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121 lines
2.5 KiB
Mathematica
121 lines
2.5 KiB
Mathematica
%-----------------------------------------------------------------------------%
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%
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% A simple sorting program.
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%
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% It works on text files, considering each line to be a record.
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% The entire line is considered to be the sort key.
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%
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% The algorithm used is simple insertion sort.
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%
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% This source file is hereby placed in the public domain. -fjh (the author).
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%
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%-----------------------------------------------------------------------------%
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:- module sort.
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:- interface.
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:- import_module io.
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:- pred main(io__state::di, io__state::uo) is det.
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%-----------------------------------------------------------------------------%
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:- implementation.
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:- import_module string, list, char, require, std_util.
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main -->
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io__command_line_arguments(Args),
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(
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{ Args = [] },
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handle_args(no, no),
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sort
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;
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{ Args = [Input] },
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handle_args(yes(Input), no),
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sort
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;
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{ Args = [Input, Output] },
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handle_args(yes(Input), yes(Output)),
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sort
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;
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{ Args = [_, _, _ | _] },
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io__write_string("Usage: sort [Input [Output]]\\n")
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).
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:- pred handle_args(maybe(string), maybe(string), io__state, io__state).
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:- mode handle_args(in, in, di, uo) is det.
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handle_args(InArg, OutArg) -->
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(
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{ InArg = yes(InFilename) },
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io__see(InFilename, InResult),
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(
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{ InResult = ok }
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;
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{ InResult = error(InError) },
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{ io__error_message(InError, InMsg) },
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{ error(InMsg) }
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)
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;
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{ InArg = no }
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),
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(
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{ OutArg = yes(OutFilename) },
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io__tell(OutFilename, OutResult),
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(
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{ OutResult = ok }
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;
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{ OutResult = error(OutError) },
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{ io__error_message(OutError, OutMsg) },
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{ error(OutMsg) }
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)
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;
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{ OutArg = no }
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).
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:- pred sort(io__state, io__state).
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:- mode sort(di, uo) is det.
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sort -->
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sort_2([]).
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:- pred sort_2(list(list(char)), io__state, io__state).
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:- mode sort_2(in, di, uo) is det.
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sort_2(Lines0) -->
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io__read_line(Result),
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(
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{ Result = error(Error) },
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{ io__error_message(Error, Msg) },
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{ error(Msg) }
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;
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{ Result = eof },
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sort_output(Lines0)
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;
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{ Result = ok(Line) },
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{ insert(Lines0, Line, Lines1) },
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sort_2(Lines1)
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).
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:- pred insert(list(T), T, list(T)).
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:- mode insert(in, in, out) is det.
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insert([], I, [I]).
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insert([H | T], I, L) :-
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compare(R, I, H),
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( R = (<) ->
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L = [I, H | T]
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;
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insert(T, I, NT),
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L = [H | NT]
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).
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:- pred sort_output(list(list(char)), io__state, io__state).
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:- mode sort_output(in, di, uo) is det.
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sort_output([]) --> [].
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sort_output([Line | Lines]) -->
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{ string__from_char_list(Line, LineStr) },
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io__write_string(LineStr),
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sort_output(Lines).
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