/*************************************************************** * Function: rule * Description: Recursive descent regular expression parser. **************************************************************/ private CNfa rule ( ) { CNfaPair pair; //CNfa p; CNfa start = null; CNfa end = null; int anchor = CSpec.NONE; if (CUtility.DESCENT_DEBUG) { CUtility.enter("rule", m_spec.m_lexeme, m_spec.m_current_token); } pair = CAlloc.newCNfaPair(); if (CLexGen.AT_BOL == m_spec.m_current_token) { anchor = anchor | CSpec.START; m_lexGen.advance(); expr(pair); // CSA: fixed beginning-of-line operator. 8-aug-1999 start = CAlloc.newCNfa(m_spec); start.m_edge = m_spec.BOL; start.m_next = pair.m_start; end = pair.m_end; } else { expr(pair); start = pair.m_start; end = pair.m_end; } if (CLexGen.AT_EOL == m_spec.m_current_token) { m_lexGen.advance(); // CSA: fixed end-of-line operator. 8-aug-1999 CNfaPair nlpair = CAlloc.newNLPair(m_spec); end.m_next = CAlloc.newCNfa(m_spec); end.m_next.m_next = nlpair.m_start; end.m_next.m_next2 = CAlloc.newCNfa(m_spec); end.m_next.m_next2.m_edge = m_spec.EOF; end.m_next.m_next2.m_next = nlpair.m_end; end = nlpair.m_end; anchor = anchor | CSpec.END; } /* Check for null rules. Charles Fischer found this bug. [CSA] */ if (end == null) { CError.parse_error(CError.E_ZERO, m_input.m_line_number); } /* Handle end of regular expression. See page 103. */ end.m_accept = m_lexGen.packAccept(); end.m_anchor = anchor; /* Begin: Removed for states. */ /*m_lexGen.advance();*/ /* End: Removed for states. */ if (CUtility.DESCENT_DEBUG) { CUtility.leave("rule", m_spec.m_lexeme, m_spec.m_current_token); } return(start); }