package votorola.g.lang; // Copyright 2007-2008, 2011, 2013, Michael Allan.  Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Votorola Software"), to deal in the Votorola Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicence, and/or sell copies of the Votorola Software, and to permit persons to whom the Votorola Software is furnished to do so, subject to the following conditions: The preceding copyright notice and this permission notice shall be included in all copies or substantial portions of the Votorola Software. THE VOTOROLA SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE VOTOROLA SOFTWARE OR THE USE OR OTHER DEALINGS IN THE VOTOROLA SOFTWARE.

import java.util.*;


/** Throwable utilities.
  */
public final @ThreadSafe class ThrowableX
{


    private ThrowableX() {}



    /** An empty and immutable list of throwables for use with {@linkplain
      * #listedThrowable(Throwable,List) listedThrowable}.
      */
    public static final List<Throwable> ENLIST_NONE = Collections.emptyList();



    /** Returns true if both throwables are similar, or both null.  Compares class,
      * message, nested causes and stack trace.  These comparisons are sufficient to
      * discriminate among basic throwables, but not necessarily among their subclasses.
      */
    public static boolean isSimilar( final Throwable t1, final Throwable t2 )
    {
        if( t1 == null || t2 == null ) return t1 == t2;

        return t1.getClass().equals( t2.getClass() )
          && ObjectX.nullEquals( t1.getMessage(), t2.getMessage() )
          && isSimilar( t1.getCause(), t2.getCause() )
          && Arrays.equals( t1.getStackTrace(), t2.getStackTrace() );
    }



    /** Enlists the specified throwable and returns the list.
      *
      *     @param list the pre-constructed list to use.  {@linkplain #ENLIST_NONE
      *       ENLIST_NONE} may be specified in order to defeat enlistment and instead
      *       force immediate throwing, but the caller is responsible for detecting and
      *       implementing that.  Passing ENLIST_NONE into this method will raise
      *       UnsupportedOperationException.
      *     @return the pre-constructed list, or if necessary a lazily constructed linked
      *       list.
      */
    public static List<Throwable> listedThrowable( final Throwable x, List<Throwable> list )
    {
        if( list == null ) list = new LinkedList<Throwable>();

        list.add( x );
        return list;
    }



    /** Contructs an expanded <code>toString</code> that includes the throwable's own,
      * plus that of all nested causes.
      */
    public static String toStringExpanded( final Throwable t )
    {
        StringBuilder b = new StringBuilder();
        for( Throwable cause = t;; )
        {
            b.append( cause.toString() );
            cause = cause.getCause();
            if( cause == null ) break;

            b.append( ": " );
        }
        return b.toString();
    }


}