fix: replace custom mappings as needed

package.json

@@ -89,6 +89,10 @@
     "rollup-plugin-terser": "^7.0.2",
     "shelljs": "^0.8.5",
     "static-server": "^3.0.0"
+  },
+   "dependencies": {
+    "dequal": "^2.0.2",
+    "memoize-one": "^6.0.0"
   },
   "lint-staged": {
     "src/**/*.js": [

src/toKana.js

@@ -1,10 +1,34 @@
+import memoizeOne from 'memoize-one';
+import { dequal } from 'dequal';
+
 import { TO_KANA_METHODS } from './constants';
 import mergeWithDefaultOptions from './utils/mergeWithDefaultOptions';
-import { getRomajiToKanaTree, IME_MODE_MAP, USE_OBSOLETE_KANA_MAP } from './utils/romajiToKanaMap';
+import {
+  getRomajiToKanaTree,
+  IME_MODE_MAP,
+  USE_OBSOLETE_KANA_MAP,
+} from './utils/romajiToKanaMap';
 import { applyMapping, mergeCustomMapping } from './utils/kanaMapping';
 import isCharUpperCase from './utils/isCharUpperCase';
 import hiraganaToKatakana from './utils/hiraganaToKatakana';
 
+// memoize and deeply compare args so we only recreate when necessary
+export const createRomajiToKanaMap = memoizeOne(
+  (IMEMode, useObsoleteKana, customKanaMapping) => {
+    let map = getRomajiToKanaTree();
+
+    map = IMEMode ? IME_MODE_MAP(map) : map;
+    map = useObsoleteKana ? USE_OBSOLETE_KANA_MAP(map) : map;
+
+    if (customKanaMapping) {
+      map = mergeCustomMapping(map, customKanaMapping);
+    }
+
+    return map;
+  },
+  dequal
+);
+
 /**
  * Convert [Romaji](https://en.wikipedia.org/wiki/Romaji) to [Kana](https://en.wikipedia.org/wiki/Kana), lowercase text will result in [Hiragana](https://en.wikipedia.org/wiki/Hiragana) and uppercase text will result in [Katakana](https://en.wikipedia.org/wiki/Katakana).
  * @param  {String} [input=''] text
@@ -30,7 +54,11 @@ export function toKana(input = '', options = {}, map) {
   let config;
   if (!map) {
     config = mergeWithDefaultOptions(options);
-    map = createRomajiToKanaMap(config);
+    map = createRomajiToKanaMap(
+      config.IMEMode,
+      config.useObsoleteKana,
+      config.customKanaMapping
+    );
   } else {
     config = options;
   }
@@ -48,7 +76,9 @@ export function toKana(input = '', options = {}, map) {
         config.IMEMode === TO_KANA_METHODS.KATAKANA ||
         [...input.slice(start, end)].every(isCharUpperCase);
 
-      return enforceHiragana || !enforceKatakana ? kana : hiraganaToKatakana(kana);
+      return enforceHiragana || !enforceKatakana
+        ? kana
+        : hiraganaToKatakana(kana);
     })
     .join('');
 }
@@ -57,34 +87,21 @@ export function toKana(input = '', options = {}, map) {
  *
  * @private
  * @param {String} [input=''] input text
- * @param {Object} [options={}] toKana options
+ * @param {DefaultOptions} [options=defaultOptions] toKana options
+ * @param {Object} [map] custom mapping
  * @returns {Array[]} [[start, end, token]]
  * @example
  * splitIntoConvertedKana('buttsuuji')
  * // => [[0, 2, 'ぶ'], [2, 6, 'っつ'], [6, 7, 'う'], [7, 9, 'じ']]
  */
 export function splitIntoConvertedKana(input = '', options = {}, map) {
-  if (!map) {
-    map = createRomajiToKanaMap(options);
-  }
-  return applyMapping(input.toLowerCase(), map, !options.IMEMode);
-}
-
-let customMapping = null;
-export function createRomajiToKanaMap(options = {}) {
-  let map = getRomajiToKanaTree();
+  const { IMEMode, useObsoleteKana, customKanaMapping } = options;
 
-  map = options.IMEMode ? IME_MODE_MAP(map) : map;
-  map = options.useObsoleteKana ? USE_OBSOLETE_KANA_MAP(map) : map;
-
-  if (options.customKanaMapping) {
-    if (customMapping == null) {
-      customMapping = mergeCustomMapping(map, options.customKanaMapping);
-    }
-    map = customMapping;
+  if (!map) {
+    map = createRomajiToKanaMap(IMEMode, useObsoleteKana, customKanaMapping);
   }
 
-  return map;
+  return applyMapping(input.toLowerCase(), map, !IMEMode);
 }
 
 export default toKana;

src/toRomaji.js

@@ -1,13 +1,31 @@
+import memoizeOne from 'memoize-one';
+import { dequal } from 'dequal';
+
 import mergeWithDefaultOptions from './utils/mergeWithDefaultOptions';
 import katakanaToHiragana from './utils/katakanaToHiragana';
 import isKatakana from './isKatakana';
 import { getKanaToRomajiTree } from './utils/kanaToRomajiMap';
 import { applyMapping, mergeCustomMapping } from './utils/kanaMapping';
 
+// memoize and deeply compare args so we only recreate when necessary
+export const createKanaToRomajiMap = memoizeOne(
+  (romanization, customRomajiMapping) => {
+    let map = getKanaToRomajiTree(romanization);
+
+    if (customRomajiMapping) {
+      map = mergeCustomMapping(map, customRomajiMapping);
+    }
+
+    return map;
+  },
+  dequal
+);
+
 /**
  * Convert kana to romaji
  * @param  {String} kana text input
  * @param  {DefaultOptions} [options=defaultOptions]
+ * @param  {Object} map custom mapping
  * @return {String} converted text
  * @example
  * toRomaji('ひらがな　カタカナ')
@@ -19,30 +37,40 @@ import { applyMapping, mergeCustomMapping } from './utils/kanaMapping';
  * toRomaji('つじぎり', { customRomajiMapping: { じ: 'zi', つ: 'tu', り: 'li' } });
  * // => 'tuzigili'
  */
-export function toRomaji(input = '', options = {}) {
-  const mergedOptions = mergeWithDefaultOptions(options);
-  // just throw away the substring index information and just concatenate all the kana
-  return splitIntoRomaji(input, mergedOptions)
+export function toRomaji(input = '', options = {}, map) {
+  const config = mergeWithDefaultOptions(options);
+
+  if (!map) {
+    map = createKanaToRomajiMap(
+      config.romanization,
+      config.customRomajiMapping
+    );
+  }
+
+  // just throw away the substring index information and simply concatenate all the kana
+  return splitIntoRomaji(input, config, map)
     .map((romajiToken) => {
       const [start, end, romaji] = romajiToken;
-      const makeUpperCase = options.upcaseKatakana && isKatakana(input.slice(start, end));
+      const makeUpperCase =
+        config.upcaseKatakana && isKatakana(input.slice(start, end));
       return makeUpperCase ? romaji.toUpperCase() : romaji;
     })
     .join('');
 }
 
-let customMapping = null;
-function splitIntoRomaji(input, options) {
-  let map = getKanaToRomajiTree(options);
-
-  if (options.customRomajiMapping) {
-    if (customMapping == null) {
-      customMapping = mergeCustomMapping(map, options.customRomajiMapping);
-    }
-    map = customMapping;
+function splitIntoRomaji(input, options, map) {
+  if (!map) {
+    map = createKanaToRomajiMap(
+      options.romanization,
+      options.customRomajiMapping
+    );
   }
 
-  return applyMapping(katakanaToHiragana(input, toRomaji, true), map, !options.IMEMode);
+  return applyMapping(
+    katakanaToHiragana(input, toRomaji, true),
+    map,
+    !options.IMEMode
+  );
 }
 
 export default toRomaji;

src/utils/kanaToRomajiMap.js

@@ -59,7 +59,19 @@ const SMALL_AIUEO = {
   ぇ: 'e',
   ぉ: 'o',
 };
-const YOON_KANA = ['き', 'に', 'ひ', 'み', 'り', 'ぎ', 'び', 'ぴ', 'ゔ', 'く', 'ふ'];
+const YOON_KANA = [
+  'き',
+  'に',
+  'ひ',
+  'み',
+  'り',
+  'ぎ',
+  'び',
+  'ぴ',
+  'ゔ',
+  'く',
+  'ふ',
+];
 const YOON_EXCEPTIONS = {
   し: 'sh',
   ち: 'ch',
@@ -108,10 +120,10 @@ function getKanaToHepburnTree() {
   return kanaToHepburnMap;
 }
 
-export function getKanaToRomajiTree(fullOptions) {
-  switch (fullOptions.romanization) {
+export function getKanaToRomajiTree(romanization) {
+  switch (romanization) {
     case ROMANIZATIONS.HEPBURN:
-      return getKanaToHepburnTree(fullOptions);
+      return getKanaToHepburnTree();
     default:
       return {};
   }
@@ -129,9 +141,11 @@ function createKanaToHepburnMap() {
     subtreeOf(jsymbol)[''] = symbol;
   });
 
-  [...Object.entries(SMALL_Y), ...Object.entries(SMALL_AIUEO)].forEach(([roma, kana]) => {
-    setTrans(roma, kana);
-  });
+  [...Object.entries(SMALL_Y), ...Object.entries(SMALL_AIUEO)].forEach(
+    ([roma, kana]) => {
+      setTrans(roma, kana);
+    }
+  );
 
   // きゃ -> kya
   YOON_KANA.forEach((kana) => {

test/utils/kanaMapping.test.js → test/utils/customMapping.test.js

@@ -33,6 +33,33 @@ describe('Test custom mappings options', () => {
     ).toBe('tuzigili');
   });
 
+  it('will replace previous custom mappings', () => {
+    expect(
+      toRomaji('つじぎり', {
+        customRomajiMapping: createCustomMapping({ じ: 'zi', つ: 'tu', り: 'li' }),
+      })
+    ).toBe('tuzigili');
+
+    expect(
+      toRomaji('つじぎり', {
+        customRomajiMapping: createCustomMapping({ じ: 'bi', つ: 'bu', り: 'bi' }),
+      })
+    ).toBe('bubigibi');
+
+    expect(
+      toKana('wanakana', {
+        customKanaMapping: createCustomMapping({ na: 'に', ka: 'Bana' }),
+      })
+    ).toBe('わにBanaに');
+
+    expect(
+      toKana('wanakana', {
+        customKanaMapping: createCustomMapping({ na: 'り', ka: 'Cabana' }),
+      })
+    ).toBe('わりCabanaり');
+  });
+
+
   it('will accept a plain object and merge it internally via createCustomMapping()', () => {
     expect(
       toKana('wanakana', {

yarn.lock

@@ -2679,6 +2679,11 @@ delayed-stream@~1.0.0:
   resolved "https://registry.yarnpkg.com/delayed-stream/-/delayed-stream-1.0.0.tgz#df3ae199acadfb7d440aaae0b29e2272b24ec619"
   integrity sha1-3zrhmayt+31ECqrgsp4icrJOxhk=
 
+dequal@^2.0.2:
+  version "2.0.2"
+  resolved "https://registry.yarnpkg.com/dequal/-/dequal-2.0.2.tgz#85ca22025e3a87e65ef75a7a437b35284a7e319d"
+  integrity sha512-q9K8BlJVxK7hQYqa6XISGmBZbtQQWVXSrRrWreHC94rMt1QL/Impruc+7p2CYSYuVIUr+YCt6hjrs1kkdJRTug==
+
 detect-file@^1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/detect-file/-/detect-file-1.0.0.tgz#f0d66d03672a825cb1b73bdb3fe62310c8e552b7"
@@ -5083,6 +5088,11 @@ mdurl@^1.0.1:
   resolved "https://registry.yarnpkg.com/mdurl/-/mdurl-1.0.1.tgz#fe85b2ec75a59037f2adfec100fd6c601761152e"
   integrity sha1-/oWy7HWlkDfyrf7BAP1sYBdhFS4=
 
+memoize-one@^6.0.0:
+  version "6.0.0"
+  resolved "https://registry.yarnpkg.com/memoize-one/-/memoize-one-6.0.0.tgz#b2591b871ed82948aee4727dc6abceeeac8c1045"
+  integrity sha512-rkpe71W0N0c0Xz6QD0eJETuWAJGnJ9afsl1srmwPrI+yBCkge5EycXXbYRyvL29zZVUWQCY7InPRCv3GDXuZNw==
+
 memorystream@^0.3.1:
   version "0.3.1"
   resolved "https://registry.yarnpkg.com/memorystream/-/memorystream-0.3.1.tgz#86d7090b30ce455d63fbae12dda51a47ddcaf9b2"