/TCL/src/commands/LreplaceCmd.cs

/*
* LreplaceCmd.java
*
* Copyright (c) 1997 Cornell University.
* Copyright (c) 1997 Sun Microsystems, Inc.
*
* See the file "license.terms" for information on usage and
* redistribution of this file, and for a DISCLAIMER OF ALL
* WARRANTIES.
* 
* Included in SQLite3 port to C# for use in testharness only;  2008 Noah B Hart
*
* RCS @(#) $Id: LreplaceCmd.java,v 1.5 2003/01/09 02:15:39 mdejong Exp $
*
*/
using System;
namespace tcl.lang
{

  /// <summary> This class implements the built-in "lreplace" command in Tcl.</summary>

  class LreplaceCmd : Command
  {
    /// <summary> See Tcl user documentation for details.</summary>
    /// <exception cref=""> TclException If incorrect number of arguments.
    /// </exception>

    public TCL.CompletionCode cmdProc( Interp interp, TclObject[] argv )
    {
      if ( argv.Length < 4 )
      {
        throw new TclNumArgsException( interp, 1, argv, "list first last ?element element ...?" );
      }
      int size = TclList.getLength( interp, argv[1] );
      int first = Util.getIntForIndex( interp, argv[2], size - 1 );
      int last = Util.getIntForIndex( interp, argv[3], size - 1 );
      int numToDelete;

      if ( first < 0 )
      {
        first = 0;
      }

      // Complain if the user asked for a start element that is greater
      // than the list length. This won't ever trigger for the "end*"
      // case as that will be properly constrained by getIntForIndex
      // because we use size-1 (to allow for replacing the last elem).

      if ( ( first >= size ) && ( size > 0 ) )
      {

        throw new TclException( interp, "list doesn't contain element " + argv[2] );
      }
      if ( last >= size )
      {
        last = size - 1;
      }
      if ( first <= last )
      {
        numToDelete = ( last - first + 1 );
      }
      else
      {
        numToDelete = 0;
      }

      TclObject list = argv[1];
      bool isDuplicate = false;

      // If the list object is unshared we can modify it directly. Otherwise
      // we create a copy to modify: this is "copy on write".

      if ( list.Shared )
      {
        list = list.duplicate();
        isDuplicate = true;
      }

      try
      {
        TclList.replace( interp, list, first, numToDelete, argv, 4, argv.Length - 1 );
        interp.setResult( list );
      }
      catch ( TclException e )
      {
        if ( isDuplicate )
        {
          list.release();
        }
        throw;
      }
      return TCL.CompletionCode.RETURN;
    }
  }
}