public override object Visit(BinaryOperationAstNode node)
{
var leftVal = (dynamic)node.Left.Accept(this);
var rightVal = (dynamic)node.Right.Accept(this);
switch (node.Operation.Type)
{
// Relop
case TokenType.EQ:
return(leftVal == rightVal);
case TokenType.NEQ:
return(leftVal != rightVal);
case TokenType.GT:
return(leftVal > rightVal);
case TokenType.LT:
return(leftVal < rightVal);
case TokenType.GTE:
return(leftVal >= rightVal);
case TokenType.LTE:
return(leftVal <= rightVal);
// Addop
case TokenType.OR:
return((bool)leftVal || (bool)rightVal);
case TokenType.PLUS:
return(leftVal + rightVal);
case TokenType.MINUS:
return(leftVal - rightVal);
// Mulop
case TokenType.AND:
return((bool)leftVal && (bool)rightVal);
case TokenType.MUL:
return(leftVal * rightVal);
case TokenType.DIV:
return(leftVal / rightVal);
}
throw Error(node);
}
/// <summary>
/// simple_expression : term
/// | term addop term
/// </summary>
private AstNode ParseSimpleExpression()
{
var node = ParseTerm();
EatWhiteSpace();
while (AddOp.Contains(CurrentToken.Type))
{
var token = CurrentToken;
Eat(CurrentToken.Type);
EatWhiteSpace();
node = new BinaryOperationAstNode(token, node, ParseTerm());
}
return(node);
}
/// <summary>
/// term : factor (mulop factor)*
/// </summary>
private AstNode ParseTerm()
{
// First parse the initial factor
var node = ParseFactor();
EatWhiteSpace();
while (MulOp.Contains(CurrentToken.Type))
{
var token = CurrentToken;
Eat(token.Type);
// Eat further whitespace
EatWhiteSpace();
node = new BinaryOperationAstNode(token, node, ParseFactor());
}
return(node);
}
public virtual object Visit(BinaryOperationAstNode node)
{
return(null);
}
