Newline in code with MakeExpression

Question

I start with

f[x].

In boxes, this is

RowBox[{"f", "[", "x", "]"}].

I apply MakeExpression to give f[x] again, as desired.

Then I try

f[ x],

which in boxes is RowBox[{"f", "[", "\[IndentingNewLine]", "x", "]"}]. Applying MakeExpressiongives f[x], which is ok for my current purposes.

The problem arises when I try to apply this to Table. Without the newline character, eg.

Table[x, {x, 2}],

converting to boxes and then using MakeExpression works as expected.

Then I try

Table[x , {x, 2}].

In boxes, this is RowBox[{"Table", "[", RowBox[{"x", "\[IndentingNewLine]", ",", RowBox[{"{", RowBox[{"x", ",", "2"}], "}"}]}], "]"}]

When I apply MakeExpression to this, I get ErrorBox[RowBox[{"Table", "[", ErrorBox[ RowBox[{"x", "\[IndentingNewLine]", ",", RowBox[{"{", RowBox[{"x", ",", "2"}], "}"}]}]], "]"}]]

Does anyone know how I can get around this?

Answer 1

If the problem comes from the "[IndentingNewLine]", one can simply remove it. For example:

RowBox[{"Table", "[", 
    RowBox[{"x", "\[IndentingNewLine]", ",", 
      RowBox[{"{", RowBox[{"x", ",", "2"}], "}"}]}], "]"}] /. 
  "\[IndentingNewLine]" -> Nothing // MakeExpression

(* HoldComplete[Table[x, {x, 2}]] *)

If you use versions early than 10.2, then this seems to work

DeleteCases[
 RowBox[{"Table", "[", 
   RowBox[{"x", "\[IndentingNewLine]", ",", 
     RowBox[{"{", RowBox[{"x", ",", "2"}], "}"}]}], 
   "]"}], "\[IndentingNewLine]", ∞]
(* HoldComplete[Table[x, {x, 2}]] *)

Answer 2

Why don't you use ToExpression instead?

ToExpression[RowBox[{"f", "[", "x", "]"}], StandardForm, Defer]

f[x]

ToExpression[RowBox[{"f", "[", "\[IndentingNewLine]", "x", "]"}], StandardForm, Defer]

f[x]

ToExpression[RowBox[{"Table", "[", 
RowBox[{"x", "\[IndentingNewLine]", ",", 
RowBox[{"{", RowBox[{"x", ",", "2"}], "}"}]}], "]"}], StandardForm, Defer]

Table[x, {x, 2}]