205 lines
5.2 KiB
JavaScript
205 lines
5.2 KiB
JavaScript
/* eslint-disable complexity */
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import {isBigIntLiteral, isCallExpression} from './ast/index.js';
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import {fixSpaceAroundKeyword} from './fix/index.js';
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const MESSAGE_ID = 'prefer-math-min-max';
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const messages = {
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[MESSAGE_ID]: 'Prefer `Math.{{method}}()` to simplify ternary expressions.',
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};
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const isNumberTypeAnnotation = typeAnnotation => {
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if (typeAnnotation.type === 'TSNumberKeyword') {
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return true;
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}
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if (typeAnnotation.type === 'TSTypeAnnotation' && typeAnnotation.typeAnnotation.type === 'TSNumberKeyword') {
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return true;
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}
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if (typeAnnotation.type === 'TSTypeReference' && typeAnnotation.typeName.name === 'Number') {
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return true;
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}
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return false;
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};
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const getExpressionText = (node, sourceCode) => {
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const expressionNode = node.type === 'TSAsExpression' ? node.expression : node;
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if (node.type === 'TSAsExpression') {
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return getExpressionText(expressionNode, sourceCode);
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}
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return sourceCode.getText(expressionNode);
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};
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/** @param {import('eslint').Rule.RuleContext} context */
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const create = context => ({
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/** @param {import('estree').ConditionalExpression} conditionalExpression */
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ConditionalExpression(conditionalExpression) {
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const {test, consequent, alternate} = conditionalExpression;
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if (test.type !== 'BinaryExpression') {
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return;
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}
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const {operator, left, right} = test;
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const hasBigInt = [left, right].some(
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node =>
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isBigIntLiteral(node)
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|| isCallExpression(node, {
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name: 'BigInt',
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argumentsLength: 1,
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optional: false,
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}),
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);
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if (hasBigInt) {
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return;
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}
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const [leftText, rightText, alternateText, consequentText] = [left, right, alternate, consequent].map(node => getExpressionText(node, context.sourceCode));
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const isGreaterOrEqual = operator === '>' || operator === '>=';
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const isLessOrEqual = operator === '<' || operator === '<=';
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let method;
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// Prefer `Math.min()`
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if (
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// `height > 50 ? 50 : height`
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(isGreaterOrEqual && leftText === alternateText && rightText === consequentText)
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// `height < 50 ? height : 50`
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|| (isLessOrEqual && leftText === consequentText && rightText === alternateText)
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) {
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method = 'min';
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} else if (
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// `height > 50 ? height : 50`
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(isGreaterOrEqual && leftText === consequentText && rightText === alternateText)
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// `height < 50 ? 50 : height`
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|| (isLessOrEqual && leftText === alternateText && rightText === consequentText)
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) {
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method = 'max';
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}
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if (!method) {
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return;
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}
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for (const node of [left, right]) {
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let expressionNode = node;
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if (expressionNode.typeAnnotation && expressionNode.type === 'TSAsExpression') {
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// Ignore if the test is not a number comparison operator
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if (!isNumberTypeAnnotation(expressionNode.typeAnnotation)) {
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return;
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}
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expressionNode = expressionNode.expression;
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}
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// Find variable declaration
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if (expressionNode.type === 'Identifier') {
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const variable = context.sourceCode.getScope(expressionNode).variables.find(variable => variable.name === expressionNode.name);
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for (const definition of variable?.defs ?? []) {
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switch (definition.type) {
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case 'Parameter': {
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const identifier = definition.name;
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/**
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Capture the following statement
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```js
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function foo(a: number) {}
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```
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*/
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if (identifier.typeAnnotation?.type === 'TSTypeAnnotation' && !isNumberTypeAnnotation(identifier.typeAnnotation)) {
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return;
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}
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/**
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Capture the following statement
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```js
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function foo(a = 10) {}
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```
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*/
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if (identifier.parent.type === 'AssignmentPattern' && identifier.parent.right.type === 'Literal' && typeof identifier.parent.right.value !== 'number') {
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return;
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}
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break;
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}
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case 'Variable': {
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/** @type {import('estree').VariableDeclarator} */
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const variableDeclarator = definition.node;
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/**
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Capture the following statement
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```js
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var foo: number
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```
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*/
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if (variableDeclarator.id.typeAnnotation?.type === 'TSTypeAnnotation' && !isNumberTypeAnnotation(variableDeclarator.id.typeAnnotation)) {
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return;
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}
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/**
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Capture the following statement
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```js
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var foo = 10
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```
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*/
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if (variableDeclarator.init?.type === 'Literal' && typeof variableDeclarator.init.value !== 'number') {
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return;
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}
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break;
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}
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default:
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}
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}
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}
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}
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return {
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node: conditionalExpression,
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messageId: MESSAGE_ID,
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data: {method},
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/** @param {import('eslint').Rule.RuleFixer} fixer */
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* fix(fixer) {
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const {sourceCode} = context;
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yield fixSpaceAroundKeyword(fixer, conditionalExpression, context);
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const argumentsText = [left, right]
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.map(node => node.type === 'SequenceExpression' ? `(${sourceCode.getText(node)})` : sourceCode.getText(node))
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.join(', ');
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yield fixer.replaceText(conditionalExpression, `Math.${method}(${argumentsText})`);
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},
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};
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},
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});
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/** @type {import('eslint').Rule.RuleModule} */
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const config = {
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create,
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meta: {
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type: 'problem',
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docs: {
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description: 'Prefer `Math.min()` and `Math.max()` over ternaries for simple comparisons.',
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recommended: 'unopinionated',
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},
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fixable: 'code',
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messages,
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},
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};
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export default config;
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