feat: add deinflection for -得る

Adds a new deinflection reason '-eru/-uru', with three new rules:

- masu-stem + 得る
- しえる → する
- しうる → する

The rules for しえる and しうる are explicitly included since,
when 得る is used with する, it is common that it is written in
kana instead of kanji.

CHANGELOG.md

@@ -10,6 +10,8 @@ app.
 
 - (Chrome) Fixed language code for Chinese localization
   ([#2051](https://github.com/birchill/10ten-ja-reader/issues/2051)).
+- Added deinflection for -得る
+  ([#2060](https://github.com/birchill/10ten-ja-reader/pull/2060)).
 
 ## [1.22.0] - 2024-10-17
 

_locales/en/messages.json

@@ -359,6 +359,9 @@
   "deinflect_continuous": {
     "message": "continuous"
   },
+  "deinflect_eru_uru": {
+    "message": "-eru/-uru"
+  },
   "deinflect_humble": {
     "message": "humble"
   },

_locales/ja/messages.json

@@ -359,6 +359,9 @@
   "deinflect_continuous": {
     "message": "進行形"
   },
+  "deinflect_eru_uru": {
+    "message": "-得る"
+  },
   "deinflect_humble": {
     "message": "謙譲語"
   },

_locales/zh_CN/messages.json

@@ -359,6 +359,9 @@
   "deinflect_continuous": {
     "message": "现在进行形"
   },
+  "deinflect_eru_uru": {
+    "message": "-得る"
+  },
   "deinflect_humble": {
     "message": "谦让语"
   },

src/background/deinflect.test.ts

@@ -549,4 +549,21 @@ describe('deinflect', () => {
       expect(match!.reasonChains[0][0]).toBe(Reason.NegativeTe);
     }
   });
+
+  it('deinflects -得る', () => {
+    const cases = [
+      ['し得る', 'する'],
+      ['しえる', 'する'],
+      ['しうる', 'する'],
+      ['来得る', '来る'],
+      ['あり得る', 'ある'],
+      ['考え得る', '考える'],
+    ];
+    for (const [inflected, plain] of cases) {
+      const result = deinflect(inflected);
+      const match = result.find((candidate) => candidate.word == plain);
+      expect(match).toBeDefined();
+      expect(match!.reasonChains).toEqual([[Reason.EruUru]]);
+    }
+  });
 });

src/background/deinflect.ts

@@ -24,6 +24,7 @@ export const enum Reason {
   Ba,
   Volitional,
   Potential,
+  EruUru,
   CausativePassive,
   Te,
   Zu,
@@ -64,6 +65,7 @@ export const deinflectL10NKeys: { [key: number]: string } = {
   [Reason.Ba]: 'deinflect_ba',
   [Reason.Volitional]: 'deinflect_volitional',
   [Reason.Potential]: 'deinflect_potential',
+  [Reason.EruUru]: 'deinflect_eru_uru',
   [Reason.CausativePassive]: 'deinflect_causative_passive',
   [Reason.Te]: 'deinflect_te',
   [Reason.Zu]: 'deinflect_zu',
@@ -211,6 +213,8 @@ const deinflectRuleData: Array<
   ['さない', 'する', Type.IAdj, Type.SpecialSuruVerb, [Reason.Irregular, Reason.Negative]],
   ['される', '', Type.IchidanVerb, Type.IrrealisStem, [Reason.CausativePassive]],
   ['される', 'する', Type.IchidanVerb, Type.SuruVerb, [Reason.Passive]],
+  ['しうる', 'する', Type.Initial, Type.SuruVerb, [Reason.EruUru]],
+  ['しえる', 'する', Type.IchidanVerb, Type.SuruVerb, [Reason.EruUru]],
   ['しない', 'する', Type.IAdj, Type.SuruVerb, [Reason.Negative]],
   ['しよう', 'する', Type.Initial, Type.SuruVerb, [Reason.Volitional]],
   ['じゃう', '', Type.GodanVerb, Type.DaDeStem, [Reason.Chau]],
@@ -245,6 +249,7 @@ const deinflectRuleData: Array<
   ['致す', '', Type.GodanVerb, Type.NounVS, [Reason.SuruNoun, Reason.Humble]],
   ['えば', 'う', Type.Initial, Type.GodanVerb, [Reason.Ba]],
   ['える', 'う', Type.IchidanVerb, Type.GodanVerb, [Reason.Potential]],
+  ['得る', '', Type.IchidanVerb, Type.MasuStem, [Reason.EruUru]],
   ['おう', 'う', Type.Initial, Type.GodanVerb, [Reason.Volitional]],
   ['仰い', '仰る', Type.MasuStem, Type.GodanVerb, [Reason.MasuStem]],
   ['仰い', '仰る', Type.Initial, Type.GodanVerb, [Reason.Imperative]],