Rueden
 */
public interface BrowsableLocation extends Location {

	/**
	 * Obtains a location pointing to the parent directory of this one.
	 * 
	 * @return the parent location of this one, or null if this
	 *         location has no parent.
	 * @throws IOException if something goes wrong obtaining the parent.
	 */
	BrowsableLocation parent() throws IOException;

	/**
	 * Obtains a collection of locations for whom this location is the parent.
	 * Note that this will only succeed if calls to {@link #isDirectory()} on this
	 * location return true.
	 * 
	 * @return A set containing the children of this location, or
	 *         {@link Collections#EMPTY_SET} if this location has no children.
	 * @throws IOException if something goes wrong obtaining the children.
	 * @throws IllegalArgumentException if this location is not a directory (i.e.,
	 *           {@link #isDirectory()} returns false).
	 */
	Set children() throws IOException;

	/**
	 * Obtains a location relative to this one, which will be configured
	 * like the current location, but point to a the file specified by the
	 * path parameter.
	 *
	 * @param path the relative path of the desired location.
	 * @return A location that points to the specified file location.
	 * @throws IOException if something goes wrong obtaining the sibling
	 */
	BrowsableLocation sibling(String path) throws IOException;

	/**
	 * Tests whether this location is a directory, meaning that it can have
	 * children. It is recommended to use this method before calling
	 * {@link #child(String)} or {@link #children()}, to ensure those calls
	 * succeed.
	 * 
	 * @return True iff the location represents a directory.
	 */
	boolean isDirectory();

	/**
	 * Obtains a location with the given name, for whom this location is the
	 * parent. Note that this will only succeed if calls to {@link #isDirectory()}
	 * on this location return true.
	 *
	 * @param name the name of the child
	 * @return a location pointing to the child
	 * @throws IOException if something goes wrong obtaining the child.
	 * @throws IllegalArgumentException if this location is not a directory (i.e.,
	 *           {@link #isDirectory()} returns false).
	 */
	BrowsableLocation child(String name) throws IOException;
}