internal static int GetNextToken(string source, int position, out Token token, Token prevToken = null)
{
char symbol = source[position];
token = null;
if (DoubleToken.IsStartSymbol(symbol))
{
token = new DoubleToken().FromString(source, ref position);
return position;
}
if (BracketToken.IsStartSymbol(symbol))
{
token = BracketToken.GetBracket(symbol, prevToken);
return position + 1;
}
if (OperationToken.TryGetOperation(symbol, prevToken, out token))
{
return position + 1;
}
if (FunctionToken.IsStartSymbol(symbol))
{
token = new FunctionToken().FromString(source, ref position);
return position;
}
throw new ArgumentOutOfRangeException("symbol", symbol, "Unexpected symbol");
}
public OpenBracket(Token prevToken)
{
if (prevToken != null && (prevToken.TokenType != TokenType.Operation && prevToken.TokenType != TokenType.OpenBracket))
{
throw new InvalidOperationException("Open bracket can't follow after: " + prevToken.TokenType);
}
}
public static BracketToken GetBracket(char symbol, Token prevToken = null)
{
switch (symbol)
{
case '(': return new OpenBracket(prevToken);
case ')': return new CloseBracket(prevToken);
default: throw new ArgumentOutOfRangeException("symbol", symbol, string.Format("Have not this bracket: '{0}'", symbol));
}
}
public CloseBracket(Token prevToken)
{
if (prevToken == null)
throw new InvalidOperationException("Close bracket be first in expression.");
if (prevToken.TokenType != TokenType.Value && prevToken.TokenType != TokenType.CloseBracket)
{
throw new InvalidOperationException("Close bracket can't follow after: " + prevToken.TokenType);
}
}
protected static bool TryGetUnary(char symbol, Token prevToken, out Token unaryOperation)
{
unaryOperation = null;
return (prevToken == null || prevToken.AllowUnaryAfter) && UnarySpecialChars.TryGetValue(symbol, out unaryOperation);
}
public static bool TryGetOperation(char symbol, Token prevToken, out Token token)
{
return TryGetUnary(symbol, prevToken, out token) || SpecialChars.TryGetValue(symbol, out token);
}
