reinstate shallowClone - saw a use for it in p.complement - and write p.valueComplement
(better error message for the set functions) |
(reinstate shallowClone - saw a use for it in p.complement - and write p.valueComplement) |
||
| Line 52: | Line 52: | ||
return false | return false | ||
end | 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(t) | |||
local ret = {} | |||
for k, v in pairs(t) do | |||
ret[k] = v | |||
end | |||
return ret | |||
end | end | ||
| Line 264: | Line 281: | ||
local tn = select(lim, ...) | local tn = select(lim, ...) | ||
checkType('complement', lim, tn, 'table') | checkType('complement', lim, tn, 'table') | ||
local ret = | local ret = p.shallowClone(tn) | ||
-- Remove all the key/value pairs in t1, t2, ..., tn-1. | -- Remove all the key/value pairs in t1, t2, ..., tn-1. | ||
for i = 1, lim - 1 do | for i = 1, lim - 1 do | ||
| Line 276: | Line 290: | ||
ret[k] = nil | ret[k] = nil | ||
end | end | ||
end | |||
end | |||
return ret | |||
end | |||
--[[ | |||
------------------------------------------------------------------------------------ | |||
-- valueComplement | |||
-- | |||
-- This returns an array containing the relative complement of t1, t2, ..., in tn. | |||
-- The complement is of values only. This is equivalent to all the values that are | |||
-- in tn but are not in t1, t2, ... tn-1. | |||
------------------------------------------------------------------------------------ | |||
--]] | |||
function p.valueComplement(...) | |||
local lim = select('#', ...) | |||
if lim < 2 then | |||
error("too few arguments to 'valueComplement' (minimum is 2, received " .. lim .. ')', 2) | |||
end | |||
local isNan = p.isNan | |||
local ret, exists = {}, {} | |||
for i = 1, lim - 1 do | |||
local t = select(i, ...) | |||
checkType('valueComplement', i, t, 'table') | |||
for k, v in pairs(t) do | |||
if not isNan(v) then | |||
-- NaNs cannot be table keys, and they are also unique so cannot be equal to anything in tn. | |||
exists[v] = true | |||
end | |||
end | |||
end | |||
local tn = select(lim, ...) | |||
checkType('valueComplement', lim, tn, 'table') | |||
for k, v in pairs(tn) do | |||
if isNan(v) or exists[v] == nil then | |||
ret[#ret + 1] = v | |||
end | end | ||
end | end | ||