%%% BEGIN pibfi_optimizer.erl %%%
%%%
%%% pibfi - Platonic Ideal Brainf*ck Interpreter
%%% Copyright (c)2003 Cat's Eye Technologies. All rights reserved.
%%%
%%% Redistribution and use in source and binary forms, with or without
%%% modification, are permitted provided that the following conditions
%%% are met:
%%%
%%% Redistributions of source code must retain the above copyright
%%% notice, this list of conditions and the following disclaimer.
%%%
%%% Redistributions in binary form must reproduce the above copyright
%%% notice, this list of conditions and the following disclaimer in
%%% the documentation and/or other materials provided with the
%%% distribution.
%%%
%%% Neither the name of Cat's Eye Technologies nor the names of its
%%% contributors may be used to endorse or promote products derived
%%% from this software without specific prior written permission.
%%%
%%% THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
%%% CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
%%% INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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%%% DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE
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%% @doc Optimizer for <code>pibfi</code>.
%%
%% <p>Takes an internal format as generated by the parser and
%% returns a (hopefully) more efficient internal format.</p>
%%
%% @end
-module(pibfi_optimizer).
-vsn('2003.0425').
-copyright('Copyright (c)2003 Cat`s Eye Technologies. All rights reserved.').
-export([optimize/1]).
%% @spec optimize(program()) -> program()
%% @doc Optimizes a Brainf*ck program.
optimize(Program) ->
list_to_tuple(lists:reverse(optimize(Program, 1, undefined, 0, []))).
optimize(Program, Pos, Current, Count, Acc) when Pos > size(Program) ->
Acc;
optimize(Program, Pos, Current, Count, Acc) ->
Element = element(Pos, Program),
NewElement = case Element of
{instruction, R0, C0, Current} ->
Acc0 = [{instruction, R0, C0, {Current, Count + 1}} | tl(Acc)],
optimize(Program, Pos + 1, Current, Count + 1, Acc0);
{instruction, R0, C0, Instruction}=I
when Instruction == $<; Instruction == $>;
Instruction == $+; Instruction == $- ->
optimize(Program, Pos + 1, Instruction, 1, [I | Acc]);
{instruction, R0, C0, Other}=I ->
optimize(Program, Pos + 1, undefined, 1, [I | Acc]);
{while, R0, C0, Block} ->
optimize(Program, Pos + 1, undefined, 1,
[{while, R0, C0, optimize(Block)} | Acc])
end.
%%% END of pibfi_optimizer.erl %%%