/// <summary>
/// Parsers the given string.
/// </summary>
/// <param name="value">String to parse.</param>
/// <returns>
/// Topmost reduction if the parsing was successful.
/// Retuns null if the value was not parsed.
/// </returns>
public SyntaxNode Parse(TextReader reader)
{
int reductionNumber = 0;
Parser parser = new Parser(reader, m_grammar);
parser.TrimReductions = true;
while (true)
{
ParseMessage response = parser.Parse();
switch (response)
{
case ParseMessage.LexicalError:
AddParseAction(parser, response, "Cannot Recognize Token",
"", parser.TokenText, "");
return(null);
case ParseMessage.SyntaxError:
StringBuilder expectedTokens = new StringBuilder();
foreach (Symbol token in parser.GetExpectedTokens())
{
expectedTokens.Append(token.Name);
expectedTokens.Append(' ');
}
AddParseAction(parser, response, "Expecting the following tokens",
"", expectedTokens.ToString(), "");
return(null);
case ParseMessage.Reduction:
NonTerminalNode nonTerminal = new NonTerminalNode(parser.ReductionRule);
nonTerminal.ReductionNumber = ++reductionNumber;
parser.TokenSyntaxNode = nonTerminal;
StringBuilder childReductionList = new StringBuilder();
for (int i = 0; i < parser.ReductionCount; i++)
{
SyntaxNode node = parser.GetReductionSyntaxNode(i) as SyntaxNode;
nonTerminal.Add(node);
NonTerminalNode childNode = node as NonTerminalNode;
if (childNode != null)
{
childReductionList.Append('#');
childReductionList.Append(childNode.ReductionNumber);
childReductionList.Append(' ');
}
}
AddParseAction(parser, response, nonTerminal.Rule.ToString(),
reductionNumber.ToString(),
childReductionList.ToString(),
nonTerminal.Rule.Index.ToString());
break;
case ParseMessage.Accept: //=== Success!
AddParseAction(parser, response, parser.ReductionRule.ToString(),
"", "", "");
return((SyntaxNode)parser.TokenSyntaxNode);
case ParseMessage.TokenRead:
TerminalNode terminal = new TerminalNode(
parser.TokenSymbol,
parser.TokenText,
parser.TokenString,
parser.TokenLineNumber,
parser.TokenLinePosition);
parser.TokenSyntaxNode = terminal;
AddParseAction(parser, response,
terminal.Symbol.Name, "",
terminal.ToString(),
terminal.Symbol.Index.ToString());
break;
case ParseMessage.InternalError:
AddParseAction(parser, response, "Error in LR state engine",
"", "", "");
return(null);
case ParseMessage.NotLoadedError:
//=== Due to the if-statement above, this case statement should never be true
AddParseAction(parser, response, "Compiled Grammar Table not loaded",
"", "", "");
return(null);
case ParseMessage.CommentError:
AddParseAction(parser, response, "Unexpected end of file",
"", "", "");
return(null);
}
}
}
