Manages set of 2D points.

point_set.lua

#!/usr/bin/luajit

local point_set_mt = {}

function point_set_mt:has_point(x, y)
    return self._points[x .. ',' .. y] ~= nil
end

function point_set_mt:add_point(x, y)
    if not self:has_point(x, y) then
        self._points[x .. ',' .. y] = true
        table.insert(self._points, {x = x, y = y})
    end
end

function point_set_mt:remove_point(x, y)
    if self:has_point(x, y) then
        self._points[x .. ',' .. y] = nil
        for i = 1, #self._points do
            local point = self._points[i]
            if point.x == x and point.y == y then
                table.remove(self._points, i)
                break
            end
        end
    end
end

function point_set_mt:random_point()
    if #self._points > 0 then
        local point = self._points[math.random(#self._points)]
        return point.x, point.y
    end
end

function point_set_mt:iterate()
    local i = 1
    return function()
        if i <= #self._points then
            local point = self._points[i]
            i = i + 1
            return point.x, point.y
        end
    end
end

function point_set_mt:merge(other)
    for x, y in other:iterate() do
        self:add_point(x, y)
    end
end

local function point_set()
    local self = {}
    self._points = {}

    setmetatable(self, {__index = point_set_mt})

    return self
end

return point_set