On 2012-02-01 20:26, Jaroslav Hajtmar wrote:
> I want to use Lua to write characters (substrings) from a string,
> but I get an error message:
> 
> ! String contains an invalid utf-8 sequence.
> 
> Can you please someone help?

Have you tried the unicode library? The standard string library
operates on bytes, therefore extracting a single byte yields an
incomplete multibyte char if the codepoint is beyond ascii.

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\def\mymacro#1{%
  \startluacode
    local utf = unicode.utf8
    local target = [==[\detokenize{#1}]==]
    for i=1, utf.len(target) do
      context(utf.sub(target,i,i)..", ")
    end
  \stopluacode%
}

%% alternatively, use utfcharacters
\define[1]\myothermacro{%
  \startluacode
    local result = { }
    for i in string.utfcharacters[==[\detokenize{#1}]==] do
      result[\letterhash result+1] = i
    end
    context(table.concat(result, ", "))
  \stopluacode
}

\starttext

\mymacro{šěřěžřýčřčžáýčý}\par
\myothermacro{šěřěžřýčřčžáýčý}

\stoptext

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(Lazy people would just do a “local string = unicode.utf8” at the
top of the file.)

Regards
Philipp




> 
> Thanks
> Jaroslav Hajtmar
> 
> Here is my minimal example:
> 
> \def\mymacro#1{\ctxlua{for i=1, string.len('#1') do
> context(string.sub('#1',i,i)..", ") end}}
> 
> \starttext
> 
> %\mymacro{šěřěžřýčřčžáýčý} % Here is a problem
> \mymacro{asdfghjklqwertt} % Here is all OK
> 
> \stoptext
> 
> 
> 
> 
> 
> 
> 
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