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diff --git a/nselib/tableaux.lua b/nselib/tableaux.lua
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+--- Auxiliary functions for table manipulation
+--
+-- @author Daniel Miller
+-- @copyright Same as Nmap--See https://nmap.org/book/man-legal.html
+-- @class module
+-- @name tableaux
+
+local next = next
+local pairs = pairs
+local ipairs = ipairs
+local type = type
+local _ENV = {}
+
+local tcopy_local
+--- Recursively copy a table.
+--
+-- Uses simple assignment to copy keys and values from a table, recursing into
+-- subtables as necessary.
+-- @param t the table to copy
+-- @return a deep copy of the table
+function tcopy (t)
+  local tc = {};
+  for k,v in pairs(t) do
+    if type(v) == "table" then
+      tc[k] = tcopy_local(v);
+    else
+      tc[k] = v;
+    end
+  end
+  return tc;
+end
+tcopy_local = tcopy
+
+--- Copy one level of a table.
+--
+-- Iterates over the keys of a table and copies their values into a new table.
+-- If any values are tables, they are copied by reference only, and modifying
+-- the copy will modify the original table value as well.
+-- @param t the table to copy
+-- @return a shallow copy of the table
+function shallow_tcopy(t)
+  local k = next(t)
+  local out = {}
+  while k do
+    out[k] = t[k]
+    k = next(t, k)
+  end
+  return out
+end
+
+--- Invert a one-to-one mapping
+-- @param t the table to invert
+-- @return an inverted mapping
+function invert(t)
+  local out = {}
+  for k, v in pairs(t) do
+    out[v] = k
+  end
+  return out
+end
+
+--- Check for the presence of a value in a table
+--@param t the table to search into
+--@param item the searched value
+--@array (optional) If true, then use ipairs to only search the array indices of the table.
+--@return Boolean true if the item was found, false if not
+--@return The index or key where the value was found, or nil
+function contains(t, item, array)
+  local iter = array and ipairs or pairs
+  for k, val in iter(t) do
+    if val == item then
+      return true, k
+    end
+  end
+  return false, nil
+end
+
+--- Returns the keys of a table as an array
+-- @param t The table
+-- @return A table of keys
+function keys(t)
+  local ret = {}
+  local k, v = next(t)
+  while k ~= nil do
+    ret[#ret+1] = k
+    k, v = next(t, k)
+  end
+  return ret
+end
+
+return _ENV