tslint
Version:
An extensible static analysis linter for the TypeScript language
116 lines (115 loc) • 4.87 kB
JavaScript
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/**
* @license
* Copyright 2017 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.
*/
Object.defineProperty(exports, "__esModule", { value: true });
exports.Rule = void 0;
var tslib_1 = require("tslib");
var tsutils_1 = require("tsutils");
var ts = require("typescript");
var Lint = require("../index");
var utils_1 = require("../utils");
var Rule = /** @class */ (function (_super) {
tslib_1.__extends(Rule, _super);
function Rule() {
return _super !== null && _super.apply(this, arguments) || this;
}
Rule.prototype.apply = function (sourceFile) {
return this.applyWithFunction(sourceFile, walk);
};
/* tslint:disable:object-literal-sort-keys */
Rule.metadata = {
ruleName: "no-return-await",
description: "Disallows unnecessary `return await`.",
rationale: Lint.Utils.dedent(templateObject_1 || (templateObject_1 = tslib_1.__makeTemplateObject(["\n An async function always wraps the return value in a Promise.\n Using `return await` just adds extra time before the overreaching promise is resolved without changing the semantics.\n "], ["\n An async function always wraps the return value in a Promise.\n Using \\`return await\\` just adds extra time before the overreaching promise is resolved without changing the semantics.\n "]))),
optionsDescription: "Not configurable.",
options: null,
optionExamples: [true],
type: "functionality",
typescriptOnly: false,
hasFix: true,
};
/* tslint:enable:object-literal-sort-keys */
Rule.FAILURE_STRING = "Unnecessary 'await'.";
return Rule;
}(Lint.Rules.AbstractRule));
exports.Rule = Rule;
function walk(ctx) {
return ts.forEachChild(ctx.sourceFile, function cb(node) {
if (node.kind === ts.SyntaxKind.AwaitExpression && isUnnecessaryAwait(node)) {
var expression = node.expression;
var keywordStart = expression.pos - "await".length;
ctx.addFailure(keywordStart, expression.pos, Rule.FAILURE_STRING, Lint.Replacement.deleteFromTo(keywordStart, expression.getStart(ctx.sourceFile)));
}
return ts.forEachChild(node, cb);
});
}
function isUnnecessaryAwait(node) {
while (true) {
var parent = node.parent;
outer: switch (parent.kind) {
case ts.SyntaxKind.ArrowFunction:
return true;
case ts.SyntaxKind.ReturnStatement:
return !isInsideTryBlock(parent.parent);
case ts.SyntaxKind.ParenthesizedExpression:
break;
case ts.SyntaxKind.ConditionalExpression:
if (parent.condition === node) {
return false;
}
break;
case ts.SyntaxKind.BinaryExpression:
if (parent.right === node) {
switch (parent.operatorToken.kind) {
case ts.SyntaxKind.AmpersandAmpersandToken:
case ts.SyntaxKind.BarBarToken:
case ts.SyntaxKind.CommaToken:
break outer;
}
}
return false;
default:
return false;
}
node = parent;
}
}
function isInsideTryBlock(node) {
while (node.parent !== undefined) {
// tslint:disable:deprecation This is needed for https://github.com/palantir/tslint/pull/4274 and will be fixed once TSLint
// requires tsutils > 3.0.
if (utils_1.isFunctionScopeBoundary(node)) {
// tslint:enable:deprecation
return false;
}
if (tsutils_1.isTryStatement(node.parent)) {
if (
// statements inside the try block always have an error handler, either catch or finally
node.parent.tryBlock === node ||
// statement inside the catch block only have an error handler if there is a finally block
(node.parent.finallyBlock !== undefined && node.parent.catchClause === node)) {
return true;
}
node = node.parent.parent;
}
else {
node = node.parent;
}
}
return false;
}
var templateObject_1;