feat: resolve locale message translation new API rt

docs/api/injection.md

@@ -511,6 +511,108 @@ Overloaded `$t`. About details, see the [$t](injection#t-key) remarks.
 
 Translation message
 
+### $rt(message)
+
+Resolve locale message translation
+
+**Signature:**
+```typescript
+$rt(message: MessageFunction<VueMessageType> | VueMessageType): string;
+```
+
+**Details**
+
+If this is used in a reactive context, it will re-evaluate once the locale changes.
+
+In [Composition API mode](general#mode), the `$rt` is injected by `app.config.globalProperties`. The input / output is the same as for Composer, and it works on **global scope**. About that details, see [Composer#rt](composition#rt-message).
+
+In [Legacy API mode](general#mode), the input / output is the same as for VueI18n instance. About details, see [VueI18n#rt](legacy#rt-message).
+
+**See Also**
+- [Scope and Locale Changing](../../guide/essentials/scope)
+- [Composition API](../../guide/advanced/composition)
+
+#### Parameters
+| Parameter | Type | Description |
+| --- | --- | --- |
+| message | MessageFunction&lt;VueMessageType&gt; \| VueMessageType | A target locale message to be resolved. You will need to specify the locale message returned by `$tm`. |
+
+#### Returns
+
+Translation message
+
+### $rt(message, plural, options)
+
+Resolve locale message translation for plurals
+
+**Signature:**
+```typescript
+$rt(message: MessageFunction<VueMessageType> | VueMessageType, plural: number, options?: TranslationOptions): string;
+```
+
+**Details**
+
+Overloaded `$rt`. About details, see the [$rt](injection#rt-message) remarks.
+
+#### Parameters
+| Parameter | Type | Description |
+| --- | --- | --- |
+| message | MessageFunction&lt;VueMessageType&gt; \| VueMessageType | A target locale message to be resolved. You will need to specify the locale message returned by `$tm`. |
+| plural | number | Which plural string to get. `1` returns the first one. |
+| options | TranslateOptions | Additional [TranslateOptions](general#translateoptions) |
+
+#### Returns
+
+Translation message
+
+### $rt(message, list, options)
+
+Resolve locale message translation for list interpolations
+
+**Signature:**
+```typescript
+$rt(message: MessageFunction<VueMessageType> | VueMessageType, list: unknown[], options?: TranslationOptions): string;
+```
+
+**Details**
+
+Overloaded `$rt`. About details, see the [$rt](injection#rt-message) remarks.
+
+#### Parameters
+| Parameter | Type | Description |
+| --- | --- | --- |
+| message | MessageFunction&lt;VueMessageType&gt; \| VueMessageType | A target locale message to be resolved. You will need to specify the locale message returned by `$tm`. |
+| list | unknown[] | A values of list interpolation. |
+| options | TranslateOptions | Additional [TranslateOptions](general#translateoptions) |
+
+#### Returns
+
+Translation message
+
+### $rt(message, named, options)
+
+Resolve locale message translation for named interpolations
+
+**Signature:**
+```typescript
+$rt(message: MessageFunction<VueMessageType> | VueMessageType, named: NamedValue, options?: TranslationOptions): string;
+```
+
+**Details**
+
+Overloaded `$rt`. About details, see the [$rt](injection#rt-message) remarks.
+
+#### Parameters
+| Parameter | Type | Description |
+| --- | --- | --- |
+| message | MessageFunction&lt;VueMessageType&gt; \| VueMessageType | A target locale message to be resolved. You will need to specify the locale message returned by `$tm`. |
+| named | NamedValue | A values of named interpolation. |
+| options | TranslateOptions | Additional [TranslateOptions](general#translateoptions) |
+
+#### Returns
+
+Translation message
+
 ### $tc(key)
 
 Locale message pluralization

docs/guide/advanced/composition.md

@@ -318,6 +318,7 @@ This allows Vue I18n to inject the following properties and functions into the c
   - `fallbackLocale`
   - `availableLocales`
 - `$t`: `t` function of Composer that is global scope
+- `$rt`: `rt` function of Composer that is global scope
 - `$d`: `d` function of Composer that is global scope
 - `$n`: `n` function of Composer that is global scope
 - `$tm`: `tm` function of Composer that is global scope

packages/core-base/src/translate.ts

@@ -143,6 +143,11 @@ export interface TranslateOptions {
    * Whether do escape parameter for list or named interpolation values
    */
   escapeParameter?: boolean
+  /**
+   * @remarks
+   * Whether the message has been resolved
+   */
+  resolvedMessage?: boolean
 }
 
 // `translate` function overloads
@@ -161,6 +166,12 @@ export function translate<Messages, Message = string>(
   plural: number,
   options: TranslateOptions
 ): MessageType<Message> | number
+export function translate<Messages, Message = string>(
+  context: CoreTranslationContext<Messages, Message>,
+  message: MessageFunction<Message> | string,
+  plural: number,
+  options: TranslateOptions
+): MessageType<Message> | number
 export function translate<Messages, Message = string>(
   context: CoreTranslationContext<Messages, Message>,
   key: Path | number,
@@ -195,6 +206,12 @@ export function translate<Messages, Message = string>(
   list: unknown[],
   options: TranslateOptions
 ): MessageType<Message> | number
+export function translate<Messages, Message = string>(
+  context: CoreTranslationContext<Messages, Message>,
+  message: MessageFunction<Message> | string,
+  list: unknown[],
+  options: TranslateOptions
+): MessageType<Message> | number
 export function translate<Messages, Message = string>(
   context: CoreTranslationContext<Messages, Message>,
   key: Path | number,
@@ -218,6 +235,12 @@ export function translate<Messages, Message = string>(
   named: NamedValue,
   options: TranslateOptions
 ): MessageType<Message> | number
+export function translate<Messages, Message = string>(
+  context: CoreTranslationContext<Messages, Message>,
+  message: MessageFunction<Message> | string,
+  named: NamedValue,
+  options: TranslateOptions
+): MessageType<Message> | number
 export function translate<Messages, Message = string>(
   context: CoreTranslationContext<Messages, Message>,
   ...args: unknown[]
@@ -232,9 +255,10 @@ export function translate<Messages, Message = string>(
     fallbackFormat,
     postTranslation,
     unresolving,
-    fallbackLocale
+    fallbackLocale,
+    messages
   } = context
-  const [key, options] = parseTranslateArgs(...args)
+  const [key, options] = parseTranslateArgs<Message>(...args)
 
   const missingWarn = isBoolean(options.missingWarn)
     ? options.missingWarn
@@ -248,8 +272,10 @@ export function translate<Messages, Message = string>(
     ? options.escapeParameter
     : context.escapeParameter
 
+  const resolvedMessage = !!options.resolvedMessage
+
   // prettier-ignore
-  const defaultMsgOrKey: string =
+  const defaultMsgOrKey =
     isString(options.default) || isBoolean(options.default) // default by function option
       ? !isBoolean(options.default)
         ? options.default
@@ -265,28 +291,42 @@ export function translate<Messages, Message = string>(
 
   // resolve message format
   // eslint-disable-next-line prefer-const
-  let [format, targetLocale, message] = resolveMessageFormat(
-    context,
-    key,
-    locale,
-    fallbackLocale,
-    fallbackWarn,
-    missingWarn
-  )
+  let [format, targetLocale, message]: [
+    PathValue | MessageFunction<Message>,
+    Locale | undefined,
+    LocaleMessageValue<Message>
+  ] = !resolvedMessage
+    ? resolveMessageFormat(
+        context,
+        key as string,
+        locale,
+        fallbackLocale,
+        fallbackWarn,
+        missingWarn
+      )
+    : [
+        key,
+        locale,
+        ((messages as unknown) as LocaleMessages<Message>)[locale] || {}
+      ]
 
   // if you use default message, set it as message format!
   let cacheBaseKey = key
-  if (!(isString(format) || isMessageFunction<Message>(format))) {
+  if (
+    !resolvedMessage &&
+    !(isString(format) || isMessageFunction<Message>(format))
+  ) {
     if (enableDefaultMsg) {
       format = defaultMsgOrKey
-      cacheBaseKey = format
+      cacheBaseKey = format as Path | MessageFunction<Message>
     }
   }
 
   // checking message format and target locale
   if (
-    !(isString(format) || isMessageFunction<Message>(format)) ||
-    !isString(targetLocale)
+    !resolvedMessage &&
+    (!(isString(format) || isMessageFunction<Message>(format)) ||
+      !isString(targetLocale))
   ) {
     return unresolving ? NOT_REOSLVED : (key as MessageType<Message>)
   }
@@ -308,14 +348,16 @@ export function translate<Messages, Message = string>(
   }
 
   // compile message format
-  const msg = compileMessageFormat(
-    context,
-    key,
-    targetLocale,
-    format,
-    cacheBaseKey,
-    errorDetector
-  )
+  const msg = !isMessageFunction(format)
+    ? compileMessageFormat(
+        context,
+        key as string,
+        targetLocale!,
+        format,
+        cacheBaseKey as string,
+        errorDetector
+      )
+    : format
 
   // if occurred compile error, return the message format
   if (occurred) {
@@ -325,7 +367,7 @@ export function translate<Messages, Message = string>(
   // evaluate message with context
   const ctxOptions = getMessageContextOptions<Messages, Message>(
     context,
-    targetLocale,
+    targetLocale!,
     message,
     options
   )
@@ -562,16 +604,22 @@ function evaluateMessage<Messages, Message>(
 }
 
 /** @internal */
-export function parseTranslateArgs(
+export function parseTranslateArgs<Message = string>(
   ...args: unknown[]
-): [Path, TranslateOptions] {
+): [Path | MessageFunction<Message>, TranslateOptions] {
   const [arg1, arg2, arg3] = args
   const options = {} as TranslateOptions
 
-  if (!isString(arg1) && !isNumber(arg1)) {
+  if (!isString(arg1) && !isNumber(arg1) && !isMessageFunction(arg1)) {
     throw createCoreError(CoreErrorCodes.INVALID_ARGUMENT)
   }
-  const key = isNumber(arg1) ? String(arg1) : arg1
+
+  // prettier-ignore
+  const key = isNumber(arg1)
+    ? String(arg1)
+    : isMessageFunction(arg1)
+      ? (arg1 as MessageFunction<Message>)
+      : arg1
 
   if (isNumber(arg2)) {
     options.plural = arg2

packages/core-base/test/translate.test.ts

@@ -13,6 +13,8 @@ import { CoreErrorCodes, errorMessages } from '../src/errors'
 import { registerMessageCompiler } from '../src/context'
 import { compileToFunction } from '../src/compile'
 
+import type { MessageContext } from '@intlify/runtime'
+
 beforeEach(() => {
   registerMessageCompiler(compileToFunction)
 })
@@ -665,6 +667,40 @@ describe('error', () => {
   })
 })
 
+test('resolvedMessage', () => {
+  const ctx = context({
+    locale: 'en',
+    messages: {
+      en: {}
+    }
+  })
+  expect(translate(ctx, 'car', 1, { resolvedMessage: true })).toEqual('car')
+  expect(
+    translate(ctx, () => 'hello!', 1, {
+      resolvedMessage: true
+    })
+  ).toEqual('hello!')
+  expect(translate(ctx, 'list {0}', [1], { resolvedMessage: true })).toEqual(
+    'list 1'
+  )
+  expect(
+    translate(ctx, (ctx: MessageContext) => `list ${ctx.list(0)}`, [1], {
+      resolvedMessage: true
+    })
+  ).toEqual('list 1')
+  expect(
+    translate(ctx, 'named {name}', { name: 'dio' }, { resolvedMessage: true })
+  ).toEqual('named dio')
+  expect(
+    translate(
+      ctx,
+      (ctx: MessageContext) => `named ${ctx.named('name')}`,
+      { name: 'dio' },
+      { resolvedMessage: true }
+    )
+  ).toEqual('named dio')
+})
+
 const enum ErrorCodes {
   CODE1 = 1
 }