/***************************************************************
* 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);
}
