private ASTNode OrCondition()
{
var node = AndCondition();
while (_currentToken.Type == TokenType.Or)
{
var token = _currentToken;
Eat(TokenType.Or);
node = new ASTBinaryOperator(node, token, AndCondition());
}
return(node);
}
private ASTNode Term()
{
var node = Factor();
while (FactorOperators.Contains(_currentToken.Type))
{
var token = _currentToken;
Eat(token.Type);
node = new ASTBinaryOperator(node, token, Factor());
}
return(node);
}
private ASTNode Comparision()
{
if (_currentToken.Type == TokenType.ConstBool)
{
var token = _currentToken;
Eat(TokenType.ConstBool);
return(new ASTBool(token));
}
var node = ArithmeticExpression();
while (CompareOperators.Contains(_currentToken.Type))
{
var token = _currentToken;
Eat(token.Type);
node = new ASTBinaryOperator(node, token, ArithmeticExpression());
}
return(node);
}
private ASTNode ArithmeticExpression()
{
var node = Term();
while (TermOperators.Contains(_currentToken.Type))
{
var token = _currentToken;
switch (token.Type)
{
case TokenType.Plus:
Eat(TokenType.Plus);
break;
case TokenType.Minus:
Eat(TokenType.Minus);
break;
}
node = new ASTBinaryOperator(node, token, Term());
}
return(node);
}
private VisitResult VisitBinaryOperator(ASTBinaryOperator node)
{
switch (node.Type)
{
case TokenType.Plus:
return(new VisitResult
{
Value = Visit(node.Left).Value + Visit(node.Right).Value
});
case TokenType.Minus:
return(new VisitResult
{
Value = Visit(node.Left).Value - Visit(node.Right).Value
});
case TokenType.Multiplication:
return(new VisitResult
{
Value = Visit(node.Left).Value *Visit(node.Right).Value
});
case TokenType.Divide:
return(new VisitResult
{
Value = Visit(node.Left).Value / Visit(node.Right).Value
});
case TokenType.Modulo:
return(new VisitResult
{
Value = Visit(node.Left).Value % Visit(node.Right).Value
});
case TokenType.Equal:
return(new VisitResult
{
Value = Visit(node.Left).Value == Visit(node.Right).Value
});
case TokenType.NotEqual:
return(new VisitResult
{
Value = Visit(node.Left).Value != Visit(node.Right).Value
});
case TokenType.Greater:
return(new VisitResult
{
Value = Visit(node.Left).Value > Visit(node.Right).Value
});
case TokenType.GreaterEqual:
return(new VisitResult
{
Value = Visit(node.Left).Value >= Visit(node.Right).Value
});
case TokenType.Less:
return(new VisitResult
{
Value = Visit(node.Left).Value < Visit(node.Right).Value
});
case TokenType.LessEqual:
return(new VisitResult
{
Value = Visit(node.Left).Value <= Visit(node.Right).Value
});
case TokenType.And:
return(new VisitResult
{
Value = Visit(node.Left).Value&& Visit(node.Right).Value
});
case TokenType.Or:
return(new VisitResult
{
Value = Visit(node.Left).Value || Visit(node.Right).Value
});
}
throw new ArgumentException($"Invalid AST node type {node.GetType()}");
}