Added prefer-named-backreference rule (#140)

Author: RunDevelopment

README.md

@@ -118,6 +118,7 @@ The rules with the following star :star: are included in the `plugin:regexp/reco
 | [regexp/prefer-character-class](https://ota-meshi.github.io/eslint-plugin-regexp/rules/prefer-character-class.html) | enforce using character class | :wrench: |
 | [regexp/prefer-d](https://ota-meshi.github.io/eslint-plugin-regexp/rules/prefer-d.html) | enforce using `\d` | :star::wrench: |
 | [regexp/prefer-escape-replacement-dollar-char](https://ota-meshi.github.io/eslint-plugin-regexp/rules/prefer-escape-replacement-dollar-char.html) | enforces escape of replacement `$` character (`$$`). |  |
+| [regexp/prefer-named-backreference](https://ota-meshi.github.io/eslint-plugin-regexp/rules/prefer-named-backreference.html) | enforce using named backreferences | :wrench: |
 | [regexp/prefer-plus-quantifier](https://ota-meshi.github.io/eslint-plugin-regexp/rules/prefer-plus-quantifier.html) | enforce using `+` quantifier | :star::wrench: |
 | [regexp/prefer-quantifier](https://ota-meshi.github.io/eslint-plugin-regexp/rules/prefer-quantifier.html) | enforce using quantifier | :wrench: |
 | [regexp/prefer-question-quantifier](https://ota-meshi.github.io/eslint-plugin-regexp/rules/prefer-question-quantifier.html) | enforce using `?` quantifier | :star::wrench: |

docs/rules/README.md

@@ -46,6 +46,7 @@ The rules with the following star :star: are included in the `plugin:regexp/reco
 | [regexp/prefer-character-class](./prefer-character-class.md) | enforce using character class | :wrench: |
 | [regexp/prefer-d](./prefer-d.md) | enforce using `\d` | :star::wrench: |
 | [regexp/prefer-escape-replacement-dollar-char](./prefer-escape-replacement-dollar-char.md) | enforces escape of replacement `$` character (`$$`). |  |
+| [regexp/prefer-named-backreference](./prefer-named-backreference.md) | enforce using named backreferences | :wrench: |
 | [regexp/prefer-plus-quantifier](./prefer-plus-quantifier.md) | enforce using `+` quantifier | :star::wrench: |
 | [regexp/prefer-quantifier](./prefer-quantifier.md) | enforce using quantifier | :wrench: |
 | [regexp/prefer-question-quantifier](./prefer-question-quantifier.md) | enforce using `?` quantifier | :star::wrench: |

docs/rules/prefer-named-backreference.md

@@ -0,0 +1,40 @@
+---
+pageClass: "rule-details"
+sidebarDepth: 0
+title: "regexp/prefer-named-backreference"
+description: "enforce using named backreferences"
+---
+# regexp/prefer-named-backreference
+
+> enforce using named backreferences
+
+- :exclamation: <badge text="This rule has not been released yet." vertical="middle" type="error"> ***This rule has not been released yet.*** </badge>
+- :wrench: The `--fix` option on the [command line](https://eslint.org/docs/user-guide/command-line-interface#fixing-problems) can automatically fix some of the problems reported by this rule.
+
+## :book: Rule Details
+
+This rule reports and fixes backreferences that do not use the name of their referenced capturing group.
+
+<eslint-code-block fix>
+
+```js
+/* eslint regexp/prefer-named-backreference: "error" */
+
+/* ✓ GOOD */
+var foo = /(a)\1/
+var foo = /(?<foo>a)\k<foo>/
+
+/* ✗ BAD */
+var foo = /(?<foo>a)\1/
+```
+
+</eslint-code-block>
+
+## :wrench: Options
+
+Nothing.
+
+## :mag: Implementation
+
+- [Rule source](https://github.com/ota-meshi/eslint-plugin-regexp/blob/master/lib/rules/prefer-named-backreference.ts)
+- [Test source](https://github.com/ota-meshi/eslint-plugin-regexp/blob/master/tests/lib/rules/prefer-named-backreference.ts)

lib/rules/prefer-named-backreference.ts

@@ -0,0 +1,54 @@
+import type { Expression } from "estree"
+import type { RegExpVisitor } from "regexpp/visitor"
+import {
+    createRule,
+    defineRegexpVisitor,
+    fixReplaceNode,
+    getRegexpLocation,
+} from "../utils"
+
+export default createRule("prefer-named-backreference", {
+    meta: {
+        docs: {
+            description: "enforce using named backreferences",
+            recommended: false,
+        },
+        fixable: "code",
+        schema: [],
+        messages: {
+            unexpected: "Unexpected unnamed backreference.",
+        },
+        type: "suggestion", // "problem",
+    },
+    create(context) {
+        const sourceCode = context.getSourceCode()
+
+        /**
+         * Create visitor
+         * @param node
+         */
+        function createVisitor(node: Expression): RegExpVisitor.Handlers {
+            return {
+                onBackreferenceEnter(bNode) {
+                    if (bNode.resolved.name && !bNode.raw.startsWith("\\k<")) {
+                        context.report({
+                            node,
+                            loc: getRegexpLocation(sourceCode, node, bNode),
+                            messageId: "unexpected",
+                            fix: fixReplaceNode(
+                                sourceCode,
+                                node,
+                                bNode,
+                                () => `\\k<${bNode.resolved.name}>`,
+                            ),
+                        })
+                    }
+                },
+            }
+        }
+
+        return defineRegexpVisitor(context, {
+            createVisitor,
+        })
+    },
+})

lib/utils/rules.ts

@@ -34,6 +34,7 @@ import orderInCharacterClass from "../rules/order-in-character-class"
 import preferCharacterClass from "../rules/prefer-character-class"
 import preferD from "../rules/prefer-d"
 import preferEscapeReplacementDollarChar from "../rules/prefer-escape-replacement-dollar-char"
+import preferNamedBackreference from "../rules/prefer-named-backreference"
 import preferPlusQuantifier from "../rules/prefer-plus-quantifier"
 import preferQuantifier from "../rules/prefer-quantifier"
 import preferQuestionQuantifier from "../rules/prefer-question-quantifier"
@@ -81,6 +82,7 @@ export const rules = [
     preferCharacterClass,
     preferD,
     preferEscapeReplacementDollarChar,
+    preferNamedBackreference,
     preferPlusQuantifier,
     preferQuantifier,
     preferQuestionQuantifier,

tests/lib/rules/prefer-named-backreference.ts

@@ -0,0 +1,20 @@
+import { RuleTester } from "eslint"
+import rule from "../../../lib/rules/prefer-named-backreference"
+
+const tester = new RuleTester({
+    parserOptions: {
+        ecmaVersion: 2020,
+        sourceType: "module",
+    },
+})
+
+tester.run("prefer-named-backreference", rule as any, {
+    valid: [`/(a)\\1/`, `/(?<foo>a)\\k<foo>/`, `/(a)\\1 (?<foo>a)\\k<foo>/`],
+    invalid: [
+        {
+            code: `/(?<foo>a)\\1/`,
+            output: `/(?<foo>a)\\k<foo>/`,
+            errors: [{ messageId: "unexpected" }],
+        },
+    ],
+})