Add @babel/plugin-transform-named-capturing-groups-regex (#7105)

When the `runtime` flag is on (by default), this plugin adds a new helper which wraps the native `RegExp` class to provide groups support. People nees to use a polyfill (I implemented it in core-js) for browsers that don't support ES6 regexps.

packages/babel-helpers/src/helpers.js

@@ -1783,3 +1783,75 @@ helpers.classPrivateMethodSet = helper("7.1.6")`
     throw new TypeError("attempted to reassign private method");
   }
 `;
+
+helpers.wrapRegExp = helper("7.2.6")`
+  import wrapNativeSuper from "wrapNativeSuper";
+  import getPrototypeOf from "getPrototypeOf";
+  import possibleConstructorReturn from "possibleConstructorReturn";
+  import inherits from "inherits";
+
+  export default function _wrapRegExp(re, groups) {
+    _wrapRegExp = function(re, groups) {
+      return new BabelRegExp(re, groups);
+    };
+
+    var _RegExp = wrapNativeSuper(RegExp);
+    var _super = RegExp.prototype;
+    var _groups = new WeakMap();
+
+    function BabelRegExp(re, groups) {
+      var _this = _RegExp.call(this, re);
+      _groups.set(_this, groups);
+      return _this;
+    }
+    inherits(BabelRegExp, _RegExp);
+
+    BabelRegExp.prototype.exec = function(str) {
+      var result = _super.exec.call(this, str);
+      if (result) result.groups = buildGroups(result, this);
+      return result;
+    };
+    BabelRegExp.prototype[Symbol.replace] = function(str, substitution) {
+      if (typeof substitution === "string") {
+        var groups = _groups.get(this);
+        return _super[Symbol.replace].call(
+          this,
+          str,
+          substitution.replace(/\\$<([^>]+)>/g, function(_, name) {
+            return "$" + groups[name];
+          })
+        );
+      } else if (typeof substitution === "function") {
+        var _this = this;
+        return _super[Symbol.replace].call(
+          this,
+          str,
+          function() {
+            var args = [];
+            args.push.apply(args, arguments);
+            if (typeof args[args.length - 1] !== "object") {
+              // Modern engines already pass result.groups as the last arg.
+              args.push(buildGroups(args, _this));
+            }
+            return substitution.apply(this, args);
+          }
+        );
+      } else {
+        return _super[Symbol.replace].call(this, str, substitution);
+      }
+    }
+
+    function buildGroups(result, re) {
+      // NOTE: This function should return undefined if there are no groups,
+      // but in that case Babel doesn't add the wrapper anyway.
+
+      var g = _groups.get(re);
+      return Object.keys(groups).reduce(function(groups, name) {
+        groups[name] = result[g[name]];
+        return groups;
+      }, Object.create(null));
+    }
+
+    return _wrapRegExp.apply(this, arguments);
+  }
+`;

packages/babel-plugin-transform-named-capturing-groups-regex/.npmignore

@@ -0,0 +1,3 @@
+src
+test
+*.log

packages/babel-plugin-transform-named-capturing-groups-regex/README.md

@@ -0,0 +1,19 @@
+# @babel/plugin-transform-named-capturing-groups-regex
+
+> Compile regular expressions using named groups to ES5.
+
+See our website [@babel/plugin-transform-named-capturing-groups-regex](https://babeljs.io/docs/en/next/babel-plugin-transform-named-capturing-groups-regex.html) for more information.
+
+## Install
+
+Using npm:
+
+```sh
+npm install --save-dev @babel/plugin-transform-named-capturing-groups-regex
+```
+
+or using yarn:
+
+```sh
+yarn add @babel/plugin-transform-named-capturing-groups-regex --dev
+```

packages/babel-plugin-transform-named-capturing-groups-regex/package.json

@@ -0,0 +1,26 @@
+{
+  "name": "@babel/plugin-transform-named-capturing-groups-regex",
+  "version": "7.2.5",
+  "description": "Compile regular expressions using named groups to ES5.",
+  "homepage": "https://babeljs.io/",
+  "license": "MIT",
+  "main": "lib/index.js",
+  "keywords": [
+    "babel-plugin",
+    "regex",
+    "regexp",
+    "regular expressions"
+  ],
+  "repository": "https://github.com/babel/babel/tree/master/packages/babel-plugin-transform-named-capturing-groups-regex",
+  "bugs": "https://github.com/babel/babel/issues",
+  "dependencies": {
+    "regexp-tree": "^0.1.0"
+  },
+  "peerDependencies": {
+    "@babel/core": "^7.0.0"
+  },
+  "devDependencies": {
+    "@babel/core": "^7.0.0",
+    "@babel/helper-plugin-test-runner": "^7.0.0"
+  }
+}

packages/babel-plugin-transform-named-capturing-groups-regex/src/index.js

@@ -0,0 +1,54 @@
+import regexpTree from "regexp-tree";
+
+export default function({ types: t }, options) {
+  const { runtime = true } = options;
+  if (typeof runtime !== "boolean") {
+    throw new Error("The 'runtime' option must be boolean");
+  }
+
+  return {
+    name: "transform-named-capturing-groups-regex",
+
+    visitor: {
+      RegExpLiteral(path) {
+        const node = path.node;
+        if (node.pattern.indexOf("(?<") === -1) {
+          // Return early if there are no named groups.
+          // The .indexOf check may have false positives (e.g. /\(?</); in
+          // this case we parse the regex and regexp-tree won't transform it.
+          return;
+        }
+
+        const result = regexpTree.compatTranspile(node.extra.raw, [
+          "namedCapturingGroups",
+        ]);
+        const { namedCapturingGroups } = result.getExtra();
+
+        if (
+          namedCapturingGroups &&
+          Object.keys(namedCapturingGroups).length > 0
+        ) {
+          node.pattern = result.getSource();
+
+          if (runtime && !isRegExpTest(path)) {
+            path.replaceWith(
+              t.callExpression(this.addHelper("wrapRegExp"), [
+                node,
+                t.valueToNode(namedCapturingGroups),
+              ]),
+            );
+          }
+        }
+      },
+    },
+  };
+}
+
+function isRegExpTest(path) {
+  return (
+    path.parentPath.isMemberExpression({
+      object: path.node,
+      computed: false,
+    }) && path.parentPath.get("property").isIdentifier({ name: "test" })
+  );
+}

packages/babel-plugin-transform-named-capturing-groups-regex/test/fixtures/runtime/exec.js

@@ -0,0 +1,15 @@
+var re = /(?<year>\d{4})-(?<month>\d{2})-(?<day>\d{2})/;
+
+var result = re.exec("2017-12-23");
+
+expect(result.groups).toEqual({
+  year: "2017",
+  month: "12",
+  day: "23",
+});
+
+expect(result.groups).toEqual({
+  year: result[1],
+  month: result[2],
+  day: result[3],
+});

packages/babel-plugin-transform-named-capturing-groups-regex/test/fixtures/runtime/instanceof-regexp.js

@@ -0,0 +1,3 @@
+var re = /(?<group>)/;
+
+expect(re instanceof RegExp).toBeTruthy();

packages/babel-plugin-transform-named-capturing-groups-regex/test/fixtures/runtime/match.js

@@ -0,0 +1,15 @@
+var re = /(?<year>\d{4})-(?<month>\d{2})-(?<day>\d{2})/;
+
+var result = "1999-09-29".match(re);
+
+expect(result.groups).toEqual({
+  year: "1999",
+  month: "09",
+  day: "29",
+});
+
+expect(result.groups).toEqual({
+  year: result[1],
+  month: result[2],
+  day: result[3],
+});

packages/babel-plugin-transform-named-capturing-groups-regex/test/fixtures/runtime/no-groups.js

@@ -0,0 +1,4 @@
+var re = /no-groups-\(?<looks-like-a-group>looks\)/;
+var result = re.exec("no-groups-(<looks-like-a-group>looks)")
+
+expect(result.groups).toBeUndefined();

packages/babel-plugin-transform-named-capturing-groups-regex/test/fixtures/runtime/options.json

@@ -0,0 +1,3 @@
+{
+  "plugins": ["transform-named-capturing-groups-regex"]
+}

packages/babel-plugin-transform-named-capturing-groups-regex/test/fixtures/runtime/replace-string.js

@@ -0,0 +1,5 @@
+var re = /(?<year>\d{4})-(?<month>\d{2})-(?<day>\d{2})/;
+
+var result = "2015-10-31".replace(re, "$<day>/$<month>/$<year>")
+
+expect(result).toBe("31/10/2015");

packages/babel-plugin-transform-named-capturing-groups-regex/test/fixtures/syntax/basic/input.js

@@ -0,0 +1 @@
+/(?<name>)\k<name>/;

packages/babel-plugin-transform-named-capturing-groups-regex/test/fixtures/syntax/basic/options.json

@@ -0,0 +1,6 @@
+{
+  "plugins": [
+    "external-helpers",
+    ["transform-named-capturing-groups-regex", { "runtime": false }]
+  ]
+}

packages/babel-plugin-transform-named-capturing-groups-regex/test/fixtures/syntax/basic/output.js

@@ -0,0 +1 @@
+/()\1/;

packages/babel-plugin-transform-named-capturing-groups-regex/test/fixtures/syntax/escape-no-unicode-flag/input.js

@@ -0,0 +1 @@
+/(?<\u{41}>)\k<\u{41}>/;

packages/babel-plugin-transform-named-capturing-groups-regex/test/fixtures/syntax/escape-no-unicode-flag/options.json

@@ -0,0 +1,3 @@
+{
+  "throws": "invalid group Unicode name \"\\u{41}\", use `u` flag."
+}

packages/babel-plugin-transform-named-capturing-groups-regex/test/fixtures/syntax/escape-unicode-flag/input.js

@@ -0,0 +1 @@
+/(?<\u{41}>)\k<\u{41}>/u;

packages/babel-plugin-transform-named-capturing-groups-regex/test/fixtures/syntax/escape-unicode-flag/output.js

@@ -0,0 +1 @@
+/()\1/u;

packages/babel-plugin-transform-named-capturing-groups-regex/test/fixtures/syntax/options.json

@@ -0,0 +1,6 @@
+{
+  "plugins": [
+    ["external-helpers", { "helperVersion": "7.1000.0" }],
+    ["transform-named-capturing-groups-regex", { "runtime": false }]
+  ]
+}

packages/babel-plugin-transform-named-capturing-groups-regex/test/fixtures/wrapper/basic/input.js

@@ -0,0 +1 @@
+"foo".match(/(?<double>.)\k<double>/);

packages/babel-plugin-transform-named-capturing-groups-regex/test/fixtures/wrapper/basic/output.js

@@ -0,0 +1,3 @@
+"foo".match(babelHelpers.wrapRegExp(/(.)\1/, {
+  double: 1
+}));

packages/babel-plugin-transform-named-capturing-groups-regex/test/fixtures/wrapper/looks-like-a-group/input.js

@@ -0,0 +1 @@
+/no-groups-\(?<looks-like-a-group>looks\)/;

packages/babel-plugin-transform-named-capturing-groups-regex/test/fixtures/wrapper/looks-like-a-group/output.js

@@ -0,0 +1 @@
+/no-groups-\(?<looks-like-a-group>looks\)/;

packages/babel-plugin-transform-named-capturing-groups-regex/test/fixtures/wrapper/only-when-named-groups/input.js

@@ -0,0 +1 @@
+"foo".match(/(.)\1/);

packages/babel-plugin-transform-named-capturing-groups-regex/test/fixtures/wrapper/only-when-named-groups/output.js

@@ -0,0 +1 @@
+"foo".match(/(.)\1/);

packages/babel-plugin-transform-named-capturing-groups-regex/test/fixtures/wrapper/options.json

@@ -0,0 +1,6 @@
+{
+  "plugins": [
+    ["external-helpers", { "helperVersion": "7.1000.0" }],
+    "transform-named-capturing-groups-regex"
+  ]
+}

packages/babel-plugin-transform-named-capturing-groups-regex/test/fixtures/wrapper/skips-anonymous-capturing-groups/input.js

@@ -0,0 +1 @@
+"abba".match(/(.)(?<n>.)\k<n>\1/);

packages/babel-plugin-transform-named-capturing-groups-regex/test/fixtures/wrapper/skips-anonymous-capturing-groups/output.js

@@ -0,0 +1,3 @@
+"abba".match(babelHelpers.wrapRegExp(/(.)(.)\2\1/, {
+  n: 2
+}));

packages/babel-plugin-transform-named-capturing-groups-regex/test/fixtures/wrapper/test-method/input.js

@@ -0,0 +1 @@
+/^(?<x>.)\k<x>$/.test("aa");

packages/babel-plugin-transform-named-capturing-groups-regex/test/fixtures/wrapper/test-method/output.js

@@ -0,0 +1 @@
+/^(.)\1$/.test("aa");

packages/babel-plugin-transform-named-capturing-groups-regex/test/index.js

@@ -0,0 +1,3 @@
+import runner from "@babel/helper-plugin-test-runner";
+
+runner(__dirname);