Add regexp/no-useless-non-greedy rule (#31)

Author: ota-meshi

README.md

@@ -90,6 +90,7 @@ The rules with the following star :star: are included in the `plugin:regexp/reco
 | [regexp/no-useless-backreference](https://ota-meshi.github.io/eslint-plugin-regexp/rules/no-useless-backreference.html) | disallow useless backreferences in regular expressions |  |
 | [regexp/no-useless-character-class](https://ota-meshi.github.io/eslint-plugin-regexp/rules/no-useless-character-class.html) | disallow character class with one character | :wrench: |
 | [regexp/no-useless-exactly-quantifier](https://ota-meshi.github.io/eslint-plugin-regexp/rules/no-useless-exactly-quantifier.html) | disallow unnecessary exactly quantifier | :star: |
+| [regexp/no-useless-non-greedy](https://ota-meshi.github.io/eslint-plugin-regexp/rules/no-useless-non-greedy.html) | disallow unnecessary quantifier non-greedy (`?`) | :wrench: |
 | [regexp/no-useless-two-nums-quantifier](https://ota-meshi.github.io/eslint-plugin-regexp/rules/no-useless-two-nums-quantifier.html) | disallow unnecessary `{n,m}` quantifier | :star: |
 | [regexp/prefer-d](https://ota-meshi.github.io/eslint-plugin-regexp/rules/prefer-d.html) | enforce using `\d` | :star::wrench: |
 | [regexp/prefer-plus-quantifier](https://ota-meshi.github.io/eslint-plugin-regexp/rules/prefer-plus-quantifier.html) | enforce using `+` quantifier | :star::wrench: |

docs/rules/README.md

@@ -22,6 +22,7 @@ The rules with the following star :star: are included in the `plugin:regexp/reco
 | [regexp/no-useless-backreference](./no-useless-backreference.md) | disallow useless backreferences in regular expressions |  |
 | [regexp/no-useless-character-class](./no-useless-character-class.md) | disallow character class with one character | :wrench: |
 | [regexp/no-useless-exactly-quantifier](./no-useless-exactly-quantifier.md) | disallow unnecessary exactly quantifier | :star: |
+| [regexp/no-useless-non-greedy](./no-useless-non-greedy.md) | disallow unnecessary quantifier non-greedy (`?`) | :wrench: |
 | [regexp/no-useless-two-nums-quantifier](./no-useless-two-nums-quantifier.md) | disallow unnecessary `{n,m}` quantifier | :star: |
 | [regexp/prefer-d](./prefer-d.md) | enforce using `\d` | :star::wrench: |
 | [regexp/prefer-plus-quantifier](./prefer-plus-quantifier.md) | enforce using `+` quantifier | :star::wrench: |

docs/rules/no-useless-non-greedy.md

@@ -0,0 +1,44 @@
+---
+pageClass: "rule-details"
+sidebarDepth: 0
+title: "regexp/no-useless-non-greedy"
+description: "disallow unnecessary quantifier non-greedy (`?`)"
+---
+# regexp/no-useless-non-greedy
+
+> disallow unnecessary quantifier non-greedy (`?`)
+
+- :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 unnecessary quantifier non-greedy (`?`).
+
+<eslint-code-block fix>
+
+```js
+/* eslint regexp/no-useless-non-greedy: "error" */
+
+/* ✓ GOOD */
+var foo = /a*?/;
+var foo = /a+?/;
+var foo = /a{4,}?/;
+var foo = /a{2,4}?/;
+
+/* ✗ BAD */
+var foo = /a{1}?/;
+var foo = /a{4}?/;
+var foo = /a{2,2}?/;
+```
+
+</eslint-code-block>
+
+## :wrench: Options
+
+Nothing.
+
+## :mag: Implementation
+
+- [Rule source](https://github.com/ota-meshi/eslint-plugin-regexp/blob/master/lib/rules/no-useless-non-greedy.ts)
+- [Test source](https://github.com/ota-meshi/eslint-plugin-regexp/blob/master/tests/lib/rules/no-useless-non-greedy.ts)

docs/rules/no-useless-two-nums-quantifier.md

@@ -26,7 +26,6 @@ var foo = /a{1,5}/;
 var foo = /a{1,}/;
 var foo = /a{2}/;
 
-
 /* ✗ BAD */
 var foo = /a{0,0}/;
 var foo = /a{1,1}/;

lib/rules/no-useless-non-greedy.ts

@@ -0,0 +1,68 @@
+import type { Expression } from "estree"
+import type { RegExpVisitor } from "regexpp/visitor"
+import {
+    createRule,
+    defineRegexpVisitor,
+    getRegexpLocation,
+    getRegexpRange,
+} from "../utils"
+
+export default createRule("no-useless-non-greedy", {
+    meta: {
+        docs: {
+            description: "disallow unnecessary quantifier non-greedy (`?`)",
+            // TODO In the major version
+            // recommended: true,
+            recommended: false,
+        },
+        fixable: "code",
+        schema: [],
+        messages: {
+            unexpected: "Unexpected quantifier non-greedy.",
+        },
+        type: "suggestion", // "problem",
+    },
+    create(context) {
+        const sourceCode = context.getSourceCode()
+
+        /**
+         * Create visitor
+         * @param node
+         */
+        function createVisitor(node: Expression): RegExpVisitor.Handlers {
+            return {
+                onQuantifierEnter(qNode) {
+                    if (qNode.greedy === false && qNode.min === qNode.max) {
+                        const offset = qNode.raw.length - 1
+                        context.report({
+                            node,
+                            loc: getRegexpLocation(sourceCode, node, qNode, [
+                                offset,
+                                offset + 1,
+                            ]),
+                            messageId: "unexpected",
+                            fix(fixer) {
+                                const range = getRegexpRange(
+                                    sourceCode,
+                                    node,
+                                    qNode,
+                                )
+                                if (range == null) {
+                                    return null
+                                }
+                                return fixer.removeRange([
+                                    range[1] - 1,
+                                    range[1],
+                                ])
+                            },
+                        })
+                    }
+                },
+            }
+        }
+
+        return defineRegexpVisitor(context, {
+            createVisitor,
+        })
+    },
+})

lib/utils/rules.ts

@@ -10,6 +10,7 @@ import noOctal from "../rules/no-octal"
 import noUselessBackreference from "../rules/no-useless-backreference"
 import noUselessCharacterClass from "../rules/no-useless-character-class"
 import noUselessExactlyQuantifier from "../rules/no-useless-exactly-quantifier"
+import noUselessNonGreedy from "../rules/no-useless-non-greedy"
 import noUselessTwoNumsQuantifier from "../rules/no-useless-two-nums-quantifier"
 import preferD from "../rules/prefer-d"
 import preferPlusQuantifier from "../rules/prefer-plus-quantifier"
@@ -31,6 +32,7 @@ export const rules = [
     noUselessBackreference,
     noUselessCharacterClass,
     noUselessExactlyQuantifier,
+    noUselessNonGreedy,
     noUselessTwoNumsQuantifier,
     preferD,
     preferPlusQuantifier,

tests/lib/rules/no-useless-non-greedy.ts

@@ -0,0 +1,46 @@
+import { RuleTester } from "eslint"
+import rule from "../../../lib/rules/no-useless-non-greedy"
+
+const tester = new RuleTester({
+    parserOptions: {
+        ecmaVersion: 2020,
+        sourceType: "module",
+    },
+})
+
+tester.run("no-useless-non-greedy", rule as any, {
+    valid: [`/a*?/`, `/a+?/`, `/a{4,}?/`, `/a{2,4}?/`, `/a{2,2}/`, `/a{3}/`],
+    invalid: [
+        {
+            code: `/a{1}?/`,
+            output: `/a{1}/`,
+            errors: [
+                {
+                    message: "Unexpected quantifier non-greedy.",
+                    line: 1,
+                    column: 6,
+                    endLine: 1,
+                    endColumn: 7,
+                },
+            ],
+        },
+        {
+            code: `/a{4}?/`,
+            output: `/a{4}/`,
+            errors: [
+                {
+                    message: "Unexpected quantifier non-greedy.",
+                    line: 1,
+                    column: 6,
+                    endLine: 1,
+                    endColumn: 7,
+                },
+            ],
+        },
+        {
+            code: `/a{2,2}?/`,
+            output: `/a{2,2}/`,
+            errors: ["Unexpected quantifier non-greedy."],
+        },
+    ],
+})