sonic-bluestreak/sonic-boost.love/libs/level-libs/tsort.lua

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-- See: https://github.com/bungle/lua-resty-tsort
--
-- Copyright (c) 2016, Aapo Talvensaari
-- All rights reserved.
--
-- Redistribution and use in source and binary forms, with or without modification,
-- are permitted provided that the following conditions are met:
--
-- * Redistributions of source code must retain the above copyright notice, this
-- list of conditions and the following disclaimer.
--
-- * Redistributions in binary form must reproduce the above copyright notice, this
-- list of conditions and the following disclaimer in the documentation and/or
-- other materials provided with the distribution.
--
-- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
-- ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
-- WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
-- DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
-- ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
-- (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
-- LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
-- ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-- (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
-- SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
local setmetatable = setmetatable
local pairs = pairs
local type = type
local function visit(k, n, m, s)
if m[k] == 0 then return 1 end
if m[k] == 1 then return end
m[k] = 0
local f = n[k]
for i=1, #f do
if visit(f[i], n, m, s) then return 1 end
end
m[k] = 1
s[#s+1] = k
end
local tsort = {}
tsort.__index = tsort
function tsort.new()
return setmetatable({ n = {} }, tsort)
end
function tsort:add(...)
local p = { ... }
local c = #p
if c == 0 then return self end
if c == 1 then
p = p[1]
if type(p) == "table" then
c = #p
else
p = { p }
end
end
local n = self.n
for i=1, c do
local f = p[i]
if n[f] == nil then n[f] = {} end
end
for i=2, c, 1 do
local f = p[i]
local t = p[i-1]
local o = n[f]
o[#o+1] = t
end
return self
end
function tsort:sort()
local n = self.n
local s = {}
local m = {}
for k in pairs(n) do
if m[k] == nil then
if visit(k, n, m, s) then
return nil, "There is a circular dependency in the graph. It is not possible to derive a topological sort."
end
end
end
return s
end
return tsort