engine: the Hanja search composes from its seed, and Escape gives it back

Ctrl+H took the pending syllable as the query, but the keys typed after
it started a composition of their own: gk, Ctrl+H, s showed 하ㄴ, and r,
Ctrl+H, k showed ㄱㅏ.  transstr now composes from a pending text, so
the search goes on where the syllable left off.  Escape ended the search
and dropped the syllable it had taken; it puts it back as pending text.

README.md

@@ -38,7 +38,8 @@ syllable and goes on to the application, so it still leaves insert mode.
 Hiragana mode composes a complete reading before offering Kanji candidates.
 Katakana mode does not perform Kanji conversion. Emoji and Hanja searches
 return to the previous mode after use; switching language during a search
-commits the shown query. The Emoji search matches the typed keys, and what
+commits the shown query; `Esc` in a Hanja search gives the syllable back
+to the composition. The Emoji search matches the typed keys, and what
 they spell in the current language, against a prefix of every emoji's
 CLDR name and keywords in English, Korean, and Japanese, and against ASCII
 symbol aliases such as `->` and `<=`. `Ctrl+H` takes the syllable being composed as its

fn.h

@@ -31,7 +31,7 @@ void	popuplayout(Drawcmd*, int, int, Popup*);
 void	popupdraw(u32int*, Drawcmd*, Popup*);
 void	imthread(void*);
 void	impre(Im*, Str*);
-void	transstr(Lang*, Str*, Str*);
+void	transstr(Lang*, Str*, Str*, Str*);
 Emit	transmap(Im*, Rune);
 Emit	transko(Im*, Rune);
 Emit	transvi(Im*, Rune);

strans.c

@@ -526,21 +526,27 @@ foldascii(Str *s)
 			s->r[i] += 'a' - 'A';
 }
 
-/* What typing raw in language l would produce, composition included. */
+/*
+ * What typing raw in language l would produce, composition included,
+ * after pre, which may be nil, was already pending.
+ */
 void
-transstr(Lang *l, Str *raw, Str *out)
+transstr(Lang *l, Str *pre, Str *raw, Str *out)
 {
 	Im q;
 	Emit e;
 	int i;
 
-	sclear(out);
-	if(l->trans == nil){
-		*out = *raw;
-		return;
-	}
 	memset(&q, 0, sizeof q);
 	q.l = l;
+	if(pre != nil)
+		q.pre = *pre;
+	sclear(out);
+	if(l->trans == nil){
+		sappend(out, &q.pre);
+		sappend(out, raw);
+		return;
+	}
 	for(i = 0; i < raw->n; i++){
 		e = l->trans(&q, raw->r[i]);
 		sappend(out, &e.s);
@@ -561,7 +567,7 @@ emojiquery(void)
 
 	raw = search.raw;
 	foldascii(&raw);
-	transstr(im.l, &search.raw, &local);
+	transstr(im.l, nil, &search.raw, &local);
 	foldascii(&local);
 	clearkouho();
 	n = dictlookup(getlang(LangEMOJI), &raw, kouho, Maxkouho);
@@ -579,14 +585,11 @@ emojiquery(void)
 	selectfirst();
 }
 
+/* The keys typed since Ctrl+H go on composing from the seed. */
 static void
 hanjaquery(void)
 {
-	Str key;
-
-	transstr(im.l, &search.raw, &key);
-	search.text = search.seed;
-	sappend(&search.text, &key);
+	transstr(im.l, &search.seed, &search.raw, &search.text);
 	clearkouho();
 	im.nkouho = dictlookup(getlang(LangHANJA), &search.text, im.kouho,
 		Maxkouho);
@@ -711,6 +714,7 @@ searchkey(u32int ks, u32int mod, Str *com)
 		return 1;
 	}
 	if(ks == Kesc){
+		im.pre = search.seed;	/* the syllable Ctrl+H took is pending again */
 		endsearch();
 		return 1;
 	}

tests/engine_test.c

@@ -1101,7 +1101,7 @@ engine_japanese_readings(struct ct *t)
 	}
 	for(i = 0; i < nelem(replay); i++){
 		raw = mkstr(replay[i].raw);
-		transstr(getlang(LangJP), &raw, &shown);
+		transstr(getlang(LangJP), nil, &raw, &shown);
 		checkstr(t, replay[i].raw, replay[i].want, &shown);
 	}
 }
@@ -1891,6 +1891,25 @@ engine_hanja_backspace(struct ct *t)
 	CT_CHECK(t, keystroke(Kback, 0, &com));
 	CT_EQ_INT(t, 0, search.lang);
 	CT_EQ_INT(t, LangKO, im.l->lang);
+	/* Escape gives the seed back; keys typed compose from it. */
+	if(!typekeys(t, "gks", &com))
+		goto cleanup;
+	CT_CHECK(t, keystroke('h', Mctrl, &com));
+	CT_CHECK(t, keystroke(Kesc, 0, &com));
+	CT_EQ_INT(t, 0, search.lang);
+	checkstr(t, "seed pending again", "한", &im.pre);
+	checkstr(t, "nothing committed", "", &com);
+	CT_CHECK(t, keystroke(Kback, 0, &com));
+	CT_CHECK(t, keystroke('h', Mctrl, &com));
+	checkstr(t, "seed 하", "하", &search.text);
+	CT_CHECK(t, keystroke('s', 0, &com));
+	checkstr(t, "key composes with the seed", "한", &search.text);
+	CT_EQ_INT(t, 2, im.nkouho);
+	CT_CHECK(t, keystroke(Kesc, 0, &com));
+	checkstr(t, "seed alone comes back", "하", &im.pre);
+	CT_CHECK(t, !keystroke(Kesc, 0, &com));
+	checkstr(t, "Korean Escape commits", "하", &com);
+	CT_EQ_INT(t, 0, im.pre.n);
 cleanup:
 	searchend(&f);
 }

tests/ko_test.c

@@ -8,7 +8,7 @@ kotrans(char *keys)
 	Str out, raw;
 
 	raw = mkstr(keys);
-	transstr(getlang(LangKO), &raw, &out);
+	transstr(getlang(LangKO), nil, &raw, &out);
 	return out;
 }
 

tests/vi_test.c

@@ -8,7 +8,7 @@ typevi(struct ct *t, char *keys, char *want)
 	Str out, raw;
 
 	raw = mkstr(keys);
-	transstr(&testvi, &raw, &out);
+	transstr(&testvi, nil, &raw, &out);
 	checkstr(t, keys, want, &out);
 }