How to make RawBoxes to be Expression

Question

expr = First@
  Level[Values@
    WolframLanguageData["Plot", 
     EntityProperty["WolframLanguageSymbol", 
      "DocumentationExampleInputs"]], {3}]

Plot[Sin[x], {x, 0, 6 Pi}]

But I find the Head of expr is RawBoxes

Head@expr
(* RawBoxes *)

And I cannot get the string like "Plot[Sin[x],{x,0,6 Pi}]"

ToString@expr
(* "RawBoxes[Cell[BoxData[RowBox[{Plot, [, RowBox[{RowBox[{Sin, 
[, x, ]}], ,, RowBox[{{, RowBox[{x, ,, 0, ,, RowBox[{6, Pi}]}], 
}}]}], ]}]], Input, ShowStringCharacters -> True]]" *)

Answer 1

Actually MakeExpression works. If you want to evaluate that expression,

expr//ToBoxes//MakeExpression//ReleaseHold

will work. If you want to get similar output as Wjx

(expr // ToBoxes // MakeExpression) /. ExpressionCell[a_, __] :> a

Answer 2

Will this help?

Cases[Hold[Plot[Sin[x], {x, 0, 6 Pi}]], ExpressionCell[cont_, ___] :> Hold@cont, Infinity]

{Hold[Plot[Sin[x], {x, 0, 6 [Pi]}]]}

A trick using Cases to extract stuffs in a Held Expression. Is this what you need? :)

Also, if your real application needs you to convert them into a string:

Cases[Hold[Plot[Sin[x], {x, 0, 6 Pi}]], 
  ExpressionCell[cont_, ___] :> ToString@Unevaluated@cont, 
  Infinity][[1]]

"Plot[Sin[x], {x, 0, 6 Pi}]"

Answer 3

A solution that is not very satisfactory is to grab the argument of BoxData and turn that into an expression.

expr = First@
  Level[Values@
    WolframLanguageData["Plot", 
     EntityProperty["WolframLanguageSymbol", 
      "DocumentationExampleInputs"]], {3}]
FirstCase[expr, BoxData[data_]:>data,,Infinity]//ToExpression

(one can also use MakeExpression[#,StandardForm]& instead of ToExpression to get a held expression).