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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.
69 lines
1.9 KiB
Mathematica
69 lines
1.9 KiB
Mathematica
%-----------------------------------------------------------------------------%
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:- module stream_putback.
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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_input("stream_putback.data", OpenRes, !IO),
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(
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OpenRes = ok(Stream),
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print_read(Stream, !IO), % a
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% Can only expect one pushback.
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print_putback(Stream, 'X', !IO),
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print_read(Stream, !IO), % X
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print_read(Stream, !IO), % b
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print_read(Stream, !IO), % c
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print_read(Stream, !IO), % \n
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print_read(Stream, !IO), % eof
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io.close_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(io.input_stream::in, io::di, io::uo) is det.
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print_read(Stream, !IO) :-
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io.read_char(Stream, ReadRes, !IO),
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(
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ReadRes = ok(Char),
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io.write_string("Read: ", !IO),
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io.write(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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:- pred print_putback(io.input_stream::in, char::in, io::di, io::uo) is det.
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print_putback(Stream, Char, !IO) :-
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io.putback_char(Stream, 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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%-----------------------------------------------------------------------------%
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% vim: ft=mercury ts=8 sts=4 sw=4 et
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