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