Modul:parameters
This module provides processing and checking of template arguments.
process
[redaktə]process(args, params, return_unknown)
Processes arguments with a given list of parameters, and returns a table containing the processed arguments. The args parameter specifies the arguments to be processed; they are the arguments you might retrieve from frame:getParent().args. The params parameter specifies a list of valid parameters, and consists of a table. If an argument is encountered that is not in the parameter table, an error is shown.
The parameters table should have the parameter names as the indexes, and a (possibly empty) table of parameter tags as the value. An empty table as the value merely states that the parameter exists, but should not receive any special treatment. Possible parameter tags are listed below.
An example parameters table (from Module:translations):
{
[1] = {required = true, default = "und"},
[2] = {},
[3] = {list = true},
["alt"] = {},
["sc"] = {},
["tr"] = {},
}
The return_unknown parameter, if set to true prevents the function from triggering an error when it comes across an argument with a name it doesn't recognise. Instead, the return value is a pair of values: the first is the processed arguments as usual, while the second contains all the unrecognised arguments that were left unprocessed. This allows you to do multi-stage processing, where the entire set of arguments that a template should accept is not known at once. For example, an inflection-table might do some generic processing on some arguments, but then defer processing of the remainder to the function that handles a specific inflectional type.
Parameter tags
[redaktə]required=true- The parameter is required; an error is shown if it is not present. The template's page itself is an exception; no error is shown there.
allow_empty=true- If the argument is an empty string value, it is not converted to
nil, but kept as-is. type=- Specifies what value type to convert the argument into. The default is to leave it as a text string. Alternatives are:
type="boolean"- The value is treated as a boolean value, either true or false. No value, the empty string, and the strings "0", "no", "n" and "false" are treated as false, all other values are considered true.
type="number"- The value is converted into a number, unless it is nil.
alias_of=- Treat the parameter as an alias of another. When arguments are specified for this parameter, they will automatically be renamed and stored under the alias name. This allows for parameters with multiple alternative names, while still treating them as if they had only one name. It is even possible for the
alias_of=to have a name that is not a parameter itself. list=- Treat the parameter as a list of values, each having its own parameter name, rather than a single value. The parameters will have a number at the end, except for the first. For example,
list=trueon a parameter named "head" will include the parametershead=,head2=,head3=and so on. If the parameter name is a number, another number doesn't get appended, but the counting simply continues, e.g. for parameter 3 the sequence is3=,4=,5=etc. List parameters are returned as numbered lists, so for a template that is given the parametershead=a|head2=b|head3=c, the processed value of the parameterheadwill be{"a", "b", "c"}. - The value for
list=can also be a string. This tells the module that parameters other than the first should have a different name, which is useful when the first parameter in a list is a number, but the remainder is named. An example would be for genders:list="g"on a parameter named 1 would have parameters1=,g2=,g3=etc. - If the number is not located at the end, it can be specified by putting an equal sign "=" at the number position. For example, parameters "f1accel", "f2accel", ... can be captured by using the parameter name "f=accel", as is in Module:headword/templates.
allow_holes=true- This is used in conjunction with list-type parameters. By default, the values are tightly packed in the resulting list. This means that if, for example, an entry specified
head=a|head3=cbut nothead2=, the returned list will be{"a", "c"}, with the values stored as index 1 and 2, not 1 and 3. If it is desirable to keep the numbering intact, for example if the numbers of several list parameters correlate with each other (like those of{{compound}}), then this tag can be specified. - If
allow_holes=trueis given, there may be nil values in between two real values, which makes many of Lua's table processing functions no longer work, like#oripairs. To remedy this, the resulting table will contain an additional named value,maxindex, which tells you the highest numeric index that is present in the table. In the example above, the resulting table will now be{"a", nil, "c", maxindex=3}. That way, you can iterate over the values from 1 tomaxindex, while skipping nil values in between. default=- Specifies a default value for the parameter, if it is absent or empty. When used on list parameters, this specifies a default value for the first item in the list only. Note that it is not possible to generate a default that depends on the value of other parameters.
- If used together with
required=true, the default applies only to the template's page itself. This can be used to show an example text.
local export = {}
-- A helper function to escape magic characters in a string
-- Magic characters: ^$()%.[]*+-?
local plain = require("Module:string").pattern_escape
-- A helper function that removes empty numeric indexes in a table,
-- so that the values are tightly packed like in a normal Lua table.
local remove_holes = require("Module:table").compressSparseArray
function export.process(args, params, return_unknown)
local args_new = {}
-- Process parameters for specific properties
local required = {}
local patterns = {}
local list_from_index = nil
for name, param in pairs(params) do
if param.required then
if param.alias_of then
require("Module:debug").track("parameters/required alias")
end
required[name] = true
end
if param.list then
local key = name
if type(name) == "string" then
key = string.gsub(name, "=", "")
end
if param.default ~= nil then
args_new[key] = {param.default, maxindex = 1}
else
args_new[key] = {maxindex = 0}
end
if type(param.list) == "string" then
-- If the list property is a string, then it represents the name
-- to be used as the prefix for list items. This is for use with lists
-- where the first item is a numbered parameter and the
-- subsequent ones are named, such as 1, pl2, pl3.
if string.find(param.list, "=") then
patterns["^" .. string.gsub(plain(param.list), "=", "(%%d+)") .. "$"] = name
else
patterns["^" .. plain(param.list) .. "(%d+)$"] = name
end
elseif type(name) == "number" then
-- If the name is a number, then all indexed parameters from
-- this number onwards go in the list.
list_from_index = name
else
if string.find(name, "=") then
patterns["^" .. string.gsub(plain(name), "=", "(%%d+)") .. "$"] = string.gsub(name, "=", "")
else
patterns["^" .. plain(name) .. "(%d+)$"] = name
end
end
if string.find(name, "=") then
require("Module:debug").track("parameters/name with equals")
params[string.gsub(name, "=", "")] = params[name]
params[name] = nil
end
elseif param.default ~= nil then
args_new[name] = param.default
end
end
-- Process the arguments
local args_unknown = {}
for name, val in pairs(args) do
local index = nil
if type(name) == "number" then
if list_from_index ~= nil and name >= list_from_index then
index = name - list_from_index + 1
name = list_from_index
end
else
-- Does this argument name match a pattern?
for pattern, pname in pairs(patterns) do
index = mw.ustring.match(name, pattern)
-- It matches, so store the parameter name and the
-- numeric index extracted from the argument name.
if index then
index = tonumber(index)
name = pname
break
end
end
end
-- If no index was found, use 1 as the default index.
-- This makes list parameters like g, g2, g3 put g at index 1.
index = index or 1
local param = params[name]
-- If the argument is not in the list of parameters, trigger an error.
-- return_unknown suppresses the error, and stores it in a separate list instead.
if not param then
if return_unknown then
args_unknown[name] = val
else
error("The parameter \"" .. name .. "\" is not used by this template.", 2)
end
else
-- Remove leading and trailing whitespace unless allow_whitespace is true.
if not param.allow_whitespace then
val = mw.text.trim(val)
end
-- Empty string is equivalent to nil unless allow_empty is true.
if val == "" and not param.allow_empty then
val = nil
end
-- Convert to proper type if necessary.
if param.type == "boolean" then
val = not (not val or val == "" or val == "0" or val == "no" or val == "n" or val == "false")
elseif param.type == "number" and val ~= nil then
val = tonumber(val)
end
-- Can't use "if val" alone, because val may be a boolean false.
if val ~= nil then
-- Mark it as no longer required, as it is present.
required[param.alias_of or name] = nil
-- Store the argument value.
if param.list then
-- If the parameter is an alias of another, store it as the original,
-- but avoid overwriting it; the original takes precedence.
if not param.alias_of then
args_new[name][index] = val
-- Store the highest index we find.
args_new[name].maxindex = math.max(index, args_new[name].maxindex)
elseif args[param.alias_of] == nil then
if params[param.alias_of] and params[param.alias_of].list then
args_new[param.alias_of][index] = val
-- Store the highest index we find.
args_new[param.alias_of].maxindex = math.max(1, args_new[param.alias_of].maxindex)
else
args_new[param.alias_of] = val
end
end
else
-- If the parameter is an alias of another, store it as the original,
-- but avoid overwriting it; the original takes precedence.
if not param.alias_of then
args_new[name] = val
elseif args[param.alias_of] == nil then
if params[param.alias_of] and params[param.alias_of].list then
args_new[param.alias_of][1] = val
-- Store the highest index we find.
args_new[param.alias_of].maxindex = math.max(1, args_new[param.alias_of].maxindex)
else
args_new[param.alias_of] = val
end
end
end
end
end
end
-- The required table should now be empty.
-- If any entry remains, trigger an error, unless we're in the template namespace.
if mw.title.getCurrentTitle().nsText ~= "Template" then
local list = {}
for name, param in pairs(required) do
table.insert(list, name)
end
local count = #list
if count == 1 then
error('The parameter "' .. list[1] .. '" is required.', 2)
elseif count == 2 then
error('The parameters "' .. table.concat(list, '" and "') .. '" are required.', 2)
elseif count > 2 then
error('The parameters "' .. mw.text.listToText(list, '", "', '", and "') .. '" are required.', 2)
end
end
-- Remove holes in any list parameters if needed.
for name, val in pairs(args_new) do
if type(val) == "table" and not params[name].allow_holes then
args_new[name] = remove_holes(val)
end
end
if return_unknown then
return args_new, args_unknown
else
return args_new
end
end
return export