275 lines
9.2 KiB
JavaScript
275 lines
9.2 KiB
JavaScript
/**
|
|
* @fileoverview Rule to flag use of constructors without capital letters
|
|
* @author Nicholas C. Zakas
|
|
*/
|
|
|
|
"use strict";
|
|
|
|
//------------------------------------------------------------------------------
|
|
// Requirements
|
|
//------------------------------------------------------------------------------
|
|
|
|
const astUtils = require("./utils/ast-utils");
|
|
|
|
//------------------------------------------------------------------------------
|
|
// Helpers
|
|
//------------------------------------------------------------------------------
|
|
|
|
const CAPS_ALLOWED = [
|
|
"Array",
|
|
"Boolean",
|
|
"Date",
|
|
"Error",
|
|
"Function",
|
|
"Number",
|
|
"Object",
|
|
"RegExp",
|
|
"String",
|
|
"Symbol",
|
|
"BigInt"
|
|
];
|
|
|
|
/**
|
|
* Ensure that if the key is provided, it must be an array.
|
|
* @param {Object} obj Object to check with `key`.
|
|
* @param {string} key Object key to check on `obj`.
|
|
* @param {*} fallback If obj[key] is not present, this will be returned.
|
|
* @returns {string[]} Returns obj[key] if it's an Array, otherwise `fallback`
|
|
*/
|
|
function checkArray(obj, key, fallback) {
|
|
|
|
/* istanbul ignore if */
|
|
if (Object.prototype.hasOwnProperty.call(obj, key) && !Array.isArray(obj[key])) {
|
|
throw new TypeError(`${key}, if provided, must be an Array`);
|
|
}
|
|
return obj[key] || fallback;
|
|
}
|
|
|
|
/**
|
|
* A reducer function to invert an array to an Object mapping the string form of the key, to `true`.
|
|
* @param {Object} map Accumulator object for the reduce.
|
|
* @param {string} key Object key to set to `true`.
|
|
* @returns {Object} Returns the updated Object for further reduction.
|
|
*/
|
|
function invert(map, key) {
|
|
map[key] = true;
|
|
return map;
|
|
}
|
|
|
|
/**
|
|
* Creates an object with the cap is new exceptions as its keys and true as their values.
|
|
* @param {Object} config Rule configuration
|
|
* @returns {Object} Object with cap is new exceptions.
|
|
*/
|
|
function calculateCapIsNewExceptions(config) {
|
|
let capIsNewExceptions = checkArray(config, "capIsNewExceptions", CAPS_ALLOWED);
|
|
|
|
if (capIsNewExceptions !== CAPS_ALLOWED) {
|
|
capIsNewExceptions = capIsNewExceptions.concat(CAPS_ALLOWED);
|
|
}
|
|
|
|
return capIsNewExceptions.reduce(invert, {});
|
|
}
|
|
|
|
//------------------------------------------------------------------------------
|
|
// Rule Definition
|
|
//------------------------------------------------------------------------------
|
|
|
|
module.exports = {
|
|
meta: {
|
|
type: "suggestion",
|
|
|
|
docs: {
|
|
description: "require constructor names to begin with a capital letter",
|
|
category: "Stylistic Issues",
|
|
recommended: false,
|
|
url: "https://eslint.org/docs/rules/new-cap"
|
|
},
|
|
|
|
schema: [
|
|
{
|
|
type: "object",
|
|
properties: {
|
|
newIsCap: {
|
|
type: "boolean",
|
|
default: true
|
|
},
|
|
capIsNew: {
|
|
type: "boolean",
|
|
default: true
|
|
},
|
|
newIsCapExceptions: {
|
|
type: "array",
|
|
items: {
|
|
type: "string"
|
|
}
|
|
},
|
|
newIsCapExceptionPattern: {
|
|
type: "string"
|
|
},
|
|
capIsNewExceptions: {
|
|
type: "array",
|
|
items: {
|
|
type: "string"
|
|
}
|
|
},
|
|
capIsNewExceptionPattern: {
|
|
type: "string"
|
|
},
|
|
properties: {
|
|
type: "boolean",
|
|
default: true
|
|
}
|
|
},
|
|
additionalProperties: false
|
|
}
|
|
],
|
|
messages: {
|
|
upper: "A function with a name starting with an uppercase letter should only be used as a constructor.",
|
|
lower: "A constructor name should not start with a lowercase letter."
|
|
}
|
|
},
|
|
|
|
create(context) {
|
|
|
|
const config = Object.assign({}, context.options[0]);
|
|
|
|
config.newIsCap = config.newIsCap !== false;
|
|
config.capIsNew = config.capIsNew !== false;
|
|
const skipProperties = config.properties === false;
|
|
|
|
const newIsCapExceptions = checkArray(config, "newIsCapExceptions", []).reduce(invert, {});
|
|
const newIsCapExceptionPattern = config.newIsCapExceptionPattern ? new RegExp(config.newIsCapExceptionPattern, "u") : null;
|
|
|
|
const capIsNewExceptions = calculateCapIsNewExceptions(config);
|
|
const capIsNewExceptionPattern = config.capIsNewExceptionPattern ? new RegExp(config.capIsNewExceptionPattern, "u") : null;
|
|
|
|
const listeners = {};
|
|
|
|
const sourceCode = context.getSourceCode();
|
|
|
|
//--------------------------------------------------------------------------
|
|
// Helpers
|
|
//--------------------------------------------------------------------------
|
|
|
|
/**
|
|
* Get exact callee name from expression
|
|
* @param {ASTNode} node CallExpression or NewExpression node
|
|
* @returns {string} name
|
|
*/
|
|
function extractNameFromExpression(node) {
|
|
return node.callee.type === "Identifier"
|
|
? node.callee.name
|
|
: astUtils.getStaticPropertyName(node.callee) || "";
|
|
}
|
|
|
|
/**
|
|
* Returns the capitalization state of the string -
|
|
* Whether the first character is uppercase, lowercase, or non-alphabetic
|
|
* @param {string} str String
|
|
* @returns {string} capitalization state: "non-alpha", "lower", or "upper"
|
|
*/
|
|
function getCap(str) {
|
|
const firstChar = str.charAt(0);
|
|
|
|
const firstCharLower = firstChar.toLowerCase();
|
|
const firstCharUpper = firstChar.toUpperCase();
|
|
|
|
if (firstCharLower === firstCharUpper) {
|
|
|
|
// char has no uppercase variant, so it's non-alphabetic
|
|
return "non-alpha";
|
|
}
|
|
if (firstChar === firstCharLower) {
|
|
return "lower";
|
|
}
|
|
return "upper";
|
|
|
|
}
|
|
|
|
/**
|
|
* Check if capitalization is allowed for a CallExpression
|
|
* @param {Object} allowedMap Object mapping calleeName to a Boolean
|
|
* @param {ASTNode} node CallExpression node
|
|
* @param {string} calleeName Capitalized callee name from a CallExpression
|
|
* @param {Object} pattern RegExp object from options pattern
|
|
* @returns {boolean} Returns true if the callee may be capitalized
|
|
*/
|
|
function isCapAllowed(allowedMap, node, calleeName, pattern) {
|
|
const sourceText = sourceCode.getText(node.callee);
|
|
|
|
if (allowedMap[calleeName] || allowedMap[sourceText]) {
|
|
return true;
|
|
}
|
|
|
|
if (pattern && pattern.test(sourceText)) {
|
|
return true;
|
|
}
|
|
|
|
const callee = astUtils.skipChainExpression(node.callee);
|
|
|
|
if (calleeName === "UTC" && callee.type === "MemberExpression") {
|
|
|
|
// allow if callee is Date.UTC
|
|
return callee.object.type === "Identifier" &&
|
|
callee.object.name === "Date";
|
|
}
|
|
|
|
return skipProperties && callee.type === "MemberExpression";
|
|
}
|
|
|
|
/**
|
|
* Reports the given messageId for the given node. The location will be the start of the property or the callee.
|
|
* @param {ASTNode} node CallExpression or NewExpression node.
|
|
* @param {string} messageId The messageId to report.
|
|
* @returns {void}
|
|
*/
|
|
function report(node, messageId) {
|
|
let callee = astUtils.skipChainExpression(node.callee);
|
|
|
|
if (callee.type === "MemberExpression") {
|
|
callee = callee.property;
|
|
}
|
|
|
|
context.report({ node, loc: callee.loc, messageId });
|
|
}
|
|
|
|
//--------------------------------------------------------------------------
|
|
// Public
|
|
//--------------------------------------------------------------------------
|
|
|
|
if (config.newIsCap) {
|
|
listeners.NewExpression = function(node) {
|
|
|
|
const constructorName = extractNameFromExpression(node);
|
|
|
|
if (constructorName) {
|
|
const capitalization = getCap(constructorName);
|
|
const isAllowed = capitalization !== "lower" || isCapAllowed(newIsCapExceptions, node, constructorName, newIsCapExceptionPattern);
|
|
|
|
if (!isAllowed) {
|
|
report(node, "lower");
|
|
}
|
|
}
|
|
};
|
|
}
|
|
|
|
if (config.capIsNew) {
|
|
listeners.CallExpression = function(node) {
|
|
|
|
const calleeName = extractNameFromExpression(node);
|
|
|
|
if (calleeName) {
|
|
const capitalization = getCap(calleeName);
|
|
const isAllowed = capitalization !== "upper" || isCapAllowed(capIsNewExceptions, node, calleeName, capIsNewExceptionPattern);
|
|
|
|
if (!isAllowed) {
|
|
report(node, "upper");
|
|
}
|
|
}
|
|
};
|
|
}
|
|
|
|
return listeners;
|
|
}
|
|
};
|