public UnaryOperandNode VisitUnaryOperand(UnaryOperandNode uon)
{
if (uon.Type == SymbolType.Identifier)
{
SymbolTableEntry entry = CheckThatIdentifierIsDeclaredAndGetEntry(uon.Value, uon.Token);
if (entry.Type == SymbolType.IntegerValue && uon.Negative)
{
int v = ConvertStringToInteger(entry.Value, uon.Token);
return(new UnaryOperandNode(OppositeOfInteger(v), entry.Type, uon.Token));
}
else if (entry.Type == SymbolType.Boolean && uon.Not)
{
string newValue;
if (entry.Value == "true")
{
newValue = "false";
}
else
{
newValue = "true";
}
return(new UnaryOperandNode(newValue, SymbolType.Boolean, uon.Token));
}
return(new UnaryOperandNode(entry.Value, entry.Type, uon.Token));
}
else if (uon.Type == SymbolType.IntegerValue)
{
int value = ConvertStringToInteger(uon.Value, uon.Token);
return(new UnaryOperandNode(value.ToString(), uon.Type, uon.Token, uon.Negative));
}
// Do not return the AST node. Create a copy
return(new UnaryOperandNode(uon.Value, uon.Type, uon.Token, uon.Negative));
}
public void VisitForLoop(ForLoopNode fln)
{
fln.Assignment.Visit(this);
string op = CreateOperatorToForLoopCondition(fln);
UnaryOperandNode cond = fln.Condition.Visit(this);
UnaryOperandNode assignment = new UnaryOperandNode(
this.symbolTable.GetEntry(cond.Token.Value).Value,
SymbolType.IntegerValue,
cond.Token
);
this.symbolTable.LockVariable(cond.Token.Value);
while (cond.Type == SymbolType.Boolean && cond.Value == "true")
{
this.symbolTable.PushBlock();
VisitStatements(fln);
this.symbolTable.PopBlock();
// Left value of BinaryExpression needs to be incremented by one (Has to be Identifier)
assignment = HandleIntegerOperation(
assignment,
new UnaryOperandNode("1", SymbolType.IntegerValue, assignment.Token),
op
);
this.symbolTable.ForceModifyEntry(cond.Token.Value, assignment.Value);
cond = fln.Condition.Visit(this);
}
this.symbolTable.ReleaseVariable(cond.Token.Value);
}
public UnaryOperandNode VisitBinaryExpression(BinaryExpressionNode ben)
{
UnaryOperandNode left = ben.Left.Visit(this);
UnaryOperandNode right = ben.Right.Visit(this);
return(HandleOperation(left, right, ben.Operator));
}
private UnaryOperandNode HandleBooleanOperation(UnaryOperandNode left, UnaryOperandNode right, string operation)
{
switch (operation)
{
case "=":
if (left.Value == right.Value)
{
return(new UnaryOperandNode("true", SymbolType.Boolean, left.Token));
}
else
{
return(new UnaryOperandNode("false", SymbolType.Boolean, left.Token));
}
case "&":
if (left.Value == right.Value && left.Value == "true")
{
return(new UnaryOperandNode("true", SymbolType.Boolean, left.Token));
}
else
{
return(new UnaryOperandNode("false", SymbolType.Boolean, left.Token));
}
default:
throw new Error($"Illegal Operation: Can not do operation {operation} between Booleans", left.Token);
}
}
public UnaryOperandNode VisitUnaryOperand(UnaryOperandNode uon)
{
int temp = this.depth;
string spaces = IncreaseDepth();
this.io.WriteLine($"{spaces}UnaryOperand: (\n{spaces} Value: {uon.Value},\n{spaces} Type: {uon.Type},\n{spaces} Token: {uon.Token},\n{spaces} Negative: {uon.Negative},\n{spaces} Not: {uon.Not}\n{spaces})");
this.depth = temp;
return(new UnaryOperandNode("", SymbolType.Invalid));
}
private UnaryOperandNode HandleDifferentTypeOperation(UnaryOperandNode left, UnaryOperandNode right, string operation)
{
switch (operation)
{
case "+":
if (left.Type == SymbolType.StringValue || right.Type == SymbolType.StringValue)
{
return(new UnaryOperandNode($"{left.Value}{right.Value}", SymbolType.StringValue, left.Token));
}
throw new Error($"Illegal Operation: Can not add {left.Type} to {right.Type}", left.Token);
default:
throw new Error($"Illegal Operation: Can not do operation {operation} between {left.Type} and {right.Type}", left.Token);
}
}
public void VisitAssignment(AssignmentNode an)
{
SymbolType typeOfIdentifier = CheckThatIdentifierIsDeclaredAndGetEntry(an.Identifier, an.Token).Type;
UnaryOperandNode expression = an.Expression.Visit(this);
if (typeOfIdentifier != expression.Type)
{
throw new Error($"Illegal Assignment: Can not assign {expression.Type} to variable {an.Identifier}, because it is a {typeOfIdentifier}", expression.Token);
}
if (!this.symbolTable.ModifyEntry(an.Identifier, expression.Value))
{
throw new Error($"Illegal Assignment: Can not assign to variable {an.Identifier}, because it is used in For Loop", expression.Token);
}
}
public UnaryOperandNode VisitExpressionOperand(ExpressionOperandNode eon)
{
UnaryOperandNode node = eon.Expression.Visit(this);
if (node.Type == SymbolType.IntegerValue)
{
if (eon.Not)
{
throw new Error($"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($"Can not have ! in front of an expression that returns {node.Type}", node.Token);
}
}
return(node);
}
private UnaryOperandNode HandleStringOperation(UnaryOperandNode left, UnaryOperandNode right, string operation)
{
switch (operation)
{
case "+":
return(new UnaryOperandNode(left.Value + right.Value, SymbolType.StringValue, left.Token));
case "=":
if (left.Value == right.Value)
{
return(new UnaryOperandNode("true", SymbolType.Boolean, left.Token));
}
return(new UnaryOperandNode("false", SymbolType.Boolean, left.Token));
default:
throw new Error($"Illegal Operation: Strings can only be concatenated with + operator", left.Token);
}
}
/***************** HELPER METHODS *************************/
private string CreateOperatorToForLoopCondition(ForLoopNode fln)
{
UnaryOperandNode left = fln.Condition.Left.Visit(this);
UnaryOperandNode right = fln.Condition.Right.Visit(this);
UnaryOperandNode res = HandleIntegerOperation(left, right, ">");
string op = "+";
if (res.Value == "true")
{
fln.Condition.Operator = ">=";
op = "-";
}
else
{
fln.Condition.Operator = "<=";
}
return(op);
}
private UnaryOperandNode HandleOperation(UnaryOperandNode left, UnaryOperandNode right, string operation)
{
if (left.Type == right.Type && left.Type == SymbolType.StringValue)
{
return(HandleStringOperation(left, right, operation));
}
if (left.Type == right.Type && left.Type == SymbolType.IntegerValue)
{
return(HandleIntegerOperation(left, right, operation));
}
if (left.Type == right.Type && left.Type == SymbolType.Boolean)
{
return(HandleBooleanOperation(left, right, operation));
}
if (left.Type != right.Type)
{
return(HandleDifferentTypeOperation(left, right, operation));
}
throw new Error($"Unexpected Error occured..", left.Token);
}
public void VisitAssert(AssertNode an)
{
UnaryOperandNode node = an.Expression.Visit(this);
if (node.Type == SymbolType.Boolean && node.Value == "false")
{
UnaryOperandNode left = an.Expression.Left.Visit(this);
UnaryOperandNode right = an.Expression.Right.Visit(this);
string op;
string message = "Assert was false.";
if (right.Type != SymbolType.Invalid)
{
// BinaryExpression
op = an.Expression.Operator;
message = $"Assert was false. Received assert ({left.Value} {op} {right.Value})";
}
throw new Error(message, node.Token);
}
if (node.Type != SymbolType.Boolean)
{
throw new Error($"Expected Boolean value inside assert (Boolean). Instead found {node.Type}", node.Token);
}
}
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($"Unexpected token: {this.token.SymbolType}", this.token);
}
}
public void VisitPrint(PrintNode prn)
{
UnaryOperandNode expr = prn.Expression.Visit(this);
this.io.WriteLine(expr.Value);
}
private UnaryOperandNode HandleIntegerOperation(UnaryOperandNode left, UnaryOperandNode right, string operation)
{
int leftValue = ConvertStringToInteger(left.Value, left.Token);
int rightValue = ConvertStringToInteger(right.Value, right.Token);
int result;
switch (operation)
{
case "+":
result = leftValue + rightValue;
return(new UnaryOperandNode(result.ToString(), SymbolType.IntegerValue, left.Token));
case "-":
result = leftValue - rightValue;
return(new UnaryOperandNode(result.ToString(), SymbolType.IntegerValue, left.Token));
case "*":
result = leftValue * rightValue;
return(new UnaryOperandNode(result.ToString(), SymbolType.IntegerValue, left.Token));
case "/":
result = leftValue / rightValue;
return(new UnaryOperandNode(result.ToString(), SymbolType.IntegerValue, left.Token));
case "<":
if (leftValue < rightValue)
{
return(new UnaryOperandNode("true", SymbolType.Boolean, left.Token));
}
return(new UnaryOperandNode("false", SymbolType.Boolean, left.Token));
case ">":
if (leftValue > rightValue)
{
return(new UnaryOperandNode("true", SymbolType.Boolean, left.Token));
}
return(new UnaryOperandNode("false", SymbolType.Boolean, left.Token));
case "<=":
if (leftValue <= rightValue)
{
return(new UnaryOperandNode("true", SymbolType.Boolean, left.Token));
}
return(new UnaryOperandNode("false", SymbolType.Boolean, left.Token));
case ">=":
if (leftValue >= rightValue)
{
return(new UnaryOperandNode("true", SymbolType.Boolean, left.Token));
}
return(new UnaryOperandNode("false", SymbolType.Boolean, left.Token));
case "=":
if (leftValue == rightValue)
{
return(new UnaryOperandNode("true", SymbolType.Boolean, left.Token));
}
return(new UnaryOperandNode("false", SymbolType.Boolean, left.Token));
default:
throw new Error($"Can not do operation {operation} between two Integers", left.Token);
}
}