Hojun-Cho
bfcd9f6786
Backspace, Enter, Tab, Escape and the arrow and page keys are matched by keysym alone -- strans.c:852, 875 and 882 name them, and searchkey names the same set at strans.c:746-786. Every other key above Kspec falls through to the catch-all at strans.c:898, `ks >= Kspec || chord(mod)`, and goes to the application. So the special keys strans knows by name are the ones it takes under a modifier, and the ones it does not know are the ones it hands over. That is backwards: a named special key under a modifier is exactly the one the application has a binding for. In Korean a syllable is pending for nearly all the time anyone is typing, ko.c holding one and no more, and the guards at strans.c:876 and 883 return 0 only when nothing is pending -- so the key is eaten precisely when it is wanted. Type 안녕하세요 and reach for Ctrl+Backspace to take the word back: 요 loses ㅛ, then ㅇ, and the word itself goes on the third press. Ctrl+Enter in a chat box, Ctrl+Tab in a browser and Ctrl+PageDown in either are the same key eaten by the same lines. before after Korean 가, Ctrl+Backspace eaten, pre ㄱ passed, commit 가 Korean 가, Alt+Backspace eaten, pre ㄱ passed, commit 가 Korean 가, Super+Backspace eaten, pre ㄱ passed, commit 가 Korean 가, Backspace eaten, pre ㄱ unchanged Korean 가, Shift+Backspace eaten, pre ㄱ unchanged かく, Ctrl+Enter eaten, commit かく passed, commit かく かく, Ctrl+Tab eaten, commit かく passed, commit かく かく Space, Ctrl+PageDown eaten, sel 0 -> 9 passed, commit 確 かく Space, PageDown eaten, sel 0 -> 9 unchanged かく Space, Shift+Tab eaten, sel 0 -> 30 unchanged Ctrl+E sm, Ctrl+Backspace eaten, query s passed, commit sm Ctrl+E sm, Backspace eaten, query s unchanged chord() cannot be reused here. It is `(mod & ~Mshift) != 0 && mod != Mctrl` and the exclusion is deliberate, since Ctrl+letter is strans's whole command set and chord() has to let plain Ctrl through. The rule this needs is the other one -- any modifier that is not Shift -- and Shift must stay in: Shift+Tab cycles the candidates backwards, pinned by engine/candidate-completion and engine/emoji-navigation at engine_test.c:914 and 1649, and Shift on a Korean key is what makes ㅃ. One line serves both paths because it sits above the searchkey dispatch, and it has to sit below the switch at strans.c:829: 한자, 한/영, 変換 and 無変換 arrive as keys above Kspec and are rewritten there into the Ctrl chords they stand for. Above the switch, 한자 would commit and pass instead of opening the Hanja list; below it, pressing it with Ctrl held still opens the list, because the switch sets the modifier itself. What this does not cover: Space, which is below Kspec, so searchkey:763 still picks a candidate on Ctrl+Space inside a search. transition tests !(mod & ~Mshift) for its own Space at strans.c:865, so the two disagree there. Left alone: what Ctrl+Space should mean wants its own argument, not a widened guard.
178 lines
7.5 KiB
Markdown
178 lines
7.5 KiB
Markdown
# strans
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strans is a small, single-user input method for Korean, Japanese, English,
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emoji and symbols, with Vietnamese Telex as a compatibility mode. One
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engine serves four frontends: `zwp_input_method_v2` on Wayland — sway and
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any other compositor that offers it — IBus, which GTK 4 and Qt use, XIM,
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and a GTK 3 module.
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## Modes
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| Key | Mode |
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| --- | --- |
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| `Ctrl+S` | Korean Hangul (2-beolsik) |
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| `Ctrl+N` | Japanese Hiragana, converting to Kanji |
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| `Ctrl+K` | Japanese Katakana |
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| `Ctrl+T` | English |
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| `Ctrl+V` | Vietnamese Telex |
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| `Ctrl+E` | Emoji and symbol search |
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| `Ctrl+H` | One-shot Hanja and symbol search |
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Only a plain `Ctrl` chord is a strans key: with `Shift`, `Alt` or `Super`
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held it commits what is pending and goes to the application, so
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`Ctrl+Shift+V` still pastes. `Backspace`, `Enter`, `Tab`, `Esc` and the
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arrow and page keys do the same under `Ctrl`, so `Ctrl+Backspace` still
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deletes a word. The mode switched to — `한`, `あ`, `ア`, `ă`, `A` — shows
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in the popup until the next key. A Korean keyboard's 한/영 and 한자 keys
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stand for `Ctrl+S`/`Ctrl+T` and `Ctrl+H`; a Japanese one's 半角/全角,
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ひらがな/カタカナ, 変換 and 無変換 for the kana modes, `Space` and English.
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## Composing
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Japanese composes a whole reading and then offers its Kanji with none
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chosen. `Space` and `Tab` step through the candidates and wrap (`Shift`
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reverses), the reading in Katakana last, so a word the dictionary lacks
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converts with one `Space`; `Up`/`Down` and `PageUp`/`PageDown` move without
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wrapping. `Enter` commits the chosen candidate, or the reading, as `0` and
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typing on always do. Once a candidate is chosen `1`-`9` take that row of
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the page shown; before that the digits type. `Backspace` deletes the last
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kana shown, and romaji that made no kana stays as typed until it is mended;
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`Esc` cancels the reading, and on a chosen candidate both go back to it.
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The dictionary keys verbs and adjectives by stem and okurigana, so `kaku`
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offers かく's readings and then 書く and its kin — typing the okurigana
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with `Shift`, as SKK does, `kaKu`, asks for that split first. Katakana
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mode does not convert.
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Korean composes one syllable at a time. `Enter`, `Tab`, `Esc` and any key
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that is not a jamo commit the syllable and go on to the application, so
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`Esc` still leaves insert mode. Two lone consonants join into the compound
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final they make (rt → ㄳ), and a vowel typed before its consonant is
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reordered under it (kr → 가), as in libhangul.
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A search takes the keys until `Enter`, `Space` or `1`-`9` picks a result or
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`Esc` cancels, then returns to the previous mode. Emoji matches the typed
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keys, and what they spell in the current mode, against a prefix of every
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emoji's CLDR name and keywords in English, Korean and Japanese, and against
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ASCII aliases such as `->` and `<=`. `Ctrl+H` takes the syllable being
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composed as its query and composes on from it, converting a word as well as
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a syllable — 한자 gives 漢字, 대한민국 gives 大韓民國 — and `Esc` gives the
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syllable back. A lone consonant is a reading too, and answers with the
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symbol table a Korean keyboard's 한자 key has always offered: ㅁ gives ※ ○
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△ ㈜, ㄴ the brackets 「」『』, ㄹ the units ℃ ㎏ ℓ, ㅇ the circled numbers
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①②③. Text already committed belongs to the application and cannot be
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converted.
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Dead keys and Compose sequences are composed by strans itself for the
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Wayland, XIM and IBus frontends, from `XCOMPOSEFILE` or the locale; the
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GTK 3 module leaves them to GtkIMContextSimple.
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## Preedit and candidates
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| Frontend | Preedit | Candidates |
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| --- | --- | --- |
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| Wayland input method | inline in the client | popup |
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| GTK 3 and IBus | inline in the client | popup |
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| XIM PreeditCallbacks | inline through XIM callbacks | popup |
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| XIM PreeditPosition, PreeditNothing | popup | popup |
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On Wayland the popup is a surface the compositor places at the text cursor,
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flipping it above the line when there is no room below. Elsewhere it is an
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X11 window, placed from the XIM spot or from the GTK caret, and XIM text
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travels as `COMPOUND_TEXT`. Either way `GDK_SCALE` sizes it for HiDPI
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displays.
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## Build and test
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```sh
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git submodule update --init
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make docker-image
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make docker-build
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```
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That leaves `strans`, the daemon, and `gtk/im-strans.so`, the GTK 3 module.
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Tests come in three tiers:
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```sh
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make check # generated-map validation and unit tests
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make check-live # one IBus, GTK, XIM and IPC daemon smoke each
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make check-stress # randomized, capacity, collision, failure and restart
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```
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`make docker-check` runs all three in the container, and
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`make docker-valgrind` the unit suite under Valgrind; rerun
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`make docker-image` after changing `Dockerfile`. `UNITARGS=hangul` filters
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the unit suite alone, not the other tiers.
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A native build wants a C toolchain, Make, pkg-config and Plan 9 port, plus
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development files for D-Bus, XCB and xcb-imdkit, Wayland and
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`wayland-scanner`, xkbcommon, Pango and Cairo, and GTK 3; the tests also
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want Xvfb, Python 3 and fonts covering Latin, CJK and emoji.
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[`Dockerfile`](Dockerfile) names the exact packages.
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## Run
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```sh
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./run.sh # restart the daemon in the background
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./strans map # or run it in the foreground
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```
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`./strans DIR` reads `hira.map`, `kata.map`, `telex.map`, `kanji.dict`,
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`emoji.dict` and `hanja.dict` from `DIR` at runtime; nothing but the GTK
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module is installed. A service supervisor wants the session's
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`XDG_RUNTIME_DIR` and its `WAYLAND_DISPLAY` or `DISPLAY`: the GTK module
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finds the daemon at `$XDG_RUNTIME_DIR/strans.sock`, else
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`/tmp/strans.UID`, and IBus clients through the address file libibus
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expects under `~/.config/ibus/bus/`, which strans writes as `ibus-daemon`
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would.
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strans shows one popup per session, so it picks a frontend at startup: a
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compositor offering `zwp_input_method_v2` gets the Wayland frontend, and
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then neither XIM nor the X11 popup runs; every other session gets XIM. The
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IBus endpoint and the GTK 3 module are served in both.
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On Wayland, then, set none of the variables below. GTK, Qt and Firefox
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speak text-input-v3 themselves — GTK 4 binds it with `GTK_IM_MODULE` unset
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— and setting these is what pushes them off the path that works: such a
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client still composes inline but shows no candidates, because the popup
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belongs to the Wayland frontend. Chromium is beyond help either way, since
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it asks for `text-input-v1`, which wlroots does not implement.
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```sh
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export XMODIFIERS=@im=strans # XIM
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doas make -C gtk install # GTK 3 module
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export GTK_IM_MODULE=strans
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GLFW_IM_MODULE=ibus kitty # IBus client example
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```
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strans provides its own IBus endpoint, so `ibus-daemon` and fcitx are not
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needed. Building the GTK module wants GTK development files; installing
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one built elsewhere does not. The install target takes `GTK_MODULE_DIR`
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when set, else asks GTK where its modules live; `doas make -C gtk uninstall`
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removes it. With neither `WAYLAND_DISPLAY` nor `DISPLAY` the daemon still
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serves IBus and its socket, but nothing draws a popup.
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## Dictionary data
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After changing an input source, regenerate and verify:
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```sh
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python3 map/mktelex.py >map/telex.map
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map/mkemoji >map/emoji.dict
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map/mkhanja >map/hanja.dict
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make verify-map
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```
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[`map/README`](map/README) says where the emoji, Hanja and Japanese data
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comes from.
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## Benchmark
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`make bench` builds `bench/bench`. With the daemon stopped, `./bench.sh`
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starts one, warms it up and records the workload with Linux `perf` into
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`bench/perf.data`.
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## Licensing
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Third-party notices are in [`LICENSES`](LICENSES). The repository declares
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no license for the strans source as a whole.
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