add well formed unicode strings proposal

packages/core-js-compat/src/data.mjs

@@ -2352,10 +2352,14 @@ export const data = {
   },
   'esnext.string.code-points': {
   },
+  'esnext.string.is-well-formed': {
+  },
   // TODO: Remove from `core-js@4`
   'esnext.string.match-all': null,
   // TODO: Remove from `core-js@4`
   'esnext.string.replace-all': null,
+  'esnext.string.to-well-formed': {
+  },
   'esnext.symbol.async-dispose': {
   },
   'esnext.symbol.dispose': {

packages/core-js-compat/src/modules-by-versions.mjs

@@ -157,4 +157,8 @@ export default {
   3.25: [
     'es.object.proto',
   ],
+  3.26: [
+    'esnext.string.is-well-formed',
+    'esnext.string.to-well-formed',
+  ],
 };

packages/core-js/full/instance/is-well-formed.js

@@ -0,0 +1,10 @@
+var isPrototypeOf = require('../../internals/object-is-prototype-of');
+var method = require('../string/virtual/is-well-formed');
+
+var StringPrototype = String.prototype;
+
+module.exports = function (it) {
+  var own = it.isWellFormed;
+  return typeof it == 'string' || it === StringPrototype
+    || (isPrototypeOf(StringPrototype, it) && own === StringPrototype.isWellFormed) ? method : own;
+};

packages/core-js/full/instance/to-well-formed.js

@@ -0,0 +1,10 @@
+var isPrototypeOf = require('../../internals/object-is-prototype-of');
+var method = require('../string/virtual/to-well-formed');
+
+var StringPrototype = String.prototype;
+
+module.exports = function (it) {
+  var own = it.toWellFormed;
+  return typeof it == 'string' || it === StringPrototype
+    || (isPrototypeOf(StringPrototype, it) && own === StringPrototype.toWellFormed) ? method : own;
+};

packages/core-js/full/string/index.js

@@ -3,8 +3,10 @@ var parent = require('../../actual/string');
 require('../../modules/esnext.string.at');
 require('../../modules/esnext.string.cooked');
 require('../../modules/esnext.string.code-points');
+require('../../modules/esnext.string.is-well-formed');
 // TODO: remove from `core-js@4`
 require('../../modules/esnext.string.match-all');
 require('../../modules/esnext.string.replace-all');
+require('../../modules/esnext.string.to-well-formed');
 
 module.exports = parent;

packages/core-js/full/string/is-well-formed.js

@@ -0,0 +1,3 @@
+require('../../modules/esnext.string.is-well-formed');
+
+module.exports = require('../../internals/entry-unbind')('String', 'isWellFormed');

packages/core-js/full/string/to-well-formed.js

@@ -0,0 +1,3 @@
+require('../../modules/esnext.string.to-well-formed');
+
+module.exports = require('../../internals/entry-unbind')('String', 'toWellFormed');

packages/core-js/full/string/virtual/index.js

@@ -2,8 +2,10 @@ var parent = require('../../../actual/string/virtual');
 // TODO: remove from `core-js@4`
 require('../../../modules/esnext.string.at');
 require('../../../modules/esnext.string.code-points');
+require('../../../modules/esnext.string.is-well-formed');
 // TODO: remove from `core-js@4`
 require('../../../modules/esnext.string.match-all');
 require('../../../modules/esnext.string.replace-all');
+require('../../../modules/esnext.string.to-well-formed');
 
 module.exports = parent;

packages/core-js/full/string/virtual/is-well-formed.js

@@ -0,0 +1,3 @@
+require('../../../modules/esnext.string.is-well-formed');
+
+module.exports = require('../../../internals/entry-virtual')('String').isWellFormed;

packages/core-js/full/string/virtual/to-well-formed.js

@@ -0,0 +1,3 @@
+require('../../../modules/esnext.string.to-well-formed');
+
+module.exports = require('../../../internals/entry-virtual')('String').toWellFormed;

packages/core-js/modules/esnext.string.is-well-formed.js

@@ -0,0 +1,23 @@
+'use strict';
+var $ = require('../internals/export');
+var uncurryThis = require('../internals/function-uncurry-this');
+var requireObjectCoercible = require('../internals/require-object-coercible');
+var toString = require('../internals/to-string');
+
+var charCodeAt = uncurryThis(''.charCodeAt);
+
+// `String.prototype.isWellFormed` method
+// https://github.com/tc39/proposal-is-usv-string
+$({ target: 'String', proto: true, forced: true }, {
+  isWellFormed: function isWellFormed() {
+    var S = toString(requireObjectCoercible(this));
+    var length = S.length;
+    for (var i = 0; i < length; i++) {
+      var charCode = charCodeAt(S, i);
+      // single UTF-16 code unit
+      if ((charCode & 0xF800) != 0xD800) continue;
+      // unpaired surrogate
+      if (charCode >= 0xDC00 || ++i >= length || (charCodeAt(S, i) & 0xFC00) != 0xDC00) return false;
+    } return true;
+  }
+});

packages/core-js/modules/esnext.string.to-well-formed.js

@@ -0,0 +1,33 @@
+'use strict';
+var $ = require('../internals/export');
+var uncurryThis = require('../internals/function-uncurry-this');
+var requireObjectCoercible = require('../internals/require-object-coercible');
+var toString = require('../internals/to-string');
+
+var $Array = Array;
+var charAt = uncurryThis(''.charAt);
+var charCodeAt = uncurryThis(''.charCodeAt);
+var join = uncurryThis([].join);
+var REPLACEMENT_CHARACTER = '\uFFFD';
+
+// `String.prototype.toWellFormed` method
+// https://github.com/tc39/proposal-is-usv-string
+$({ target: 'String', proto: true, forced: true }, {
+  toWellFormed: function toWellFormed() {
+    var S = toString(requireObjectCoercible(this));
+    var length = S.length;
+    var result = $Array(length);
+    for (var i = 0; i < length; i++) {
+      var charCode = charCodeAt(S, i);
+      // single UTF-16 code unit
+      if ((charCode & 0xF800) != 0xD800) result[i] = charAt(S, i);
+      // unpaired surrogate
+      else if (charCode >= 0xDC00 || i + 1 >= length || (charCodeAt(S, i + 1) & 0xFC00) != 0xDC00) result[i] = REPLACEMENT_CHARACTER;
+      // surrogate pair
+      else {
+        result[i] = charAt(S, i);
+        result[++i] = charAt(S, i);
+      }
+    } return join(result, '');
+  }
+});

packages/core-js/proposals/well-formed-unicode-strings.js

@@ -0,0 +1,2 @@
+require('../modules/esnext.string.is-well-formed');
+require('../modules/esnext.string.to-well-formed');

packages/core-js/stage/2.js

@@ -4,6 +4,7 @@ require('../proposals/iterator-helpers');
 require('../proposals/map-upsert-stage-2');
 require('../proposals/set-methods');
 require('../proposals/using-statement');
+require('../proposals/well-formed-unicode-strings');
 // TODO: Obsolete versions, remove from `core-js@4`
 require('../proposals/array-grouping');
 require('../proposals/decorators');

tests/commonjs.mjs

@@ -786,6 +786,10 @@ for (PATH of ['core-js-pure', 'core-js']) {
     ok(load(NS, 'string/cooked')`a${ 1 }b` === 'a1b');
     ok('next' in load(NS, 'string/code-points')('a'));
     ok('next' in load(NS, 'string/virtual/code-points').call('a'));
+    ok(load(NS, 'string/is-well-formed')('a'));
+    ok(load(NS, 'string/virtual/is-well-formed').call('a'));
+    ok(load(NS, 'string/to-well-formed')('a') === 'a');
+    ok(load(NS, 'string/virtual/to-well-formed').call('a') === 'a');
     ok(load(NS, 'symbol/async-dispose'));
     ok(load(NS, 'symbol/dispose'));
     ok(load(NS, 'symbol/matcher'));
@@ -822,6 +826,18 @@ for (PATH of ['core-js-pure', 'core-js']) {
     ok(typeof instanceFilterReject([]) == 'function');
     ok(instanceFilterReject([]).call([1, 2, 3], it => it % 2).length === 1);
 
+    const instanceIsWellFormed = load(NS, 'instance/is-well-formed');
+    ok(typeof instanceIsWellFormed == 'function');
+    ok(instanceIsWellFormed({}) === undefined);
+    ok(typeof instanceIsWellFormed('') == 'function');
+    ok(instanceIsWellFormed('').call('a'));
+
+    const instanceToWellFormed = load(NS, 'instance/to-well-formed');
+    ok(typeof instanceToWellFormed == 'function');
+    ok(instanceToWellFormed({}) === undefined);
+    ok(typeof instanceToWellFormed('') == 'function');
+    ok(instanceToWellFormed('').call('a') === 'a');
+
     const instanceUniqueBy = load(NS, 'instance/unique-by');
     ok(typeof instanceUniqueBy == 'function');
     ok(instanceUniqueBy({}) === undefined);
@@ -897,6 +913,7 @@ for (PATH of ['core-js-pure', 'core-js']) {
   load('proposals/url');
   load('proposals/using-statement');
   load('proposals/well-formed-stringify');
+  load('proposals/well-formed-unicode-strings');
   load('proposals');
 
   ok(load('stage/4'));

tests/compat/tests.js

@@ -1698,6 +1698,12 @@ GLOBAL.tests = {
   'esnext.string.cooked': function () {
     return String.cooked;
   },
+  'esnext.string.is-well-formed': function () {
+    return String.prototype.isWellFormed;
+  },
+  'esnext.string.to-well-formed': function () {
+    return String.prototype.toWellFormed;
+  },
   'esnext.symbol.async-dispose': function () {
     return Symbol.dispose;
   },