298 lines
11 KiB
JavaScript
298 lines
11 KiB
JavaScript
/**
|
|
* @fileoverview Prefer destructuring from arrays and objects
|
|
* @author Alex LaFroscia
|
|
*/
|
|
"use strict";
|
|
|
|
//------------------------------------------------------------------------------
|
|
// Requirements
|
|
//------------------------------------------------------------------------------
|
|
|
|
const astUtils = require("./utils/ast-utils");
|
|
|
|
//------------------------------------------------------------------------------
|
|
// Helpers
|
|
//------------------------------------------------------------------------------
|
|
|
|
const PRECEDENCE_OF_ASSIGNMENT_EXPR = astUtils.getPrecedence({ type: "AssignmentExpression" });
|
|
|
|
//------------------------------------------------------------------------------
|
|
// Rule Definition
|
|
//------------------------------------------------------------------------------
|
|
|
|
module.exports = {
|
|
meta: {
|
|
type: "suggestion",
|
|
|
|
docs: {
|
|
description: "require destructuring from arrays and/or objects",
|
|
category: "ECMAScript 6",
|
|
recommended: false,
|
|
url: "https://eslint.org/docs/rules/prefer-destructuring"
|
|
},
|
|
|
|
fixable: "code",
|
|
|
|
schema: [
|
|
{
|
|
|
|
/*
|
|
* old support {array: Boolean, object: Boolean}
|
|
* new support {VariableDeclarator: {}, AssignmentExpression: {}}
|
|
*/
|
|
oneOf: [
|
|
{
|
|
type: "object",
|
|
properties: {
|
|
VariableDeclarator: {
|
|
type: "object",
|
|
properties: {
|
|
array: {
|
|
type: "boolean"
|
|
},
|
|
object: {
|
|
type: "boolean"
|
|
}
|
|
},
|
|
additionalProperties: false
|
|
},
|
|
AssignmentExpression: {
|
|
type: "object",
|
|
properties: {
|
|
array: {
|
|
type: "boolean"
|
|
},
|
|
object: {
|
|
type: "boolean"
|
|
}
|
|
},
|
|
additionalProperties: false
|
|
}
|
|
},
|
|
additionalProperties: false
|
|
},
|
|
{
|
|
type: "object",
|
|
properties: {
|
|
array: {
|
|
type: "boolean"
|
|
},
|
|
object: {
|
|
type: "boolean"
|
|
}
|
|
},
|
|
additionalProperties: false
|
|
}
|
|
]
|
|
},
|
|
{
|
|
type: "object",
|
|
properties: {
|
|
enforceForRenamedProperties: {
|
|
type: "boolean"
|
|
}
|
|
},
|
|
additionalProperties: false
|
|
}
|
|
],
|
|
|
|
messages: {
|
|
preferDestructuring: "Use {{type}} destructuring."
|
|
}
|
|
},
|
|
create(context) {
|
|
|
|
const enabledTypes = context.options[0];
|
|
const enforceForRenamedProperties = context.options[1] && context.options[1].enforceForRenamedProperties;
|
|
let normalizedOptions = {
|
|
VariableDeclarator: { array: true, object: true },
|
|
AssignmentExpression: { array: true, object: true }
|
|
};
|
|
|
|
if (enabledTypes) {
|
|
normalizedOptions = typeof enabledTypes.array !== "undefined" || typeof enabledTypes.object !== "undefined"
|
|
? { VariableDeclarator: enabledTypes, AssignmentExpression: enabledTypes }
|
|
: enabledTypes;
|
|
}
|
|
|
|
//--------------------------------------------------------------------------
|
|
// Helpers
|
|
//--------------------------------------------------------------------------
|
|
|
|
// eslint-disable-next-line jsdoc/require-description
|
|
/**
|
|
* @param {string} nodeType "AssignmentExpression" or "VariableDeclarator"
|
|
* @param {string} destructuringType "array" or "object"
|
|
* @returns {boolean} `true` if the destructuring type should be checked for the given node
|
|
*/
|
|
function shouldCheck(nodeType, destructuringType) {
|
|
return normalizedOptions &&
|
|
normalizedOptions[nodeType] &&
|
|
normalizedOptions[nodeType][destructuringType];
|
|
}
|
|
|
|
/**
|
|
* Determines if the given node is accessing an array index
|
|
*
|
|
* This is used to differentiate array index access from object property
|
|
* access.
|
|
* @param {ASTNode} node the node to evaluate
|
|
* @returns {boolean} whether or not the node is an integer
|
|
*/
|
|
function isArrayIndexAccess(node) {
|
|
return Number.isInteger(node.property.value);
|
|
}
|
|
|
|
/**
|
|
* Report that the given node should use destructuring
|
|
* @param {ASTNode} reportNode the node to report
|
|
* @param {string} type the type of destructuring that should have been done
|
|
* @param {Function|null} fix the fix function or null to pass to context.report
|
|
* @returns {void}
|
|
*/
|
|
function report(reportNode, type, fix) {
|
|
context.report({
|
|
node: reportNode,
|
|
messageId: "preferDestructuring",
|
|
data: { type },
|
|
fix
|
|
});
|
|
}
|
|
|
|
/**
|
|
* Determines if a node should be fixed into object destructuring
|
|
*
|
|
* The fixer only fixes the simplest case of object destructuring,
|
|
* like: `let x = a.x`;
|
|
*
|
|
* Assignment expression is not fixed.
|
|
* Array destructuring is not fixed.
|
|
* Renamed property is not fixed.
|
|
* @param {ASTNode} node the node to evaluate
|
|
* @returns {boolean} whether or not the node should be fixed
|
|
*/
|
|
function shouldFix(node) {
|
|
return node.type === "VariableDeclarator" &&
|
|
node.id.type === "Identifier" &&
|
|
node.init.type === "MemberExpression" &&
|
|
!node.init.computed &&
|
|
node.init.property.type === "Identifier" &&
|
|
node.id.name === node.init.property.name;
|
|
}
|
|
|
|
/**
|
|
* Fix a node into object destructuring.
|
|
* This function only handles the simplest case of object destructuring,
|
|
* see {@link shouldFix}.
|
|
* @param {SourceCodeFixer} fixer the fixer object
|
|
* @param {ASTNode} node the node to be fixed.
|
|
* @returns {Object} a fix for the node
|
|
*/
|
|
function fixIntoObjectDestructuring(fixer, node) {
|
|
const rightNode = node.init;
|
|
const sourceCode = context.getSourceCode();
|
|
|
|
// Don't fix if that would remove any comments. Only comments inside `rightNode.object` can be preserved.
|
|
if (sourceCode.getCommentsInside(node).length > sourceCode.getCommentsInside(rightNode.object).length) {
|
|
return null;
|
|
}
|
|
|
|
let objectText = sourceCode.getText(rightNode.object);
|
|
|
|
if (astUtils.getPrecedence(rightNode.object) < PRECEDENCE_OF_ASSIGNMENT_EXPR) {
|
|
objectText = `(${objectText})`;
|
|
}
|
|
|
|
return fixer.replaceText(
|
|
node,
|
|
`{${rightNode.property.name}} = ${objectText}`
|
|
);
|
|
}
|
|
|
|
/**
|
|
* Check that the `prefer-destructuring` rules are followed based on the
|
|
* given left- and right-hand side of the assignment.
|
|
*
|
|
* Pulled out into a separate method so that VariableDeclarators and
|
|
* AssignmentExpressions can share the same verification logic.
|
|
* @param {ASTNode} leftNode the left-hand side of the assignment
|
|
* @param {ASTNode} rightNode the right-hand side of the assignment
|
|
* @param {ASTNode} reportNode the node to report the error on
|
|
* @returns {void}
|
|
*/
|
|
function performCheck(leftNode, rightNode, reportNode) {
|
|
if (rightNode.type !== "MemberExpression" || rightNode.object.type === "Super") {
|
|
return;
|
|
}
|
|
|
|
if (isArrayIndexAccess(rightNode)) {
|
|
if (shouldCheck(reportNode.type, "array")) {
|
|
report(reportNode, "array", null);
|
|
}
|
|
return;
|
|
}
|
|
|
|
const fix = shouldFix(reportNode)
|
|
? fixer => fixIntoObjectDestructuring(fixer, reportNode)
|
|
: null;
|
|
|
|
if (shouldCheck(reportNode.type, "object") && enforceForRenamedProperties) {
|
|
report(reportNode, "object", fix);
|
|
return;
|
|
}
|
|
|
|
if (shouldCheck(reportNode.type, "object")) {
|
|
const property = rightNode.property;
|
|
|
|
if (
|
|
(property.type === "Literal" && leftNode.name === property.value) ||
|
|
(property.type === "Identifier" && leftNode.name === property.name && !rightNode.computed)
|
|
) {
|
|
report(reportNode, "object", fix);
|
|
}
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Check if a given variable declarator is coming from an property access
|
|
* that should be using destructuring instead
|
|
* @param {ASTNode} node the variable declarator to check
|
|
* @returns {void}
|
|
*/
|
|
function checkVariableDeclarator(node) {
|
|
|
|
// Skip if variable is declared without assignment
|
|
if (!node.init) {
|
|
return;
|
|
}
|
|
|
|
// We only care about member expressions past this point
|
|
if (node.init.type !== "MemberExpression") {
|
|
return;
|
|
}
|
|
|
|
performCheck(node.id, node.init, node);
|
|
}
|
|
|
|
/**
|
|
* Run the `prefer-destructuring` check on an AssignmentExpression
|
|
* @param {ASTNode} node the AssignmentExpression node
|
|
* @returns {void}
|
|
*/
|
|
function checkAssignmentExpression(node) {
|
|
if (node.operator === "=") {
|
|
performCheck(node.left, node.right, node);
|
|
}
|
|
}
|
|
|
|
//--------------------------------------------------------------------------
|
|
// Public
|
|
//--------------------------------------------------------------------------
|
|
|
|
return {
|
|
VariableDeclarator: checkVariableDeclarator,
|
|
AssignmentExpression: checkAssignmentExpression
|
|
};
|
|
}
|
|
};
|