eslint-plugin-unicorn/rules/utils/should-add-parentheses-to-member-expression-object.js

Various awesome ESLint rules

'use strict';

const isNewExpressionWithParentheses = require('./is-new-expression-with-parentheses');

// Determine whether this node is a decimal integer literal.
// Copied from https://github.com/eslint/eslint/blob/cc4871369645c3409dc56ded7a555af8a9f63d51/lib/rules/utils/ast-utils.js#L1237
const DECIMAL_INTEGER_PATTERN = /^(?:0|0[0-7]*[89]\d*|[1-9](?:_?\d)*)$/u;
const isDecimalInteger = node =>
	node.type === 'Literal' &&
	typeof node.value === 'number' &&
	DECIMAL_INTEGER_PATTERN.test(node.raw);

/**
Check if parentheses should to be added to a `node` when it's used as an `object` of `MemberExpression`.

@param {Node} node - The AST node to check.
@param {SourceCode} sourceCode - The source code object.
@returns {boolean}
*/
function shouldAddParenthesesToMemberExpressionObject(node, sourceCode) {
	switch (node.type) {
		// This is not a full list. Some other nodes like `FunctionDeclaration` don't need parentheses,
		// but it's not possible to be in the place we are checking at this point.
		case 'Identifier':
		case 'MemberExpression':
		case 'CallExpression':
		case 'ChainExpression':
		case 'TemplateLiteral':
			return false;
		case 'NewExpression':
			return !isNewExpressionWithParentheses(node, sourceCode);
		case 'Literal': {
			/* istanbul ignore next */
			if (isDecimalInteger(node)) {
				return true;
			}

			return false;
		}

		default:
			return true;
	}
}

module.exports = shouldAddParenthesesToMemberExpressionObject;