forked from palantir/tslint
/
noAsyncWithoutAwaitRule.ts
132 lines (112 loc) · 4.87 KB
/
noAsyncWithoutAwaitRule.ts
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/**
* @license
* Copyright 2018 Palantir Technologies, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import * as ts from "typescript";
import * as Lint from "../index";
import { codeExamples } from "./code-examples/noAsyncWithoutAwait.examples";
export class Rule extends Lint.Rules.AbstractRule {
public static FAILURE_STRING = "Functions marked async must contain an await or return statement.";
public static metadata: Lint.IRuleMetadata = {
codeExamples,
description: Rule.FAILURE_STRING,
hasFix: false,
optionExamples: [true],
options: null,
optionsDescription: "Not configurable.",
/* tslint:disable:max-line-length */
rationale: Lint.Utils.dedent`
Marking a function as \`async\` without using \`await\` or returning a value inside it can lead to an unintended promise return and a larger transpiled output.
Often the function can be synchronous and the \`async\` keyword is there by mistake.
Return statements are allowed has sometimes it is desirable to wrap the returned value in promise`,
/* tslint:enable:max-line-length */
ruleName: "no-async-without-await",
type: "functionality",
typescriptOnly: false,
};
public apply(sourceFile: ts.SourceFile): Lint.RuleFailure[] {
return this.applyWithWalker(new Walk(sourceFile, this.getOptions()));
}
}
class Walk extends Lint.RuleWalker {
protected visitFunctionDeclaration(node: ts.FunctionDeclaration) {
this.addFailureIfAsyncFunctionHasNoAwait(node);
super.visitFunctionDeclaration(node);
}
protected visitArrowFunction(node: ts.ArrowFunction) {
this.addFailureIfAsyncFunctionHasNoAwait(node);
super.visitArrowFunction(node);
}
protected visitMethodDeclaration(node: ts.MethodDeclaration) {
this.addFailureIfAsyncFunctionHasNoAwait(node);
super.visitMethodDeclaration(node);
}
private isAsyncFunction(node: ts.Node): boolean {
return this.getAsyncModifier(node) !== undefined;
}
private getAsyncModifier(node: ts.Node) {
if (node.modifiers !== undefined) {
return node.modifiers.find((modifier) => modifier.kind === ts.SyntaxKind.AsyncKeyword);
}
return undefined;
}
private isAwait(node: ts.Node): boolean {
return node.kind === ts.SyntaxKind.AwaitKeyword;
}
private isReturn(node: ts.Node): boolean {
return node.kind === ts.SyntaxKind.ReturnKeyword;
}
private functionBlockHasAwait(node: ts.Node): boolean {
if (this.isAwait(node)) {
return true;
}
// tslint:disable-next-line:no-unsafe-any
if (node.kind === ts.SyntaxKind.ArrowFunction
|| node.kind === ts.SyntaxKind.FunctionDeclaration) {
return false;
}
const awaitInChildren = node.getChildren()
.map((functionBlockNode: ts.Node) => this.functionBlockHasAwait(functionBlockNode));
return awaitInChildren.some(Boolean);
}
private functionBlockHasReturn(node: ts.Node): boolean {
if (this.isReturn(node)) {
return true;
}
// tslint:disable-next-line:no-unsafe-any
if (node.kind === ts.SyntaxKind.ArrowFunction
|| node.kind === ts.SyntaxKind.FunctionDeclaration) {
return false;
}
const returnInChildren = node.getChildren()
.map((functionBlockNode: ts.Node) => this.functionBlockHasReturn(functionBlockNode));
return returnInChildren.some(Boolean);
}
private isShortArrowReturn(node: ts.ArrowFunction | ts.FunctionDeclaration | ts.MethodDeclaration) {
return node.kind === ts.SyntaxKind.ArrowFunction && node.body.kind !== ts.SyntaxKind.Block;
}
private addFailureIfAsyncFunctionHasNoAwait(node: ts.ArrowFunction | ts.FunctionDeclaration | ts.MethodDeclaration) {
if (!this.isShortArrowReturn(node)
&& this.isAsyncFunction(node)
&& !this.functionBlockHasAwait(node.body as ts.Node)
&& !this.functionBlockHasReturn(node.body as ts.Node)
) {
const asyncModifier = this.getAsyncModifier(node);
if (asyncModifier !== undefined) {
this.addFailureAt(asyncModifier.getStart(), asyncModifier.getEnd() - asyncModifier.getStart(), Rule.FAILURE_STRING);
}
}
}
}