Module:TableTools: Difference between revisions

    From Nonbinary Wiki
    m>Mr. Stradivarius
    (start module with useful tools for dealing with Lua tables)
     
    m>Mr. Stradivarius
    (add getNumKeys function and improve the comments, add the beginnings of a sparseIpairs function)
    Line 9: Line 9:
    --[[
    --[[
    -----------------------------------------------------------------------------------
    -----------------------------------------------------------------------------------
    -- Helper functions
    -- isPositiveInteger
    --
    -- This function returns true if the given number 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 the table.
    -----------------------------------------------------------------------------------
    -----------------------------------------------------------------------------------
    --]]
    --]]
     
    function p.isPositiveInteger(num)
    local function isPositiveInteger(num)
    -- Returns true if the given number is a positive integer, and false if not.
    if type(num) == 'number' and num >= 1 and floor(num) == num and num < infinity then
    if type(num) == 'number' and num >= 1 and floor(num) == num and num < infinity then
    return true
    return true
    Line 20: Line 23:
    return false
    return false
    end
    end
    end
    --[[
    -----------------------------------------------------------------------------------
    -- getNumKeys
    --
    -- 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.getNumKeys(t)
    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
    end


    Line 32: Line 55:
    --]]
    --]]
    function p.compressSparseArray(t)
    function p.compressSparseArray(t)
    local nums, ret = {}, {}
    local ret = {}
    for k, v in pairs(t) do
    local nums = p.getNumKeys(t)
    if isPositiveInteger(k) then
    nums[#nums + 1] = k
    end
    end
    table.sort(nums)
    table.sort(nums)
    for _, num in ipairs(nums) do
    for _, num in ipairs(nums) do
    Line 44: Line 63:
    return ret
    return ret
    end
    end
    --[[
    -----------------------------------------------------------------------------------
    -- sparseIpairs
    --
    -- This is an iterator for sparse arrays. It can be used like ipairs, but can
    -- handle nil values.
    -----------------------------------------------------------------------------------
    --]]
    -- function p.sparseIpairs(t)
    -- local nums = p.getNumKeys(t)


    return p
    return p

    Revision as of 11:33, 15 December 2013

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

    -- This module includes a number of functions that can be useful when dealing with Lua tables.
    
    local p = {}
    
    -- Define often-used variables and functions.
    local floor = math.floor
    local infinity = math.huge
    
    --[[
    -----------------------------------------------------------------------------------
    -- isPositiveInteger
    --
    -- This function returns true if the given number 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 the table.
    -----------------------------------------------------------------------------------
    --]]
    function p.isPositiveInteger(num)
    	if type(num) == 'number' and num >= 1 and floor(num) == num and num < infinity then
    		return true
    	else
    		return false
    	end
    end
    
    --[[
    -----------------------------------------------------------------------------------
    -- getNumKeys
    --
    -- 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.getNumKeys(t)
    	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
    
    --[[
    -----------------------------------------------------------------------------------
    -- 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)
    	local ret = {}
    	local nums = p.getNumKeys(t)
    	table.sort(nums)
    	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)
    --	local nums = p.getNumKeys(t)
    
    return p