From 72e032447232f3f89056f352d3f6b8e2abc499cb Mon Sep 17 00:00:00 2001
From: Hans Hagen <pragma@wxs.nl>
Date: Wed, 21 Dec 2016 20:09:16 +0100
Subject: 2016-12-21 18:57:00

---
 tex/context/base/mkiv/l-table.lua | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

(limited to 'tex/context/base/mkiv/l-table.lua')

diff --git a/tex/context/base/mkiv/l-table.lua b/tex/context/base/mkiv/l-table.lua
index 1cf63db0c..39357bd25 100644
--- a/tex/context/base/mkiv/l-table.lua
+++ b/tex/context/base/mkiv/l-table.lua
@@ -971,6 +971,41 @@ end
 
 table.flattened = flattened
 
+local function collapsed(t,f,h)
+    if f == nil then
+        f = { }
+        h = { }
+    end
+    for k=1,#t do
+        local v = t[k]
+        if type(v) == "table" then
+            collapsed(v,f,h)
+        elseif not h[v] then
+            f[#f+1] = v
+            h[v] = true
+        end
+    end
+    return f
+end
+
+local function collapsedhash(t,h)
+    if h == nil then
+        h = { }
+    end
+    for k=1,#t do
+        local v = t[k]
+        if type(v) == "table" then
+            collapsedhash(v,h)
+        else
+            h[v] = true
+        end
+    end
+    return h
+end
+
+table.collapsed     = collapsed     -- 20% faster than unique(collapsed(t))
+table.collapsedhash = collapsedhash
+
 local function unnest(t,f) -- only used in mk, for old times sake
     if not f then          -- and only relevant for token lists
         f = { }            -- this one can become obsolete
-- 
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