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56687d235e
library/string.m:
Define first_char/3 to fail if the input string begins with an
ill-formed code unit sequence.
Define the reverse mode to throw an exception on an attempt to
encode a null character or surrogate code point in the output
string.
Reimplement first_char/3 in Mercury.
hard_coded/Mmakefile:
hard_coded/string_first_char_ilseq.exp:
hard_coded/string_first_char_ilseq.m:
Add test case.
98 lines
3.2 KiB
Mathematica
98 lines
3.2 KiB
Mathematica
%---------------------------------------------------------------------------%
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% vim: ts=4 sw=4 et ft=mercury
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%---------------------------------------------------------------------------%
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:- module string_first_char_ilseq.
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:- interface.
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:- import_module io.
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:- pred main(io::di, io::uo) is cc_multi.
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%---------------------------------------------------------------------------%
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:- implementation.
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:- import_module char.
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:- import_module string.
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%---------------------------------------------------------------------------%
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main(!IO) :-
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S0 = "😀", % UTF-16: 0xD83D 0xDE00
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S1 = string.between(S0, 1, length(S0)), % UTF-16: 0xDE00
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Rest = "rest",
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S = S1 ++ Rest,
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test_first_char_ioi(S, Rest, !IO),
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test_first_char_ioo(S, !IO),
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% An implementation might return U+FFFD as the first char of a string
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% beginning with an ill-formed code unit sequence, which is wrong by our
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% definition.
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Replacement = char.det_from_int(0xFFFD),
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test_first_char_iii(S, Replacement, Rest, !IO),
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test_first_char_iio(S, Replacement, !IO),
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% An implementation might separate out a surrogate code point as the
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% first code point, which is wrong by our definition.
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HiSurr = char.det_from_int(0xD83D),
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LoSurr = char.det_from_int(0xDE00),
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test_first_char_iii(S, HiSurr, Rest, !IO),
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test_first_char_iio(S, HiSurr, !IO),
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test_first_char_iii(S, LoSurr, Rest, !IO),
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test_first_char_iio(S, LoSurr, !IO),
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% Prepending a surrogate code point is disallowed.
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test_first_char_oii(HiSurr, S, !IO),
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test_first_char_oii(LoSurr, S, !IO).
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:- pred test_first_char_iii(string::in, char::in, string::in, io::di, io::uo)
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is det.
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test_first_char_iii(Str, FirstChar, Rest, !IO) :-
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( if string.first_char(Str, FirstChar, Rest) then
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io.write_string("first_char(in, in, in) succeeded\n", !IO)
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else
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io.write_string("first_char(in, in, in) failed\n", !IO)
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).
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:- pred test_first_char_ioi(string::in, string::in, io::di, io::uo) is det.
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test_first_char_ioi(Str, Rest, !IO) :-
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( if string.first_char(Str, _FirstChar, Rest) then
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io.write_string("first_char(in, out, in) succeeded\n", !IO)
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else
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io.write_string("first_char(in, out, in) failed\n", !IO)
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).
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:- pred test_first_char_iio(string::in, char::in, io::di, io::uo) is det.
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test_first_char_iio(Str, FirstChar, !IO) :-
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( if string.first_char(Str, FirstChar, _Rest) then
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io.write_string("first_char(in, in, out) succeeded\n", !IO)
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else
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io.write_string("first_char(in, in, out) failed\n", !IO)
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).
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:- pred test_first_char_ioo(string::in, io::di, io::uo) is det.
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test_first_char_ioo(Str, !IO) :-
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( if string.first_char(Str, _FirstChar, _Rest) then
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io.write_string("first_char(in, out, out) succeeded\n", !IO)
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else
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io.write_string("first_char(in, out, out) failed\n", !IO)
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).
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:- pred test_first_char_oii(char::in, string::in, io::di, io::uo) is cc_multi.
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test_first_char_oii(FirstChar, Rest, !IO) :-
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( try []
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string.first_char(_Str, FirstChar, Rest)
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then
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io.write_string("first_char(out, in, in) succeeded\n", !IO)
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catch_any Excp ->
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io.write_string("first_char(out, in, in) threw exception: ", !IO),
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io.print_line(Excp, !IO)
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).
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