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87 lines
2.1 KiB
Mathematica
87 lines
2.1 KiB
Mathematica
%-----------------------------------------------------------------------------%
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:- module cat.
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% Simple implementation of the standard unix `cat' filter:
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% copy input files (or stdin, if no input files) to stdout.
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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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:- 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.
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main -->
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io__command_line_arguments(Args),
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( { Args = [] } ->
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cat
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;
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cat_file_list(Args)
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).
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:- pred cat_file_list(list(string)::in, io__state::di, io__state::uo) is det.
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cat_file_list([]) --> [].
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cat_file_list([File | Files]) -->
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cat_file(File),
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cat_file_list(Files).
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:- pred cat_file(string::in, io__state::di, io__state::uo) is det.
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cat_file(File) -->
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io__open_input(File, Result),
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( { Result = ok(Stream) },
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cat_stream(Stream)
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; { Result = error(Error) },
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io__progname("cat", Progname),
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{ io__error_message(Error, Message) },
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io__write_strings([
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Progname, ": ",
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"error opening file `", File, "' for input:\n\t",
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Message, "\n"
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])
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).
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:- pred cat_stream(io__input_stream::in, io__state::di, io__state::uo) is det.
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cat_stream(Stream) -->
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io__set_input_stream(Stream, _OldStream),
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cat.
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:- pred cat(io__state::di, io__state::uo) is det.
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cat -->
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io__read_line(Result),
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cat_2(Result).
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:- pred cat_2(io__result(list(char))::in, io__state::di, io__state::uo) is det.
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cat_2(Result) -->
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( { Result = ok(CharList) },
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{ string__from_char_list(CharList, String) },
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io__write_string(String),
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io__read_line(NextResult),
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cat_2(NextResult)
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; { Result = eof }
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; { Result = error(Error) },
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{ io__error_message(Error, Message) },
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io__input_stream_name(StreamName),
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io__progname("cat", ProgName),
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io__write_strings([
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ProgName, ": ",
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"error reading input file `", StreamName, "': \n\t",
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Message, "\n"
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])
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).
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%-----------------------------------------------------------------------------%
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