eslint-plugin-sonarjs
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JavaScript
;
/*
* SonarQube JavaScript Plugin
* Copyright (C) SonarSource Sàrl
* mailto:info AT sonarsource DOT com
*
* You can redistribute and/or modify this program under the terms of
* the Sonar Source-Available License Version 1, as published by SonarSource Sàrl.
*
* 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/S2310/javascript
var __createBinding = (this && this.__createBinding) || (Object.create ? (function(o, m, k, k2) {
if (k2 === undefined) k2 = k;
var desc = Object.getOwnPropertyDescriptor(m, k);
if (!desc || ("get" in desc ? !m.__esModule : desc.writable || desc.configurable)) {
desc = { enumerable: true, get: function() { return m[k]; } };
}
Object.defineProperty(o, k2, desc);
}) : (function(o, m, k, k2) {
if (k2 === undefined) k2 = k;
o[k2] = m[k];
}));
var __setModuleDefault = (this && this.__setModuleDefault) || (Object.create ? (function(o, v) {
Object.defineProperty(o, "default", { enumerable: true, value: v });
}) : function(o, v) {
o["default"] = v;
});
var __importStar = (this && this.__importStar) || (function () {
var ownKeys = function(o) {
ownKeys = Object.getOwnPropertyNames || function (o) {
var ar = [];
for (var k in o) if (Object.prototype.hasOwnProperty.call(o, k)) ar[ar.length] = k;
return ar;
};
return ownKeys(o);
};
return function (mod) {
if (mod && mod.__esModule) return mod;
var result = {};
if (mod != null) for (var k = ownKeys(mod), i = 0; i < k.length; i++) if (k[i] !== "default") __createBinding(result, mod, k[i]);
__setModuleDefault(result, mod);
return result;
};
})();
Object.defineProperty(exports, "__esModule", { value: true });
exports.rule = void 0;
const generate_meta_js_1 = require("../helpers/generate-meta.js");
const ancestor_js_1 = require("../helpers/ancestor.js");
const ast_js_1 = require("../helpers/ast.js");
const location_js_1 = require("../helpers/location.js");
const meta = __importStar(require("./generated-meta.js"));
exports.rule = {
meta: (0, generate_meta_js_1.generateMeta)(meta),
create(context) {
function checkLoop(updateNode, extractCounters, loopBody) {
const counters = [];
extractCounters(updateNode, counters);
for (const counter of counters) {
checkCounter(counter, loopBody);
}
}
function checkCounter(counter, block) {
const variable = (0, ast_js_1.getVariableFromName)(context, counter.name, block);
if (!variable) {
return;
}
for (const ref of variable.references) {
if (ref.isWrite() && isUsedInsideBody(ref.identifier, block)) {
if (isIntentionalSkipAhead(ref.identifier, block)) {
continue;
}
(0, location_js_1.report)(context, {
node: ref.identifier,
message: `Remove this assignment of "${counter.name}".`,
}, [(0, location_js_1.toSecondaryLocation)(counter, 'Counter variable update')]);
}
}
}
return {
'ForStatement > BlockStatement': (node) => {
const forLoop = (0, ancestor_js_1.getParent)(context, node);
if (forLoop.update) {
checkLoop(forLoop.update, collectCountersFor, node);
}
},
// Note: for-of and for-in loops are not checked because reassigning
// the iterator variable does not affect loop iteration (the iterator
// protocol controls progression, not the variable value)
};
},
};
function collectCountersFor(updateExpression, counters) {
let counter = undefined;
if (updateExpression.type === 'AssignmentExpression') {
counter = updateExpression.left;
}
else if (updateExpression.type === 'UpdateExpression') {
counter = updateExpression.argument;
}
else if (updateExpression.type === 'SequenceExpression') {
for (const e of updateExpression.expressions) {
collectCountersFor(e, counters);
}
}
if (counter?.type === 'Identifier') {
counters.push(counter);
}
}
/**
* Checks if a loop counter modification is an intentional skip-ahead pattern
* (UpdateExpression or compound assignment) rather than a simple assignment.
* Simple assignments (=) are allowed when a splice() call using the same
* counter variable exists in the enclosing block (splice compensation pattern).
* Modifications in nested for-loop update clauses are not considered skip-ahead.
*/
function isIntentionalSkipAhead(id, outerLoopBody) {
if (isInNestedForLoopUpdate(id, outerLoopBody)) {
return false;
}
const parent = (0, ancestor_js_1.getNodeParent)(id);
if (parent?.type === 'UpdateExpression') {
return true;
}
if (parent?.type === 'AssignmentExpression' && parent.operator !== '=') {
return true;
}
if (parent?.type === 'AssignmentExpression' && parent.operator === '=') {
const block = findEnclosingBlock(id);
if (block && blockContainsSpliceWithCounter(block, id.name)) {
return true;
}
}
return false;
}
/**
* Walks up the AST from the given node to find the nearest enclosing BlockStatement.
*/
function findEnclosingBlock(node) {
let current = (0, ancestor_js_1.getNodeParent)(node);
while (current) {
if (current.type === 'BlockStatement') {
return current;
}
current = (0, ancestor_js_1.getNodeParent)(current);
}
return undefined;
}
/**
* Checks whether a block contains a splice() call whose first argument
* is an Identifier matching the given counter variable name.
*/
function blockContainsSpliceWithCounter(block, counterName) {
return block.body.some(stmt => containsSpliceWithCounter(stmt, counterName));
}
/**
* Checks whether a statement contains a splice() call whose first argument
* references the given counter variable name. Only checks direct statements
* in the block — not ones nested inside conditional branches.
*/
function containsSpliceWithCounter(node, counterName) {
if (node.type === 'ExpressionStatement') {
return expressionContainsSplice(node.expression, counterName);
}
if (node.type === 'VariableDeclaration' &&
node.declarations.some(d => d.init?.type === 'CallExpression' && isSpliceCallWithCounter(d.init, counterName))) {
return true;
}
return false;
}
/**
* Checks whether an expression is or contains a splice() call whose first argument
* matches the given counter variable name. Handles both direct splice calls
* and splice calls on the right side of assignments (e.g., removed = arr.splice(i, 1)).
*/
function expressionContainsSplice(expr, counterName) {
if (expr.type === 'CallExpression') {
return isSpliceCallWithCounter(expr, counterName);
}
return (expr.type === 'AssignmentExpression' &&
expr.right.type === 'CallExpression' &&
isSpliceCallWithCounter(expr.right, counterName));
}
/**
* Checks if a CallExpression is a .splice() call whose first argument
* is an Identifier matching the counter variable name.
*/
function isSpliceCallWithCounter(call, counterName) {
return (call.callee.type === 'MemberExpression' &&
call.callee.property.type === 'Identifier' &&
call.callee.property.name === 'splice' &&
call.arguments.length >= 1 &&
call.arguments[0].type === 'Identifier' &&
call.arguments[0].name === counterName);
}
function isUsedInsideBody(id, loopBody) {
const bodyRange = loopBody.range;
return id.range && bodyRange && id.range[0] > bodyRange[0] && id.range[1] < bodyRange[1];
}
function isInNestedForLoopUpdate(id, outerLoopBody) {
let node = id;
let parent = (0, ancestor_js_1.getNodeParent)(node);
while (parent) {
// Stop if we've reached the outer loop body
if (parent === outerLoopBody) {
return false;
}
// Check if we're in a nested for-loop's update clause
if (parent.type === 'ForStatement' && parent.update) {
const updateRange = parent.update.range;
if (updateRange &&
id.range &&
id.range[0] >= updateRange[0] &&
id.range[1] <= updateRange[1]) {
return true;
}
}
node = parent;
parent = (0, ancestor_js_1.getNodeParent)(node);
}
return false;
}