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1/**
2 * @fileoverview Rule to disallow use of the `RegExp` constructor in favor of regular expression literals
3 * @author Milos Djermanovic
4 */
5
6"use strict";
7
8//------------------------------------------------------------------------------
9// Requirements
10//------------------------------------------------------------------------------
11
12const astUtils = require("./utils/ast-utils");
13const { CALL, CONSTRUCT, ReferenceTracker, findVariable } = require("eslint-utils");
14
15//------------------------------------------------------------------------------
16// Helpers
17//------------------------------------------------------------------------------
18
19/**
20 * Determines whether the given node is a string literal.
21 * @param {ASTNode} node Node to check.
22 * @returns {boolean} True if the node is a string literal.
23 */
24function isStringLiteral(node) {
25    return node.type === "Literal" && typeof node.value === "string";
26}
27
28/**
29 * Determines whether the given node is a template literal without expressions.
30 * @param {ASTNode} node Node to check.
31 * @returns {boolean} True if the node is a template literal without expressions.
32 */
33function isStaticTemplateLiteral(node) {
34    return node.type === "TemplateLiteral" && node.expressions.length === 0;
35}
36
37
38//------------------------------------------------------------------------------
39// Rule Definition
40//------------------------------------------------------------------------------
41
42module.exports = {
43    meta: {
44        type: "suggestion",
45
46        docs: {
47            description: "disallow use of the `RegExp` constructor in favor of regular expression literals",
48            category: "Best Practices",
49            recommended: false,
50            url: "https://eslint.org/docs/rules/prefer-regex-literals"
51        },
52
53        schema: [],
54
55        messages: {
56            unexpectedRegExp: "Use a regular expression literal instead of the 'RegExp' constructor."
57        }
58    },
59
60    create(context) {
61
62        /**
63         * Determines whether the given identifier node is a reference to a global variable.
64         * @param {ASTNode} node `Identifier` node to check.
65         * @returns {boolean} True if the identifier is a reference to a global variable.
66         */
67        function isGlobalReference(node) {
68            const scope = context.getScope();
69            const variable = findVariable(scope, node);
70
71            return variable !== null && variable.scope.type === "global" && variable.defs.length === 0;
72        }
73
74        /**
75         * Determines whether the given node is a String.raw`` tagged template expression
76         * with a static template literal.
77         * @param {ASTNode} node Node to check.
78         * @returns {boolean} True if the node is String.raw`` with a static template.
79         */
80        function isStringRawTaggedStaticTemplateLiteral(node) {
81            return node.type === "TaggedTemplateExpression" &&
82                astUtils.isSpecificMemberAccess(node.tag, "String", "raw") &&
83                isGlobalReference(astUtils.skipChainExpression(node.tag).object) &&
84                isStaticTemplateLiteral(node.quasi);
85        }
86
87        /**
88         * Determines whether the given node is considered to be a static string by the logic of this rule.
89         * @param {ASTNode} node Node to check.
90         * @returns {boolean} True if the node is a static string.
91         */
92        function isStaticString(node) {
93            return isStringLiteral(node) ||
94                isStaticTemplateLiteral(node) ||
95                isStringRawTaggedStaticTemplateLiteral(node);
96        }
97
98        return {
99            Program() {
100                const scope = context.getScope();
101                const tracker = new ReferenceTracker(scope);
102                const traceMap = {
103                    RegExp: {
104                        [CALL]: true,
105                        [CONSTRUCT]: true
106                    }
107                };
108
109                for (const { node } of tracker.iterateGlobalReferences(traceMap)) {
110                    const args = node.arguments;
111
112                    if (
113                        (args.length === 1 || args.length === 2) &&
114                        args.every(isStaticString)
115                    ) {
116                        context.report({ node, messageId: "unexpectedRegExp" });
117                    }
118                }
119            }
120        };
121    }
122};
123