public ParserOperation.ParserOp Lookup(int CurrentState, ParserStackItem NextInput)
{
int lookaheadIndex;
if (NextInput == null)
{
lookaheadIndex = ProductionPatterns.Length + TokenPatterns.Length;
}
else if (NextInput.ProductionName != null)
{
lookaheadIndex = IndexOfFirstMatch(ProductionPatterns, NextInput);
}
else
{
lookaheadIndex = IndexOfFirstMatch(TokenPatterns, NextInput) + ProductionPatterns.Length;
}
if (lookaheadIndex == -1)
{
throw new Exceptions.UnknownTokenException(NextInput);
}
else
{
var transition = operations[CurrentState, lookaheadIndex];
if (transition == null)
{
throw new Exceptions.SyntaxError(NextInput.Token, ValidNextPatterns(CurrentState));
}
return(transition);
}
}
public ParserStackItem Run()
{
ParserStackItem result = null;
while ((result = Step()) == null)
{
}
return(result);
}
private int IndexOfFirstMatch(StackItemPattern[] pattern, ParserStackItem item)
{
for (var i = 0; i < pattern.Length; i++)
{
if (pattern[i].Matches(item))
{
return(i);
}
}
return(-1);
}
internal bool Matches(ParserStackItem stackItem)
{
if (stackItem == null)
{
return(PatternType == EPatternType.EndOfInput);
}
switch (PatternType)
{
case EPatternType.Literal:
return(stackItem.Token != null && stackItem.Token.Value == Value);
case EPatternType.TokenType:
return(stackItem.Token != null && stackItem.Token.TokenType == Value);
case EPatternType.Production:
return(stackItem.ProductionName != null && stackItem.ProductionName == Value);
case EPatternType.EndOfInput:
return(false);
default:
throw new InvalidOperationException("Unknown Pattern Type");
}
}
