69 lines
1.6 KiB
JavaScript
69 lines
1.6 KiB
JavaScript
/**
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* @fileoverview Disallow sparse arrays
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* @author Nicholas C. Zakas
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*/
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'use strict';
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const astUtils = require('./utils/ast-utils');
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//------------------------------------------------------------------------------
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// Rule Definition
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//------------------------------------------------------------------------------
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/** @type {import('../types').Rule.RuleModule} */
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module.exports = {
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meta: {
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type: 'problem',
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docs: {
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description: 'Disallow sparse arrays',
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recommended: true,
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url: 'https://eslint.org/docs/latest/rules/no-sparse-arrays',
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},
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schema: [],
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messages: {
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unexpectedSparseArray: 'Unexpected comma in middle of array.',
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},
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},
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create(context) {
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//--------------------------------------------------------------------------
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// Public
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//--------------------------------------------------------------------------
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return {
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ArrayExpression(node) {
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if (!node.elements.includes(null)) {
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return;
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}
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const { sourceCode } = context;
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let commaToken;
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for (const [index, element] of node.elements.entries()) {
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if (index === node.elements.length - 1 && element) {
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return;
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}
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commaToken = sourceCode.getTokenAfter(
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element ?? commaToken ?? sourceCode.getFirstToken(node),
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astUtils.isCommaToken
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);
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if (element) {
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continue;
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}
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context.report({
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node,
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loc: commaToken.loc,
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messageId: 'unexpectedSparseArray',
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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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