eslint-plugin-sonarjs
Version:
SonarJS rules for ESLint
133 lines (132 loc) • 5.01 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/S4030
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");
exports.rule = {
meta: (0, index_js_1.generateMeta)(meta_js_1.meta, {
messages: {
unusedCollection: "Either use this collection's contents or remove the collection.",
},
}),
create(context) {
return {
'Program:exit': (node) => {
const unusedArrays = [];
collectUnusedCollections(context.sourceCode.getScope(node), unusedArrays);
unusedArrays.forEach(unusedArray => {
context.report({
messageId: 'unusedCollection',
node: unusedArray.identifiers[0],
});
});
},
};
},
};
function collectUnusedCollections(scope, unusedArray) {
if (scope.type !== 'global') {
scope.variables.filter(isUnusedCollection).forEach(v => {
unusedArray.push(v);
});
}
scope.childScopes.forEach(childScope => {
collectUnusedCollections(childScope, unusedArray);
});
}
function isExported(variable) {
const definition = variable.defs[0];
return definition && definition.node.parent?.parent?.type.startsWith('Export');
}
function isUnusedCollection(variable) {
if (isExported(variable)) {
return false;
}
if (variable.references.length <= 1) {
return false;
}
let assignCollection = false;
for (const ref of variable.references) {
if (ref.isWriteOnly()) {
if (isReferenceAssigningCollection(ref)) {
assignCollection = true;
}
else {
//One assignment is not a collection, we don't go further
return false;
}
}
else if (isRead(ref)) {
//Unfortunately, isRead (!isWrite) from Scope.Reference consider A[1] = 1; and A.xxx(); as a read operation, we need to filter further
return false;
}
}
return assignCollection;
}
function isReferenceAssigningCollection(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 isCollectionType(declOrExprStmt.init);
}
if (declOrExprStmt.type === 'ExpressionStatement') {
const { expression } = declOrExprStmt;
return (expression.type === 'AssignmentExpression' &&
isReferenceTo(ref, expression.left) &&
isCollectionType(expression.right));
}
}
return false;
}
function isCollectionType(node) {
if (node && node.type === 'ArrayExpression') {
return true;
}
else if (node && (node.type === 'CallExpression' || node.type === 'NewExpression')) {
return (0, index_js_1.isIdentifier)(node.callee, ...index_js_1.collectionConstructor);
}
return false;
}
function isRead(ref) {
const expressionStatement = (0, index_js_1.findFirstMatchingAncestor)(ref.identifier, n => n.type === 'ExpressionStatement');
if (expressionStatement) {
return !((0, index_js_1.isElementWrite)(expressionStatement, ref, false) ||
isWritingMethodCall(expressionStatement, ref));
}
//All the write statement that we search are part of ExpressionStatement, if there is none, it's a read
return true;
}
/**
* Detect expression statements like the following:
* myArray.push(1);
*/
function isWritingMethodCall(statement, ref) {
if (statement.expression.type === 'CallExpression') {
const { callee } = statement.expression;
if (callee.type === 'MemberExpression') {
const { property } = callee;
return isReferenceTo(ref, callee.object) && (0, index_js_1.isIdentifier)(property, ...index_js_1.writingMethods);
}
}
return false;
}
function isReferenceTo(ref, node) {
return node.type === 'Identifier' && node === ref.identifier;
}