private void CheckIndexType(HeronValue index)
{
if (index.As(layout.GetIndexType()) == null)
{
throw new Exception(index.ToString() + " is not a valid index type, expected " + layout.GetIndexType().ToString());
}
}
/// <summary>
/// Converts a HeronValue into the expected type. Checks for legal null
/// passing (i.e. assures only nullable types receive nulls), and does type-checking.
/// </summary>
/// <param name="x"></param>
/// <returns></returns>
public HeronValue Coerce(HeronValue x)
{
HeronValue r = x;
if (r is NullValue)
{
if (!type.nullable)
{
throw new Exception("Passing null to a non-nullable variable " + name);
}
else
{
return(r);
}
}
else if (type != null)
{
r = x.As(type.type);
if (r == null)
{
throw new Exception("Failed to convert variable " + x + " from a " + x.Type.name + " to " + type.name);
}
}
return(r);
}
public override HeronValue Eval(VM vm)
{
HeronValue a = operand1.Eval(vm);
HeronValue b = operand2.Eval(vm);
switch (opcode)
{
case OpCode.opEq:
return(new BoolValue(a.Equals(b)));
case OpCode.opNEq:
return(new BoolValue(!a.Equals(b)));
case OpCode.opIs:
{
TypeValue tv = b as TypeValue;
if (tv == null)
{
throw new Exception("The second argument of the 'is' operator must be a type");
}
return(new BoolValue(a.Is(tv.Type)));
}
case OpCode.opAs:
{
HeronType t = b as HeronType;
if (t == null)
{
throw new Exception("The 'as' operator expects a type as a right hand argument");
}
HeronValue r = a.As(t);
if (r != null)
{
return(r);
}
if (t is InterfaceDefn && a is ClassInstance)
{
DuckValue dv = new DuckValue(a as ClassInstance, t as InterfaceDefn);
return(dv);
}
throw new Exception("Failed to convert " + a.Type.name + " to a " + t.name);
};
}
return(a.InvokeBinaryOperator(vm, opcode, b));
}
public bool IsCompatible(ListValue x)
{
if (x.InternalCount() != Count)
{
return(false);
}
for (int i = 0; i < Count; ++i)
{
HeronValue val = x.InternalAt(i);
HeronType type = GetTypes()[i];
HeronValue test = val.As(type);
if (test == null)
{
return(false);
}
}
return(true);
}
public bool IsCompatible(RecordValue x)
{
for (int i = 0; i < names.Count; ++i)
{
string name = names[i];
HeronType type = types[i];
int n = x.GetFieldIndex(name);
if (n < 0)
{
return(false);
}
HeronValue val = x.GetValue(n);
HeronValue test = val.As(type);
if (test == null)
{
return(false);
}
}
return(true);
}
