public UnaryOperandNode VisitExpressionOperand(ExpressionOperandNode eon)
{
int temp = this.depth;
string spaces = IncreaseDepth();
this.io.WriteLine($"{spaces}ExpressionOperand: (");
this.io.WriteLine($"{spaces} Negative: {eon.Negative},");
this.io.WriteLine($"{spaces} Not: {eon.Not},");
eon.Expression.Visit(this);
this.io.WriteLine($"{spaces})");
this.depth = temp;
return(new UnaryOperandNode("", SymbolType.Invalid));
}
public UnaryOperandNode VisitExpressionOperand(ExpressionOperandNode eon)
{
UnaryOperandNode node = eon.Expression.Visit(this);
if (node.Type == SymbolType.IntegerValue)
{
if (eon.Not)
{
throw new Error($"Can not have ! in front of an expression that returns {node.Type}", node.Token);
}
if (eon.Negative)
{
int v = ConvertStringToInteger(node.Value, node.Token);
node.Value = OppositeOfInteger(v);
}
}
else if (node.Type == SymbolType.Boolean)
{
if (eon.Negative)
{
throw new Error($"Can not have a - in front of an expression that returns {node.Type}", node.Token);
}
if (eon.Not)
{
if (node.Value == "true")
{
node.Value = "false";
}
else
{
node.Value = "true";
}
}
}
else
{
if (eon.Negative)
{
throw new Error($"Can not have a - in front of an expression that returns {node.Type}", node.Token);
}
if (eon.Not)
{
throw new Error($"Can not have ! in front of an expression that returns {node.Type}", node.Token);
}
}
return(node);
}
private Operand Operand()
{
// <opnd> ::= [Minus] <int> | <string> | [Minus | Exclamation] <var_ident> | [Minus | Exclamation] "(" expr ")"
bool negative = false;
bool not = false;
Token minus = this.token;
if (this.token.SymbolType == SymbolType.Minus)
{
negative = true;
this.token = this.scanner.NextToken();
}
else if (this.token.SymbolType == SymbolType.Exclamation)
{
not = true;
this.token = this.scanner.NextToken();
}
Operand o;
switch (this.token.SymbolType)
{
case SymbolType.IntegerValue:
if (not)
{
throw new Error($"! is not allowed in front of an IntegerValue", minus);
}
if (negative)
{
o = new UnaryOperandNode($"{Integer.minus}{this.token.Value}", this.token.SymbolType, minus);
}
else
{
o = new UnaryOperandNode(this.token.Value, this.token.SymbolType, this.token);
}
this.token = this.scanner.NextToken();
return(o);
case SymbolType.StringValue:
if (not)
{
throw new Error($"! is not allowed in front of a StringValue", minus);
}
if (negative)
{
throw new Error($"- is not allowed in front of a StringValue", minus);
}
o = new UnaryOperandNode(this.token.Value, this.token.SymbolType, this.token);
this.token = this.scanner.NextToken();
return(o);
case SymbolType.Identifier:
if (not)
{
o = new UnaryOperandNode(this.token.Value, this.token.SymbolType, this.token, false, true);
}
else if (negative)
{
o = new UnaryOperandNode(this.token.Value, this.token.SymbolType, this.token, true);
}
else
{
o = new UnaryOperandNode(this.token.Value, this.token.SymbolType, this.token);
}
this.token = this.scanner.NextToken();
return(o);
case SymbolType.LeftParenthesis:
this.token = this.scanner.NextToken();
Expression e = Expression();
if (negative)
{
o = new ExpressionOperandNode(e, true);
}
else if (not)
{
o = new ExpressionOperandNode(e, false, true);
}
else
{
o = new ExpressionOperandNode(e);
}
Match(SymbolType.RightParenthesis);
return(o);
default:
throw new Error($"Unexpected token: {this.token.SymbolType}", this.token);
}
}
