Re: Trimming strings and Lua string.trim question

[Rik Kabel <context@rik.users.panix.com>]

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On 2014-03-06 05:38, Hans Hagen wrote:
> On 3/6/2014 12:00 AM, Rik Kabel wrote:
>> On 2014-03-05 10:54, Wolfgang Schuster wrote:
>>>
>>> Am 05.03.2014 um 16:18 schrieb Wolfgang Schuster
>>> <schuster.wolfgang@gmail.com <mailto:schuster.wolfgang@gmail.com>>:
>>>
>>>>
>>>> Am 05.03.2014 um 16:07 schrieb Rik Kabel <context@rik.users.panix.com
>>>> <mailto:context@rik.users.panix.com>>:
>>>>
>>>>>> striplong
>>>>>>
>>>>>
>>>>> It would be nice if striplong worked, but the example fails when
>>>>> string.striplong is used in place of string.strip. The log says:
>>>>>
>>>>>     ! LuaTeX error [string "\directlua "]:1: attempt to call field
>>>>>     'striplong' (a nil value)
>>>>>     stack traceback:
>>>>>         [string "\directlua "]:1: in main chunk.
>>>>>
>>>>> Is the format of the call different than shown in the wiki, or is a
>>>>> different mechanism required to quote a potentially long string?
>>>>
>>>> The name of the function is “strings.striplong”.
>>>
>>> This should be “utilities.strings.striplong” but it has no effect
>>> because when take a look
>>> at the saved string in Lua you can see that blank lines are removed
>>> from the text.
>>>
>>> Wolfgang
>>
>> Indeed. This does build without error, but the
>> utilities.strings.striplong result is worse than the string.strip
>> result, with some additional whitespace at the end of the test string
>> from the earlier example.
>
> the definition of 'worse' depends on expectations and given the fact 
> that in tex a newline or two newlines in a row have a different 
> meaning it is just a guess what you want to achieve
>
> anyway, the next beta will have
>
> local str = table.concat( {
> "  ",
> "    aap",
> "  noot mies",
> "  ",
> "    ",
> " zus    wim jet",
> "zus    wim jet",
> "       zus    wim jet",
> "    ",
> }, "\n")
>
> utilities.strings.striplines(str,'prune'):
>
> [[aap
> noot mies
>
>
> zus    wim jet
> zus    wim jet
> zus    wim jet]]
>
> utilities.strings.striplines(str,'prune and collapse'):
>
> [[aap
> noot mies
>
> zus    wim jet
> zus    wim jet
> zus    wim jet]]
>
> utilities.strings.striplines(str,'prune and no empty'):
>
> [[aap
> noot mies
> zus    wim jet
> zus    wim jet
> zus    wim jet]]
>
> utilities.strings.striplines(str,'retain'):
>
> [[
> aap
> noot mies
>
>
> zus    wim jet
> zus    wim jet
> zus    wim jet
> ]]
>
> utilities.strings.striplines(str,'retain and collapse'):
>
> [[
> aap
> noot mies
>
> zus    wim jet
> zus    wim jet
> zus    wim jet
> ]]
>
> utilities.strings.striplines(str,'retain and no empty'):
>
> [[
> aap
> noot mies
> zus    wim jet
> zus    wim jet
> zus    wim jet
> ]]
>
> so you can choose what you like
>
> Hans

indeed, beauty is in the eye of the beholder.

Thank you for the flexible solution that allows each of us to find beauty.

Could you please ensure that this handles text in buffers the same way 
that it handles other strings? I noticed that this is handled a bit 
differently, as the following shows,but perhaps it is my clumsy coding. 
The buffer result is closer to what I expect in terms of internal 
whitespace, but still does not show expected trimming of leading and 
trailing whitespace. That trimming, of course, is the point of the exercise.


    \def\StringsStripLong#1%
       {\ctxlua{context(utilities.strings.striplong([==[#1]==]))}}

    \def\StringStrip#1%
       {\ctxlua{context(string.strip([==[#1]==]))}}

    \startbuffer[testbuffer]

    B This is a test.

    And it has an unexpected result.


    \stopbuffer

    \long\def\testmacro{

    M This is a test.

    And it has an unexpected result.


    }

    \starttext

    \subject{Lua string.strip passed TeX buffer}
    ¦\StringStrip{\getbuffer[testbuffer]}¦

    \subject{Lua string.strip passed TeX macro}
    ¦\StringStrip{\testmacro}¦

    \subject{Lua utilities.strings.striplong passed TeX buffer}
    ¦\StringsStripLong{\getbuffer[testbuffer]}¦

    \subject{Lua utilities.strings.striplong passed TeX macro}
    ¦\StringsStripLong{\testmacro}¦

    \stoptext

-- 
Rik

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