public bool CheckSyntax(IEnumerable <Token> tokens)
{
var precedenceTable = _helper.GetPrecedenceTable(Grammar);
var tokensList = tokens as List <Token> ?? tokens.ToList();
var sharp = TokenEnum.Sharp;
sharp.Line = tokensList[tokensList.Count - 1].Line;
tokensList.Add(sharp);
var tokensArray = tokensList.ToArray();
var array = tokensArray.Select(t =>
{
if (t is TokenEnum)
{
return(t);
}
var tEnum =
Grammar.SelectMany(x => x.CompositeToken)
.Cast <TokenEnum>()
.FirstOrDefault(x => x.IsTheSame(t))?.Clone() as TokenEnum;
if (tEnum != null)
{
tEnum.Line = t.Line;
}
return(tEnum);
}).ToArray();
if (array.Any(x => x == null))
{
Logger.Error("Unknown token: {0}", tokensArray[Array.FindIndex(array, x => x == null)]);
}
var stack = new Stack <Token>();
stack.Push(TokenEnum.Sharp);
var i = 0;
var popped = new List <Token>();
Prn = new List <Token>();
while (stack.Peek().Type != TokenType.Axiom || array[i] != TokenEnum.Sharp)
{
try
{
var relation = precedenceTable[stack.Peek()][array[i]];
if (relation == PrecedenceRelation.More)
{
//Base search
popped.Clear();
popped.Add(stack.Pop());
while (precedenceTable[stack.Peek()][popped.Last()] != PrecedenceRelation.Less)
{
popped.Add(stack.Pop());
}
popped.Reverse();
try
{
var toReplace = Grammar.First(x => x.CompositeToken.SequenceEqual(popped));
toReplace.OnReplaceAction?.Invoke(tokensArray.Skip(i - popped.Count).Take(popped.Count).ToList(), Prn);
PRNChanged?.Invoke(toReplace.Token, Prn);
stack.Push(toReplace.Token);
}
catch (Exception exc)
{
Logger.Error("Can't replace sequence {0}, Line = {1}", popped, array[i].Line);
return(false);
}
}
else
//Copy the symbol to stack
{
stack.Push(array[i++]);
}
OnStackChanged(stack, relation.Value,
new ArraySegment <Token>(tokensArray, i, tokensArray.Length - i), Prn);
}
catch
{
Logger.Error("There is no relation for a pair {0}-{1}, Line = {2}", stack.Peek(), array[i],
array[i].Line);
return(false);
}
}
return(true);
}
protected virtual void OnPrnChanged(Token tokenReplaced, List <Token> prn)
{
PRNChanged?.Invoke(tokenReplaced, prn);
}