public TokenParseResult ParseRule(Rule rule, Token startToken, ParserSettings settings)
{
TokenParseResult ruleResult = TokenParseResult.Failed(startToken);
Token token = startToken;
TokenParseResult result;
List <SyntaxNode> nodes = new List <SyntaxNode>();
token = startToken;
do
{
result = rule.Parse(token, settings);
if (result)
{
nodes.Add(result.Node);
token = result.NextToken;
}
/* the while checks
* - the last result was good
* - at least one node returned (indicative of an empty if 0)
* - haven't exceeded or equaled max value
* - tokens remain */
} while (result && result.Node.Count > 0 && nodes.Count < rule.Quantifier.MaxValue && token != null);
if (nodes.Count >= Math.Max(1, rule.Quantifier.MinValue))
{
if (nodes.Count > 1)
{
SyntaxNode parent = new SyntaxNode(rule, startToken);
parent.AddRange(nodes);
ruleResult = TokenParseResult.Success(parent, token);
}
else
{
ruleResult = TokenParseResult.Success(nodes[0], token);
}
}
else if (result && nodes.Count == 0)
{
ruleResult = TokenParseResult.Success(new SyntaxNode(rule, token), result.NextToken);
}
return(ruleResult);
}
public virtual ParserResult Parse(List <Token> tokens)
{
TokenParseResult tokenResult;
ParserResult docResult = new ParserResult();
Token token = tokens.FirstOrDefault();
Token startToken;
List <Rule> rules = Productions.Compile(Lexer)
.Where(r => Settings.RootProductionNames.Count == 0 || Settings.RootProductionNames.Contains(r.ProductionName)).ToList();
while (token != null)
{
startToken = token;
tokenResult = TokenParseResult.Failed(token);
foreach (Rule rule in rules)
{
tokenResult = ParseRule(rule, token, Settings);
if (tokenResult && (startToken != tokenResult.NextToken || Settings.ZeroLengthRulesOK))
{
break;
}
}
if (tokenResult)
{
docResult.Root.Add(tokenResult);
// if 0 length result move next.
token = (tokenResult.NextToken != startToken) ? tokenResult.NextToken : startToken.Next;
}
else
{
docResult.PassedTokens.Add(token);
// no result then advanced to next token
token = token.Next;
}
}
return(docResult);
}