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4 years ago
/**
* @fileoverview Enforce newlines between operands of ternary expressions
* @author Kai Cataldo
*/
"use strict";
const astUtils = require("./utils/ast-utils");
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
module.exports = {
meta: {
type: "layout",
docs: {
description: "enforce newlines between operands of ternary expressions",
category: "Stylistic Issues",
recommended: false,
url: "https://eslint.org/docs/rules/multiline-ternary"
},
schema: [
{
enum: ["always", "always-multiline", "never"]
}
],
messages: {
expectedTestCons: "Expected newline between test and consequent of ternary expression.",
expectedConsAlt: "Expected newline between consequent and alternate of ternary expression.",
unexpectedTestCons: "Unexpected newline between test and consequent of ternary expression.",
unexpectedConsAlt: "Unexpected newline between consequent and alternate of ternary expression."
}
},
create(context) {
const option = context.options[0];
const multiline = option !== "never";
const allowSingleLine = option === "always-multiline";
//--------------------------------------------------------------------------
// Helpers
//--------------------------------------------------------------------------
/**
* Tests whether node is preceded by supplied tokens
* @param {ASTNode} node node to check
* @param {ASTNode} parentNode parent of node to report
* @param {boolean} expected whether newline was expected or not
* @returns {void}
* @private
*/
function reportError(node, parentNode, expected) {
context.report({
node,
messageId: `${expected ? "expected" : "unexpected"}${node === parentNode.test ? "TestCons" : "ConsAlt"}`
});
}
//--------------------------------------------------------------------------
// Public
//--------------------------------------------------------------------------
return {
ConditionalExpression(node) {
const areTestAndConsequentOnSameLine = astUtils.isTokenOnSameLine(node.test, node.consequent);
const areConsequentAndAlternateOnSameLine = astUtils.isTokenOnSameLine(node.consequent, node.alternate);
if (!multiline) {
if (!areTestAndConsequentOnSameLine) {
reportError(node.test, node, false);
}
if (!areConsequentAndAlternateOnSameLine) {
reportError(node.consequent, node, false);
}
} else {
if (allowSingleLine && node.loc.start.line === node.loc.end.line) {
return;
}
if (areTestAndConsequentOnSameLine) {
reportError(node.test, node, true);
}
if (areConsequentAndAlternateOnSameLine) {
reportError(node.consequent, node, true);
}
}
}
};
}
};