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Merge pull request #57 from alexreardon/memoize-one@5.0.0
adding codemod for memoize one@5.0.0
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‎community/memoize-one/5.0.0/motions/.gitkeep

Whitespace-only changes.

‎community/memoize-one/5.0.0/transform.spec.ts

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import { applyTransform } from '@codeshift/test-utils';
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import * as transformer from './transform';
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import prettier from 'prettier';
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function format(source: string): string {
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return prettier
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.format(source, {
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parser: 'typescript',
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trailingComma: 'all',
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semi: true,
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tabWidth: 2,
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useTabs: false,
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singleQuote: true,
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printWidth: 100,
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})
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.trim();
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}
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describe('memoize-one@5.0.0 transform', () => {
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it('should not touch usages that do not use a custom equality function', () => {
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const result = applyTransform(
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transformer,
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format(`
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import memoize from 'memoize-one';
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function add(a: number, b: number) {
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return a + b;
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}
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const memoized = memoize(add);
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`),
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{ parser: 'tsx' },
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);
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expect(result).toEqual(
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format(`
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import memoize from 'memoize-one';
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function add(a: number, b: number) {
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return a + b;
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}
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const memoized = memoize(add);
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`),
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);
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});
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it('should wrap inline equality arrow functions', () => {
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const result = applyTransform(
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transformer,
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format(`
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import memoize from 'memoize-one';
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function add(a: number, b: number) {
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return a + b;
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}
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const memoized = memoize(add, (a, b) => {
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return a === b;
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});
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`),
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{ parser: 'tsx' },
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);
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expect(result).toEqual(
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format(`
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import memoize from 'memoize-one';
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function add(a: number, b: number) {
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return a + b;
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}
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const memoized = memoize(add, (newArgs, lastArgs) => {
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if (newArgs.length !== lastArgs.length) {
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return false;
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}
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const __equalityFn = (a, b) => {
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return a === b;
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};
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return newArgs.every((newArg, index) => __equalityFn(newArg, lastArgs[index]));
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});
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`),
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);
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});
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it('should wrap inline equality function declarations', () => {
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const result = applyTransform(
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transformer,
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format(`
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import memoize from 'memoize-one';
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function add(a: number, b: number) {
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return a + b;
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}
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const memoized = memoize(add, function isEqual(a, b) {
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return a === b;
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});
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`),
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{ parser: 'tsx' },
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);
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expect(result).toEqual(
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format(`
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import memoize from 'memoize-one';
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function add(a: number, b: number) {
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return a + b;
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}
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const memoized = memoize(add, (newArgs, lastArgs) => {
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if (newArgs.length !== lastArgs.length) {
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return false;
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}
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const __equalityFn = function isEqual(a, b) {
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return a === b;
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}
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return newArgs.every((newArg, index) => __equalityFn(newArg, lastArgs[index]));
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});
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`),
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);
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});
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it('should wrap function identifiers', () => {
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const result = applyTransform(
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transformer,
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format(`
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import memoize from 'memoize-one';
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import isEqual from 'something';
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function add(a: number, b: number) {
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return a + b;
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}
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const memoized = memoize(add, isEqual);
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`),
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{ parser: 'tsx' },
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);
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expect(result).toEqual(
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format(`
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import memoize from 'memoize-one';
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import isEqual from 'something';
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function add(a: number, b: number) {
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return a + b;
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}
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const memoized = memoize(add, (newArgs, lastArgs) => {
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if (newArgs.length !== lastArgs.length) {
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return false;
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}
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const __equalityFn = isEqual;
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return newArgs.every((newArg, index) => __equalityFn(newArg, lastArgs[index]));
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});
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`),
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);
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});
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it('should add a comment when an unsupported equality fn is encountered', () => {
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const result = applyTransform(
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transformer,
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format(`
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import memoize from 'memoize-one';
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function add(a: number, b: number) {
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return a + b;
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}
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const memoized = memoize(add, {});
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`),
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{ parser: 'tsx' },
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);
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expect(result).toEqual(
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format(`
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/* TODO: (@codeshift) Unable to migrate memoize-one custom equality function.
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Expected a function or an identifier */
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import memoize from 'memoize-one';
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function add(a: number, b: number) {
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return a + b;
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}
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const memoized = memoize(add, {});
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`),
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);
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});
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});

‎community/memoize-one/5.0.0/transform.ts

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import {
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hasImportDeclaration,
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getDefaultImportSpecifierName,
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insertCommentToStartOfFile,
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} from '@codeshift/utils';
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import { API, FileInfo, Options } from 'jscodeshift';
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export default function transformer(
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file: FileInfo,
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{ jscodeshift: j }: API,
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options: Options,
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) {
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const source = j(file.source);
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// Exit early if file is not importing memoize-one
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if (!hasImportDeclaration(j, source, 'memoize-one')) {
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return file.source;
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}
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const importName = getDefaultImportSpecifierName(j, source, 'memoize-one');
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source
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.find(j.CallExpression)
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// looking for calls to memoize-one
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.filter(
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call =>
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call.value.callee.type === 'Identifier' &&
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call.value.callee.name === importName,
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)
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.forEach(call => {
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const equalityFn = call.value.arguments[1];
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// we don't need to do anything for calls without an equality fn
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if (equalityFn == null) {
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return;
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}
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// We are going to wrap the existing customEqualityFn in our new one
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// 4.0.0 EqualityFn → (a, b) => boolean [called for each argument]
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// 5.0.0 EqualityFn → ([newArgs], [lastArgs]) => boolean [called once with all arguments]
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if (
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equalityFn.type === 'FunctionExpression' ||
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equalityFn.type === 'ArrowFunctionExpression' ||
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equalityFn.type === 'Identifier'
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) {
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const customEqualityFn = j.arrowFunctionExpression(
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[j.identifier('newArgs'), j.identifier('lastArgs')],
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// Exit early if the newArgs and lastArgs are different lengths
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j.blockStatement([
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j.ifStatement(
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j.binaryExpression(
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'!==',
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j.memberExpression(
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j.identifier('newArgs'),
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j.identifier('length'),
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),
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j.memberExpression(
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j.identifier('lastArgs'),
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j.identifier('length'),
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),
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),
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j.blockStatement([j.returnStatement(j.booleanLiteral(false))]),
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),
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// create a __equalityFn constant that points to the existing equality function
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j.variableDeclaration('const', [
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j.variableDeclarator(j.identifier('__equalityFn'), equalityFn),
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]),
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// Call the original equalityFn for each argument
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j.returnStatement(
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j.callExpression(
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j.memberExpression(
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j.identifier('newArgs'),
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j.identifier('every'),
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),
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[
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j.arrowFunctionExpression(
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[j.identifier('newArg'), j.identifier('index')],
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j.callExpression(j.identifier('__equalityFn'), [
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j.identifier('newArg'),
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j.memberExpression(
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j.identifier('lastArgs'),
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j.identifier('index'),
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// computed: lastArgs[index]
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true,
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),
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]),
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),
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],
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),
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),
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]),
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);
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call.value.arguments[1] = customEqualityFn;
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return;
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}
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insertCommentToStartOfFile(
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j,
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source,
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'Unable to migrate memoize-one custom equality function.\nExpected a function or an identifier',
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);
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});
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return source.toSource(options.printOptions);
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}

‎community/memoize-one/codeshift.config.js

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export default {
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maintainers: ['alexreardon'],
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transforms: { '5.0.0': require.resolve('./5.0.0/transform') },
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};

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