public TypeDenoter VisitBinaryExpression(BinaryExpression ast, Void arg)
{
TypeDenoter e1Type = ast.LeftExpression.Visit(this, null);
TypeDenoter e2Type = ast.RightExpression.Visit(this, null);
Declaration binding = ast.Operation.Visit(this, null);
if (binding is BinaryOperatorDeclaration bbinding)
{
if (bbinding.FirstArgument == StandardEnvironment.AnyType)
{
CheckAndReportError(e1Type.Equals(e2Type), "incompatible argument types for \"%\"", ast.Operation, ast);
}
else
{
CheckAndReportError(e1Type.Equals(bbinding.FirstArgument), "wrong argument type for \"%\"", ast.Operation, ast.LeftExpression);
CheckAndReportError(e2Type.Equals(bbinding.SecondArgument), "wrong argument type for \"%\"", ast.Operation, ast.RightExpression);
}
ast.Type = bbinding.Result;
}
else
{
ReportUndeclaredOrError(binding, ast.Operation, "\"%\" is not a binary operator");
ast.Type = StandardEnvironment.ErrorType;
}
return(ast.Type);
}
public TypeDenoter VisitTernaryExpression(TernaryExpression ast, Void arg)
{
TypeDenoter e2Type = ast.LeftExpression.Visit(this, null);
TypeDenoter e3Type = ast.RightExpression.Visit(this, null);
TypeDenoter e1Type = ast.Condition.Visit(this, null);
if (e1Type is BoolTypeDenoter)
{
if (e1Type.Equals(true))
{
ast.Type = e2Type;
}
else
{
ast.Type = e3Type;
CheckAndReportError(e2Type.Equals(e3Type), "incompatible argument type for \"%\"", ast.Type.ToString(), ast.RightExpression.Position);
}
}
else
{
ReportError("\"%\" is not a valid boolean", e1Type);
}
return(ast.Type);
}
public TypeDenoter VisitTernaryExpression(TernaryExpression ast, Void arg)
{
TypeDenoter e1Type = ast.Condition.Visit(this, null);
TypeDenoter e2Type = ast.LeftExpression.Visit(this, null);
TypeDenoter e3Type = ast.RightExpression.Visit(this, null);
if (e1Type == StandardEnvironment.BooleanType)
{
if (e2Type == e3Type)
{
ast.Type = StandardEnvironment.AnyType;
}
else
{
CheckAndReportError(e2Type.Equals(e3Type), "ternary expression member \"%\" must have the same type", ast.LeftExpression);
CheckAndReportError(e3Type.Equals(e2Type), "ternary expression member \"%\" must have the same type", ast.RightExpression);
ast.Type = StandardEnvironment.ErrorType;
}
}
else
{
CheckAndReportError(e1Type.Equals(StandardEnvironment.BooleanType), "argument type \"%\" is not a boolean", ast.Condition);
ast.Type = StandardEnvironment.ErrorType;
}
return(ast.Type);
}
public Void VisitWhileCommand(WhileCommand ast, Void arg)
{
System.Console.WriteLine("Visiting WhileCommand");
TypeDenoter expressionType = ast.Expression.Visit(this, null);
CheckAndReportError(expressionType.Equals(StandardEnvironment.BooleanType), "expression type must be boolean", ast);
return(ast.Command.Visit(this, null));
}
public Void VisitAssignCommand(AssignCommand ast, Void arg)
{
TypeDenoter identifierType = ast.Identifier.Visit(this, null).Type;
TypeDenoter expressionType = ast.Expression.Visit(this, null);
CheckAndReportError(ast.Identifier.IsVariable, "LHS of assignment is not a variable", ast.Identifier);
CheckAndReportError(expressionType.Equals(identifierType), "assignment incompatibilty", ast);
return(null);
}
// Actual Parameters
// Always returns null. Uses the given FormalParameter.
public Void VisitValueParameter(ValueParameter ast, FormalParameter arg)
{
TypeDenoter expressionType = ast.Expression.Visit(this, null);
if (arg is ConstFormalParameter param)
{
CheckAndReportError(expressionType.Equals(param.Type), "wrong type for const actual parameter", ast.Expression);
}
else
{
ReportError("const actual parameter not expected here", ast);
}
return(null);
}
public TypeDenoter VisitUnaryExpression(UnaryExpression ast, Void arg)
{
TypeDenoter expressionType = ast.Expression.Visit(this, null);
Declaration binding = ast.Operator.Visit(this, null);
if (binding is UnaryOperatorDeclaration ubinding)
{
CheckAndReportError(expressionType.Equals(ubinding.Argument), "wrong argument type for \"%\"", ast.Operator);
ast.Type = ubinding.Result;
}
else
{
ReportUndeclaredOrError(binding, ast.Operator, "\"%\" is not a unary operator");
ast.Type = StandardEnvironment.ErrorType;
}
return(ast.Type);
}
public TypeDenoter VisitTernaryExpression(TernaryExpression ast, Void arg)
{
TypeDenoter condition = ast.Condition.Visit(this, null);
TypeDenoter e2Type = ast.LeftExpression.Visit(this, null);
TypeDenoter e3Type = ast.RightExpression.Visit(this, null);
if (condition is BoolTypeDenoter)
{
if (e2Type.GetType() == e3Type.GetType())
{
ast.Type = e3Type;
}
else
{
CheckAndReportError(e2Type.Equals(e3Type), "icompatible arguement types for \"%\"", ast.Type.ToString(), ast.Position);
}
}
else
{
ReportError("\"%\" incompatible boolean", condition);
}
return(ast.Type);
}
