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-rw-r--r--util/iterators.lua21
1 files changed, 21 insertions, 0 deletions
diff --git a/util/iterators.lua b/util/iterators.lua
index 6a437dd7..ba33bc80 100644
--- a/util/iterators.lua
+++ b/util/iterators.lua
@@ -90,6 +90,27 @@ function head(n, f, s, var)
end, s;
end
+function tail(n, f, s, var)
+ local results, count = {}, 0;
+ while true do
+ local ret = { f(s, var) };
+ var = ret[1];
+ if var == nil then break; end
+ results[(count%n)+1] = ret;
+ count = count + 1;
+ end
+
+ if n > count then n = count; end
+
+ local pos = 0;
+ return function ()
+ pos = pos + 1;
+ if pos > n then return nil; end
+ return unpack(results[((count-1+pos)%n)+1]);
+ end
+ --return reverse(head(n, reverse(f, s, var)));
+end
+
-- Convert the values returned by an iterator to an array
function it2array(f, s, var)
local t, var = {};