From e84f0fbd0d66eed93b5f0cb07e34aec75e285706 Mon Sep 17 00:00:00 2001
From: TATSUNO Yasuhiro <tatsuno_yasuhiro@kurusugawa.jp>
Date: Sun, 14 Oct 2018 03:15:25 +0900
Subject: [PATCH] :zap: improvement(index): Pre-defined named arguments for
 Pluraization (#440) by @exoego

* Add implicit "choice" exposing

* Add doc

* Rename variables

* Better title
---
 src/index.js                    |  5 ++++
 test/unit/basic.test.js         | 24 ++++++++++++++++++
 test/unit/fixture/index.js      |  1 +
 vuepress/guide/pluralization.md | 44 +++++++++++++++++++++++++++++++++
 4 files changed, 74 insertions(+)

diff --git a/src/index.js b/src/index.js
index dcebb5ddc..7188029ec 100644
--- a/src/index.js
+++ b/src/index.js
@@ -400,6 +400,11 @@ export default class VueI18n {
     if (choice === undefined) {
       choice = 1
     }
+
+    const predefined = { 'count': choice, 'n': choice }
+    const parsedArgs = parseArgs(...values)
+    parsedArgs.params = Object.assign(predefined, parsedArgs.params)
+    values = parsedArgs.locale === null ? [parsedArgs.params] : [parsedArgs.locale, parsedArgs.params]
     return fetchChoice(this._t(key, _locale, messages, host, ...values), choice)
   }
 
diff --git a/test/unit/basic.test.js b/test/unit/basic.test.js
index 3527f6da8..7342d84fa 100644
--- a/test/unit/basic.test.js
+++ b/test/unit/basic.test.js
@@ -191,6 +191,30 @@ describe('basic', () => {
       })
     })
 
+    describe('implicit choice exposing', () => {
+      describe('en locale', () => {
+        it('should expose "count" implicitly to locale message', () => {
+          assert.strictEqual(i18n.tc('plurals.apple', 10), '10 apples')
+        })
+
+        it('should not expose if given explicitly', () => {
+          const explicitArgs = { 'count': 'Many' }
+          assert.strictEqual(i18n.tc('plurals.apple', 10, explicitArgs), 'Many apples')
+        })
+      })
+
+      describe('ja locale', () => {
+        it('should expose "count" and "n" implicitly to locale message', () => {
+          assert.strictEqual(i18n.tc('plurals.implicitPluralCount', 10, 'ja'), 'count:10, n:10')
+        })
+
+        it('should not expose if given explicitly', () => {
+          const explicitArgs = { 'count': 'たくさん', 'n': '大量' }
+          assert.strictEqual(i18n.tc('plurals.implicitPluralCount', 10, 'ja', explicitArgs), 'count:たくさん, n:大量')
+        })
+      })
+    })
+
     describe('en locale', () => {
       it('should translate an english', () => {
         assert.equal(i18n.tc('plurals.car', 1), 'car')
diff --git a/test/unit/fixture/index.js b/test/unit/fixture/index.js
index d8cfc995a..1271cc96b 100644
--- a/test/unit/fixture/index.js
+++ b/test/unit/fixture/index.js
@@ -71,6 +71,7 @@ export default {
     },
     plurals: {
       car: 'ザ・ワールド | これはフォールバック',
+      implicitPluralCount: 'こっちには来ない | count:{count}, n:{n}',
       format: {
         named: 'こんにちは {name}, ごきげんいかが？ | こんにちは {name}, ごきげんいかが？',
         list: 'こんにちは {0}, ごきげんいかが？| こんにちは {0}, ごきげんいかが？'
diff --git a/vuepress/guide/pluralization.md b/vuepress/guide/pluralization.md
index 798df4629..ee015d591 100644
--- a/vuepress/guide/pluralization.md
+++ b/vuepress/guide/pluralization.md
@@ -34,3 +34,47 @@ Output the below:
 <p>one apple</p>
 <p>10 apples</p>
 ```    
+
+## Accessing the number via the pre-defined argument
+
+You don't need to explicitly give the number for pluralization.
+The number can be accessed within locale messages via pre-defined named arguments `{count}` and/or `{n}`.
+You can overwrite those pre-defined named arguments if necessary.
+
+Locale messages the below:
+    
+```js    
+const messages = {
+  en: {
+    apple: 'no apples | one apple | {count} apples',
+    banana: 'no bananas | {n} banana | {n} bananas'
+  }
+}
+```
+
+Template the below:
+
+```html 
+<p>{{ $tc('apple', 10, { count: 10 }) }}</p>
+<p>{{ $tc('apple', 10) }}</p>
+
+<p>{{ $tc('banana', 1, { n: 1 }) }}</p>
+<p>{{ $tc('banana', 1) }}</p>
+<p>{{ $tc('banana', 100, { n: 'too much' }) }}</p>
+```
+
+Output the below:
+
+```html 
+<p>10 apples</p>
+<p>10 apples</p>
+
+<p>1 banana</p>
+<p>1 banana</p>
+<p>too much bananas</p>
+```    
+
+
+
+
+