Hoehrmann DFA from ref/hare/encoding/utf8/decodetable.ha flattened
to 1D [2048]i8 (task #20: 2D-array jagged cgen still pending);
encoderune takes a caller buffer matching lib/encoding/hex.encode;
done/more/invalid all spelled as plain void aliases per lib/io's
eof precedent. Surface ports decoder + decode + next + encoderune
+ runesz + utf8sz + validate from ref/hare/encoding/utf8/{types,
decode,encode,rune}.ha. next() polarity rewritten from Hare's
`(state-1):uint >> 31` to an explicit `if state == 0` branch
because ww's uint is 64-bit (cmd/wcc/type.c:58); same effect, no
hidden 32-bit assumption.
Deferred (no in-tree callers): prev, slice, position, remaining,
appendrune, strencode, strdecode. String iteration (chars/
newchars/nextchar in the session-4 draft) dropped per Hare
discipline — belongs in lib/strings::iterator, not encoding/utf8.
Tests:
- 968_utf8_run drives lib/encoding/utf8/utf8test.ww via ww run.
21 @test fns: boundaries (ASCII, 2-byte, 3-byte, 4-byte
encode/decode), surrogate/overlong/out-of-range/bad-continuation
reject, max-in-range (U+10FFFF) accept, truncated→more, done@EOI,
validate empty/mixed/malformed, encode/decode roundtrip. Two
rows ported from ref/hare/encoding/utf8/decode.ha @test that
were missing in the session-4 draft: bad-continuation
[0xC2,0xFF]→invalid and max-in-range [0xF4,0x8F,0xBF,0xBF]→
U+10FFFF.
- 9xx stdlib runtime slot range extended from 970-989 to 960-989
to accommodate utf8 at 968 (970-989 block was full).
90/90 ok. 995_self_rebuild stays green (ww2==ww3==ww4 byte-id).
Both used the -1 sentinel return; both had no external callers, so
the graduation is purely the API-shape change. utf8.runesz uses void
for "rune outside legal range"; bufio.readbyte uses void for EOF
(empty buffer). The full Hare shapes ((size | invalid) and
(u8 | EOF | io::error)) are still richer than this — those richer
returns arrive when utf8 grows an explicit invalid type and bufio
wires through io::stream's error path.
