introduce TranslatedString type to require an string but exclude non-translated strings

1 files changed, 12 insertions, 9 deletions

diff --git a/packages/taler-util/src/i18n.ts b/packages/taler-util/src/i18n.ts
index 001735325..f43f543ea 100644
--- a/packages/taler-util/src/i18n.ts
+++ b/packages/taler-util/src/i18n.ts
@@ -10,7 +10,7 @@ export let jed: any = undefined;
  * Set up jed library for internationalization,
  * based on browser language settings.
  */
-export function setupI18n(lang: string, strings: { [s: string]: any }): any {
+export function setupI18n(lang: string, strings: { [s: string]: any }): void {
   lang = lang.replace("_", "-");
 
   if (!strings[lang]) {
@@ -28,10 +28,13 @@ export function internalSetStrings(langStrings: any): void {
   jed = new jedLib.Jed(langStrings);
 }
 
+declare const __translated: unique symbol;
+export type TranslatedString = string & { [__translated]: true };
+
 /**
  * Convert template strings to a msgid
  */
-function toI18nString(stringSeq: ReadonlyArray<string>): string {
+function toI18nString(stringSeq: ReadonlyArray<string>): TranslatedString {
   let s = "";
   for (let i = 0; i < stringSeq.length; i++) {
     s += stringSeq[i];
@@ -39,7 +42,7 @@ function toI18nString(stringSeq: ReadonlyArray<string>): string {
       s += `%${i + 1}$s`;
     }
   }
-  return s;
+  return s as TranslatedString;
 }
 
 /**
@@ -48,7 +51,7 @@ function toI18nString(stringSeq: ReadonlyArray<string>): string {
 export function singular(
   stringSeq: TemplateStringsArray,
   ...values: any[]
-): string {
+): TranslatedString {
   const s = toI18nString(stringSeq);
   const tr = jed
     .translate(s)
@@ -63,10 +66,10 @@ export function singular(
 export function translate(
   stringSeq: TemplateStringsArray,
   ...values: any[]
-): any[] {
+): TranslatedString[] {
   const s = toI18nString(stringSeq);
   if (!s) return [];
-  const translation: string = jed.ngettext(s, s, 1);
+  const translation: TranslatedString = jed.ngettext(s, s, 1);
   return replacePlaceholderWithValues(translation, values);
 }
 
@@ -83,7 +86,7 @@ export function Translate({
   const c = [].concat(children);
   const s = stringifyArray(c);
   if (!s) return [];
-  const translation: string = jed.ngettext(s, s, 1);
+  const translation: TranslatedString = jed.ngettext(s, s, 1);
   if (debug) {
     console.log("looking for ", s, "got", translation);
   }
@@ -104,12 +107,12 @@ export function getJsonI18n<K extends string>(
 
 export function getTranslatedArray(array: Array<any>) {
   const s = stringifyArray(array);
-  const translation: string = jed.ngettext(s, s, 1);
+  const translation: TranslatedString = jed.ngettext(s, s, 1);
   return replacePlaceholderWithValues(translation, array);
 }
 
 function replacePlaceholderWithValues(
-  translation: string,
+  translation: TranslatedString,
   childArray: Array<any>,
 ): Array<any> {
   const tr = translation.split(/%(\d+)\$s/);