eslint-plugin-sonarjs
Version:
SonarJS rules for ESLint
193 lines (192 loc) • 6.49 kB
JavaScript
;
/*
* SonarQube JavaScript Plugin
* Copyright (C) 2011-2025 SonarSource SA
* mailto:info AT sonarsource DOT com
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the Sonar Source-Available License Version 1, as published by SonarSource SA.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
* See the Sonar Source-Available License for more details.
*
* You should have received a copy of the Sonar Source-Available License
* along with this program; if not, see https://sonarsource.com/license/ssal/
*/
// https://sonarsource.github.io/rspec/#/rspec/S4158
Object.defineProperty(exports, "__esModule", { value: true });
exports.rule = void 0;
const index_js_1 = require("../helpers/index.js");
const meta_js_1 = require("./meta.js");
// Methods that mutate the collection but can't add elements
const nonAdditiveMutatorMethods = [
// array methods
'copyWithin',
'pop',
'reverse',
'shift',
'sort',
// map, set methods
'clear',
'delete',
];
const accessorMethods = [
// array methods
'concat',
'flat',
'flatMap',
'includes',
'indexOf',
'join',
'lastIndexOf',
'slice',
'toSource',
'toString',
'toLocaleString',
// map, set methods
'get',
'has',
];
const iterationMethods = [
'entries',
'every',
'filter',
'find',
'findIndex',
'forEach',
'keys',
'map',
'reduce',
'reduceRight',
'some',
'values',
];
const strictlyReadingMethods = new Set([
...nonAdditiveMutatorMethods,
...accessorMethods,
...iterationMethods,
]);
exports.rule = {
meta: (0, index_js_1.generateMeta)(meta_js_1.meta, {
messages: {
reviewUsageOfIdentifier: 'Review this usage of "{{identifierName}}" as it can only be empty here.',
},
}),
create(context) {
return {
'Program:exit': (node) => {
reportEmptyCollectionsUsage(context.sourceCode.getScope(node), context);
},
};
},
};
function reportEmptyCollectionsUsage(scope, context) {
if (scope.type !== 'global') {
scope.variables.forEach(v => {
reportEmptyCollectionUsage(v, context);
});
}
scope.childScopes.forEach(childScope => {
reportEmptyCollectionsUsage(childScope, context);
});
}
function reportEmptyCollectionUsage(variable, context) {
if (variable.references.length <= 1) {
return;
}
if (variable.defs.some(d => d.type === 'Parameter' || d.type === 'ImportBinding')) {
// Bound value initialized elsewhere, could be non-empty.
return;
}
const readingUsages = [];
let hasAssignmentOfEmptyCollection = false;
for (const ref of variable.references) {
if (ref.isWriteOnly()) {
if (isReferenceAssigningEmptyCollection(ref)) {
hasAssignmentOfEmptyCollection = true;
}
else {
// There is at least one operation that might make the collection non-empty.
// We ignore the order of usages, and consider all reads to be safe.
return;
}
}
else if (isReadingCollectionUsage(ref)) {
readingUsages.push(ref);
}
else {
// some unknown operation on the collection.
// To avoid any FPs, we assume that it could make the collection non-empty.
return;
}
}
if (hasAssignmentOfEmptyCollection) {
readingUsages.forEach(ref => {
context.report({
messageId: 'reviewUsageOfIdentifier',
data: {
identifierName: ref.identifier.name,
},
node: ref.identifier,
});
});
}
}
function isReferenceAssigningEmptyCollection(ref) {
const declOrExprStmt = (0, index_js_1.findFirstMatchingAncestor)(ref.identifier, n => n.type === 'VariableDeclarator' || n.type === 'ExpressionStatement');
if (declOrExprStmt) {
if (declOrExprStmt.type === 'VariableDeclarator' && declOrExprStmt.init) {
return isEmptyCollectionType(declOrExprStmt.init);
}
if (declOrExprStmt.type === 'ExpressionStatement') {
const { expression } = declOrExprStmt;
return (expression.type === 'AssignmentExpression' &&
(0, index_js_1.isReferenceTo)(ref, expression.left) &&
isEmptyCollectionType(expression.right));
}
}
return false;
}
function isEmptyCollectionType(node) {
if (node && node.type === 'ArrayExpression') {
return node.elements.length === 0;
}
else if (node && (node.type === 'CallExpression' || node.type === 'NewExpression')) {
return (0, index_js_1.isIdentifier)(node.callee, ...index_js_1.collectionConstructor) && node.arguments.length === 0;
}
return false;
}
function isReadingCollectionUsage(ref) {
return isStrictlyReadingMethodCall(ref) || isForIterationPattern(ref) || isElementRead(ref);
}
function isStrictlyReadingMethodCall(usage) {
const { parent } = usage.identifier;
if (parent && parent.type === 'MemberExpression') {
const memberExpressionParent = parent.parent;
if (memberExpressionParent && memberExpressionParent.type === 'CallExpression') {
return (0, index_js_1.isIdentifier)(parent.property, ...strictlyReadingMethods);
}
}
return false;
}
function isForIterationPattern(ref) {
const forInOrOfStatement = (0, index_js_1.findFirstMatchingAncestor)(ref.identifier, n => n.type === 'ForOfStatement' || n.type === 'ForInStatement');
return forInOrOfStatement && forInOrOfStatement.right === ref.identifier;
}
function isElementRead(ref) {
const { parent } = ref.identifier;
return (parent &&
parent.type === 'MemberExpression' &&
parent.computed &&
!isElementWrite(parent));
}
function isElementWrite(memberExpression) {
const ancestors = (0, index_js_1.ancestorsChain)(memberExpression, new Set());
const assignment = ancestors.find(n => n.type === 'AssignmentExpression');
if (assignment && assignment.operator === '=') {
return [memberExpression, ...ancestors].includes(assignment.left);
}
return false;
}