ABT.TypeCast.ToPointer C# (CSharp) Method

        public static Expr ToPointer(Expr expr, ExprType type, Env env) {
            ExprTypeKind from = expr.Type.Kind;
            ExprTypeKind to = type.Kind;

            if (to != ExprTypeKind.POINTER) {
                throw new InvalidOperationException("Error: expected casting to pointer.");
            }

            if (from == ExprTypeKind.POINTER) {
                if (expr.IsConstExpr) {
                    return new ConstPtr(((ConstPtr)expr).Value, type, env);
                }
                return new TypeCast(TypeCastType.NOP, expr, type, env);
            }

            if (expr.Type.IsIntegral) {
                // if we are casting from an integral

                // whatever integral -> ulong
                switch (expr.Type.Kind) {
                    case ExprTypeKind.CHAR:
                    case ExprTypeKind.SHORT:
                    case ExprTypeKind.LONG:
                        expr = SignedIntegralToArith(expr, new ULongType(type.IsConst, type.IsVolatile));
                        break;
                    case ExprTypeKind.UCHAR:
                    case ExprTypeKind.USHORT:
                    case ExprTypeKind.ULONG:
                        expr = UnsignedIntegralToArith(expr, new ULongType(type.IsConst, type.IsVolatile));
                        break;
                    default:
                        break;
                }

                // ulong -> pointer
                if (expr.IsConstExpr) {
                    return new ConstPtr(((ConstULong)expr).Value, type, env);
                }
                return new TypeCast(TypeCastType.NOP, expr, type, env);
            }
            if (expr.Type is FunctionType) {
                if (!expr.Type.EqualType(((PointerType)type).RefType)) {
                    throw new InvalidOperationException("Casting from an incompatible function.");
                }

                // TODO: only allow compatible Type?
                return new TypeCast(TypeCastType.NOP, expr, type, env);

            }
            if (expr.Type is ArrayType) {

                // TODO: allow any pointer Type to cast to?
                return new TypeCast(TypeCastType.NOP, expr, type, env);
            }

            throw new InvalidOperationException("Error: casting from an unsupported Type to pointer.");
        }