= Duplicate Code Elimination =

The “ Duplicate Code Elimination” transformation eliminates a duplicate code group. This transformation needs a duplicate code group found with the filtered_suffix_tree algorithm, with max_invalid_seq length parameter set to 0. More information about duplicate code analysis can be found at [http://pnyf.inf.elte.hu/trac/refactorerl/wiki/CloneIdentifiErl here]. If the members of the group are found in different modules the transformation asks the user to enter a module name where the extracted function should be placed, and exported. Every occurrence of the group will be replaced with a function call to the extracted function. The transformation asks the user to enter the extracted function's name.



Eliminate a clone gorup:

{{{
-module(clone).

-export([f/0, g/0]).

f() ->
   A = 5,
   B = A + A,
   case A of
      5 -> io:format("~p~n",[A]);
      _ -> io:format("Function f")
   end.

g() ->
   C = 6,
   case C of
      6 -> io:format("~p~n",[C]);
      _ -> io:format("Function g")
   end.
}}}

Result:

{{{
-module(clone).

-export([f/0, g/0]).

f() ->
   A = 5,
   B = A + A,
   new_fun(A, 5, "Function f").

g() ->
   C = 6,
   new_fun(C, 6, "Function g").

new_fun(NewVar1, NewVar2, NewVar3) ->
   case NewVar1 of
      NewVar2 -> io:format("~p~n",[NewVar1]);
      _       -> io:format(NewVar3)
   end.
}}}

== Side conditions ==

 * The extracted function name should not conflict with an already used function name.


== Transformation steps and compensations ==

 1. Given the clone name, clone group, the transformation analyses the group and finds the variables which will be extracted.
 2. Calls the extract_funcion transformation to create a new function, and replaces the group members to a call to the extracted function.