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059ddea15f
Branches: main
library/io.m:
Document the effect of io.putback_byte on the stream position, based
on the behaviour of ungetc().
Document the effect of io.seek_binary_input on the pushback buffer.
Implement io.read_line_as_string and io.read_file_as_string
efficiently for Java.
Make the globals ML_next_stream_id and MR_io_exception in Java
thread-safe.
Make the type of ML_io_stream_db more specific in Java.
Use the FileChannel class unconditionally. We no longer support
Java < 1.5 so we don't need to use reflection to access that class at
runtime.
Throw Mercury-catchable exceptions on Java I/O errors.
Add class qualification or `may_not_duplicate' attributes on
foreign_procs to prevent problems with intermodule optimisation.
tests/hard_coded/Mmakefile:
tests/hard_coded/stream_putback.data:
tests/hard_coded/stream_putback.exp:
tests/hard_coded/stream_putback.m:
tests/hard_coded/stream_putback_binary.exp:
tests/hard_coded/stream_putback_binary.m:
Add test cases for io.putback_char, io.putback_byte and seeking.
89 lines
2.7 KiB
Mathematica
89 lines
2.7 KiB
Mathematica
%-----------------------------------------------------------------------------%
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:- module stream_putback_binary.
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:- interface.
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:- import_module io.
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:- pred main(io::di, io::uo) is det.
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%-----------------------------------------------------------------------------%
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%-----------------------------------------------------------------------------%
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:- implementation.
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:- import_module char.
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:- import_module int.
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:- import_module list.
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:- import_module require.
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:- import_module string.
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%-----------------------------------------------------------------------------%
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main(!IO) :-
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io.open_binary_input("stream_putback.data", OpenRes, !IO),
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(
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OpenRes = ok(Stream),
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print_position(Stream, !IO), % pos 0
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print_read_byte(Stream, !IO), % pos 1
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print_relseek(Stream, 1, !IO), % pos 2
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print_read_byte(Stream, !IO), % pos 3
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print_putback(Stream, 'X', !IO), % pos 2
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print_read_byte(Stream, !IO), % X, pos 3
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print_read_byte(Stream, !IO), % \n, pos 4
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print_read_byte(Stream, !IO), % eof, pos 4
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print_putback(Stream, 'Y', !IO), % pos 3
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print_relseek(Stream, -2, !IO), % pos 1; pushback dropped
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print_read_byte(Stream, !IO), % b, pos 2
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io.close_binary_input(Stream, !IO)
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;
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OpenRes = error(Error),
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error(io.error_message(Error))
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).
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:- pred print_read_byte(io.binary_input_stream::in, io::di, io::uo) is det.
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print_read_byte(Stream, !IO) :-
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io.read_byte(Stream, ReadRes, !IO),
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(
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ReadRes = ok(Byte),
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io.write_string("Read: ", !IO),
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io.write(det_from_int(Byte) : char, !IO),
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io.nl(!IO)
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;
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ReadRes = eof,
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io.write_string("Read: eof\n", !IO)
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;
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ReadRes = error(Error),
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error(io.error_message(Error))
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),
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print_position(Stream, !IO).
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:- pred print_putback(io.binary_input_stream::in, char::in, io::di, io::uo)
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is det.
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print_putback(Stream, Char, !IO) :-
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io.putback_byte(Stream, char.to_int(Char), !IO),
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io.write_string("Put back: ", !IO),
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io.write(Char, !IO),
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io.nl(!IO),
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print_position(Stream, !IO).
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:- pred print_relseek(io.binary_input_stream::in, int::in, io::di, io::uo)
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is det.
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print_relseek(Stream, Offset, !IO) :-
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io.seek_binary_input(Stream, cur, Offset, !IO),
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io.format("Seek: %+d\n", [i(Offset)], !IO),
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print_position(Stream, !IO).
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:- pred print_position(io.binary_input_stream::in, io::di, io::uo) is det.
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print_position(Stream, !IO) :-
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io.binary_input_stream_offset(Stream, Offset, !IO),
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io.format("Position: %d\n\n", [i(Offset)], !IO).
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%-----------------------------------------------------------------------------%
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% vim: ft=mercury ts=8 sts=4 sw=4 et
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