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/**
* @fileoverview Rule to disallow empty functions.
* @author Toru Nagashima
*/
"use strict";
//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------
const astUtils = require("./utils/ast-utils");
//------------------------------------------------------------------------------
// Helpers
//------------------------------------------------------------------------------
const ALLOW_OPTIONS = Object.freeze([
"functions",
"arrowFunctions",
"generatorFunctions",
"methods",
"generatorMethods",
"getters",
"setters",
"constructors"
]);
/**
* Gets the kind of a given function node.
*
* @param {ASTNode} node - A function node to get. This is one of
* an ArrowFunctionExpression, a FunctionDeclaration, or a
* FunctionExpression.
* @returns {string} The kind of the function. This is one of "functions",
* "arrowFunctions", "generatorFunctions", "asyncFunctions", "methods",
* "generatorMethods", "asyncMethods", "getters", "setters", and
* "constructors".
*/
function getKind(node) {
const parent = node.parent;
let kind = "";
if (node.type === "ArrowFunctionExpression") {
return "arrowFunctions";
}
// Detects main kind.
if (parent.type === "Property") {
if (parent.kind === "get") {
return "getters";
}
if (parent.kind === "set") {
return "setters";
}
kind = parent.method ? "methods" : "functions";
} else if (parent.type === "MethodDefinition") {
if (parent.kind === "get") {
return "getters";
}
if (parent.kind === "set") {
return "setters";
}
if (parent.kind === "constructor") {
return "constructors";
}
kind = "methods";
} else {
kind = "functions";
}
// Detects prefix.
let prefix = "";
if (node.generator) {
prefix = "generator";
} else if (node.async) {
prefix = "async";
} else {
return kind;
}
return prefix + kind[0].toUpperCase() + kind.slice(1);
}
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
module.exports = {
meta: {
type: "suggestion",
docs: {
description: "disallow empty functions",
category: "Best Practices",
recommended: false,
url: "https://eslint.org/docs/rules/no-empty-function"
},
schema: [
{
type: "object",
properties: {
allow: {
type: "array",
items: { enum: ALLOW_OPTIONS },
uniqueItems: true
}
},
additionalProperties: false
}
],
messages: {
unexpected: "Unexpected empty {{name}}."
}
},
create(context) {
const options = context.options[0] || {};
const allowed = options.allow || [];
const sourceCode = context.getSourceCode();
/**
* Reports a given function node if the node matches the following patterns.
*
* - Not allowed by options.
* - The body is empty.
* - The body doesn't have any comments.
*
* @param {ASTNode} node - A function node to report. This is one of
* an ArrowFunctionExpression, a FunctionDeclaration, or a
* FunctionExpression.
* @returns {void}
*/
function reportIfEmpty(node) {
const kind = getKind(node);
const name = astUtils.getFunctionNameWithKind(node);
const innerComments = sourceCode.getTokens(node.body, {
includeComments: true,
filter: astUtils.isCommentToken
});
if (allowed.indexOf(kind) === -1 &&
node.body.type === "BlockStatement" &&
node.body.body.length === 0 &&
innerComments.length === 0
) {
context.report({
node,
loc: node.body.loc.start,
messageId: "unexpected",
data: { name }
});
}
}
return {
ArrowFunctionExpression: reportIfEmpty,
FunctionDeclaration: reportIfEmpty,
FunctionExpression: reportIfEmpty
};
}
};
|
