Ah! this solves the issue. many thanks.
> On Mar 20, 2020, at 1:03 PM, Robby Findler <ro...@cs.northwestern.edu> wrote:
>
> Looks like you need a display or the text gets confused about how big
> (in pixels) characters really are:
>
> #lang racket/gui
> (require framework)
> (define f (new frame% [label ""]))
> (define t (new racket:text%))
> (define ec (new editor-canvas% [parent f] [editor t]))
> (send t insert "(+ 3\n4)")
> (send t freeze-colorer)
> (send t tabify-all)
> (display (send t get-text))
>
> On Fri, Mar 20, 2020 at 2:12 PM John Clements <cleme...@brinckerhoff.org>
> wrote:
>>
>> That actually solves a bunch of problems for me… but strangely, not the
>> initial one. If, for instance, I tabify
>>
>> (+ 3
>> 4)
>>
>> using the tabify-all method, the line with the four gets an indentation of
>> 2, not 8. This is definitely different from DrRacket’s behavior.
>>
>> Any idea how to fix this?
>>
>> (cc:ing racket-users without permission, hope that’s okay?)
>>
>> John
>>
>>
>>> On Mar 20, 2020, at 12:05 PM, John Clements <cleme...@brinckerhoff.org>
>>> wrote:
>>>
>>> Ah! That’s probably a better solution, I’ll just do that. I searched for
>>> “indent”, should I try to add that as a search term for the “tabify-all”
>>> method?
>>>
>>> Many thanks!
>>>
>>> (Also, sending mail to the list using “us...@racket-lang.org” seems to be
>>> broken right now for me, sigh.)
>>>
>>> John
>>>
>>>> On Mar 20, 2020, at 12:01 PM, Robby Findler <ro...@cs.northwestern.edu>
>>>> wrote:
>>>>
>>>> I'm not sure of the details but did you consider just inserting it
>>>> into a racket:text% and then calling the tabify-all method?
>>>>
>>>> Robby
>>>>
>>>> On Fri, Mar 20, 2020 at 1:26 PM John Clements <cleme...@brinckerhoff.org>
>>>> wrote:
>>>>>
>>>>> Hmm… followup problem. If I try to indent the string “#|\nabc\n|#” (that
>>>>> is, a block comment), the compute-racket-amount-to-indent method returns
>>>>> #f. Is this a bug, or just undocumented behavior?
>>>>>
>>>>> John
>>>>>
>>>>>> On Mar 20, 2020, at 10:41 AM, John Clements <cleme...@brinckerhoff.org>
>>>>>> wrote:
>>>>>>
>>>>>> I’m writing code to help me grade exams, and one of the issues I’ve run
>>>>>> into is that the code coming out of the LMS is all totally unindented.
>>>>>> So, for instance, a student’s response might read:
>>>>>>
>>>>>> ;Closures help a function value remember what substitutions have already
>>>>>> been applied to it.
>>>>>> '{vars {{x {lam {x} {+ 1 x}}}
>>>>>> {y {lam {y} {+ 3 y}}}}
>>>>>> {+ {x 2} {y 4}}}
>>>>>>
>>>>>> Obviously, it would be a lot easier to grade that if it was indented.
>>>>>>
>>>>>> Excellent! A chance to whip up a quick-and-dirty auto-indenter, using
>>>>>> DrRacket’s indentation framework. Specifically, the
>>>>>> `compute-racket-amount-to-indent` method of racket:text<%>.
>>>>>>
>>>>>> I’m pleased to report almost total success, aside from one strange
>>>>>> off-by-one error that I’m looking for help with. To see it, here’s the
>>>>>> result of my auto-indenter on the prior block:
>>>>>>
>>>>>> '{vars {{x {lam {x} {+ 1 x}}}
>>>>>> {y {lam {y} {+ 3 y}}}}
>>>>>> {+ {x 2} {y 4}}}
>>>>>>
>>>>>> (if you’re viewing this in a proportional-width font, that’s going to
>>>>>> look terrible, sorry.)
>>>>>>
>>>>>> The issue is that the final plus line isn’t lined up with the
>>>>>> curly-brace that’s two chars after the end of `vars`… instead, it’s one
>>>>>> character to the left.
>>>>>>
>>>>>> A much simpler test case is simply running on “(+ 3\n4)”. Rather than
>>>>>> getting the 4 lined up with the 3, I get it one character to the left.
>>>>>>
>>>>>> And… uh oh. A more illuminating test case occurs when I run my code on
>>>>>> “(+ 3\n4)”. That is, I put a bunch more spaces before the 3. After
>>>>>> indentation, the 4 is still only indented by two characters. So it looks
>>>>>> like the `compute-racket-amount-to-indent` method is not looking for the
>>>>>> token following the first one following the paren in the prior line
>>>>>> (which would account for all the spaces), but just adding one to the
>>>>>> last position of the first token following the paren. This makes me
>>>>>> wonder whether DrRacket actually uses this method to indent.
>>>>>>
>>>>>> Hmm.
>>>>>>
>>>>>> Well, here’s the code to reproduce this. Note that there’s an obvious
>>>>>> bug/assumption in that my code doesn’t account for any existing leading
>>>>>> spaces on a line, but none of my examples have leading spaces following
>>>>>> newlines.
>>>>>>
>>>>>> Advice appreciated!
>>>>>>
>>>>>> John
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> #lang racket
>>>>>>
>>>>>> (require framework)
>>>>>>
>>>>>> ;; given a string of racket text, return the corresponding indented
>>>>>> string
>>>>>> ;; NB: CURRENTLY ASSUMES ALL LINES START WITH ZERO SPACES.
>>>>>> (define (string-indent text-to-indent)
>>>>>> (define t (new racket:text%))
>>>>>> (send t erase)
>>>>>> (send t insert text-to-indent 0)
>>>>>> (define num-paragraphs (add1 (send t last-paragraph)))
>>>>>> (define indents
>>>>>> (for/list ([n (in-range num-paragraphs)])
>>>>>> (define par-start (send t paragraph-start-position n))
>>>>>> (list par-start
>>>>>> (send t compute-racket-amount-to-indent
>>>>>> par-start
>>>>>> head-sexp-type))))
>>>>>> ;; NB: OBVIOUSLY WRONG, assumes all lines start with zero leading spaces:
>>>>>> ;; act in reverse order, to avoid messing up the meaning of char posns:
>>>>>> (for ([indent (in-list (reverse indents))])
>>>>>> (send t set-position (first indent))
>>>>>> (define space-string
>>>>>> (list->string (for/list ([i (in-range (second indent))]) #\space)))
>>>>>> (send t insert space-string))
>>>>>> (send t get-text))
>>>>>>
>>>>>> ;; for now, always return 'other
>>>>>> (define (head-sexp-type str)
>>>>>> 'other)
>>>>>>
>>>>>>
>>>>>> (define text-to-indent
>>>>>> #<<|
>>>>>> ;Closures help a function value remember what substitutions have already
>>>>>> been applied to it.
>>>>>> '{vars {{x {lam {x} {+ 1 x}}}
>>>>>> {y {lam {y} {+ 3 y}}}}
>>>>>> {+ {x 2} {y 4}}}
>>>>>> |
>>>>>> )
>>>>>>
>>>>>> (displayln (string-indent text-to-indent))
>>>>>>
>>>>>>
>>>>>> (displayln (string-indent "
>>>>>> (+ 3
>>>>>> 4)"))
>>>>>>
>>>>>>
>>>>>> (module+ test
>>>>>> (require rackunit)
>>>>>>
>>>>>>
>>>>>> (check-equal? (string-indent "
>>>>>> (+ 3
>>>>>> 4)")
>>>>>> "
>>>>>> (+ 3
>>>>>> 4)")
>>>>>>
>>>>>> (check-equal? (string-indent "
>>>>>> (+ 3
>>>>>> 4)")
>>>>>> "
>>>>>> (+ 3
>>>>>> 4)")
>>>>>>
>>>>>> (check-equal? (string-indent "
>>>>>> (+ 3
>>>>>> 4)")
>>>>>> "
>>>>>> (+ 3
>>>>>> 4)"))
>>>>>>
>>>>>
>>>>>
>>>>>
>>>
>>
>>
>>
>
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