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using Ilog.Language.Util;

namespace Ilog.Language.Parsing
{
  /**
   * This is the class of objects representing errors.
   *
   * @version     Last modified on Sun May 29 08:28:30 2005 by hak
   * @author      <a href="mailto:hak@ilog.fr">Hassan A&iuml;t-Kaci</a>
   * @copyright   &copy; 2001 <a href="http://www.ilog.fr/">ILOG, S.A.</a>
   */
  public class Error : Locatable
    {
      /**
       * A string starting  this error's message. Default is "*** ".
       */
      private string prefix = "*** ";
      public string Prefix
        {
	  get { return prefix; }
	  set { prefix = value; }
	}

      /**
       * A label identifying this error's message. Default is "Error: ".
       */
      private string label = "Error: ";
      public string Label
        {
	  get { return label; }
	  set { label = value; }
	}

      /**
       * This error's message. Defaults to "an error happened".
       */
      private string message = "an error happened";
      public string Message
        {
	  get { return message; }
	  set { message = value; }
	}

      /**
       * This error's location indicator. Defaults to " - see ".
       */
      private string see = " - see ";
      public string See
        {
	  get { return see; }
	  set { see = value; }
	}

      /**
       * This error's location extent. Defaults to null.
       */
      private Locatable extent;
      public Locatable Extent
        {
	  get { return extent; }
	  set { extent = value; }
	}

      /**
       * Sets this error's prefix to the specified string, and returns
       * this error.
       */
      public Error SetPrefix (string prefix)
        {
	  this.prefix = prefix;
	  return this;
	}

      /**
       * Sets this error's label to the specified string, and returns
       * this error.
       */
      public Error SetLabel (string label)
        {
	  this.label = label;
	  return this;
	}

      /**
       * Sets this error's message to the specified string, and returns
       * this error.
       */
      public Error SetMessage (string message)
        {
	  this.message = message;
	  return this;
	}

      /**
       * Sets this error's the string indicating this error's location
       * to specified string, and returns this error.
       */
      public Error SetSee (string see)
        {
	  this.see = see;
	  return this;
	}

      /**
       * Sets this error's location extent to the specified Locatable,
       * and returns this error.
       */
      public Error SetExtent (Locatable extent)
        {
	  this.extent = extent;
	  return this;
	}

      /**
       * Returns the start of this error's location extent as a Location.
       */
      public Location GetStart ()
        {
	  return (extent == null) ? null : extent.GetStart();
	}

      /**
       * Returns the end of this error's location extent as a Location.
       */
      public Location GetEnd ()
        {
	  return (extent == null) ? null : extent.GetEnd();
	}

      /**
       * Sets the start of this error's location extent to the specified
       * Location and returns this.
       */
      public Locatable SetStart (Location location)
        {
	  if (extent == null)
	    extent = new Span();
	  extent.SetStart(location);
	  return this;
	}

      /**
       * Sets the end of this error's location extent to the specified
       * Location and returns this.
       */
      public Locatable SetEnd (Location location)
        {
	  if (extent == null)
	    extent = new Span();
	  extent.SetEnd(location);
	  return this;
	}

      /**
       * Returns an explicit string describing the location extent. The
       * default is <tt>GetExtent().LocationString()</tt> if this
       * error's location extent is non <tt>null</tt>, or the empty
       * string otherwise. This method may be overridden.
       */
      public virtual string LocationString ()
        {
	  return (extent == null) ? "" : extent.LocationString();
	}

      /**
       * Returns a string composed of all the elements of this error in
       * the form: <tt>Prefix+Label+Message+See+LocationString()</tt>.
       * Thus, the default is <tt>"*** Error: an error happened - see
       * "+LocationString()</tt>.  This method may be overridden.
       */
      public override string ToString ()
        {
	  return prefix + label + message + see + LocationString();
	}
    }
}