initial release

cosmic rage/lua/pairsbykeys.lua

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+-- pairsbykeys.lua
+-- From Programming in Lua book, 2nd edition
+-- Gives you an iterator that moves through an ordinary table (eg. string keys)
+--  but sorted into key sequence.
+-- It does that by copying the table keys into a temporary table and sorting that.
+
+-- If you need to sort keys other than strings, see:
+
+-- See: http://lua-users.org/wiki/SortedIteration
+
+function pairsByKeys (t, f)
+  local a = {}
+  -- build temporary table of the keys
+  for n in pairs (t) do 
+    table.insert (a, n) 
+  end
+  table.sort (a, f)  -- sort using supplied function, if any
+  local i = 0        -- iterator variable
+  return function () -- iterator function
+    i = i + 1
+    return a[i], t[a[i]]
+  end  -- iterator function
+end -- pairsByKeys
+
+return pairsByKeys
+
+--[[
+
+  
+  -- This prints the math functions in random order
+  for k, v in pairs (math) do
+    print (k, v)
+  end -- for
+  
+  require "pairsbykeys"
+  
+  -- This prints the math functions in key order
+  for k, v in pairsByKeys (math) do
+    print (k, v)
+  end -- for
+  
+  --]]
+