[NTG-context] How do I get an empty line in a \framed[align=flushleft]{} item?

[Gerben Wierda]

> On 30 Apr 2020, at 22:54, Wolfgang Schuster <wolfgang.schuster.lists at gmail.com> wrote:
> 
> Gerben Wierda schrieb am 30.04.2020 um 22:47:
>> In normal TeX, when I type
>> Aap\\\\Aap
>> I get something like
>> Aap
>> Aap
>> But inside a \framed[align=]{} the empty line disappears. How do I get it back?
>> Minimal example:
>> \starttext
>> Testing\\\\Testing
>> \page
>> \framed[align=flushleft]{Testing\\\\Testing}
>> \stoptext
> 
> Use \blank

Too happy too soon. And I recall I ran into this earlier a while ago in another setting ago. But I thought of a solution.

Background:

I am automatically converting input from an XML file to METAPOST/ConTeXt. The input may contain one or more newlines.The text must end up in \framed[align=??, width=??] to be typeset.

I use lua to convert and make it safe to pass to METAPOST as a string argument that METAPOST can pass on to textext(), using the following function:

function doubleQuotableEscapedConTeXtString( str)
  local rep = lpeg.replacer {
   { '\n', '\\blank ' },
   { '{', '{\\textbraceleft}' },
   { '}', '{\\textbraceright}' },
   { '#', '{\\texthash}' },
   { '$', '{\\textdollar}' },
   { '&', '{\\textampersand}' },
   { '%', '{\\textpercent}' },
   { '\\','{\\textbackslash}' },
   { '|', '{\\textbar}' },
   { '_', '{\\textunderscore}' },
   { '~', '{\\textasciitilde}' },
   { '^', '{\\textasciicircum}' },
   { '"', "\"&ditto&\"" },
  }
  return rep:match(str)
end

Where it now says \\blank, it used to say \\\\.

Problem

\\\\ gets me what I want if there is one \n (it turns into one new line), but with two \n in succession it still gets me only a single ’newline'
\\blank gets me what I want if there are multiple newlines, but gets me an extra empty line when I only want ’next line’ and multiple \blanks do not work 

But I found the solution by using \strut\\ instead of \blank. In the above table:

   { ‘\n', ‘\\strut\\\\' },

This fools ConTeXt in thinking there actually is something on that line and so multiple \\ will work.

G
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