Module:TableTools

--

-- This module includes a number of functions for dealing with Lua tables. -- -- @script TableTools -- @alias p -- @release stable -- @require libraryUtil -- @attribution Module:TableTools (Wikipedia) -- @see Wikipedia:Module:TableTools for a similar module.

local p = {} local libraryUtil = require('libraryUtil') -- Define often-used variables and functions. local floor = math.floor local infinity = math.huge local checkType = libraryUtil.checkType

-- Returns a new table with all parameters stored into keys 1, 2, etc. and with -- a field `n` with the total number of parameters. Note that the resulting -- table may not be a sequence. -- -- @function p.pack -- @param[opt] ... -- @return {table} -- @see 

function p.pack(...) return {n = select('#', ...), ...} end

-- Returns the first `n` arguments in `...`. If `n` is negative, arguments are -- counted from the end of the table. -- -- @function p.selectFirst -- @param {number} n -- @param[opt] ... -- @see Lua reference manual/Standard libraries -- @see 

function p.selectFirst(n, ...) checkType('Dev:TableTools.selectFirst', 1, n, 'number')

local function err error('bad argument #1 to \'Dev:TableTools.selectFirst\' ' ..             '(index out of range)') end

local function recurse(index, next, ...) if index == 0 then return end

return next, recurse(index - 1, ...) end

n = math.modf(n)

local count = select("#", ...)

if -count > n then err elseif -1 > n and n >= -count then return recurse(count + 1 + n, ...) elseif n == -1 then return ... elseif n == 0 then err elseif n == 1 then return (...) elseif 1 < n and n <= count then return recurse(n, ...) elseif count < n then return ... end end

-- Returns `true` if a given table is a sequence. -- -- @function p.isSequence -- @param {table} t -- @return {boolean} -- @see 

function p.isSequence(t) checkType('Dev:TableTools.isSequence', 1, t, 'table')

local i = 1

for _ in pairs(t) do       if t[i] == nil then return false end

i = i + 1 end

return true end

-- Returns the number of elements in a table, even if it is not a sequence. -- -- @function p.size -- @param {table} t -- @return {number} -- @see 

function p.size(t) checkType('Dev:TableTools.size', 1, t, 'table')

local i = 0

for _ in pairs(t) do       i = i + 1 end

return i end

-- Returns `true` if a given table contains a certain element. -- -- @function p.includes -- @param {table} t -- @param elm -- @return {boolean} -- @see 

function p.includes(t, elm) checkType('Dev:TableTools.includes', 1, t, 'table')

for _, v in pairs(t) do       if v == elm then return true end end

return false end

-- Merges the content of the second table with the content in the first one. -- -- @function p.merge -- @param {table} dest -- @param {table} source -- @return {table} -- @see 

function p.merge(dest, source) checkType('Dev:TableTools.merge', 1, dest, 'table') checkType('Dev:TableTools.merge', 2, source, 'table')

for k, v in pairs(source) do       if type(v) == 'table' and type(dest[k]) == 'table' then -- Don't overwrite one table with another; instead merge them -- recurisvely. p.merge(dest[k], v)       else dest[k] = v       end end

return dest end

-- This function returns true if the given value is a positive integer, and false -- if not. Although it doesn't operate on tables, it is included here as it is -- useful for determining whether a given table key is in the array part or the -- hash part of a table. -- -- @function p.isPositiveInteger -- @param v -- @return {boolean}

function p.isPositiveInteger(v) if type(v) == 'number' and v >= 1 and floor(v) == v and v < infinity then return true else return false end end

-- This function returns true if the given number is a NaN value, and false -- if not. Although it doesn't operate on tables, it is included here as it is -- useful for determining whether a value can be a valid table key. Lua will -- generate an error if a NaN is used as a table key. -- -- @function p.isNan -- @param v -- @return {boolean}

function p.isNan(v) if type(v) == 'number' and tostring(v) == '-nan' then return true else return false end end

-- This returns a clone of a table. The value returned is a new table, but all -- subtables and functions are shared. Metamethods are respected, but the returned -- table will have no metatable of its own. -- -- @function p.shallowClone -- @param {table} t -- @return {table}

function p.shallowClone(t) local ret = {} for k, v in pairs(t) do		ret[k] = v	end return ret end

-- This removes duplicate values from an array. Non-positive-integer keys are -- ignored. The earliest value is kept, and all subsequent duplicate values are -- removed, but otherwise the array order is unchanged. -- -- @function p.removeDuplicates -- @param {table} t -- @return {table}

function p.removeDuplicates(t) checkType('removeDuplicates', 1, t, 'table') local isNan = p.isNan local ret, exists = {}, {} for i, v in ipairs(t) do		if isNan(v) then -- NaNs can't be table keys, and they are also unique, so we don't need to check existence. ret[#ret + 1] = v		else if not exists[v] then ret[#ret + 1] = v				exists[v] = true end end end return ret end

-- This takes a table and returns an array containing the numbers of any numerical -- keys that have non-nil values, sorted in numerical order. -- -- @function p.numKeys -- @param {table} t -- @return {table}

function p.numKeys(t) checkType('numKeys', 1, t, 'table') local isPositiveInteger = p.isPositiveInteger local nums = {} for k, v in pairs(t) do		if isPositiveInteger(k) then nums[#nums + 1] = k		end end table.sort(nums) return nums end

-- This takes a table and returns an array containing the numbers of keys with the -- specified prefix and suffix. For example, for the table -- {a1 = 'foo', a3 = 'bar', a6 = 'baz'} and the prefix "a", affixNums will -- return {1, 3, 6}. -- -- @function p.affixNums -- @param {table} t -- @param[opt] {boolean} prefix -- @param[opt] {boolean} suffix -- @return {table}

function p.affixNums(t, prefix, suffix) checkType('affixNums', 1, t, 'table') checkType('affixNums', 2, prefix, 'string', true) checkType('affixNums', 3, suffix, 'string', true)

local function cleanPattern(s) -- Cleans a pattern so that the magic characters %.[]*+-?^$ are interpreted literally. s = s:gsub('([%(%)%%%.%[%]%*%+%-%?%^%$])', '%%%1') return s	end

prefix = prefix or '' suffix = suffix or '' prefix = cleanPattern(prefix) suffix = cleanPattern(suffix) local pattern = '^' .. prefix .. '([1-9]%d*)' .. suffix .. '$'

local nums = {} for k, v in pairs(t) do		if type(k) == 'string' then local num = mw.ustring.match(k, pattern) if num then nums[#nums + 1] = tonumber(num) end end end table.sort(nums) return nums end

-- Given a table with keys like ("foo1", "bar1", "foo2", "baz2"), returns a table -- of subtables in the format -- { [1] = {foo = 'text', bar = 'text'}, [2] = {foo = 'text', baz = 'text'} } -- Keys that don't end with an integer are stored in a subtable named "other". -- The compress option compresses the table so that it can be iterated over with -- ipairs. -- -- @function p.numData -- @param {table} t -- @param[opt] {boolean} compress -- @return {table}

function p.numData(t, compress) checkType('numData', 1, t, 'table') checkType('numData', 2, compress, 'boolean', true) local ret = {} for k, v in pairs(t) do		local prefix, num = mw.ustring.match(tostring(k), '^([^0-9]*)([1-9][0-9]*)$') if num then num = tonumber(num) local subtable = ret[num] or {} if prefix == '' then -- Positional parameters match the blank string; put them at the start of the subtable instead. prefix = 1 end subtable[prefix] = v			ret[num] = subtable else local subtable = ret.other or {} subtable[k] = v			ret.other = subtable end end if compress then local other = ret.other ret = p.compressSparseArray(ret) ret.other = other end return ret end

-- This takes an array with one or more nil values, and removes the nil values -- while preserving the order, so that the array can be safely traversed with -- ipairs. -- -- @function p.compressSparseArray -- @param {table} t -- @return {table}

function p.compressSparseArray(t) checkType('compressSparseArray', 1, t, 'table') local ret = {} local nums = p.numKeys(t) for _, num in ipairs(nums) do		ret[#ret + 1] = t[num] end return ret end

-- This is an iterator for sparse arrays. It can be used like ipairs, but can -- handle nil values. -- -- @function p.sparseIpairs -- @param {table} t -- @return {function}

function p.sparseIpairs(t) checkType('sparseIpairs', 1, t, 'table') local nums = p.numKeys(t) local i = 0 local lim = #nums return function i = i + 1 if i <= lim then local key = nums[i] return key, t[key] else return nil, nil end end end

return p

-- -- (Add categories here.)