public object VisitBinaryOperation(BinaryOperation node)
{
TokenType opType = node.operat.type;
object nodeLeft = Visit(node.left);
object nodeRight = Visit(node.right);
if (nodeLeft is int && nodeRight is int)
{
return(IntBinaryOperations(opType, (int)nodeLeft, (int)nodeRight));
}
else if (nodeLeft is string && nodeRight is string)
{
return(StringBinaryOperations(opType, (string)nodeLeft, (string)nodeRight));
}
else if (nodeLeft is bool && nodeRight is bool)
{
return(BoolBinaryOperations(opType, (bool)nodeLeft, (bool)nodeRight));
}
throw new InterpreterError("VisitBinaryOperation error");
}
// <term> ::= <factor> ( ("MUL" | "DIV") <factor> )*
private AST Term()
{
AST node = Factor();
while (this.currentToken.type == TokenType.MUL ||
this.currentToken.type == TokenType.DIV)
{
Token token = this.currentToken;
if (token.type == TokenType.MUL)
{
Eat(TokenType.MUL);
}
else if (token.type == TokenType.DIV)
{
Eat(TokenType.DIV);
}
node = new BinaryOperation(node, token, Factor());
}
return(node);
}
// <expr> ::= <term> ( ("PLUS" | "MINUS" | "EQUAL" | "LESS" | "AND" | "NOT") <term> )*
private AST Expr()
{
AST node = Term();
while (this.currentToken.type == TokenType.PLUS ||
this.currentToken.type == TokenType.MINUS ||
this.currentToken.type == TokenType.EQUAL ||
this.currentToken.type == TokenType.LESS ||
this.currentToken.type == TokenType.AND ||
this.currentToken.type == TokenType.NOT)
{
Token token = this.currentToken;
if (token.type == TokenType.PLUS)
{
Eat(TokenType.PLUS);
}
else if (token.type == TokenType.MINUS)
{
Eat(TokenType.MINUS);
}
else if (token.type == TokenType.EQUAL)
{
Eat(TokenType.EQUAL);
}
else if (token.type == TokenType.LESS)
{
Eat(TokenType.LESS);
}
else if (token.type == TokenType.AND)
{
Eat(TokenType.AND);
}
else if (token.type == TokenType.NOT)
{
Eat(TokenType.NOT);
}
node = new BinaryOperation(node, token, Term());
}
return(node);
}
