Katakana to hiragana conversion options (#1965)

* Refactor convertKatakanaToHiragana

* Add keepProlongedSoundMarks option

* Test keepProlongedSoundMarks option

* Refactor

* Add keepProlongedSoundMarks option to hiragana handlebars helper

* Update documentation

2 files changed, 23 insertions, 13 deletions

diff --git a/ext/js/language/sandbox/japanese-util.js b/ext/js/language/sandbox/japanese-util.js
index 9b58d255..a7542e79 100644
--- a/ext/js/language/sandbox/japanese-util.js
+++ b/ext/js/language/sandbox/japanese-util.js
@@ -297,20 +297,27 @@ const JapaneseUtil = (() => {
             return this._wanakana !== null;
         }
 
-        convertKatakanaToHiragana(text) {
+        convertKatakanaToHiragana(text, keepProlongedSoundMarks=false) {
             let result = '';
             const offset = (HIRAGANA_CONVERSION_RANGE[0] - KATAKANA_CONVERSION_RANGE[0]);
             for (let char of text) {
                 const codePoint = char.codePointAt(0);
-                if (codePoint === KATAKANA_SMALL_KA_CODE_POINT || codePoint === KATAKANA_SMALL_KE_CODE_POINT) {
-                    // No change
-                } else if (codePoint === KANA_PROLONGED_SOUND_MARK_CODE_POINT) {
-                    if (result.length > 0) {
-                        const char2 = getProlongedHiragana(result[result.length - 1]);
-                        if (char2 !== null) { char = char2; }
-                    }
-                } else if (isCodePointInRange(codePoint, KATAKANA_CONVERSION_RANGE)) {
-                    char = String.fromCodePoint(codePoint + offset);
+                switch (codePoint) {
+                    case KATAKANA_SMALL_KA_CODE_POINT:
+                    case KATAKANA_SMALL_KE_CODE_POINT:
+                        // No change
+                        break;
+                    case KANA_PROLONGED_SOUND_MARK_CODE_POINT:
+                        if (!keepProlongedSoundMarks && result.length > 0) {
+                            const char2 = getProlongedHiragana(result[result.length - 1]);
+                            if (char2 !== null) { char = char2; }
+                        }
+                        break;
+                    default:
+                        if (isCodePointInRange(codePoint, KATAKANA_CONVERSION_RANGE)) {
+                            char = String.fromCodePoint(codePoint + offset);
+                        }
+                        break;
                 }
                 result += char;
             }
diff --git a/ext/js/templates/sandbox/anki-template-renderer.js b/ext/js/templates/sandbox/anki-template-renderer.js
index b721fadc..ae89aade 100644
--- a/ext/js/templates/sandbox/anki-template-renderer.js
+++ b/ext/js/templates/sandbox/anki-template-renderer.js
@@ -607,13 +607,16 @@ class AnkiTemplateRenderer {
 
     _hiragana(context, ...args) {
         const ii = args.length - 1;
-        const value = (ii > 0 ? args[0] : args[ii].fn(context));
-        return this._japaneseUtil.convertKatakanaToHiragana(value);
+        const options = args[ii];
+        const {keepProlongedSoundMarks} = options.hash;
+        const value = (ii > 0 ? args[0] : options.fn(context));
+        return this._japaneseUtil.convertKatakanaToHiragana(value, keepProlongedSoundMarks === true);
     }
 
     _katakana(context, ...args) {
         const ii = args.length - 1;
-        const value = (ii > 0 ? args[0] : args[ii].fn(context));
+        const options = args[ii];
+        const value = (ii > 0 ? args[0] : options.fn(context));
         return this._japaneseUtil.convertHiraganaToKatakana(value);
     }
 }