Module:ParameterCount

This module counts the number of parameters that are passed to a template. For example, you might put the code {{#invoke:ParameterCount|all}} inside the {{my template}} template. If you then use {{my template}} like this:

{{my template
| one
| two
| three
}}

Then the {{#invoke:ParameterCount|all}} code inside the template will give the result 3.

This module can be configured to count all parameters, or specific parameters defined by a template author. This module is only useful in templates. It should not be used on non-template pages.

The module has two functions available, all and main.

all

The all function is used to count all parameters specified when using a template, regardless of whether or not they are used in the template itself.

Usage

{{#invoke:ParameterCount|all}}

Examples

If the code {{#invoke:ParameterCount|all}} was added to the {{my example template}} template, the code {{my example template|1|2|foo=bar}} would make ParameterCount produce 3.

main

The main function is used to count parameters with specific names. There are two ways of specifying parameters: by name, and using Lua patterns.

By name

{{#invoke:ParameterCount|main|1|2|3|abc|def}}

To specify a parameter by name, add the parameter name as a positional parameter.

By pattern

{{#invoke:ParameterCount|main|pattern1=^param%d+$|pattern2=^abc}}

To specify parameters by Lua Ustring pattern, add the pattern to |pattern1=, |pattern2= etc. For information on constructing Lua patterns, see the Lua Users' Wiki pattern tutorial, as well as the Lua reference manual sections on Lua patterns and Ustring patterns.

Examples

If the code {{#invoke:ParameterCount|main|1|2|abc}} was added to the {{my example template}} template, the code {{my example template|1|2|abc=some value|other=some other value}} would make ParameterCount produce 3.

If the code {{#invoke:ParameterCount|main|pattern1=^param%d+$}} was added to the {{my example template}} template, the code {{my example template|param1=a value|param2=another value|param5=yet another value}} would make ParameterCount produce 3.

Checking for blanks

{{#invoke:ParameterCount|all|checkblanks=no}}

{{#invoke:ParameterCount|main|checkblanks=no}}

By default, the module doesn't count parameters whose values contain only whitespace, e.g. |abc=   . If you wish to count all parameters, regardless of their value, use |checkblanks=no. This works with both the all and main functions.

Examples

If the code {{#invoke:ParameterCount|all|checkblanks=no}} was added to the {{my example template}} template, the code {{my example template|1|2|foo=bar|baz=}} would make ParameterCount produce 4.

---

-- This module produces a count of all the arguments passed to it.

local yesno = require('Module:Yesno')

-- Trim a string
local function trim(s)
	return s:match('^%s*(.-)%s*$')
end

-- Test whether a string is blank
local function isBlank(s)
	return not s:find('%S')
end

-- Tests whether a string is a valid positional key, and if so, returns it. If
-- the key is invalid, this returns nil.
local function isPositionalKey(s)
	s = trim(s)
	if s:find('^[1-9][0-9]*$') then
		return tonumber(s)
	end
end

-- Return the count of all arguments for which testFunc returns a truthy value.
local function count(args, testFunc)
	local ret = 0
	for key, val in pairs(args) do
		if testFunc(key, val) then
			ret = ret + 1
		end
	end
	return ret
end

-- Check shared arguments and get the parent argument count.
local function main(frame, testFunc)
	local blankifiedTestFunc
	if yesno(frame.args.checkblanks) ~= false then
		-- Extend the test function to check for blanks as well.
		blankifiedTestFunc = function (key, val)
			if not isBlank(val) then
				return testFunc(key, val)
			end
		end
	else
		blankifiedTestFunc = testFunc
	end
	return count(frame:getParent().args, blankifiedTestFunc)
end

return {
	-- Called with {{#invoke:ParameterCount|all}}
	-- All specified parameters are counted, even those not supported by the
	-- template.
	all = function (frame)
		return main(frame, function () return true end)
	end,

	-- Called with {{#invoke:ParameterCount|main}}
	-- Users can specify a list of parameters to check, and a list of Lua
	-- Ustring patterns to check each parameter against.
	main = function (frame)
		local args = frame.args
		local keys, patterns = {}, {}
		
		-- Get key list
		for i, key in ipairs(args) do
			local positionalKey = isPositionalKey(key)
			if positionalKey then
				keys[positionalKey] = true
			else
				keys[trim(key)] = true
			end
		end

		-- Get patterns
		do
			local function getPattern(i)
				local pattern = args['pattern' .. tostring(i)]
				if pattern and pattern ~= '' then
					return pattern
				end
			end
			local i = 1
			local pattern = getPattern(i)
			while pattern do
				patterns[i] = pattern
				i = i + 1
				pattern = getPattern(i)
			end
		end

		-- Construct the test function
		local testFunc = function (key, val)
			if keys[key] then
				return true
			end
			for i, pattern in ipairs(patterns) do
				if mw.ustring.find(tostring(key), pattern) then
					return true
				end
			end
			return false
		end

		return main(frame, testFunc)
	end
}