function formatter, add basic function formatter

packages/core/src/FormatFunction/FormatFunction.ts

@@ -0,0 +1,13 @@
+import { formatter } from './formatter';
+import { FinalFormatterMiddleware, TolgeePlugin } from '../types';
+
+function createFormatFunction(): FinalFormatterMiddleware {
+  return {
+    format: ({ translation, params }) => formatter(translation, params),
+  };
+}
+
+export const FormatFunction = (): TolgeePlugin => (tolgee, tools) => {
+  tools.setFinalFormatter(createFormatFunction());
+  return tolgee;
+};

packages/core/src/FormatFunction/formatter.test.ts

@@ -0,0 +1,101 @@
+import { TranslateParams } from '../types';
+import { formatter } from './formatter';
+
+
+describe('function formatter', () => {
+  // TODO!
+
+  // test('test test', () => {
+  //   expect(getText()).toEqual('test test');
+  // });
+
+  // test('simple test', () => {
+  //   matchIcu();
+  // });
+
+  // test('this is {name}', () => {
+  //   matchIcu({ name: 'Bob' });
+  // });
+
+  // test('this is {  name  }', () => {
+  //   matchIcu({ name: 'Bob' });
+  // });
+
+  // test('{ user } has { num } apples.', () => {
+  //   matchIcu({ user: 'John', num: 2 });
+  // });
+
+  // test('passing params, but no params here', () => {
+  //   matchIcu({ user: 'John', num: 2 });
+  // });
+
+  // test('{ user } has { user } apples.', () => {
+  //   matchIcu({ user: 'John', num: 2 });
+  // });
+
+  // test("ICU: '{ parameter '} format", () => {
+  //   matchIcu();
+  // });
+
+  // test("this '{ escaped }' well", () => {
+  //   matchIcu();
+  // });
+
+  // test("this is '{ weird } but valid", () => {
+  //   matchIcu();
+  // });
+
+  // test("edge case '", () => {
+  //   matchIcu();
+  // });
+
+  // test("What's {subject}?", () => {
+  //   matchIcu({ subject: 'that' });
+  // });
+
+  // test('this is also } right', () => {
+  //   matchIcu();
+  // });
+
+  // test('this is just {} wrong', () => {
+  //   expectToThrowWithIcu(ERROR_PARAM_EMPTY);
+  // });
+
+  // test('this also { } wrong', () => {
+  //   expectToThrowWithIcu(ERROR_PARAM_EMPTY);
+  // });
+
+  // test('this plain { , } wrong', () => {
+  //   expectToThrowWithIcu(ERROR_UNEXPECTED_CHAR);
+  // });
+
+  // test('this is { unexpected', () => {
+  //   expectToThrowWithIcu(ERROR_UNEXPECTED_END);
+  // });
+
+  // test('this is obviously bad { yo yo }', () => {
+  //   expectToThrowWithIcu(ERROR_UNEXPECTED_CHAR);
+  // });
+
+  // test('this is obviously bad { yo, }', () => {
+  //   expectToThrowWithIcu(ERROR_UNEXPECTED_CHAR);
+  // });
+
+  // test('good for icu { yo, number } not for me', () => {
+  //   unsupported(ERROR_UNEXPECTED_CHAR, { yo: 6 });
+  // });
+
+  // describe('supported characters in params', () => {
+  //   characterInParamSupported(Array.from('019_axAX'));
+  // });
+
+  // describe('invalid characters in params', () => {
+  //   characterInParamFailWithIcu('[+-@#$~^&*{%)(§\'"`!?:.;<>[]\\=|☺'.split(''));
+  // });
+
+  // describe('unsupported characters which are supported in ICU', () => {
+  //   characterInParamFail(Array.from('šřýíéúůĚŽÝÁÍÉůú¨ˇ'));
+  //   characterInParamFail(['汉字', '字', 'हि', 'हिन्दी']);
+  //   characterInParamFail(['😊']);
+  // });
+});

packages/core/src/FormatFunction/formatter.ts

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+import { DefaultParamType, TranslateParams } from '../types';
+
+export function formatter(
+  translation: string | ((p?: typeof params) => string),
+  params?: TranslateParams<DefaultParamType>
+) {
+  if (typeof (translation) === "function") {
+    switch (translation.length) {
+      case 0:
+        if (params) {
+          throw new Error(`Parameters were provided for translation ${translation.toString()}, but its function doesn't accept any arguments.`);
+        }
+        break;
+
+      case 1:
+        if (!params) {
+          throw new Error(`Parameters were not provided for translation ${translation.toString()}, but its function needs arguments.`);
+        }
+        break;
+
+      default:
+        throw new Error(`For translation ${translation.toString()}: a translation function should have exactly one parameter, with translation parameters passed as keys.\n For example, ({name}) => \`hello \${name}\``);
+    }
+    return translation(params);
+  }
+  if (params) {
+    throw new Error(`Params given to translation "${translation}" but it does not accept params. Use a function to accept params when using FormatFunction as Tolgee's formatter.`)
+  }
+  return translation;
+}