Module:TableTools: Difference between revisions

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    m>Mr. Stradivarius
    (split set functions out to Module:Set)
    m>Mr. Stradivarius
    m (Protected Module:TableTools: High-risk Lua module ([Edit=Allow only template editors and admins] (indefinite) [Move=Allow only template editors and admins] (indefinite)))
    (No difference)

    Revision as of 06:14, 20 December 2013

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

    --[[
    ------------------------------------------------------------------------------------
    --                               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(v)
    	if type(v) == 'number' and v >= 1 and floor(v) == 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(v)
    	if type(v) == 'number' and tostring(v) == '-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(t)
    	local ret = {}
    	for k, v in pairs(t) do
    		ret[k] = 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(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			
    
    --[[
    ------------------------------------------------------------------------------------
    -- 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(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
    
    --[[
    ------------------------------------------------------------------------------------
    -- 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)
    	prefix = prefix or ''
    	suffix = suffix or ''
    	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
    
    --[[
    ------------------------------------------------------------------------------------
    -- 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(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
    
    --[[
    ------------------------------------------------------------------------------------
    -- sparseIpairs
    --
    -- This is an iterator for sparse arrays. It can be used like ipairs, but can
    -- handle nil values.
    ------------------------------------------------------------------------------------
    --]]
    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]
    		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(t)
    	checkType('size', 1, t, 'table')
    	local i = 0
    	for k in pairs(t) do
    		i = i + 1
    	end
    	return i
    end
    
    return p