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// File path shortening code adapted from:
// from: http://www.rgagnon.com/javadetails/java-0661.html

package org.scijava.util;

import java.util.List;

/**
 * Useful methods for working with {@link List}s.
 * 
 * @author Curtis Rueden
 */
public final class ListUtils {

	private ListUtils() {
		// prevent instantiation of utility class
	}

	/** Gets the first element of the given list, or null if none. */
	public static  T first(final List list) {
		if (list == null || list.size() == 0) return null;
		return list.get(0);
	}

	/**
	 * Converts the given list to a string.
	 * 
	 * The list elements will be separated by a comma then a space. The list will
	 * be enclosed in square brackets.
	 * 
	 * 
	 * @param list The list to stringify.
	 * @see #string(List, String, String, String, boolean)
	 */
	public static String string(final List list) {
		return string(list, true);
	}

	/**
	 * Converts the given list to a string.
	 * 
	 * The list elements will be separated by a comma then a space. The list will
	 * be enclosed in square brackets unless it is a singleton with the
	 * {@code encloseSingletons} flag set to false.
	 * 
	 * 
	 * @param list The list to stringify.
	 * @param encloseSingletons Whether to enclose singleton lists in brackets.
	 * @return The stringified list.
	 * @see #string(List, String, String, String, boolean)
	 */
	public static String string(final List list,
		final boolean encloseSingletons)
	{
		return string(list, "[", "]", ", ", encloseSingletons);
	}

	/**
	 * Converts the given list to a string.
	 * 
	 * The list elements will be comma-separated. It will be enclosed in square
	 * brackets unless the list is a singleton with the {@code encloseSingletons}
	 * flag set to false.
	 * 
	 * 
	 * @param list The list to stringify.
	 * @param lDelimiter The left-hand symbol(s) in which to enclose the list.
	 * @param rDelimiter The right-hand symbol(s) in which to enclose the list.
	 * @param separator The symbol(s) to place in between each element.
	 * @param encloseSingletons Whether to enclose singleton lists inside the
	 *          delimiter symbols.
	 * @return The stringified list.
	 */
	public static String string(final List list, //
		final String lDelimiter, final String rDelimiter, //
		final String separator, final boolean encloseSingletons)
	{
		final boolean delimit = encloseSingletons || list.size() != 1;
		final StringBuilder sb = new StringBuilder();
		if (delimit) sb.append(lDelimiter);
		boolean first = true;
		for (final Object e : list) {
			if (first) first = false;
			else sb.append(separator);
			sb.append(e);
		}
		if (delimit) sb.append(rDelimiter);
		return sb.toString();
	}
}