XML expression to read HTML classes

XML expression to read HTML classes

[massifr]

Hello list,
I'm working on HTML typesetting with ConTeXt.
I wrote a custom expression to test whether an element has a class:

function xml.functions.classes(classAttr)
  local classes = {}
  if classAttr then
    for c in string.gmatch(classAttr, "%S+") do
      if (string.len(c) > 0) then classes[c] = true end
    end
  end
  return classes
end

function xml.expressions.hasClass(classAttr, className)
  if classAttr and className then
    return xml.functions.classes(classAttr)[className] ~= nil
  end
  return false
end

This way I can write this in my xmlsetup:
\xmlsetsetup{#1}{p[hasClass(@class,'myclass1')]}{html:p:myclass1}

That is better than 
- p[@class='myclass1']   (it fails when you have more classes)
- p[contains(@class, 'myclass1')]    (it gives you false positives when you have class="myclass12")

That works, but I would like to write:
\xmlsetsetup{#1}{p[hasClass('myclass1')]}{html:p:myclass1}

omitting the @class argument, because it's obvious.
To omit it I need to access the current collected element.

At page 25 of "Dealing with XML in ConTeXt MkIV" it is said 
that the predefined variables "list","l","ll" (I think I need that one)
and "order" are available, but I did not manage to access them.

How can I get the current element in Lua to write
local classAttr = xml.attribute(currentElement, "", "class")   ?

Thanks in advance,
Massi
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Re: XML expression to read HTML classes

[massifr]

A working example to clarify my request:

\startluacode
  -- splits the attribute class using spaces as classes' separator
  -- returns an array of strings
  function xml.functions.classes(classAttr)
    local classes = {}
    if classAttr then
      for c in string.gmatch(classAttr, "%S+") do
        if (string.len(c) > 0) then classes[c] = true end
      end
    end
    return classes
  end

  function xml.expressions.hasClass(classAttr, className)
    if classAttr and className then
      return xml.functions.classes(classAttr)[className] ~= nil
    end
    return false
  end
\stopluacode

\startbuffer[test]
<text>
  <p>Generic paragraph (no class).</p>
  <p class="myClass1">Emphasized paragraph (<tt>class="myClass1"</tt>).</p>
  <p class="otherClass myClass1">Another emphasized paragraph
  (but <tt>myClass1</tt> is not the only class specified).
  </p>
  <p class="myClass12">Another not emphasized paragraph 
  (<tt>class="myClass12"</tt>) showing why <br/>
  <tt>p[hasClass(@class, "myClass1")]</tt><br/>
  is better than <br/>
  <tt>p[@class="myClass1"]</tt><br/>
  or <br/>
  <tt>p[contains(@class, "myClass1")]</tt>.
  </p>
  <p><tt>p[hasClass("myClass1")]</tt> would be better 
  since it's obvious that the classes are specified 
  in the <tt>class</tt> attribute, but this means that 
  the lua expression needs to access the current selected element
  (<tt>ll</tt>?).
  </p>
</text>
\stopbuffer

\startxmlsetups xml:somesetups
  \xmlsetsetup{#1}{text}{xml:text}
  \xmlsetsetup{#1}{p}{xml:p}
  \xmlsetsetup{#1}{p[hasClass(@class, 'myClass1')]}{xml:p:myClass1}
  \xmlsetsetup{#1}{tt}{xml:tt}
  \xmlsetsetup{#1}{br}{xml:br}
\stopxmlsetups

\xmlregistersetup{xml:somesetups}

\startxmlsetups xml:text
  \xmlflush{#1}
\stopxmlsetups

\startxmlsetups xml:p
  \xmlflush{#1}\par\blank[line]
\stopxmlsetups

\startxmlsetups xml:p:myClass1
  {\em\xmlflush{#1}}\par\blank[line]
\stopxmlsetups

\startxmlsetups xml:br
  \\
\stopxmlsetups

\startxmlsetups xml:tt
  \dontleavehmode{\tt\xmlflush{#1}}
\stopxmlsetups

\starttext
  \xmlprocessbuffer{main}{test}{}
\stoptext

Thanks in advance for any help,
Massi
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maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
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___________________________________________________________________________________

Re: XML expression to read HTML classes

[Hans Hagen]

On 8/25/2015 5:05 PM, massifr@fastwebnet.it wrote:
> Hello list,
> I'm working on HTML typesetting with ConTeXt.
> I wrote a custom expression to test whether an element has a class:
>
> function xml.functions.classes(classAttr)
>    local classes = {}
>    if classAttr then
>      for c in string.gmatch(classAttr, "%S+") do
>        if (string.len(c) > 0) then classes[c] = true end
>      end
>    end
>    return classes
> end
>
> function xml.expressions.hasClass(classAttr, className)
>    if classAttr and className then
>      return xml.functions.classes(classAttr)[className] ~= nil
>    end
>    return false
> end
>
> This way I can write this in my xmlsetup:
> \xmlsetsetup{#1}{p[hasClass(@class,'myclass1')]}{html:p:myclass1}
>
> That is better than
> - p[@class='myclass1']   (it fails when you have more classes)
> - p[contains(@class, 'myclass1')]    (it gives you false positives when you have class="myclass12")
>
> That works, but I would like to write:
> \xmlsetsetup{#1}{p[hasClass('myclass1')]}{html:p:myclass1}
>
> omitting the @class argument, because it's obvious.
> To omit it I need to access the current collected element.
>
> At page 25 of "Dealing with XML in ConTeXt MkIV" it is said
> that the predefined variables "list","l","ll" (I think I need that one)
> and "order" are available, but I did not manage to access them.
>
> How can I get the current element in Lua to write
> local classAttr = xml.attribute(currentElement, "", "class")   ?

function xml.functions.classes(e)
     local class = e.at.class
     if class then
         local classes = { }
         for c in string.gmatch(class,"%S+") do
             classes[c] = true
         end
         return classes
     else
         return { }
     end
end



-- 

-----------------------------------------------------------------
                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
     tel: 038 477 53 69 | voip: 087 875 68 74 | www.pragma-ade.com
                                              | www.pragma-pod.nl
-----------------------------------------------------------------
___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : http://www.pragma-ade.nl / http://tex.aanhet.net
archive  : http://foundry.supelec.fr/projects/contextrev/
wiki     : http://contextgarden.net
___________________________________________________________________________________

Re: XML expression to read HTML classes

[Hans Hagen]

On 8/27/2015 10:57 PM, Hans Hagen wrote:
> On 8/25/2015 5:05 PM, massifr@fastwebnet.it wrote:
>> Hello list,
>> I'm working on HTML typesetting with ConTeXt.
>> I wrote a custom expression to test whether an element has a class:
>>
>> function xml.functions.classes(classAttr)
>>    local classes = {}
>>    if classAttr then
>>      for c in string.gmatch(classAttr, "%S+") do
>>        if (string.len(c) > 0) then classes[c] = true end
>>      end
>>    end
>>    return classes
>> end
>>
>> function xml.expressions.hasClass(classAttr, className)
>>    if classAttr and className then
>>      return xml.functions.classes(classAttr)[className] ~= nil
>>    end
>>    return false
>> end
>>
>> This way I can write this in my xmlsetup:
>> \xmlsetsetup{#1}{p[hasClass(@class,'myclass1')]}{html:p:myclass1}
>>
>> That is better than
>> - p[@class='myclass1']   (it fails when you have more classes)
>> - p[contains(@class, 'myclass1')]    (it gives you false positives
>> when you have class="myclass12")
>>
>> That works, but I would like to write:
>> \xmlsetsetup{#1}{p[hasClass('myclass1')]}{html:p:myclass1}
>>
>> omitting the @class argument, because it's obvious.
>> To omit it I need to access the current collected element.
>>
>> At page 25 of "Dealing with XML in ConTeXt MkIV" it is said
>> that the predefined variables "list","l","ll" (I think I need that one)
>> and "order" are available, but I did not manage to access them.
>>
>> How can I get the current element in Lua to write
>> local classAttr = xml.attribute(currentElement, "", "class")   ?
>
> function xml.functions.classes(e)
>      local class = e.at.class
>      if class then
>          local classes = { }
>          for c in string.gmatch(class,"%S+") do
>              classes[c] = true
>          end
>          return classes
>      else
>          return { }
>      end
> end

alternative:

function xml.functions.hasclass(e,c,class)
     class = class and e.at[class] or e.at.class
     if class and class ~= "" then
         if class == c then
             return true
         else
             for s in string.gmatch(class,"%S+") do
                 if s == c then
                     return true
                 end
             end
         end
     end
     return false
end

.. hasclass("foo")

-- 

-----------------------------------------------------------------
                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
     tel: 038 477 53 69 | voip: 087 875 68 74 | www.pragma-ade.com
                                              | www.pragma-pod.nl
-----------------------------------------------------------------
___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : http://www.pragma-ade.nl / http://tex.aanhet.net
archive  : http://foundry.supelec.fr/projects/contextrev/
wiki     : http://contextgarden.net
___________________________________________________________________________________