public bool Validate(List <Token> tokens, int idx = -1)
{
Token currentToken = null;
CurrentState = CurrentState.GoToNextState(TokenEnums.TokenType.Dollar); // move from the initialstate going forward
try
{
for (int i = idx; i < tokens.Count;)
{
if (CurrentState.StateAction == StateAction.Accept)
{
break;
}
if (CurrentState.StateAction == StateAction.Scan)
{
// do nothing
i++;
currentToken = i >= 0 ? tokens[i] : null;
}
else if (CurrentState.StateAction == StateAction.Read && currentToken.TokenType == TokenEnums.TokenType.Tag)
{
if (TagStack.Peek() == currentToken.Symbol)
{
TagStack.Pop();
}
}
else if (CurrentState.StateAction == StateAction.Read && (currentToken.TokenType == TokenEnums.TokenType.HeaderXmlOpeningSymbol || currentToken.TokenType == TokenEnums.TokenType.HeaderXmlClosingSymbol || currentToken.TokenType == TokenEnums.TokenType.ClosingSymbol || currentToken.TokenType == TokenEnums.TokenType.OpeningSymbol || currentToken.TokenType == TokenEnums.TokenType.OpeningWithBackslashSymbol || currentToken.TokenType == TokenEnums.TokenType.SelfClosingSymbol))
{
if (currentToken.TokenType == TokenEnums.TokenType.SelfClosingSymbol || currentToken.TokenType == TokenEnums.TokenType.HeaderXmlClosingSymbol)
{
TagStack.Pop();
}
var peek = SymbolStack.Peek();
if ((currentToken.Partners != null && currentToken.Partners.Any(item => item == peek)) || peek == currentToken.Partner)
{
SymbolStack.Pop();
}
// TO DO: handle partner tags
}
else if (CurrentState.StateAction == StateAction.Write && (currentToken.TokenType == TokenEnums.TokenType.Tag || currentToken.TokenType == TokenEnums.TokenType.HeaderXmlTag))
{
TagStack.Push(currentToken.Symbol);
}
else if (CurrentState.StateAction == StateAction.Write && (currentToken.TokenType == TokenEnums.TokenType.HeaderXmlClosingSymbol || currentToken.TokenType == TokenEnums.TokenType.HeaderXmlOpeningSymbol || currentToken.TokenType == TokenEnums.TokenType.ClosingSymbol || currentToken.TokenType == TokenEnums.TokenType.OpeningSymbol || currentToken.TokenType == TokenEnums.TokenType.OpeningWithBackslashSymbol || currentToken.TokenType == TokenEnums.TokenType.SelfClosingSymbol))
{
SymbolStack.Push(currentToken.Symbol);
}
var nextState = CurrentState.GoToNextState(currentToken.TokenType); // move from the initialstate going forward
if (nextState == null)
{
//// non-deterministic
//// guess next state based on next token
var nextToken = (i + 1) >= tokens.Count ? null : tokens[i + 1];
if (nextToken != null)
{
var states = CurrentState.GetPossibleNextStates(currentToken.TokenType);
nextState = states.Where(state => state.StateAction != StateAction.Accept).FirstOrDefault();
}
else
{
// end state
var states = CurrentState.GetPossibleNextStates(currentToken.TokenType);
nextState = states.Where(state => state.StateAction == StateAction.Accept).FirstOrDefault();
}
}
CurrentState = nextState;
}
}
catch (Exception ex)
{
throw;
}
// scan
//foreach (var item in tokens)
//{
// if (item.TokenType == TokenEnums.TokenType.Tag)
// {
// if (tags.Count != 0 && tags.Peek() == item.Symbol)
// {
// tags.Pop();
// }
// else
// {
// tags.Push(item.Symbol);
// }
// }
// else if (item.TokenType == TokenEnums.TokenType.OpeningSymbol || item.TokenType == TokenEnums.TokenType.OpeningWithBackslashSymbol)
// {
// symbols.Push(item);
// }
// else if (symbols.Count != 0 && item.TokenType == TokenEnums.TokenType.ClosingSymbol)
// {
// if (symbols.Peek().TokenType == TokenEnums.TokenType.OpeningSymbol || symbols.Peek().TokenType == TokenEnums.TokenType.OpeningWithBackslashSymbol)
// {
// symbols.Pop();
// }
// }
// else if (item.TokenType == TokenEnums.TokenType.SelfClosingSymbol)
// {
// tags.Pop();
// }
//}
if (TagStack.Count == 0 && SymbolStack.Count == 0 && CurrentState == FinalState)
{
return(true);
}
return(false);
}