public override IPStmt VisitAssignStmt(PParser.AssignStmtContext context)
{
IPExpr variable = exprVisitor.Visit(context.lvalue());
IPExpr value = exprVisitor.Visit(context.rvalue());
// If we're doing a move/swap assignment
if (value is ILinearRef linearRef)
{
Variable refVariable = linearRef.Variable;
switch (linearRef.LinearType)
{
case LinearType.Move:
// Moved values must be subtypes of their destinations
if (!variable.Type.IsAssignableFrom(refVariable.Type))
{
throw handler.TypeMismatch(context.rvalue(), refVariable.Type, variable.Type);
}
return(new MoveAssignStmt(context, variable, refVariable));
case LinearType.Swap:
// Within a function, swaps must only be subtyped in either direction
// the actual types are checked at runtime. This is to allow swapping
// with the `any` type.
if (!variable.Type.IsAssignableFrom(refVariable.Type) &&
!refVariable.Type.IsAssignableFrom(variable.Type))
{
throw handler.TypeMismatch(context.rvalue(), refVariable.Type, variable.Type);
}
return(new SwapAssignStmt(context, variable, refVariable));
default:
throw handler.InternalError(linearRef.SourceLocation,
new ArgumentOutOfRangeException(nameof(context)));
}
}
// If this is a value assignment, we just need subtyping
if (!variable.Type.IsAssignableFrom(value.Type))
{
throw handler.TypeMismatch(context.rvalue(), value.Type, variable.Type);
}
return(new AssignStmt(context, variable, value));
}
public override object VisitAssignStmt(PParser.AssignStmtContext context)
{
return(null);
}
