221 lines
7.9 KiB
JavaScript
221 lines
7.9 KiB
JavaScript
/**
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* @fileoverview Prefer destructuring from arrays and objects
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* @author Alex LaFroscia
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*/
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"use strict";
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//------------------------------------------------------------------------------
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// Rule Definition
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//------------------------------------------------------------------------------
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module.exports = {
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meta: {
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docs: {
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description: "require destructuring from arrays and/or objects",
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category: "ECMAScript 6",
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recommended: false,
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url: "https://eslint.org/docs/rules/prefer-destructuring"
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},
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schema: [
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{
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/*
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* old support {array: Boolean, object: Boolean}
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* new support {VariableDeclarator: {}, AssignmentExpression: {}}
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*/
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oneOf: [
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{
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type: "object",
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properties: {
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VariableDeclarator: {
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type: "object",
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properties: {
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array: {
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type: "boolean"
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},
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object: {
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type: "boolean"
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}
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},
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additionalProperties: false
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},
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AssignmentExpression: {
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type: "object",
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properties: {
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array: {
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type: "boolean"
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},
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object: {
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type: "boolean"
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}
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},
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additionalProperties: false
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}
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},
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additionalProperties: false
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},
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{
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type: "object",
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properties: {
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array: {
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type: "boolean"
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},
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object: {
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type: "boolean"
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}
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},
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additionalProperties: false
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}
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]
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},
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{
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type: "object",
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properties: {
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enforceForRenamedProperties: {
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type: "boolean"
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}
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},
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additionalProperties: false
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}
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]
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},
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create(context) {
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const enabledTypes = context.options[0];
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const enforceForRenamedProperties = context.options[1] && context.options[1].enforceForRenamedProperties;
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let normalizedOptions = {
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VariableDeclarator: { array: true, object: true },
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AssignmentExpression: { array: true, object: true }
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};
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if (enabledTypes) {
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normalizedOptions = typeof enabledTypes.array !== "undefined" || typeof enabledTypes.object !== "undefined"
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? { VariableDeclarator: enabledTypes, AssignmentExpression: enabledTypes }
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: enabledTypes;
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}
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//--------------------------------------------------------------------------
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// Helpers
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//--------------------------------------------------------------------------
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/**
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* @param {string} nodeType "AssignmentExpression" or "VariableDeclarator"
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* @param {string} destructuringType "array" or "object"
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* @returns {boolean} `true` if the destructuring type should be checked for the given node
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*/
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function shouldCheck(nodeType, destructuringType) {
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return normalizedOptions &&
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normalizedOptions[nodeType] &&
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normalizedOptions[nodeType][destructuringType];
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}
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/**
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* Determines if the given node is accessing an array index
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*
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* This is used to differentiate array index access from object property
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* access.
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*
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* @param {ASTNode} node the node to evaluate
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* @returns {boolean} whether or not the node is an integer
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*/
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function isArrayIndexAccess(node) {
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return Number.isInteger(node.property.value);
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}
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/**
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* Report that the given node should use destructuring
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*
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* @param {ASTNode} reportNode the node to report
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* @param {string} type the type of destructuring that should have been done
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* @returns {void}
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*/
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function report(reportNode, type) {
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context.report({ node: reportNode, message: "Use {{type}} destructuring.", data: { type } });
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}
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/**
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* Check that the `prefer-destructuring` rules are followed based on the
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* given left- and right-hand side of the assignment.
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*
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* Pulled out into a separate method so that VariableDeclarators and
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* AssignmentExpressions can share the same verification logic.
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*
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* @param {ASTNode} leftNode the left-hand side of the assignment
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* @param {ASTNode} rightNode the right-hand side of the assignment
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* @param {ASTNode} reportNode the node to report the error on
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* @returns {void}
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*/
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function performCheck(leftNode, rightNode, reportNode) {
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if (rightNode.type !== "MemberExpression" || rightNode.object.type === "Super") {
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return;
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}
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if (isArrayIndexAccess(rightNode)) {
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if (shouldCheck(reportNode.type, "array")) {
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report(reportNode, "array");
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}
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return;
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}
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if (shouldCheck(reportNode.type, "object") && enforceForRenamedProperties) {
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report(reportNode, "object");
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return;
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}
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if (shouldCheck(reportNode.type, "object")) {
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const property = rightNode.property;
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if (
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(property.type === "Literal" && leftNode.name === property.value) ||
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(property.type === "Identifier" && leftNode.name === property.name && !rightNode.computed)
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) {
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report(reportNode, "object");
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}
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}
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}
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/**
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* Check if a given variable declarator is coming from an property access
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* that should be using destructuring instead
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*
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* @param {ASTNode} node the variable declarator to check
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* @returns {void}
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*/
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function checkVariableDeclarator(node) {
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// Skip if variable is declared without assignment
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if (!node.init) {
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return;
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}
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// We only care about member expressions past this point
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if (node.init.type !== "MemberExpression") {
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return;
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}
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performCheck(node.id, node.init, node);
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}
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/**
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* Run the `prefer-destructuring` check on an AssignmentExpression
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*
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* @param {ASTNode} node the AssignmentExpression node
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* @returns {void}
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*/
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function checkAssigmentExpression(node) {
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if (node.operator === "=") {
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performCheck(node.left, node.right, node);
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}
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}
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//--------------------------------------------------------------------------
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// Public
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//--------------------------------------------------------------------------
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return {
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VariableDeclarator: checkVariableDeclarator,
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AssignmentExpression: checkAssigmentExpression
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};
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}
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};
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