Difference between revisions of "Module:TableTools"

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(fix cleanPattern function - some of the character classes were still being magic even when they were inside the set, so escape them all)
 
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--[[
 
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------------------------------------------------------------------------------------
 
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--                              TableTools                                      --
 
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--                                                                                --
 
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-- This module includes a number of functions for dealing with Lua tables.        --
 
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-- It is a meta-module, meant to be called from other Lua modules, and should    --
 
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-- not be called directly from #invoke.                                          --
 
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------------------------------------------------------------------------------------
 
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--]]
 
  
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local libraryUtil = require('libraryUtil')
 
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local p = {}
 
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-- Define often-used variables and functions.
 
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local floor = math.floor
 
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local infinity = math.huge
 
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local checkType = libraryUtil.checkType
 
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--[[
 
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------------------------------------------------------------------------------------
 
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-- isPositiveInteger
 
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--
 
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-- This function returns true if the given value is a positive integer, and false
 
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-- if not. Although it doesn't operate on tables, it is included here as it is
 
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-- useful for determining whether a given table key is in the array part or the
 
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-- hash part of a table.
 
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------------------------------------------------------------------------------------
 
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--]]
 
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function p.isPositiveInteger(v)
 
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if type(v) == 'number' and v >= 1 and floor(v) == v and v < infinity then
 
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return true
 
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else
 
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return false
 
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end
 
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end
 
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--[[
 
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------------------------------------------------------------------------------------
 
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-- isNan
 
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--
 
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-- This function returns true if the given number is a NaN value, and false
 
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-- if not. Although it doesn't operate on tables, it is included here as it is
 
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-- useful for determining whether a value can be a valid table key. Lua will
 
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-- generate an error if a NaN is used as a table key.
 
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------------------------------------------------------------------------------------
 
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--]]
 
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function p.isNan(v)
 
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if type(v) == 'number' and tostring(v) == '-nan' then
 
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return true
 
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else
 
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return false
 
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end
 
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end
 
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--[[
 
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------------------------------------------------------------------------------------
 
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-- shallowClone
 
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--
 
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-- This returns a clone of a table. The value returned is a new table, but all
 
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-- subtables and functions are shared. Metamethods are respected, but the returned
 
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-- table will have no metatable of its own.
 
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------------------------------------------------------------------------------------
 
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--]]
 
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function p.shallowClone(t)
 
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local ret = {}
 
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for k, v in pairs(t) do
 
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ret[k] = v
 
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end
 
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return ret
 
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end
 
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--[[
 
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------------------------------------------------------------------------------------
 
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-- removeDuplicates
 
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--
 
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-- This removes duplicate values from an array. Non-positive-integer keys are
 
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-- ignored. The earliest value is kept, and all subsequent duplicate values are
 
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-- removed, but otherwise the array order is unchanged.
 
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------------------------------------------------------------------------------------
 
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--]]
 
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function p.removeDuplicates(t)
 
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checkType('removeDuplicates', 1, t, 'table')
 
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local isNan = p.isNan
 
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local ret, exists = {}, {}
 
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for i, v in ipairs(t) do
 
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if isNan(v) then
 
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-- NaNs can't be table keys, and they are also unique, so we don't need to check existence.
 
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ret[#ret + 1] = v
 
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else
 
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if not exists[v] then
 
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ret[#ret + 1] = v
 
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exists[v] = true
 
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end
 
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end
 
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end
 
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return ret
 
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end
 
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--[[
 
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------------------------------------------------------------------------------------
 
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-- numKeys
 
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--
 
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-- This takes a table and returns an array containing the numbers of any numerical
 
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-- keys that have non-nil values, sorted in numerical order.
 
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------------------------------------------------------------------------------------
 
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--]]
 
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function p.numKeys(t)
 
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checkType('numKeys', 1, t, 'table')
 
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local isPositiveInteger = p.isPositiveInteger
 
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local nums = {}
 
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for k, v in pairs(t) do
 
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if isPositiveInteger(k) then
 
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nums[#nums + 1] = k
 
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end
 
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end
 
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table.sort(nums)
 
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return nums
 
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end
 
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--[[
 
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------------------------------------------------------------------------------------
 
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-- affixNums
 
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--
 
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-- This takes a table and returns an array containing the numbers of keys with the
 
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-- specified prefix and suffix. For example, for the table
 
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-- {a1 = 'foo', a3 = 'bar', a6 = 'baz'} and the prefix "a", affixNums will
 
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-- return {1, 3, 6}.
 
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------------------------------------------------------------------------------------
 
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--]]
 
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function p.affixNums(t, prefix, suffix)
 
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checkType('affixNums', 1, t, 'table')
 
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checkType('affixNums', 2, prefix, 'string', true)
 
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checkType('affixNums', 3, suffix, 'string', true)
 
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local function cleanPattern(s)
 
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-- Cleans a pattern so that the magic characters ()%.[]*+-?^$ are interpreted literally.
 
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s = s:gsub('([%(%)%%%.%[%]%*%+%-%?%^%$])', '%%%1')
 
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return s
 
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end
 
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prefix = prefix or ''
 
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suffix = suffix or ''
 
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prefix = cleanPattern(prefix)
 
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suffix = cleanPattern(suffix)
 
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local pattern = '^' .. prefix .. '([1-9]%d*)' .. suffix .. '$'
 
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local nums = {}
 
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for k, v in pairs(t) do
 
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if type(k) == 'string' then
 
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local num = mw.ustring.match(k, pattern)
 
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if num then
 
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nums[#nums + 1] = tonumber(num)
 
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end
 
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end
 
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end
 
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table.sort(nums)
 
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return nums
 
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end
 
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--[[
 
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------------------------------------------------------------------------------------
 
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-- numData
 
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--
 
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-- Given a table with keys like ("foo1", "bar1", "foo2", "baz2"), returns a table
 
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-- of subtables in the format
 
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-- { [1] = {foo = 'text', bar = 'text'}, [2] = {foo = 'text', baz = 'text'} }
 
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-- Keys that don't end with an integer are stored in a subtable named "other".
 
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-- The compress option compresses the table so that it can be iterated over with
 
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-- ipairs.
 
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------------------------------------------------------------------------------------
 
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--]]
 
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function p.numData(t, compress)
 
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checkType('numData', 1, t, 'table')
 
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checkType('numData', 2, compress, 'boolean', true)
 
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local ret = {}
 
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for k, v in pairs(t) do
 
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local prefix, num = mw.ustring.match(tostring(k), '^([^0-9]*)([1-9][0-9]*)$')
 
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if num then
 
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num = tonumber(num)
 
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local subtable = ret[num] or {}
 
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if prefix == '' then
 
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-- Positional parameters match the blank string; put them at the start of the subtable instead.
 
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prefix = 1
 
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end
 
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subtable[prefix] = v
 
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ret[num] = subtable
 
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else
 
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local subtable = ret.other or {}
 
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subtable[k] = v
 
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ret.other = subtable
 
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end
 
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end
 
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if compress then
 
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local other = ret.other
 
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ret = p.compressSparseArray(ret)
 
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ret.other = other
 
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end
 
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return ret
 
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end
 
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--[[
 
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------------------------------------------------------------------------------------
 
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-- compressSparseArray
 
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--
 
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-- This takes an array with one or more nil values, and removes the nil values
 
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-- while preserving the order, so that the array can be safely traversed with
 
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-- ipairs.
 
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------------------------------------------------------------------------------------
 
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--]]
 
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function p.compressSparseArray(t)
 
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checkType('compressSparseArray', 1, t, 'table')
 
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local ret = {}
 
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local nums = p.numKeys(t)
 
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for _, num in ipairs(nums) do
 
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ret[#ret + 1] = t[num]
 
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end
 
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return ret
 
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end
 
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--[[
 
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------------------------------------------------------------------------------------
 
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-- sparseIpairs
 
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--
 
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-- This is an iterator for sparse arrays. It can be used like ipairs, but can
 
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-- handle nil values.
 
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------------------------------------------------------------------------------------
 
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--]]
 
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function p.sparseIpairs(t)
 
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checkType('sparseIpairs', 1, t, 'table')
 
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local nums = p.numKeys(t)
 
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local i = 0
 
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local lim = #nums
 
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return function ()
 
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i = i + 1
 
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if i <= lim then
 
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local key = nums[i]
 
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return key, t[key]
 
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else
 
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return nil, nil
 
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end
 
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end
 
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end
 
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--[[
 
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------------------------------------------------------------------------------------
 
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-- size
 
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--
 
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-- This returns the size of a key/value pair table. It will also work on arrays,
 
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-- but for arrays it is more efficient to use the # operator.
 
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------------------------------------------------------------------------------------
 
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--]]
 
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function p.size(t)
 
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checkType('size', 1, t, 'table')
 
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local i = 0
 
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for k in pairs(t) do
 
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i = i + 1
 
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end
 
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return i
 
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end
 
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return p
 

Latest revision as of 13:01, 17 July 2014

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