moonpie.collections¶

Various collections and structures to help provide functionality to lua tables.

local a_list = moonpie.collections.list:new()
a_list:add("stuff", 1, 4, "more-stuff")
if a_list:contains(4) then
  print "It does!"
end

Array¶

Provides an easy way to manage multidimensional arrays without knowing the bounds ahead of time. The Array is more of an “Array Bag”, where you can place values based on multidimensional coordinates, but iterating over the values isn’t really supported at this time. Grid is a better implementation for 2D Arrays that have known dimensions.

local Array = require "moonpie.collections.array"
local a = Array:new(3) -- Define a 3-dimensional array
a(3, 2, 1, "bar")
print(a(3, 2, 1)) -- # bar

Grid¶

Provides a 2D array element that makes it easier to track and assign elements for 2D lists. Initialized to a specific size and can handle default values when the value has not been set.

local Grid = require "moonpie.collections.grid"
local g = Grid:new(10, 10, "default")
g:set(3, 2, "hello")
print(g:get(3, 2)) -- "hello"
print(g:get(8, 2)) -- "default"

Properties & Methods¶

default: The default returned if the location requested is empty
get(x, y): Retrieves the value at the specified location. If empty, return default or nil
height: The height of the grid data
set(x, y, value): Sets the value at the specified location, overriding any previous value assigned there.
width: The width of the grid data

moonpie.collections.iterators¶

Iterators provide a variety of functions for iterating over tables. They should work with any index based table.

The cycle iterator allows continuous looping over an array. It also provides the ability to move backwards through the list.

moonpie.collections.iterators.cycle(array_table, count) array_table = any table with an index list count = the limit of cycles to perform

local set = { 1, 2, 3, 4 }

for value, index in moonpie.collections.iterators.cycle(set, 2) do
  print(value)
end

--
-- Output:
--
-- 1
-- 2
-- 3
-- 4
-- 1
-- 2
-- 3
-- 4

local set = { 1, 2, 3, 4 }
local cycle_iter = moonpie.collections.iterators.cycle(set)
print(cycle_iter.previous()) -- Output: 4
print(cycle_iter.previous()) -- Output: 3