From e7e066ac6802ff430027ce05a42fd464d075dc88 Mon Sep 17 00:00:00 2001
From: greymoth <246701683+greymoth-jp@users.noreply.github.com>
Date: Tue, 30 Jun 2026 09:05:37 +0900
Subject: [PATCH] =?UTF-8?q?fix:=20convert=20=E3=83=B8/=E3=83=B9=20(U+30F8/?=
 =?UTF-8?q?U+30F9)=20in=20toHiraganaCase=20and=20toKatakanaCase?=
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toHiraganaCase already decomposes ヷ (U+30F7) to わ゛ and ヺ (U+30FA) to を゛,
and toKatakanaCase composes them back, but the other two wa-row voiced
katakana ヸ (U+30F8) and ヹ (U+30F9) were left out and passed through
unconverted. The base letters ヰ/ヱ already map to ゐ/ゑ, so the voiced forms
now follow the same pattern: ヸ <=> ゐ゛, ヹ <=> ゑ゛.
---
 src/index.js  | 14 +++++++++++++-
 tests/test.js | 18 ++++++++++++++++++
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/src/index.js b/src/index.js
index 191725f..02ea0df 100644
--- a/src/index.js
+++ b/src/index.js
@@ -358,6 +358,14 @@ var Encoding = {
       } else if (c === 0x30F7) {
         results[results.length] = 0x308F;
         c = 0x309B;
+      // 「ヰ゛」 => 「ゐ」 + 「゛」
+      } else if (c === 0x30F8) {
+        results[results.length] = 0x3090;
+        c = 0x309B;
+      // 「ヱ゛」 => 「ゑ」 + 「゛」
+      } else if (c === 0x30F9) {
+        results[results.length] = 0x3091;
+        c = 0x309B;
       // 「ヲ゛」 => 「を」 + 「゛」
       } else if (c === 0x30FA) {
         results[results.length] = 0x3092;
@@ -397,9 +405,13 @@ var Encoding = {
       c = data[i++];
       if (c >= 0x3041 && c <= 0x3096) {
         if ((c === 0x308F || // 「わ」 + 「゛」 => 「ワ゛」
+             c === 0x3090 || // 「ゐ」 + 「゛」 => 「ヰ゛」
+             c === 0x3091 || // 「ゑ」 + 「゛」 => 「ヱ゛」
              c === 0x3092) && // 「を」 + 「゛」 => 「ヲ゛」
             i < len && data[i] === 0x309B) {
-          c = c === 0x308F ? 0x30F7 : 0x30FA;
+          c = c === 0x308F ? 0x30F7 :
+              c === 0x3090 ? 0x30F8 :
+              c === 0x3091 ? 0x30F9 : 0x30FA;
           i++;
         } else {
           c += 0x0060;
diff --git a/tests/test.js b/tests/test.js
index 2374cf3..39967a1 100644
--- a/tests/test.js
+++ b/tests/test.js
@@ -1517,6 +1517,24 @@ describe('encoding', function() {
       });
     });
 
+    it('toHiraganaCase/toKatakanaCase wa-row voiced kana', function() {
+      // 'ヷヸヹヺ' (U+30F7 - U+30FA) <=> base hiragana + voiced mark (U+309B)
+      var katakana = 'ヷヸヹヺ';
+      var hiragana = 'わ゛ゐ゛ゑ゛を゛';
+
+      assert.equal(encoding.toHiraganaCase(katakana), hiragana);
+      assert.equal(encoding.toKatakanaCase(hiragana), katakana);
+
+      assert.deepEqual(
+        encoding.toHiraganaCase(encoding.stringToCode(katakana)),
+        encoding.stringToCode(hiragana)
+      );
+      assert.deepEqual(
+        encoding.toKatakanaCase(encoding.stringToCode(hiragana)),
+        encoding.stringToCode(katakana)
+      );
+    });
+
     it('toHankanaCase', function() {
       zenkanas.forEach(function(zenkana, i) {
         var expect = hankanas[i];