Re: [NTG-context] Trimming strings and Lua string.trim question

6 Mar 2014

      On 2014-03-06 05:38, Hans Hagen wrote:
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On 3/6/2014 12:00 AM, Rik Kabel wrote:
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On 2014-03-05 10:54, Wolfgang Schuster wrote:
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Am 05.03.2014 um 16:18 schrieb Wolfgang Schuster
mailto:schuster.wolfgang@gmail.com>:
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Am 05.03.2014 um 16:07 schrieb Rik Kabel mailto:context@rik.users.panix.com>:
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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