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1/**
2 * @fileoverview Rule for disallowing require() outside of the top-level module context
3 * @author Jamund Ferguson
4 */
5
6"use strict";
7
8const ACCEPTABLE_PARENTS = [
9    "AssignmentExpression",
10    "VariableDeclarator",
11    "MemberExpression",
12    "ExpressionStatement",
13    "CallExpression",
14    "ConditionalExpression",
15    "Program",
16    "VariableDeclaration",
17    "ChainExpression"
18];
19
20/**
21 * Finds the eslint-scope reference in the given scope.
22 * @param {Object} scope The scope to search.
23 * @param {ASTNode} node The identifier node.
24 * @returns {Reference|null} Returns the found reference or null if none were found.
25 */
26function findReference(scope, node) {
27    const references = scope.references.filter(reference => reference.identifier.range[0] === node.range[0] &&
28            reference.identifier.range[1] === node.range[1]);
29
30    /* istanbul ignore else: correctly returns null */
31    if (references.length === 1) {
32        return references[0];
33    }
34    return null;
35
36}
37
38/**
39 * Checks if the given identifier node is shadowed in the given scope.
40 * @param {Object} scope The current scope.
41 * @param {ASTNode} node The identifier node to check.
42 * @returns {boolean} Whether or not the name is shadowed.
43 */
44function isShadowed(scope, node) {
45    const reference = findReference(scope, node);
46
47    return reference && reference.resolved && reference.resolved.defs.length > 0;
48}
49
50module.exports = {
51    meta: {
52        deprecated: true,
53
54        replacedBy: [],
55
56        type: "suggestion",
57
58        docs: {
59            description: "require `require()` calls to be placed at top-level module scope",
60            category: "Node.js and CommonJS",
61            recommended: false,
62            url: "https://eslint.org/docs/rules/global-require"
63        },
64
65        schema: [],
66        messages: {
67            unexpected: "Unexpected require()."
68        }
69    },
70
71    create(context) {
72        return {
73            CallExpression(node) {
74                const currentScope = context.getScope();
75
76                if (node.callee.name === "require" && !isShadowed(currentScope, node.callee)) {
77                    const isGoodRequire = context.getAncestors().every(parent => ACCEPTABLE_PARENTS.indexOf(parent.type) > -1);
78
79                    if (!isGoodRequire) {
80                        context.report({ node, messageId: "unexpected" });
81                    }
82                }
83            }
84        };
85    }
86};
87