You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
183 lines
5.5 KiB
183 lines
5.5 KiB
/**
|
|
* @fileoverview Rule to disallow assignments where both sides are exactly the same
|
|
* @author Toru Nagashima
|
|
*/
|
|
|
|
"use strict";
|
|
|
|
//------------------------------------------------------------------------------
|
|
// Requirements
|
|
//------------------------------------------------------------------------------
|
|
|
|
const astUtils = require("./utils/ast-utils");
|
|
|
|
//------------------------------------------------------------------------------
|
|
// Helpers
|
|
//------------------------------------------------------------------------------
|
|
|
|
const SPACES = /\s+/gu;
|
|
|
|
/**
|
|
* Traverses 2 Pattern nodes in parallel, then reports self-assignments.
|
|
* @param {ASTNode|null} left A left node to traverse. This is a Pattern or
|
|
* a Property.
|
|
* @param {ASTNode|null} right A right node to traverse. This is a Pattern or
|
|
* a Property.
|
|
* @param {boolean} props The flag to check member expressions as well.
|
|
* @param {Function} report A callback function to report.
|
|
* @returns {void}
|
|
*/
|
|
function eachSelfAssignment(left, right, props, report) {
|
|
if (!left || !right) {
|
|
|
|
// do nothing
|
|
} else if (
|
|
left.type === "Identifier" &&
|
|
right.type === "Identifier" &&
|
|
left.name === right.name
|
|
) {
|
|
report(right);
|
|
} else if (
|
|
left.type === "ArrayPattern" &&
|
|
right.type === "ArrayExpression"
|
|
) {
|
|
const end = Math.min(left.elements.length, right.elements.length);
|
|
|
|
for (let i = 0; i < end; ++i) {
|
|
const leftElement = left.elements[i];
|
|
const rightElement = right.elements[i];
|
|
|
|
// Avoid cases such as [...a] = [...a, 1]
|
|
if (
|
|
leftElement &&
|
|
leftElement.type === "RestElement" &&
|
|
i < right.elements.length - 1
|
|
) {
|
|
break;
|
|
}
|
|
|
|
eachSelfAssignment(leftElement, rightElement, props, report);
|
|
|
|
// After a spread element, those indices are unknown.
|
|
if (rightElement && rightElement.type === "SpreadElement") {
|
|
break;
|
|
}
|
|
}
|
|
} else if (
|
|
left.type === "RestElement" &&
|
|
right.type === "SpreadElement"
|
|
) {
|
|
eachSelfAssignment(left.argument, right.argument, props, report);
|
|
} else if (
|
|
left.type === "ObjectPattern" &&
|
|
right.type === "ObjectExpression" &&
|
|
right.properties.length >= 1
|
|
) {
|
|
|
|
/*
|
|
* Gets the index of the last spread property.
|
|
* It's possible to overwrite properties followed by it.
|
|
*/
|
|
let startJ = 0;
|
|
|
|
for (let i = right.properties.length - 1; i >= 0; --i) {
|
|
const propType = right.properties[i].type;
|
|
|
|
if (propType === "SpreadElement" || propType === "ExperimentalSpreadProperty") {
|
|
startJ = i + 1;
|
|
break;
|
|
}
|
|
}
|
|
|
|
for (let i = 0; i < left.properties.length; ++i) {
|
|
for (let j = startJ; j < right.properties.length; ++j) {
|
|
eachSelfAssignment(
|
|
left.properties[i],
|
|
right.properties[j],
|
|
props,
|
|
report
|
|
);
|
|
}
|
|
}
|
|
} else if (
|
|
left.type === "Property" &&
|
|
right.type === "Property" &&
|
|
right.kind === "init" &&
|
|
!right.method
|
|
) {
|
|
const leftName = astUtils.getStaticPropertyName(left);
|
|
|
|
if (leftName !== null && leftName === astUtils.getStaticPropertyName(right)) {
|
|
eachSelfAssignment(left.value, right.value, props, report);
|
|
}
|
|
} else if (
|
|
props &&
|
|
astUtils.skipChainExpression(left).type === "MemberExpression" &&
|
|
astUtils.skipChainExpression(right).type === "MemberExpression" &&
|
|
astUtils.isSameReference(left, right)
|
|
) {
|
|
report(right);
|
|
}
|
|
}
|
|
|
|
//------------------------------------------------------------------------------
|
|
// Rule Definition
|
|
//------------------------------------------------------------------------------
|
|
|
|
/** @type {import('../shared/types').Rule} */
|
|
module.exports = {
|
|
meta: {
|
|
type: "problem",
|
|
|
|
docs: {
|
|
description: "Disallow assignments where both sides are exactly the same",
|
|
recommended: true,
|
|
url: "https://eslint.org/docs/latest/rules/no-self-assign"
|
|
},
|
|
|
|
schema: [
|
|
{
|
|
type: "object",
|
|
properties: {
|
|
props: {
|
|
type: "boolean",
|
|
default: true
|
|
}
|
|
},
|
|
additionalProperties: false
|
|
}
|
|
],
|
|
|
|
messages: {
|
|
selfAssignment: "'{{name}}' is assigned to itself."
|
|
}
|
|
},
|
|
|
|
create(context) {
|
|
const sourceCode = context.sourceCode;
|
|
const [{ props = true } = {}] = context.options;
|
|
|
|
/**
|
|
* Reports a given node as self assignments.
|
|
* @param {ASTNode} node A node to report. This is an Identifier node.
|
|
* @returns {void}
|
|
*/
|
|
function report(node) {
|
|
context.report({
|
|
node,
|
|
messageId: "selfAssignment",
|
|
data: {
|
|
name: sourceCode.getText(node).replace(SPACES, "")
|
|
}
|
|
});
|
|
}
|
|
|
|
return {
|
|
AssignmentExpression(node) {
|
|
if (["=", "&&=", "||=", "??="].includes(node.operator)) {
|
|
eachSelfAssignment(node.left, node.right, props, report);
|
|
}
|
|
}
|
|
};
|
|
}
|
|
};
|