Add regexp/simplify-set-operations rule

.changeset/early-islands-press.md

@@ -0,0 +1,5 @@
+---
+"eslint-plugin-regexp": minor
+---
+
+Add `regexp/require-reduce-negation` rule

README.md

@@ -165,6 +165,7 @@ The `plugin:regexp/all` config enables all rules. It's meant for testing, not fo
 | [prefer-range](https://ota-meshi.github.io/eslint-plugin-regexp/rules/prefer-range.html)                                                   | enforce using character class range                                                        | ✅  |    | 🔧 |    |
 | [prefer-regexp-exec](https://ota-meshi.github.io/eslint-plugin-regexp/rules/prefer-regexp-exec.html)                                       | enforce that `RegExp#exec` is used instead of `String#match` if no global flag is provided |    |    |    |    |
 | [prefer-regexp-test](https://ota-meshi.github.io/eslint-plugin-regexp/rules/prefer-regexp-test.html)                                       | enforce that `RegExp#test` is used instead of `String#match` and `RegExp#exec`             |    |    | 🔧 |    |
+| [require-reduce-negation](https://ota-meshi.github.io/eslint-plugin-regexp/rules/require-reduce-negation.html)                             | require to reduce negation of character classes                                            | ✅  |    | 🔧 |    |
 | [require-unicode-regexp](https://ota-meshi.github.io/eslint-plugin-regexp/rules/require-unicode-regexp.html)                               | enforce the use of the `u` flag                                                            |    |    | 🔧 |    |
 | [sort-alternatives](https://ota-meshi.github.io/eslint-plugin-regexp/rules/sort-alternatives.html)                                         | sort alternatives if order doesn't matter                                                  |    |    | 🔧 |    |
 | [use-ignore-case](https://ota-meshi.github.io/eslint-plugin-regexp/rules/use-ignore-case.html)                                             | use the `i` flag if it simplifies the pattern                                              | ✅  |    | 🔧 |    |

docs/rules/index.md

@@ -72,6 +72,7 @@ sidebarDepth: 0
 | [prefer-range](prefer-range.md)                                                   | enforce using character class range                                                        | ✅  |    | 🔧 |    |
 | [prefer-regexp-exec](prefer-regexp-exec.md)                                       | enforce that `RegExp#exec` is used instead of `String#match` if no global flag is provided |    |    |    |    |
 | [prefer-regexp-test](prefer-regexp-test.md)                                       | enforce that `RegExp#test` is used instead of `String#match` and `RegExp#exec`             |    |    | 🔧 |    |
+| [require-reduce-negation](require-reduce-negation.md)                             | require to reduce negation of character classes                                            | ✅  |    | 🔧 |    |
 | [require-unicode-regexp](require-unicode-regexp.md)                               | enforce the use of the `u` flag                                                            |    |    | 🔧 |    |
 | [sort-alternatives](sort-alternatives.md)                                         | sort alternatives if order doesn't matter                                                  |    |    | 🔧 |    |
 | [use-ignore-case](use-ignore-case.md)                                             | use the `i` flag if it simplifies the pattern                                              | ✅  |    | 🔧 |    |

docs/rules/negation.md

@@ -53,6 +53,12 @@ var foo = /[^\P{ASCII}]/u
 
 Nothing.
 
+## :couple: Related rules
+
+- [regexp/require-reduce-negation]
+
+[regexp/require-reduce-negation]: ./require-reduce-negation.md
+
 ## :rocket: Version
 
 This rule was introduced in eslint-plugin-regexp v0.4.0

docs/rules/require-reduce-negation.md

@@ -0,0 +1,92 @@
+---
+pageClass: "rule-details"
+sidebarDepth: 0
+title: "regexp/require-reduce-negation"
+description: "require to reduce negation of character classes"
+---
+# regexp/require-reduce-negation
+
+💼 This rule is enabled in the ✅ `plugin:regexp/recommended` config.
+
+🔧 This rule is automatically fixable by the [`--fix` CLI option](https://eslint.org/docs/latest/user-guide/command-line-interface#--fix).
+
+<!-- end auto-generated rule header -->
+
+> require to reduce negation of character classes
+
+## :book: Rule Details
+
+This rule is aimed at optimizing patterns by reducing the negation (complement) representation of character classes (with `v` flag).
+
+<eslint-code-block fix>
+
+```js
+/* eslint regexp/require-reduce-negation: "error" */
+
+/* ✗ BAD */
+var re = /[^[^abc]]/v; // -> /[abc]/v
+var re = /[^\D]/u; // -> /[\d]/u
+var re = /[a&&[^b]]/v; // -> /[a--b]/v
+var re = /[[^b]&&a]/v; // -> /[a--b]/v
+var re = /[a--[^b]]/v; // -> /[a&&b]/v
+var re = /[[^a]&&[^b]]/v; // -> /[^ab]/v
+var re = /[[^a][^b]]/v; // -> /[^a&&b]/v
+
+/* ✓ GOOD */
+var re = /[abc]/v;
+var re = /[\d]/u;
+var re = /[\D]/u;
+var re = /[a--b]/v;
+var re = /[a&&b]/v;
+var re = /[^ab]/v;
+var re = /[^a&&b]/v;
+```
+
+</eslint-code-block>
+
+This rule attempts to reduce complements in several ways:
+
+### Double negation elimination
+
+This rule look for patterns that can eliminate double negatives, report on them, and auto-fix them.\
+For example, `/[^[^abc]]/v` is equivalent to `/[abc]/v`.
+
+See <https://en.wikipedia.org/wiki/Double_negation#Elimination_and_introduction>.
+
+### De Morgan's laws
+
+This rule uses De Morgan's laws to look for patterns that can convert multiple negations into a single negation, reports on them, auto-fix them.\
+For example, `/[[^a]&&[^b]]/v` is equivalent to `/[^ab]/v`, `/[[^a][^b]]/v` is equivalent to `/[^a&&b]/v`.
+
+See <https://en.wikipedia.org/wiki/De_Morgan's_laws>.
+
+### Conversion from the intersection to the subtraction
+
+Intersection sets with complement operands can be converted to difference sets.\
+The rule looks for character class intersection with negation operands, reports on them, auto-fix them.\
+For example, `/[a&&[^b]]/v` is equivalent to `/[a--b]/v`, `/[[^a]&&b]/v` is equivalent to `/[b--a]/v`.
+
+### Conversion from the subtraction to the intersection
+
+Difference set with a complement operand on the right side can be converted to intersection sets.\
+The rule looks for character class subtraction with negation operand on the right side, reports on them, auto-fix them.\
+For example, `/[a--[^b]]/v` is equivalent to `/[a&&b]/v`.
+
+## :wrench: Options
+
+Nothing.
+
+## :couple: Related rules
+
+- [regexp/negation]
+
+[regexp/negation]: ./negation.md
+
+## :rocket: Version
+
+:exclamation: <badge text="This rule has not been released yet." vertical="middle" type="error"> ***This rule has not been released yet.*** </badge>
+
+## :mag: Implementation
+
+- [Rule source](https://github.com/ota-meshi/eslint-plugin-regexp/blob/master/lib/rules/require-reduce-negation.ts)
+- [Test source](https://github.com/ota-meshi/eslint-plugin-regexp/blob/master/tests/lib/rules/require-reduce-negation.ts)

lib/configs/recommended.ts

@@ -63,6 +63,7 @@ export const rules = {
     "regexp/prefer-star-quantifier": "error",
     "regexp/prefer-unicode-codepoint-escapes": "error",
     "regexp/prefer-w": "error",
+    "regexp/require-reduce-negation": "error",
     "regexp/sort-flags": "error",
     "regexp/strict": "error",
     "regexp/use-ignore-case": "error",