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--[[
------------------------------------------------------------------------------------
--                               TableTools                                       --
--                                                                                --
-- This module includes a number of functions for dealing with Lua tables.        --
-- It is a meta-module, meant to be called from other Lua modules, and should     --
-- not be called directly from #invoke.                                           --
------------------------------------------------------------------------------------
--]]

local libraryUtil = require('libraryUtil')

local p = {}

-- Define often-used variables and functions.
local floor = math.floor
local infinity = math.huge
local checkType = libraryUtil.checkType

--[[
------------------------------------------------------------------------------------
-- isPositiveInteger
--
-- 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(<span class="ltr">v</span>)
 if type(<span class="ltr">v</span>) == 'number' and v >= 1 and floor(<span class="ltr">v</span>) == v and v < infinity then
  return true
 else
  return false
 end
end

--[[
------------------------------------------------------------------------------------
-- isNan
--
-- 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(<span class="ltr">v</span>)
 if type(<span class="ltr">v</span>) == 'number' and tostring(<span class="ltr">v</span>) == '-nan' then
  return true
 else
  return false
 end
end

--[[
------------------------------------------------------------------------------------
-- shallowClone
--
-- 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(<span class="ltr">t</span>)
 local ret = {}
 for k, v in pairs(<span class="ltr">t</span>) do
  ret[<span class="ltr">k</span>] = v
 end
 return ret
end

--[[
------------------------------------------------------------------------------------
-- removeDuplicates
--
-- 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(<span class="ltr">t</span>)
 checkType('removeDuplicates', 1, t, 'table')
 local isNan = p.isNan
 local ret, exists = {}, {}
 for i, v in ipairs(<span class="ltr">t</span>) do
  if isNan(<span class="ltr">v</span>) 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[<span class="ltr">v</span>] then
    ret[#ret + 1] = v
    exists[<span class="ltr">v</span>] = true
   end
  end 
 end
 return ret
end   

--[[
------------------------------------------------------------------------------------
-- numKeys
--
-- 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(<span class="ltr">t</span>)
 checkType('numKeys', 1, t, 'table')
 local isPositiveInteger = p.isPositiveInteger
 local nums = {}
 for k, v in pairs(<span class="ltr">t</span>) do
  if isPositiveInteger(<span class="ltr">k</span>) then
   nums[#nums + 1] = k
  end
 end
 table.sort(nums)
 return nums
end

--[[
------------------------------------------------------------------------------------
-- affixNums
--
-- 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(t, prefix, suffix)
 checkType('affixNums', 1, t, 'table')
 checkType('affixNums', 2, prefix, 'string', true)
 checkType('affixNums', 3, suffix, 'string', true)

 local function cleanPattern(<span class="ltr">s</span>)
  -- 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(<span class="ltr">t</span>) do
  if type(<span class="ltr">k</span>) == '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

--[[
------------------------------------------------------------------------------------
-- numData
--
-- Given a table with keys like ("foo1", "bar1", "foo2", "baz2"), returns a table
-- of subtables in the format 
-- { [<span class="ltr">1</span>] = {foo = 'text', bar = 'text'}, [<span class="ltr">2</span>] = {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(t, compress)
 checkType('numData', 1, t, 'table')
 checkType('numData', 2, compress, 'boolean', true)
 local ret = {}
 for k, v in pairs(<span class="ltr">t</span>) do
  local prefix, num = mw.ustring.match(tostring(<span class="ltr">k</span>), '^([^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[<span class="ltr">k</span>] = v
   ret.other = subtable
  end
 end
 if compress then
  local other = ret.other
  ret = p.compressSparseArray(ret)
  ret.other = other
 end
 return ret
end

--[[
------------------------------------------------------------------------------------
-- compressSparseArray
--
-- 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(<span class="ltr">t</span>)
 checkType('compressSparseArray', 1, t, 'table')
 local ret = {}
 local nums = p.numKeys(<span class="ltr">t</span>)
 for _, num in ipairs(nums) do
  ret[#ret + 1] = t[num]
 end
 return ret
end

--[[
------------------------------------------------------------------------------------
-- sparseIpairs
--
-- This is an iterator for sparse arrays. It can be used like ipairs, but can
-- handle nil values.
------------------------------------------------------------------------------------
--]]
function p.sparseIpairs(<span class="ltr">t</span>)
 checkType('sparseIpairs', 1, t, 'table')
 local nums = p.numKeys(<span class="ltr">t</span>)
 local i = 0
 local lim = #nums
 return function ()
  i = i + 1
  if i <= lim then
   local key = nums[<span class="ltr">i</span>]
   return key, t[key]
  else
   return nil, nil
  end
 end
end

--[[
------------------------------------------------------------------------------------
-- size
--
-- This returns the size of a key/value pair table. It will also work on arrays,
-- but for arrays it is more efficient to use the # operator.
------------------------------------------------------------------------------------
--]]
function p.size(<span class="ltr">t</span>)
 checkType('size', 1, t, 'table')
 local i = 0
 for k in pairs(<span class="ltr">t</span>) do
  i = i + 1
 end
 return i
end

return p
View source for Module:TableTools

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