Re: XML expression to read HTML classes

[Hans Hagen <pragma@wxs.nl>]

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")

-- 

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