engine: Space offers the reading in Katakana last; 0 always commits the reading

Every Japanese IME converts a reading to Katakana on demand; strans made
the user switch to the Katakana mode and type again.  Space now adds
the reading in Katakana after the dictionary candidates, so a loanword
the dictionary lacks converts with one Space and Enter, and 漢字 users
still get 漢字 first.

0 committed the reading only while candidates showed; without them it
typed a 0 as well.  It now commits any Japanese reading, the counterpart
of 1-9 picking candidates, as the README always said.

README.md

@@ -26,8 +26,9 @@ unmodified `1`-`9` commits that row of the current page. `Enter` and `Tab`
 commit the chosen candidate, or the reading when none is chosen, as `0`
 always does; so does typing on, or any key that ends the composition.
 Japanese consumes the confirming key; Korean and Vietnamese pass it on to
-the application. `Space` on a reading without candidates commits it and
+the application. `Space` adds the reading in Katakana as the last
-types nothing. `Backspace` and `Esc` on a chosen candidate go back to the
+candidate, so a word the dictionary lacks converts to Katakana with one
+`Space`. `Backspace` and `Esc` on a chosen candidate go back to the
 reading. In a temporary Emoji or Hanja search, `Enter` commits the
 highlighted result and `Tab`/`Shift-Tab` wrap through the results. Leaving
 the field or clicking elsewhere commits what is pending. `Esc` cancels a

strans.c

@@ -313,6 +313,23 @@ dictqjp(void)
 	dictqokuri(&reading);
 }
 
+/* The reading in Katakana is the last candidate, as in every IME. */
+static void
+katakouho(void)
+{
+	Str reading, k;
+	int i;
+
+	if(!jpreading(im.l->map, &im.pre, &im.raw, &reading))
+		return;
+	k = reading;
+	for(i = 0; i < k.n; i++)
+		if(k.r[i] >= L'ぁ' && k.r[i] <= L'ゖ')
+			k.r[i] += L'ァ' - L'ぁ';
+	if(scmp(&k, &reading) != 0)
+		addkouho(&k);
+}
+
 static int
 setlang(int c)
 {
@@ -755,8 +772,9 @@ transition(u32int ks, u32int mod, Str *com)
 		return 1;
 	}
 	if(ks == ' ' && isjp(&im) && haspre(&im) && !(mod & ~Mshift)){
-		/* Space converts: it steps through the candidates, or
+		/* Space converts: it steps through the candidates, Katakana
-		 * commits a reading that has none. */
+		 * last; a reading with none is committed. */
+		katakouho();
 		if(im.nkouho != 0)
 			cyclekouho(mod & Mshift ? -1 : 1);
 		else
@@ -811,8 +829,8 @@ transition(u32int ks, u32int mod, Str *com)
 		flush(com);
 		return setlang(c);
 	}
-	if(ks == '0' && im.nkouho > 0){
+	if(ks == '0' && isjp(&im) && haspre(&im)){
-		im.sel = -1;
+		im.sel = -1;	/* 0 commits the reading, as 1-9 pick candidates */
 		flush(com);
 		return 1;
 	}

tests/engine_test.c

@@ -1146,12 +1146,14 @@ engine_japanese_candidates(struct ct *t)
 	CT_CHECK(t, keystroke(' ', 0, &com));
 	CT_EQ_INT(t, 1, im.sel);
 	CT_CHECK(t, keystroke(' ', 0, &com));
+	CT_EQ_INT(t, 2, im.sel);
+	CT_CHECK(t, keystroke(' ', 0, &com));
 	CT_EQ_INT(t, 0, im.sel);
 	CT_CHECK(t, keystroke(' ', Mshift, &com));
-	CT_EQ_INT(t, 1, im.sel);
+	CT_EQ_INT(t, 2, im.sel);
 	CT_CHECK(t, keystroke(Kback, 0, &com));
 	CT_EQ_INT(t, -1, im.sel);
-	CT_EQ_INT(t, 2, im.nkouho);
+	CT_EQ_INT(t, 3, im.nkouho);
 	CT_CHECK(t, keystroke(' ', 0, &com));
 	CT_CHECK(t, keystroke('w', 0, &com));
 	CT_CHECK(t, keystroke('o', 0, &com));
@@ -1160,45 +1162,22 @@ engine_japanese_candidates(struct ct *t)
 	checkstr(t, "reading after the candidate", "を", &shown);
 	sclear(&com);
 	CT_CHECK(t, keystroke(' ', 0, &com));
-	checkstr(t, "Space commits a reading without candidates", "を", &com);
+	if(CT_EQ_INT(t, 1, im.nkouho))
-	CT_EQ_INT(t, 0, im.pre.n);
+		checkstr(t, "Space offers Katakana without candidates", "ヲ",
-	CT_EQ_INT(t, 0, im.raw.n);
+			&im.kouho[0]);
+	CT_EQ_INT(t, 0, im.sel);
+	CT_CHECK(t, keystroke(Kret, 0, &com));
+	checkstr(t, "Katakana committed", "ヲ", &com);
 	CT_CHECK(t, !keystroke(' ', 0, &com));
 	sclear(&com);
 	if(!typekeys(t, "kanji", &com))
 		goto cleanup;
-	CT_CHECK(t, keystroke(' ', 0, &com));
-	CT_CHECK(t, keystroke(Kesc, 0, &com));
-	CT_EQ_INT(t, -1, im.sel);
-	impre(&im, &shown);
-	checkstr(t, "Escape goes back to the reading", "かんじ", &shown);
-	CT_CHECK(t, keystroke(Kesc, 0, &com));
-	CT_EQ_INT(t, 0, im.pre.n);
-	CT_EQ_INT(t, 0, im.raw.n);
-	CT_EQ_INT(t, 0, im.nkouho);
-	sclear(&com);
-	if(!typekeys(t, "kanji", &com))
-		goto cleanup;
-	CT_CHECK(t, keystroke(Kdown, 0, &com));
-	CT_CHECK(t, keystroke('s', Mctrl, &com));
-	checkstr(t, "language switch takes the candidate", "漢字", &com);
-	CT_EQ_INT(t, LangKO, im.l->lang);
-	im.l = jp;
-	/* A romaji typo stays in the reading for Backspace to mend. */
-	sclear(&com);
-	if(!typekeys(t, "kanjr", &com))
-		goto cleanup;
-	impre(&im, &shown);
-	checkstr(t, "typo kept", "かんjr", &shown);
-	CT_CHECK(t, keystroke(Kback, 0, &com));
-	impre(&im, &shown);
-	checkstr(t, "typo half mended", "かんj", &shown);
-	CT_CHECK(t, keystroke(Kback, 0, &com));
-	if(!typekeys(t, "ji", &com))
-		goto cleanup;
-	impre(&im, &shown);
-	checkstr(t, "typo mended", "かんじ", &shown);
 	CT_EQ_INT(t, 2, im.nkouho);
+	CT_CHECK(t, keystroke(' ', 0, &com));
+	if(CT_EQ_INT(t, 3, im.nkouho))
+		checkstr(t, "Katakana after the candidates", "カンジ",
+			&im.kouho[2]);
+	CT_CHECK(t, keystroke(Kesc, 0, &com));
 	CT_CHECK(t, keystroke(Kesc, 0, &com));
 	/* SKK's okuri-ari entries convert verbs: stem plus okurigana. */
 	setdict(jp->dict, "かk", "書 描");
@@ -1226,6 +1205,47 @@ engine_japanese_candidates(struct ct *t)
 		checkstr(t, "sokuon written in kana", "行った", &im.kouho[1]);
 	}
 	CT_CHECK(t, keystroke(Kesc, 0, &com));
+	/* A romaji typo stays in the reading for Backspace to mend. */
+	if(!typekeys(t, "kanjr", &com))
+		goto cleanup;
+	impre(&im, &shown);
+	checkstr(t, "typo kept", "かんjr", &shown);
+	CT_CHECK(t, keystroke(Kback, 0, &com));
+	impre(&im, &shown);
+	checkstr(t, "typo half mended", "かんj", &shown);
+	CT_CHECK(t, keystroke(Kback, 0, &com));
+	if(!typekeys(t, "ji", &com))
+		goto cleanup;
+	impre(&im, &shown);
+	checkstr(t, "typo mended", "かんじ", &shown);
+	CT_EQ_INT(t, 2, im.nkouho);
+	CT_CHECK(t, keystroke('0', 0, &com));
+	checkstr(t, "0 commits the reading", "かんじ", &com);
+	sclear(&com);
+	if(!typekeys(t, "wo", &com))
+		goto cleanup;
+	CT_CHECK(t, keystroke('0', 0, &com));
+	checkstr(t, "0 commits a reading without candidates", "を", &com);
+	sclear(&com);
+	if(!typekeys(t, "kanji", &com))
+		goto cleanup;
+	CT_CHECK(t, keystroke(' ', 0, &com));
+	CT_CHECK(t, keystroke(Kesc, 0, &com));
+	CT_EQ_INT(t, -1, im.sel);
+	impre(&im, &shown);
+	checkstr(t, "Escape goes back to the reading", "かんじ", &shown);
+	CT_CHECK(t, keystroke(Kesc, 0, &com));
+	CT_EQ_INT(t, 0, im.pre.n);
+	CT_EQ_INT(t, 0, im.raw.n);
+	CT_EQ_INT(t, 0, im.nkouho);
+	sclear(&com);
+	if(!typekeys(t, "kanji", &com))
+		goto cleanup;
+	CT_CHECK(t, keystroke(Kdown, 0, &com));
+	CT_CHECK(t, keystroke('s', Mctrl, &com));
+	checkstr(t, "language switch takes the candidate", "漢字", &com);
+	CT_EQ_INT(t, LangKO, im.l->lang);
+	im.l = jp;
 	/* Backspace looks a complete shorter reading up again. */
 	setdict(jp->dict, "かん", "缶");
 	if(!typekeys(t, "kanji", &com))