engine: Ctrl+H converts the pending syllable; Backspace on an empty search stays put

Ctrl+H committed the syllable being composed and opened an empty search,
so converting 한 meant typing it twice; the pending syllable now seeds the
query. Backspace on an already empty search ended it and then reached the
application, deleting a character; it now only ends the search.

README.md

@@ -28,8 +28,8 @@ what is pending; `Esc` cancels it.
 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 Hanja dictionary lists one modern Hangul
+commits the shown query. `Ctrl+H` takes the syllable being composed as its
-syllable at a time.
+query; the Hanja dictionary lists one modern Hangul syllable at a time.
 
 ## Preedit and candidates
 

strans.c

@@ -10,10 +10,12 @@ static Drawcmd lastdraw;
 static Emit transjp(Im*, Rune);
 static void backjp(Im*);
 
+/* seed is what Ctrl+H found pending; raw the keys typed since; text both. */
 typedef struct Search Search;
 struct Search
 {
 	int	lang;
+	Str	seed;
 	Str	raw;
 	Str	text;
 };
@@ -228,18 +230,6 @@ redraw(void)
 	channbsend(drawc, &dc);
 }
 
-static void
-reset(void)
-{
-	sclear(&im.pre);
-	sclear(&im.raw);
-	search.lang = 0;
-	sclear(&search.raw);
-	sclear(&search.text);
-	memset(&caret, 0, sizeof caret);
-	clearkouho();
-}
-
 /* Kanji candidates for a complete reading. */
 static void
 dictqjp(void)
@@ -526,9 +516,11 @@ hanjaquery(void)
 	Str key;
 
 	transstr(im.l, &search.raw, &key);
-	search.text = key;
+	search.text = search.seed;
+	sappend(&search.text, &key);
 	clearkouho();
-	im.nkouho = dictlookup(getlang(LangHANJA), &key, im.kouho, Maxkouho);
+	im.nkouho = dictlookup(getlang(LangHANJA), &search.text, im.kouho,
+		Maxkouho);
 	selectfirst();
 }
 
@@ -551,11 +543,21 @@ static void
 endsearch(void)
 {
 	search.lang = 0;
+	sclear(&search.seed);
 	sclear(&search.raw);
 	sclear(&search.text);
 	clearkouho();
 }
 
+static void
+reset(void)
+{
+	sclear(&im.pre);
+	sclear(&im.raw);
+	endsearch();
+	memset(&caret, 0, sizeof caret);
+}
+
 static void
 commitsearch(Str *com)
 {
@@ -563,13 +565,27 @@ commitsearch(Str *com)
 	endsearch();
 }
 
-/* A search commits whatever is pending and takes over the keys. */
+/*
+ * A search takes over the keys.  Hanja converts the pending syllable, so
+ * it becomes the query; anything else pending is committed.
+ */
 static void
 startsearch(int lang, Str *com)
 {
-	commit(com);
+	Str pending;
+
+	impre(&im, &pending);
+	if(lang == LangHANJA){
+		sclear(&im.pre);
+		sclear(&im.raw);
+	}else
+		commit(com);
 	commitsearch(com);
 	search.lang = lang;
+	if(lang == LangHANJA){
+		search.seed = pending;
+		searchquery();
+	}
 }
 
 /*
@@ -635,11 +651,14 @@ searchkey(u32int ks, u32int mod, Str *com)
 		return 1;
 	}
 	if(ks == Kback){
-		if(search.raw.n == 0){
+		if(search.raw.n != 0)
+			spopr(&search.raw);
+		else if(search.seed.n != 0)
+			spopr(&search.seed);
+		else{
 			endsearch();
-			return 0;
+			return 1;
 		}
-		spopr(&search.raw);
 		searchquery();
 		return 1;
 	}

tests/engine_test.c

@@ -1744,15 +1744,20 @@ engine_hanja_backspace(struct ct *t)
 	CT_CHECK(t, keystroke(Kback, 0, &com));
 	checkstr(t, "empty Hanja search", "", &search.text);
 	CT_EQ_INT(t, LangHANJA, search.lang);
-	CT_CHECK(t, !keystroke(Kback, 0, &com));
+	CT_CHECK(t, keystroke(Kback, 0, &com));
 	CT_EQ_INT(t, 0, search.lang);
 
+	/* Ctrl+H converts the pending syllable: it seeds the query. */
 	if(!typekeys(t, "gks", &com))
 		goto cleanup;
 	CT_CHECK(t, keystroke('h', Mctrl, &com));
-	checkstr(t, "preedit committed before Hanja", "한", &com);
+	checkstr(t, "nothing committed before Hanja", "", &com);
+	checkstr(t, "pending syllable is the query", "한", &search.text);
+	CT_EQ_INT(t, 2, im.nkouho);
+	CT_CHECK(t, keystroke(Kback, 0, &com));
+	checkstr(t, "seed backspaced", "", &search.text);
 	CT_EQ_INT(t, LangHANJA, search.lang);
-	CT_CHECK(t, !keystroke(Kback, 0, &com));
+	CT_CHECK(t, keystroke(Kback, 0, &com));
 	CT_EQ_INT(t, 0, search.lang);
 	CT_EQ_INT(t, LangKO, im.l->lang);
 cleanup: