compose: one Compose table for the XIM and IBus frontends

An IBus client throws away a dead key its engine did not take — the GTK
module's own comment says so, and Qt does the same — so é and ü were
lost in every IBus application, while XIM composed them with a table of
its own.  That table moves to compose.c, which both frontends now use;
xim.c is the shorter for it.

A finished sequence is text, not a key: the engine is asked to hand back
what it had pending, and the composed text follows it, so the composed
character can no longer land before the syllable typed before it.

Makefile

@@ -19,7 +19,7 @@ DOCKER_IMAGE = strans-build
 DOCKER_RUN = docker run --rm --user "$$(id -u):$$(id -g)" \
 	-v "$(CURDIR):/src" $(DOCKER_IMAGE)
 
-SRCS = dict.c font.c ibus.c ipc.c ko.c main.c popup_layout.c \
+SRCS = compose.c dict.c font.c ibus.c ipc.c ko.c main.c popup_layout.c \
 	srv.c str.c strans.c trie.c vi.c win.c xim.c
 OBJS = $(SRCS:.c=.o)
 
@@ -29,7 +29,7 @@ $(PROG): $(OBJS)
 	$(LD) $(LDFLAGS) -o $@ $(OBJS) $(PROJECT_LDLIBS) $(LDLIBS)
 
 $(OBJS): dat.h fn.h ipc.h
-ibus.o: PROJECT_CPPFLAGS += $(IBUS_CFLAGS)
+compose.o ibus.o: PROJECT_CPPFLAGS += $(IBUS_CFLAGS)
 font.o: PROJECT_CPPFLAGS += $(TEXT_CFLAGS)
 win.o: PROJECT_CPPFLAGS += $(POPUP_CFLAGS)
 xim.o: PROJECT_CPPFLAGS += $(XIM_CFLAGS)

README.md

@@ -69,6 +69,11 @@ a time. Leaving the field or clicking elsewhere commits what is pending.
 
 Each XIM style is offered with StatusNothing and with StatusNone.
 
+Dead keys and Compose sequences are composed by strans itself for the XIM
+and IBus frontends, from the table `XCOMPOSEFILE` or the locale names; the
+GTK 3 module leaves them to GtkIMContextSimple. Their text follows
+whatever was pending.
+
 XIM text travels as `COMPOUND_TEXT`, which carries any UTF-8. A client that
 sends `XNSpotLocation` gets the popup under that spot whatever its preedit
 style, and above the line when there is no room below; otherwise the popup

compose.c

@@ -0,0 +1,54 @@
+#include "dat.h"
+#include "fn.h"
+
+#include <locale.h>
+#include <xkbcommon/xkbcommon.h>
+#include <xkbcommon/xkbcommon-compose.h>
+
+static struct xkb_compose_state *cstate;
+
+/* Dead keys and Compose: no frontend's client does them for us. */
+void
+composeinit(void)
+{
+	struct xkb_context *ctx;
+	struct xkb_compose_table *table;
+	char *locale;
+
+	locale = setlocale(LC_CTYPE, "");
+	ctx = xkb_context_new(XKB_CONTEXT_NO_FLAGS);
+	if(ctx == nil)
+		return;
+	table = xkb_compose_table_new_from_locale(ctx,
+		locale != nil ? locale : "C", XKB_COMPOSE_COMPILE_NO_FLAGS);
+	if(table != nil)
+		cstate = xkb_compose_state_new(table, XKB_COMPOSE_STATE_NO_FLAGS);
+	xkb_compose_table_unref(table);
+	xkb_context_unref(ctx);
+}
+
+/*
+ * Feeds sym to the Compose table.  Returns 1 while a sequence is
+ * unfinished: the key belongs to the sequence, not to the engine.  A
+ * finished sequence leaves its text in buf, which the caller commits
+ * after whatever the engine had pending.
+ */
+int
+composekey(u32int sym, char *buf, int n)
+{
+	buf[0] = '\0';
+	if(cstate == nil ||
+	   xkb_compose_state_feed(cstate, sym) != XKB_COMPOSE_FEED_ACCEPTED)
+		return 0;
+	switch(xkb_compose_state_get_status(cstate)){
+	case XKB_COMPOSE_COMPOSING:
+	case XKB_COMPOSE_CANCELLED:
+		return 1;
+	case XKB_COMPOSE_COMPOSED:
+		xkb_compose_state_get_utf8(cstate, buf, n);
+		break;
+	default:
+		break;
+	}
+	return 0;
+}

fn.h

@@ -45,6 +45,9 @@ void	ibusthread(void*);
 void	ximthread(void*);
 int	keymeaningful(u32int);
 
+void	composeinit(void);
+int	composekey(u32int, char*, int);
+
 void*	emalloc(ulong);
 void*	erealloc(void*, ulong);
 

ibus.c

@@ -531,11 +531,19 @@ dropconncontexts(DBusConnection *conn)
  * focus events of two applications can cross.
  */
 static int
-processkey(Ictx *ctx, u32int sym, u32int state, Keyres *res)
+processkey(Ictx *ctx, u32int sym, u32int state, char *text, int n, Keyres *res)
 {
+	text[0] = '\0';
 	if(state & Relmask || hidden(ctx))
 		return 0;
 	ctx->focused = 1;
+	/* An IBus client drops a dead key we do not take: compose it here. */
+	if(composekey(sym, text, n))
+		return -1;
+	if(text[0] != '\0')
+		/* Composed text follows whatever was pending. */
+		sendrequest(ctx, Keyreset, 0, 0, res);
+	else
 		sendrequest(ctx, Keypress, ipckeysym(sym, xkb_keysym_to_utf32(sym)),
 			ipcmod(state), res);
 	if(preowner != nil && preowner != ctx)
@@ -641,14 +649,15 @@ handlekey(DBusConnection *c, DBusMessage *m, Ictx *ctx)
 {
 	dbus_uint32_t sym, code, state;
 	Keyres res;
-	char commit[Maxutf], preedit[Maxutf];
-	int restart;
+	char commit[Maxutf], preedit[Maxutf], text[Maxutf];
+	int restart, rv;
 
 	dbus_message_get_args(m, nil, DBUS_TYPE_UINT32, &sym,
 		DBUS_TYPE_UINT32, &code, DBUS_TYPE_UINT32, &state,
 		DBUS_TYPE_INVALID);
-	if(!processkey(ctx, sym, state, &res))
-		return replybool(c, m, 0);
+	rv = processkey(ctx, sym, state, text, sizeof text, &res);
+	if(rv <= 0)	/* below zero: a sequence in the making */
+		return replybool(c, m, rv < 0);
 	stoutf(&res.commit, commit, sizeof commit);
 	stoutf(&res.preedit, preedit, sizeof preedit);
 	/* A commit ends the preedit around it, so clients place it right. */
@@ -658,10 +667,12 @@ handlekey(DBusConnection *c, DBusMessage *m, Ictx *ctx)
 		emitpreedit(ctx, "");
 	if(commit[0] != '\0')
 		emitcommit(ctx, commit);
+	if(text[0] != '\0')
+		emitcommit(ctx, text);
 	if(clientpreedit(ctx) && (!restart || preedit[0] != '\0'))
 		emitpreedit(ctx, preedit);
 	ctx->keying = 0;
-	return replybool(c, m, res.eaten);
+	return replybool(c, m, res.eaten || text[0] != '\0');
 }
 
 /* Properties.Get PostProcessKeyEvent: what the last key produced. */

main.c

@@ -55,6 +55,7 @@ threadmain(int argc, char **argv)
 	drawc = chancreate(sizeof(Drawcmd), 4);
 	keyc = chancreate(sizeof(Keyreq), 0);
 	langinit(argv[1]);
+	composeinit();
 	srvinit();
 	proccreate(drawthread, nil, 16384);
 	proccreate(srvthread, nil, 16384);

tests/Makefile

@@ -32,10 +32,11 @@ FAULT = daemon_collision_test daemon_failure_test daemon_restart_test
 LIVE = $(SMOKE) $(FAULT)
 TESTSRC = test_util.c str_test.c trie_test.c \
 	ko_test.c vi_test.c engine_test.c dict_test.c ipc_test.c \
-	popup_test.c font_test.c ibus_test.c server_test.c xim_adapter_test.c
+	popup_test.c font_test.c ibus_test.c server_test.c compose_test.c \
+	xim_adapter_test.c
 TESTOBJ = $(TESTSRC:.c=.o)
 PARENTSRC = str.c trie.c dict.c ko.c vi.c ipc.c popup_layout.c \
-	font.c
+	font.c compose.c
 PARENTOBJ = $(PARENTSRC:%.c=unit_%.o)
 COMMONOBJ = $(TESTOBJ) $(PARENTOBJ)
 OBJS = unit_test.o stress_test.o $(COMMONOBJ)
@@ -125,6 +126,7 @@ xim_adapter_test.o: UNIT_CPPFLAGS += $(XIM_CFLAGS)
 xim_adapter_test.o: ../xim.c
 server_test.o: ../srv.c
 unit_font.o: UNIT_CPPFLAGS += $(TEXT_CFLAGS)
+unit_compose.o compose_test.o: UNIT_CPPFLAGS += $(IBUS_CFLAGS)
 
 unit_%.o: ../%.c ../dat.h ../fn.h ../ipc.h
 	$(CC) $(CPPFLAGS) $(UNIT_CPPFLAGS) $(UNIT_CFLAGS) $(CFLAGS) -c -o $@ $<

tests/compose_test.c

@@ -0,0 +1,37 @@
+#include "dat.h"
+#include "fn.h"
+#include "test.h"
+#include <xkbcommon/xkbcommon-keysyms.h>
+
+/* A sequence swallows its keys and hands its text back at the end. */
+void
+compose_sequences(struct ct *t)
+{
+	static const struct {
+		u32int	sym;
+		int	composing;
+		char	*text;
+	} keys[] = {
+		{ XKB_KEY_a,		0, "" },
+		{ XKB_KEY_dead_acute,	1, "" },
+		{ XKB_KEY_e,		0, "é" },
+		{ XKB_KEY_Multi_key,	1, "" },
+		{ XKB_KEY_o,		1, "" },
+		{ XKB_KEY_c,		0, "©" },
+		{ XKB_KEY_dead_acute,	1, "" },
+		{ XKB_KEY_Escape,	1, "" },
+		{ XKB_KEY_a,		0, "" },
+	};
+	char buf[Maxutf];
+	int i;
+
+	if(!CT_CHECK(t, setenv("XCOMPOSEFILE", "data/compose", 1) == 0))
+		return;
+	composeinit();
+	for(i = 0; i < nelem(keys); i++){
+		CT_EQ_INT(t, keys[i].composing,
+			composekey(keys[i].sym, buf, sizeof buf));
+		CT_EQ_STR(t, keys[i].text, buf);
+	}
+	unsetenv("XCOMPOSEFILE");
+}

tests/data/compose

@@ -0,0 +1,2 @@
+<dead_acute> <e> : "é"
+<Multi_key> <o> <c> : "©"

tests/ibus_test.c

@@ -153,9 +153,10 @@ static Keyres
 contextkey(struct ct *t, Ibusfix *f, Ictx *ctx, u32int sym, u32int state)
 {
 	Keyres res;
+	char text[Maxutf];
 
 	memset(&res, 0, sizeof res);
-	CT_CHECK(t, processkey(ctx, sym, state, &res));
+	CT_CHECK(t, processkey(ctx, sym, state, text, sizeof text, &res));
 	nexttrace(t, f, Keypress, ctx);
 	return res;
 }
@@ -219,6 +220,7 @@ ibus_private_input_policy(struct ct *t)
 	Ibusfix f;
 	Ictx *ctx;
 	Keyres res;
+	char text[Maxutf];
 	int i;
 
 	if(!ibusbegin(t, &f))
@@ -239,7 +241,7 @@ ibus_private_input_policy(struct ct *t)
 	checkstr(t, "preedit", "k", &res.preedit);
 	ctx->purpose = Ibuspurposepassword;
 	memset(&res, 0, sizeof res);
-	CT_CHECK(t, !processkey(ctx, 'x', 0, &res));
+	CT_CHECK(t, !processkey(ctx, 'x', 0, text, sizeof text, &res));
 	CT_CHECK(t, !res.eaten);
 	notrace(t, &f);
 	checkenginepreedit(t, "k");
@@ -270,6 +272,7 @@ ibus_context_lifecycle(struct ct *t)
 	Keyreq req;
 	Keyres res;
 	Caret at;
+	char text[Maxutf];
 
 	if(!ibusbegin(t, &f))
 		goto cleanup;
@@ -285,7 +288,7 @@ ibus_context_lifecycle(struct ct *t)
 	notrace(t, &f);
 	CT_CHECK(t, a->caret.valid);
 	memset(&res, 0, sizeof res);
-	CT_CHECK(t, !processkey(a, 'x', Relmask, &res));
+	CT_CHECK(t, !processkey(a, 'x', Relmask, text, sizeof text, &res));
 	CT_CHECK(t, !res.eaten);
 	notrace(t, &f);
 	CT_CHECK(t, !a->focused);
@@ -293,7 +296,7 @@ ibus_context_lifecycle(struct ct *t)
 
 	/* A key stands for the FocusIn a client may never send. */
 	memset(&res, 0, sizeof res);
-	CT_CHECK(t, processkey(a, 'x', 0, &res));
+	CT_CHECK(t, processkey(a, 'x', 0, text, sizeof text, &res));
 	req = nexttrace(t, &f, Keypress, a);
 	CT_CHECK(t, a->focused);
 	CT_CHECK(t, !res.eaten);
@@ -369,7 +372,7 @@ ibus_context_lifecycle(struct ct *t)
 	notrace(t, &f);
 
 	memset(&res, 0, sizeof res);
-	CT_CHECK(t, !processkey(b, 'x', Relmask, &res));
+	CT_CHECK(t, !processkey(b, 'x', Relmask, text, sizeof text, &res));
 	CT_CHECK(t, !res.eaten);
 	notrace(t, &f);
 	CT_EQ_PTR(t, b, testengineowner());

tests/test.h

@@ -112,6 +112,7 @@ void	ibus_capability_policy(struct ct*);
 void	ibus_private_input_policy(struct ct*);
 void	ibus_context_lifecycle(struct ct*);
 void	ibus_active_release_lifecycle(struct ct*);
+void	compose_sequences(struct ct*);
 void	xim_keymap_lookup(struct ct*);
 void	xim_compound_text(struct ct*);
 void	xim_adapter_key_contract(struct ct*);

tests/unit_test.c

@@ -135,6 +135,7 @@ static const struct ct_test tests[] = {
 	{ "ibus/private-input-policy", ibus_private_input_policy },
 	{ "ibus/context-lifecycle", ibus_context_lifecycle },
 	{ "ibus/active-release-lifecycle", ibus_active_release_lifecycle },
+	{ "compose/sequences", compose_sequences },
 	{ "xim/keymap-lookup", xim_keymap_lookup },
 	{ "xim/compound-text", xim_compound_text },
 	{ "xim/adapter-key-contract", xim_adapter_key_contract },

xim.c

@@ -8,7 +8,6 @@
 #include <xcb/xcb_aux.h>
 #include <xcb/xkb.h>
 #include <xkbcommon/xkbcommon.h>
-#include <xkbcommon/xkbcommon-compose.h>
 #include <xkbcommon/xkbcommon-names.h>
 #include <xkbcommon/xkbcommon-x11.h>
 #include <xcb-imdkit/imdkit.h>
@@ -35,7 +34,6 @@ struct Ic
 static xcb_connection_t *conn;
 static xcb_im_t *xim;
 static struct xkb_state *kstate;
-static struct xkb_compose_state *compose;
 static uint8_t xkbevent;
 static xcb_window_t rootwin;
 static Ic *ics;
@@ -97,26 +95,6 @@ out:
 	return ok;
 }
 
-/* Dead keys and Compose: Xlib leaves them to the input method server. */
-static void
-cinit(void)
-{
-	struct xkb_context *context;
-	struct xkb_compose_table *table;
-	char *locale;
-
-	locale = setlocale(LC_CTYPE, "");
-	context = xkb_context_new(XKB_CONTEXT_NO_FLAGS);
-	if(context == nil)
-		return;
-	table = xkb_compose_table_new_from_locale(context,
-		locale != nil ? locale : "C", XKB_COMPOSE_COMPILE_NO_FLAGS);
-	if(table != nil)
-		compose = xkb_compose_state_new(table, XKB_COMPOSE_STATE_NO_FLAGS);
-	xkb_compose_table_unref(table);
-	xkb_context_unref(context);
-}
-
 static void
 kwatch(void)
 {
@@ -401,39 +379,27 @@ static void
 kpress(Ic *state, xcb_key_press_event_t *ev)
 {
 	Keyres res;
-	char buf[Maxutf];
+	char buf[Maxutf], text[Maxutf];
 	u32int key, sym;
-	int composed, n;
+	int n;
 
 	sym = keymaplookup(kstate, ev->detail, ev->state);
-	composed = 0;
-	if(compose != nil &&
-	   xkb_compose_state_feed(compose, sym) == XKB_COMPOSE_FEED_ACCEPTED)
-		switch(xkb_compose_state_get_status(compose)){
-		case XKB_COMPOSE_COMPOSING:
-		case XKB_COMPOSE_CANCELLED:
+	if(composekey(sym, text, sizeof text))
 		return;
-		case XKB_COMPOSE_COMPOSED:
-			sym = xkb_compose_state_get_one_sym(compose);
-			composed = 1;
-			break;
-		default:
-			break;
-		}
 	key = ipckeysym(sym, xkb_keysym_to_utf32(sym));
 	if(keymeaningful(key))
 		place(state);
+	if(text[0] != '\0')
+		/* Composed text follows whatever was pending. */
+		sendrequest(state, Keyreset, 0, 0, &res);
+	else
 		keypress(state, key, ev->state, &res);
 	n = stoutf(&res.commit, buf, sizeof buf);
 	commit(state, buf, n);
 	updatepreedit(state, &res.preedit);
-	if(res.eaten)
-		;
-	else if(composed){
-		/* The event holds the last key of the sequence, not its result. */
-		n = xkb_compose_state_get_utf8(compose, buf, sizeof buf);
-		commit(state, buf, min(n, (int)sizeof buf - 1));
-	}else
+	if(text[0] != '\0')
+		commit(state, text, strlen(text));
+	else if(!res.eaten)
 		xcb_im_forward_event(xim, state->xic, ev);
 	xcb_flush(conn);
 }
@@ -554,7 +520,6 @@ ximinit(void)
 		ximlog("cannot read keyboard mapping");
 		return -1;
 	}
-	cinit();
 	kwatch();
 	win = xcb_generate_id(conn);
 	xcb_create_window(conn, XCB_COPY_FROM_PARENT, win, screen->root,