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no-unexpected-multiline.js 4.18 KiB
/**
 * @fileoverview Rule to spot scenarios where a newline looks like it is ending a statement, but is not.
 * @author Glen Mailer
 */
"use strict";
//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------
const astUtils = require("./utils/ast-utils");
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
module.exports = {
    meta: {
        type: "problem",
        docs: {
            description: "disallow confusing multiline expressions",
            category: "Possible Errors",
            recommended: true,
            url: "https://eslint.org/docs/rules/no-unexpected-multiline"
        schema: [],
        messages: {
            function: "Unexpected newline between function and ( of function call.",
            property: "Unexpected newline between object and [ of property access.",
            taggedTemplate: "Unexpected newline between template tag and template literal.",
            division: "Unexpected newline between numerator and division operator."
    create(context) {
        const REGEX_FLAG_MATCHER = /^[gimsuy]+$/u;
        const sourceCode = context.getSourceCode();
        /**
         * Check to see if there is a newline between the node and the following open bracket
         * line's expression
         * @param {ASTNode} node The node to check.
         * @param {string} messageId The error messageId to use.
         * @returns {void}
         * @private
        function checkForBreakAfter(node, messageId) {
            const openParen = sourceCode.getTokenAfter(node, astUtils.isNotClosingParenToken);
            const nodeExpressionEnd = sourceCode.getTokenBefore(openParen);
            if (openParen.loc.start.line !== nodeExpressionEnd.loc.end.line) {
                context.report({
                    node,
                    loc: openParen.loc,
                    messageId
                });
        //--------------------------------------------------------------------------
        // Public API
        //--------------------------------------------------------------------------
        return {
            MemberExpression(node) {
if (!node.computed || node.optional) { return; } checkForBreakAfter(node.object, "property"); }, TaggedTemplateExpression(node) { const { quasi } = node; // handles common tags, parenthesized tags, and typescript's generic type arguments const tokenBefore = sourceCode.getTokenBefore(quasi); if (tokenBefore.loc.end.line !== quasi.loc.start.line) { context.report({ node, loc: { start: quasi.loc.start, end: { line: quasi.loc.start.line, column: quasi.loc.start.column + 1 } }, messageId: "taggedTemplate" }); } }, CallExpression(node) { if (node.arguments.length === 0 || node.optional) { return; } checkForBreakAfter(node.callee, "function"); }, "BinaryExpression[operator='/'] > BinaryExpression[operator='/'].left"(node) { const secondSlash = sourceCode.getTokenAfter(node, token => token.value === "/"); const tokenAfterOperator = sourceCode.getTokenAfter(secondSlash); if ( tokenAfterOperator.type === "Identifier" && REGEX_FLAG_MATCHER.test(tokenAfterOperator.value) && secondSlash.range[1] === tokenAfterOperator.range[0] ) { checkForBreakAfter(node.left, "division"); } } }; } };