/*
    * Copyright (C) 1998-2000 Semiotek Inc.  All Rights Reserved.
    *
    * Redistribution and use in source and binary forms, with or without
    * modification, are permitted under the terms of either of the following
    * Open Source licenses:
    *
    * The GNU General Public License, version 2, or any later version, as
    * published by the Free Software Foundation
   * (http://www.fsf.org/copyleft/gpl.html);
   *
   *  or
   *
   * The Semiotek Public License (http://webmacro.org/LICENSE.)
   *
   * This software is provided "as is", with NO WARRANTY, not even the
   * implied warranties of fitness to purpose, or merchantability. You
   * assume all risks and liabilities associated with its use.
   *
   * See www.webmacro.org for more information on the WebMacro project.
   */
  
  /***
   * @author Brian Goetz
   */
  
  package org.webmacro.parser;
  
  import org.webmacro.engine.BlockBuilder;
  
  /***
   * ParserBlockBuilder extends BlockBuilder, and should only be used by
   * the WMParser_impl parser.  It adds methods for eating trailing
   * <WHITESPACE>  or  <WHITESPACE> <NL> <WHITESPACE>  that precede directives.
   * It assumes that literal text will not span elements (true for the
   * current parser) so if the parser changes, this will need to change too.
   */
  
  
  public class ParserBlockBuilder extends BlockBuilder
  {
  
      private int literalMark = 0;
  
      public ParserBlockBuilder ()
      {
          super();
      }
  
      public ParserBlockBuilder (String name)
      {
          super(name);
      }
  
      /*** Mark the last character in the block as being a literal (quoted
       * with backslash) so we don't eat trailing quoted whitespace.
       */
      final public void markLiteral ()
      {
          literalMark = size();
      }
  
      private final static boolean isSpaceChar (char c)
      {
          return (c == ' ' || c == '\t');
      }
  
      private final static int eatWs (String s, int pos)
      {
          while (pos >= 0 && isSpaceChar(s.charAt(pos)))
              pos--;
          return pos;
      }
  
      private final static int eatOneWs (String s, int pos)
      {
          if (pos >= 0 && isSpaceChar(s.charAt(pos)))
              pos--;
          return pos;
      }
  
      private final static int eatNl (String s, int pos)
      {
          if (pos >= 0)
          {
              if (s.charAt(pos) == '\r')
                  pos--;
              else if (s.charAt(pos) == '\n')
              {
                  pos--;
                  if (pos >= 0 && s.charAt(pos) == '\r')
                      pos--;
              }
          }
          return pos;
      }
  
      final public void eatTrailingWs ()
      {
         int i, j;
 
         i = size() - 1;
         if (i < 0 || i + 1 == literalMark)
             return;
 
         Object o = elementAt(i);
         if (!(o instanceof String))
             return;
         String s = (String) o;
         j = eatWs(s, s.length() - 1);
 
         if (j < 0)
             remove(i);
         else if (j < s.length() - 1)
             setElementAt(s.substring(0, j + 1), i);
         markLiteral();
     }
 
 
     final public void eatTrailingWsNl ()
     {
         int i, j;
 
         i = size() - 1;
         if (i < 0 || i + 1 == literalMark)
             return;
 
         Object o = elementAt(i);
         if (!(o instanceof String))
             return;
         String s = (String) o;
         j = eatWs(s, s.length() - 1);
         j = eatNl(s, j);
 
         if (j < 0)
             remove(i);
         else if (j < s.length() - 1)
             setElementAt(s.substring(0, j + 1), i);
         markLiteral();
     }
 
     final public void eatTrailingWsNlWs ()
     {
         int i, j;
 
         i = size() - 1;
         if (i < 0 || i + 1 == literalMark)
             return;
 
         Object o = elementAt(i);
         if (!(o instanceof String))
             return;
         String s = (String) o;
         j = eatWs(s, s.length() - 1);
         j = eatNl(s, j);
         j = eatWs(s, j);
 
         if (j < 0)
             remove(i);
         else if (j < s.length() - 1)
             setElementAt(s.substring(0, j + 1), i);
         markLiteral();
     }
 
     final public void eatOneWs ()
     {
         int i, j;
 
         i = size() - 1;
         if (i < 0 || i + 1 == literalMark)
             return;
 
         Object o = elementAt(i);
         if (!(o instanceof String))
             return;
         String s = (String) o;
         j = eatOneWs(s, s.length() - 1);
 
         if (j < 0)
             remove(i);
         else if (j < s.length() - 1)
             setElementAt(s.substring(0, j + 1), i);
         markLiteral();
     }
 
     final public void eatLeadingWsNl ()
     {
         int i, j, l;
 
         i = size() - 1;
         if (i < 0 || i + 1 == literalMark)
             return;
 
         Object o = elementAt(i);
         if (!(o instanceof String))
             return;
         String s = (String) o;
         j = 0;
         l = s.length();
         while (j < l && isSpaceChar(s.charAt(j)))
             j++;
         if (j < l)
         {
             if (s.charAt(j) == '\r')
                 j++;
             else if (s.charAt(j) == '\n')
             {
                 j++;
                 if (j < l && s.charAt(j) == '\r')
                     j++;
             }
         }
 
         if (j >= l)
             remove(i);
         else if (j > 0)
             setElementAt(s.substring(j), i);
         markLiteral();
     }
 
     final public boolean directiveOk ()
     {
         if (size() == 0 || size() == literalMark)
             return true;
         else
         {
             Object o = elementAt(size() - 1);
             
             // NOTE: the test for a zero length string in the following 'if' is 
             // a work-around for a bug parsing an explicit #begin followed 
             // immediately by another directive, eg, 
             // #if ($x) #begin #set $y=0 #end
             // This can be removed when/if this bug is fixed 
             // Keats 8-Aug-2003
             if (!(o instanceof String) || (((String)o).length() == 0))
                 return true;
             else
             {
                 String s = (String) o;
                 char ch = s.charAt(s.length() - 1);
                 if (ch == '=' || ch == '\'' || ch == '\"' || ch == ':'
                         || Character.isLetterOrDigit(ch))
                     return false;
             }
         }
         return true;
     }
 }