模块:Category handler

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    ----------------------------------------------------------------------------------------------------------
    --                                                                                                      --
    --                                          CATEGORY HANDLER                                            --
    --                                                                                                      --
    --      This module implements the {{category handler}} template in Lua, with a few improvements: all   --
    --      namespaces and all namespace aliases are supported, and namespace names are detected            --
    --      automatically for the local wiki. This module requires [[Module:Namespace detect]] and          --
    --      [[Module:Yesno]] to be available on the local wiki. It can be configured for different wikis    --
    --      by altering the values in the "cfg" table.                                                      --
    --                                                                                                      --
    ----------------------------------------------------------------------------------------------------------
    
    ----------------------------------------------------------------------------------------------------------
    --                                          Configuration data                                          --
    --                      Language-specific parameter names and values can be set here.                   --
    ----------------------------------------------------------------------------------------------------------
    
    local cfg = {}
    
    -- The following config values set the names of parameters that suppress categorisation. They are used
    -- with Module:Yesno, and work as follows:
    --
    -- cfg.nocat:
    -- Result of yesno(args[cfg.nocat])         Effect
    -- true                                     Categorisation is suppressed
    -- false                                    Categorisation is allowed, and the blacklist check is skipped
    -- nil                                      Categorisation is allowed
    --
    -- cfg.categories:
    -- Result of yesno(args[cfg.categories])    Effect
    -- true                                     Categorisation is allowed, and the blacklist check is skipped
    -- false                                    Categorisation is suppressed
    -- nil                                      Categorisation is allowed
    cfg.nocat = 'nocat'    
    cfg.categories = 'categories'
    
    -- The parameter name for the legacy "category2" parameter. This skips the blacklist if set to the
    -- cfg.category2Yes value, and suppresses categorisation if present but equal to anything other than
    -- cfg.category2Yes or cfg.category2Negative.
    cfg.category2 = 'category2'
    cfg.category2Yes = 'yes'
    cfg.category2Negative = '¬'
    
    -- cfg.subpage is the parameter name to specify how to behave on subpages. cfg.subpageNo is the value to
    -- specify to not categorise on subpages; cfg.only is the value to specify to only categorise on subpages.
    cfg.subpage = 'subpage'
    cfg.subpageNo = 'no'
    cfg.subpageOnly = 'only'
    
    -- The parameter for data to return in all namespaces.
    cfg.all = 'all'
    
    -- The parameter name for data to return if no data is specified for the namespace that is detected. This
    -- must be the same as the cfg.other parameter in [[Module:Namespace detect]].
    cfg.other = 'other'
    
    -- The parameter name used to specify a page other than the current page; used for testing and
    -- demonstration. This must be the same as the cfg.page parameter in [[Module:Namespace detect]].
    cfg.page = 'page'
    
    -- The categorisation blacklist. Pages that match Lua patterns in this list will not be categorised.
    -- (However, see the explanation of cfg.nocat, cfg.categories and cfg.category2 for some exceptions.)
    -- If the namespace name has a space in, it must be written with an underscore, e.g. "Wikipedia_talk".
    -- Other parts of the title can have either underscores or spaces.
    cfg.blacklist = {
        '^Main Page$', -- don't categorise the main page.
        
        -- Don't categorise the following pages or their subpages.
        '^Wikipedia:Cascade%-protected items$',
        '^Wikipedia:Cascade%-protected items/.*$',
        '^User:UBX$', -- The userbox "template" space.
        '^User:UBX/.*$',
        '^User_talk:UBX$',
        '^User_talk:UBX/.*$',
        
        -- Don't categorise subpages of these pages, but allow
        -- categorisation of the base page.
        '^Wikipedia:Template messages/.+$',
        
        '/[aA]rchive' -- Don't categorise archives.
    }
    
    -- This is a table of namespaces to categorise by default. They should be in the format of parameter
    -- names accepted by [[Module:Namespace detect]].
    cfg.defaultNamespaces = {
        'main',
        'file',
        'help',
        'category'
    }
    
    ----------------------------------------------------------------------------------------------------------
    --                                          End configuration data                                      --
    ----------------------------------------------------------------------------------------------------------
    
    -- Get dependent modules
    local nsDetect = require('Module:Namespace detect')
    local yesno = require('Module:Yesno')
    
    ----------------------------------------------------------------------------------------------------------
    --                                          Local functions                                             --
    --      The following are internal functions, which we do not want to be accessible from other modules. --
    ----------------------------------------------------------------------------------------------------------
    
    -- Find whether we need to return a category or not.
    local function needsCategory(pageObject, args)
        -- Don't categorise if the relevant options are set.
        if yesno(args[cfg.nocat])
            or yesno(args[cfg.categories]) == false
            or (
                args[cfg.category2] 
                and args[cfg.category2] ~= cfg.category2Yes 
                and args[cfg.category2] ~= cfg.category2Negative
            )
        then
            return false
        end
        -- If there is no pageObject available, then that either means that we are over
        -- the expensive function limit or that the title specified was invalid. Invalid
        -- titles will probably only be a problem during testing, so we choose the best
        -- fallback for being over the expensive function limit. The fallback behaviour
        -- of the old template was to assume the page was not a subpage, so we will do
        -- the same here.
        if args[cfg.subpage] == cfg.subpageNo and pageObject and pageObject.isSubpage then
            return false
        end
        if args[cfg.subpage] == cfg.subpageOnly 
            and (not pageObject or (pageObject and not pageObject.isSubpage))
        then
            return false
        end
        return true
    end
    
    -- Find whether we need to check the blacklist or not.
    local function needsBlacklistCheck(args)
        if yesno(args[cfg.nocat]) == false
            or yesno(args[cfg.categories]) == true
            or args[cfg.category2] == cfg.category2Yes
        then
            return false
        else
            return true
        end
    end
    
    -- Find whether any namespace parameters have been specified.
    -- Mappings is the table of parameter mappings taken from
    -- [[Module:Namespace detect]].
    local function nsParamsExist(mappings, args)
        if args[cfg.all] or args[cfg.other] then
            return true
        end
        for ns, params in pairs(mappings) do
            for i, param in ipairs(params) do
                if args[param] then
                    return true
                end
            end
        end
        return false
    end
    
    ----------------------------------------------------------------------------------------------------------
    --                                          Global functions                                            --
    --      The following functions are global, because we want them to be accessible from #invoke and      --
    --      from other Lua modules.                                                                         --
    ----------------------------------------------------------------------------------------------------------
    
    local p = {}
    
    -- Find if a string matches the blacklist. Returns the match if one is found, or nil otherwise.
    -- Input should be a page title with a namespace prefix, e.g. "Wikipedia talk:Articles for deletion".
    function p.matchesBlacklist(page)
        if type(page) ~= 'string' then return end
        for i, pattern in ipairs(cfg.blacklist) do
            local match = mw.ustring.match(page, pattern)
            if match then
                return match
            end
        end
    end
    
    -- The main structure of the module. Checks whether we need to categorise,
    -- and then passes the relevant arguments to [[Module:Namespace detect]].
    function p._main(args)
        -- Get the page object and argument mappings from
        -- [[Module:Namespace detect]], to save us from having to rewrite the
        -- code.
        local pageObject = nsDetect.getPageObject(args[cfg.page])
        local mappings = nsDetect.getParamMappings()
        
        if not needsCategory(pageObject, args) then return end
        
        local ret = ''
        -- Check blacklist if necessary.
        if not needsBlacklistCheck(args) or not p.matchesBlacklist(pageObject.prefixedText) then
            if not nsParamsExist(mappings, args) then
                -- No namespace parameters exist; basic usage. Pass args[1] to
                -- [[Module:Namespace detect]] using the default namespace
                -- parameters, and return the result.
                local ndargs = {}
                for _, ndarg in ipairs(cfg.defaultNamespaces) do
                    ndargs[ndarg] = args[1]
                end
                ndargs.page = args.page
                ndargs.demospace = args.demospace
                local ndresult = nsDetect._main(ndargs)
                if ndresult then
                    ret = ret .. ndresult
                end
            else
                -- Namespace parameters exist; advanced usage.
                -- If the all parameter is specified, return it.
                local all = args.all
                if type(all) == 'string' then
                    ret = ret .. all
                end
                
                -- Get the arguments to pass to [[Module:Namespace detect]].
                local ndargs = {}
                for ns, params in pairs(mappings) do
                    for _, param in ipairs(params) do
                        ndargs[param] = args[param] or args[cfg.other] or nil
                    end
                end
                ndargs.other = args.other
                ndargs.page = args.page
                ndargs.demospace = args.demospace
                
                local data = nsDetect._main(ndargs)
                
                -- Work out what to return based on the result of the namespace detect call.
                local datanum = tonumber(data)
                if type(datanum) == 'number' then
                    -- "data" is a number, so return that positional parameter.
                    -- Remove non-positive integer values, as only positive integers
                    -- from 1-10 were used with the old template.
                    if datanum > 0 and math.floor(datanum) == datanum then
                        local dataArg = args[datanum]
                        if type(dataArg) == 'string' then
                            ret = ret .. dataArg
                        end
                    end
                else
                    -- "data" is not a number, so return it as it is.
                    if type(data) == 'string' then
                        ret = ret .. data
                    end
                end
            end
        end
        return ret
    end
    
    function p.main(frame)
        -- If called via #invoke, use the args passed into the invoking
        -- template, or the args passed to #invoke if any exist. Otherwise
        -- assume args are being passed directly in.
        local origArgs
        if frame == mw.getCurrentFrame() then
            origArgs = frame:getParent().args
            for k, v in pairs(frame.args) do
                origArgs = frame.args
                break
            end
        else
            origArgs = frame
        end
    
        -- Trim whitespace and remove blank arguments for the following args:
        -- 1, 2, 3 etc., "nocat", "categories", "subpage", and "page".
        local args = {}
        for k, v in pairs(origArgs) do
            if type(v) == 'string' then
                v = mw.text.trim(v) -- Trim whitespace.
            end
            if type(k) == 'number'
                or k == cfg.nocat
                or k == cfg.categories
                or k == cfg.subpage
                or k == cfg.page
            then
                if v ~= '' then
                    args[k] = v
                end
            else
                args[k] = v
            end
        end
        
        -- Lower-case "nocat", "categories", "category2", and "subpage". These
        -- parameters are put in lower case whenever they appear in the old
        -- template, so we can just do it once here and save ourselves some work.
        local lowercase = {cfg.nocat, cfg.categories, cfg.category2, cfg.subpage}
        for _, v in ipairs(lowercase) do
            local argVal = args[v]
            if type(argVal) == 'string' then
                args[v] = mw.ustring.lower(argVal)
            end
        end
        
        return p._main(args)
    end
    
    return p