Module:TrainingPages

--The purpose of this module is to take a list of linked page, and use it to determine the next and previous page in the list as well as the total number of pages.

local p = {}

function p.main(frame,displacement,varstoreturn)
    local parent=frame.getParent(frame)
    local currentpage,indexmodule,defaultpage
    ---- args in the #invoke itself trump args in the parent frame
    currentpage = frame.args.page
    defaultpage = frame.args.defaultpage
    indexmodule = frame.args.index
    displacement = displacement or frame.args.displacement -- can get from function name
    ---- args in the parent frame come next
    if parent then
        currentpage=currentpage or parent.args.page
        indexmodule=indexmodule or parent.args.index -- index is a module return{'page1','page2', ...}
        defaultpage=defaultpage or parent.args.defaultpage
        end
    ---- default values if parameters aren't provided
    defaultpage=defaultpage or "" -- don't know where to send people by default
    indexmodule=indexmodule or "Module:TrainingPages/default index" -- example given in Lua:Requests
    if not(currentpage) then
        local pp=mw.title.getCurrentTitle()
        assert(pp,"failed to access getCurrentTitle")
        currentpage=pp.fullText
    end
    local index={}
    if mw.ustring.sub(indexmodule,1,6)=="Module" then
        ---- get a table of the pages in order from indexmodule
        index=mw.loadData(indexmodule)
    else pp=mw.title.new(indexmodule)
        assert(pp,"failed to access mw.title.new("..indexmodule..") to load the index")
        local textindex=pp.getContent(pp)
        prowl=mw.ustring.gmatch(textindex,"%[%[(.-)[%]|]") -- first half of any wikilink
        index={}
        repeat
            link=prowl()
            if not(link) then break end
            if link~="" then table.insert(index,link) end
        until false
    end
    displacement=displacement or 0 -- assume a null parameter is just display the same
    ---- set up the reverse lookup in lookup.
    ---- it would be faster to set this up in the indexmodule
    ---- but we don't want inconsistencies from user input!
    local lookup={}
    local i=0
    repeat
        i=i+1
        local j=index[i]
        if j then lookup[mw.uri.decode(j)]=i else break end -- lookup["page name"] => page number
    until false
    --- get the page to return
    local returnpage,currentpagenumber
    if (lookup[mw.uri.decode(currentpage)]) then
        currentpagenumber=lookup[currentpage]
        returnpage=index[currentpagenumber+displacement] or defaultpage
    else returnpage=defaultpage
    end
    if not(varstoreturn) then return tostring(returnpage) else return tostring(returnpage),currentpagenumber,#index end
end

-- Return the next page in the index
-- Used like if on a page that is part of the index:
--{{#invoke:TrainingPages| next_page | index=Wikipedia:Training/For students/Editing module index }}
-- Used like this to find the next page after a specified page:
--{{#invoke:TrainingPages| next_page | index=Wikipedia:Training/For students/Editing module index | currentpage=Wikipedia:Training/For students/My sandbox }}
function p.next_page(frame)
    local returnpage,pagenumber,totalpages=p.main(frame,1,true)
    return returnpage
end

-- Same as above, but returns the previous page
function p.last_page(frame)
    local returnpage,pagenumber,totalpages=p.main(frame,-1,true)
    return returnpage
end

function p.page_number(frame)
    local returnpage,pagenumber,totalpages=p.main(frame,0,true)
    return pagenumber
end

function p.total_pages(frame)
    local returnpage,pagenumber,totalpages=p.main(frame,0,true)
    return totalpages
end

return p
Module:TrainingPages

Functions

Parameters
