Re: changing an XML node and reprocess it (or xmlflushing a string)

[Hans Hagen <j.hagen@xs4all.nl>]

On 10/8/2019 11:17 AM, mf wrote:
> Solved with a dirty hack:
> 
> \startbuffer[text]
> <p>A paragraph with a fraction made of text with styles:
> <span class="fraction">a <i>fraction</i> made of text/with 
> <red><b>nested</b> styles</red> inside</span>.</p>
> \stopbuffer
> 
> \startluacode
> local gsub = string.gsub
> local sfind = string.find
> local xmlflush = lxml.flush
> 
> local startTextFraction = "$\\frac{\\text{"
> local stopTextFraction  = "}}$"
> 
> function xml.functions.textfraction( t )
>    local dt = t.dt
>    inspect( dt )
>    local wrapper
>    local slashfound = false
>    context( startTextFraction )
>    local index, child

^^ Not needed, they are local to the for loop

>    for index, child in ipairs( dt ) do
>      if type( child ) == "string" then
>        if not slashfound and sfind( child, "/" ) then
>          context( gsub( child, "/", "}}{\\text{" ) )
>          slashfound = true
>        else
>          context( child )
>        end
>      elseif type( child ) == "table" then
>        wrapper = {
>          __parent__ = child.__parent__,
>          at = {},
>          dt = child
>        }
>        child.__parent__ = wrapper
>        xmlflush( wrapper )
>      end
>    end
>    context( stopTextFraction )
> end
> \stopluacode

or, to get rid of the wrapper:

\startluacode
local gsub, find = string.gsub, string.find
local xmlprint = xml.sprint
local context = context

local startTextFraction = "$\\frac{\\text{"
local stopTextFraction  = "}}$"

function xml.functions.textfraction(t)
     context(startTextFraction)
     local slashfound = false
     local elements   = t.dt
     for i=1,#elements do
         local child = elements[i]
         if type(child) == "table" then
          -- lxml.all(child,".")
             xmlprint(child,t)
         elseif not slashfound and find(child,"/") then
             context((gsub(child,"/","}}{\\text{")))
             slashfound = true
         else
             context(child)
         end
     end
     context(stopTextFraction)
end
\stopluacode

i'll add the example to the "todo" for a "very dirty tricks" chapter 
some day

> \startxmlsetups xml:textsetups
>    \xmlsetsetup{#1}{*}{+}
>    \xmlsetsetup{#1}{p|i|b|red}{xml:*}
>    \xmlsetsetup{#1}{{span.fraction}}{xml:fraction}
> \stopxmlsetups
> 
> \xmlregistersetup{xml:textsetups}
> 
> \startxmlsetups xml:p
>    \xmlflush{#1}\par
> \stopxmlsetups
> 
> \startxmlsetups xml:i
>    {\it \xmlflush{#1}}
> \stopxmlsetups
> 
> \startxmlsetups xml:red
>    {\red \xmlflush{#1}}
> \stopxmlsetups
> 
> \startxmlsetups xml:b
>    {\bf \xmlflush{#1}}
> \stopxmlsetups
> 
> \startxmlsetups xml:fraction
>    \xmlfunction{#1}{textfraction}
> \stopxmlsetups
> 
> \starttext
>    \xmlprocessbuffer{main}{text}{}
> \stoptext
> 
> 
> Il 07/10/19 18:26, mf ha scritto:
>> Hello,
>> i'm using XML and i find useful specifying a fraction made of text 
>> this way:
>>
>> <span class="fraction">text for numerator/text for denominator</span>
>>
>> With some lua, i can transform it into
>>
>> \frac{\text{text for numerator}}{\text{text for denominator}}
>>
>> which typesets something like this:
>>
>>   text for numerator
>> --------------------
>> text for denominator
>>
>> Suppose you want to add some styling to the texts, like this:
>>
>> <span class="fraction">text for <i>numerator</i>/text for 
>> <b>denominator</b></span>
>>
>> You should split the span node into two elements and the xmlflush them.
>> This is my M(not)WE:
>>
>> \startbuffer[text]
>> <p>A paragraph with a fraction made of text with styles:
>> <span class="fraction">a <i>fraction</i> made of text/with 
>> <red>styles</red> inside</span>.</p>
>> \stopbuffer
>>
>> \startluacode
>> local sub = string.sub
>> local sfind = string.find
>> local xmltext = xml.text
>> local xmlconvert = xml.convert
>>
>> local function numeratorDenominator( text )
>>    local before, after = sfind( text, "[^<]/[^>]" )
>>    local num, den
>>    if before and after then
>>      num = sub( text, 1, before )
>>      den = sub( text, after )
>>    end
>>    return num, den
>> end
>>
>>
>> function xml.functions.textfraction( t )
>>    local text = xmltext( t, '' )
>>    local num, den = numeratorDenominator( text )
>>    if num and den then
>>      local fontstyle = tokens.getters.macro( "fontstyle" )
>>      local xml_num = xmlconvert( num )
>>      local xml_den = xmlconvert( den )
>> --    context( "$\\frac{\\text{\\" ..fontstyle .. " " .. num .. 
>> "}}{\\text{\\" ..fontstyle .. " " .. den .. "}}$" )
>>      context( "$\\frac{\\text{\\" ..fontstyle .. " " )
>>      context( num ) -- context.xmlprocessstring( xml_num )
>>      context( "}}{\\text{\\" ..fontstyle .. " " )
>>      context( den ) -- context.xmlprocessstring( xml_den )
>>      context( "}}$" )
>>    else
>>      context.xmlflush( t )
>>    end
>> end
>> \stopluacode
>>
>> \startxmlsetups xml:textsetups
>>    \xmlsetsetup{#1}{*}{+}
>>    \xmlsetsetup{#1}{p|i|red}{xml:*}
>>    \xmlsetsetup{#1}{{span.fraction}}{xml:fraction}
>> \stopxmlsetups
>>
>> \xmlregistersetup{xml:textsetups}
>>
>> \startxmlsetups xml:p
>>    \xmlflush{#1}\par
>> \stopxmlsetups
>>
>> \startxmlsetups xml:i
>>    {\it \xmlflush{#1}}
>> \stopxmlsetups
>>
>> \startxmlsetups xml:red
>>    {\red \xmlflush{#1}}
>> \stopxmlsetups
>>
>> \startxmlsetups xml:fraction
>>    \xmlfunction{#1}{textfraction}
>> \stopxmlsetups
>>
>> \starttext
>>    \xmlprocessbuffer{main}{text}{}
>> \stoptext
>>
>> Massi
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