From 907f610040e3dfb54a83155c36527a65b7f08e78 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Asbj=C3=B8rn=20Sloth=20T=C3=B8nnesen?= <ast@fiberby.net>
Date: Mon, 13 Feb 2017 16:04:41 +0000
Subject: initial commit
MIME-Version: 1.0
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Content-Transfer-Encoding: 8bit

Signed-off-by: Asbjørn Sloth Tønnesen <ast@fiberby.net>
---
 lua/inet/set.lua | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)
 create mode 100644 lua/inet/set.lua

(limited to 'lua/inet/set.lua')

diff --git a/lua/inet/set.lua b/lua/inet/set.lua
new file mode 100644
index 0000000..effb0f2
--- /dev/null
+++ b/lua/inet/set.lua
@@ -0,0 +1,49 @@
+local M = {}
+
+local function table_compact(t, n)
+	-- remove nil entries, and reorder
+	local i = 0
+	for j=1,n do
+		if t[j] then
+			if i > 0 then
+				t[i] = t[j]
+				i = i + 1
+			end
+		elseif i == 0 then
+			i = j
+		end
+	end
+	if i > 0 then
+		for j=i,n do
+			t[j] = nil
+		end
+	end
+end
+
+function M.aggregate(t)
+	local flag = true
+	local n = #t
+	for i=1,n do
+		t[i] = t[i]:network()
+	end
+	while flag do -- loop until no aggregatable addresses are found
+		flag = false
+		for i=1,n do
+			local ia = t[i]
+			if ia then
+				local ib = ia:flip() -- counterpart
+				for j=1,n do
+					if j ~= i and t[j] == ib then
+						-- counterpart found, aggregating
+						t[i] = (ia ^ -1):network()
+						t[j] = nil
+						flag = true
+					end
+				end
+			end
+		end
+	end
+	table_compact(t, n)
+end
+
+return M
-- 
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