Module:Arguments

    From Nonbinary Wiki
    Revision as of 02:19, 9 December 2013 by m>Mr. Stradivarius (return a table rather than a function, improve the comments)

    Documentation for this module may be created at Module:Arguments/doc

    -- This module provides easy processing of arguments passed to Scribunto from #invoke.
    -- It is intended for use by other Lua modules, and should not be called from #invoke directly.
    
    local arguments = {}
    
    function arguments.getArgs(frame, options)
    	options = type(options) == 'table' and options or {}
    
    	-- Get the arguments from the frame object if available. If the frame object is not available, we are being called
    	-- from another Lua module or from the debug console, so assume arguments are passed directly in.
    	local fargs, pargs
    	if frame == mw.getCurrentFrame() then
    		fargs = frame.args
    		pargs = frame:getParent().args
    	else
    		fargs = type(frame) == 'table' and frame or {}
    		pargs = {}
    	end
    
    	local args, metaArgs, metatable = {}, {}, {}
    	setmetatable(args, metatable)
    
    	local function tidyVal(key, val)
    		-- Processes a value according to the options given to getArguments. Can trim whitespace and remove blanks.
    		-- Keys are not used here, but they can be used by user-generated functions, so defining it here to avoid breakage.
    		if type(val) == 'string' then
    			if options.trim ~= false then
    				val = mw.text.trim(val)
    			end
    			if options.removeBlanks == false or mw.ustring.find(val, '%S') then
    				return val
    			end
    		else
    			return val
    		end
    	end
    
    	-- Use a user-generated functions to tidy the values if specified.
    	local valueFunc = options.valueFunc
    	if valueFunc then
    		local valueFuncType = type(valueFunc)
    		if valueFuncType == 'function' then
    			tidyVal = valueFunc
    		else
    			error('type error in option "valueFunc": expected function, got ' .. valueFuncType, 2)
    		end
    	end
    
    	local function mergeArgs(iterator, ...)
    		-- Accepts multiple tables as input and merges their keys and values into one table using the specified iterator.
    		-- If a value is already present it is not overwritten; tables listed earlier have precendence.
    		local tables = {...}
    		for _, t in ipairs(tables) do
    			for key, val in iterator(t) do
    				if metaArgs[key] == nil then
    					metaArgs[key] = tidyVal(key, val)
    				end
    			end
    		end
    	end
    
    	-- Set the order of precedence of frame args and parent args.
    	local firstArgs, secondArgs = fargs, pargs
    	if options.parentFirst then
    		firstArgs, secondArgs = pargs, fargs
    	end
    
    	-- Define metatable behaviour.
    	metatable.__index = function (t, key)
    		local val = metaArgs[key]
    		if val ~= nil then
    			return val
    		else
    			local firstVal = tidyVal(key, firstArgs[key])
    			if firstVal ~= nil then
    				return firstVal
    			else
    				return tidyVal(key, secondArgs[key])
    			end
    		end
    	end
    
    	metatable.__newindex = function (t, key, val)
    		if not options.readOnly and (not options.noOverwrite or metaArgs[key] == nil) then
    			metaArgs[key] = val
    		end
    	end
    
    	metatable.__pairs = function ()
    		if not metatable.donePairs then
    			mergeArgs(pairs, firstArgs, secondArgs)
    			metatable.donePairs = true
    			metatable.doneIpairs = true
    		end
    		return pairs(metaArgs)
    	end
    
    	metatable.__ipairs = function ()
    		if not metatable.doneIpairs then
    			mergeArgs(ipairs, firstArgs, secondArgs)
    			metatable.doneIpairs = true
    		end
    		return ipairs(metaArgs)
    	end
    	
    	return args
    end
    
    return arguments