static void Main(string[] args)
{
string expr = "1+a*3";
Dictionary <string, double> variables = new();
List <ITokenAcceptor <IToken> > constantAcceptors = new();
constantAcceptors.Add(new ConstantToken.Acceptor());
constantAcceptors.Add(new VariableToken.Acceptor());
List <ITokenAcceptor <IToken> > binaryAcceptors = new();
binaryAcceptors.Add(new AddToken.Acceptor());
binaryAcceptors.Add(new SubtractToken.Acceptor());
binaryAcceptors.Add(new MultiplyToken.Acceptor());
int index = 0;
ITokenBuilder <IToken>? root = null;
IBinaryTokenBuilder <IBinaryToken>?lastBinary = null;
ITokenBuilder <IToken>? _left = null;
List <ITokenAcceptor <IToken> > acceptors = constantAcceptors;
while (index < expr.Length)
{
bool foundAcceptor = false;
foreach (ITokenAcceptor <IToken> acceptor in acceptors)
{
ITokenBuilder <IToken>?builder = acceptor.Accept(expr, ref index);
if (builder != null)
{
IBinaryTokenBuilder <IBinaryToken>?builderAsBinary = builder as IBinaryTokenBuilder <IBinaryToken>;
if (root == null)
{
if (builderAsBinary != null)
{
throw new Exception("First token cannot be a binary token");
}
root = builder;
}
if (builderAsBinary != null)
{
if (lastBinary == null || lastBinary.IsMultiply || !builderAsBinary.IsMultiply)
{
if (lastBinary != null)
{
lastBinary.Right = _left;
}
builderAsBinary.Left = root;
root = builder;
}
else
{
builderAsBinary.Left = _left;
lastBinary.Right = builder;
}
lastBinary = builderAsBinary;
_left = null;
acceptors = constantAcceptors;
}
else
{
_left = builder;
acceptors = binaryAcceptors;
if (builder is VariableToken variableToken)
{
variables[variableToken.Name] = 0;
}
}
foundAcceptor = true;
break;
}
}
if (!foundAcceptor)
{
Console.WriteLine($"Cannot determine token '{expr[index]}'");
Console.WriteLine(expr);
Console.WriteLine($"{new string(' ', index)}^{new string('-', expr.Length - index + 2)}");
root = null;
break;
}
}
if (_left != null && lastBinary != null)
{
lastBinary.Right = _left;
}
if (root != null)
{
foreach (string key in variables.Keys)
{
Console.WriteLine($"Define the value for {key}:");
while (true)
{
string answer = Console.ReadLine() ?? "";
if (double.TryParse(answer, out double result))
{
variables[key] = result;
break;
}
else
{
Console.WriteLine("Not a double!");
}
}
}
IToken rootToken = root.Build();
PrintToken(rootToken, 0, variables);
Console.WriteLine($"Calculated: {expr} = {rootToken.Calculate(variables)}");
}
else
{
Console.WriteLine("No token defined!");
}
}