tslint
Version:
An extensible static analysis linter for the TypeScript language
164 lines (163 loc) • 6.4 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 });
var tslib_1 = require("tslib");
var tsutils_1 = require("tsutils");
var ts = require("typescript");
var Lint = require("../index");
var Rule = /** @class */ (function (_super) {
tslib_1.__extends(Rule, _super);
function Rule() {
return _super !== null && _super.apply(this, arguments) || this;
}
Rule.prototype.applyWithProgram = function (sourceFile, program) {
return this.applyWithFunction(sourceFile, walk, undefined, program.getTypeChecker());
};
/* tslint:disable:object-literal-sort-keys */
Rule.metadata = {
ruleName: "return-undefined",
description: "Prefer `return;` in void functions and `return undefined;` in value-returning functions.",
optionsDescription: "Not configurable.",
options: null,
optionExamples: [true],
type: "style",
typescriptOnly: false,
requiresTypeInfo: true,
};
/* tslint:enable:object-literal-sort-keys */
Rule.FAILURE_STRING_VALUE_RETURN = "Value-returning function should use `return undefined;`, not just `return;`.";
Rule.FAILURE_STRING_VOID_RETURN = "`void` function should use `return;`, not `return undefined;`.";
return Rule;
}(Lint.Rules.TypedRule));
exports.Rule = Rule;
function walk(ctx, checker) {
return ts.forEachChild(ctx.sourceFile, function cb(node) {
if (tsutils_1.isReturnStatement(node)) {
check(node);
}
return ts.forEachChild(node, cb);
});
function check(node) {
var actualReturnKind = returnKindFromReturn(node);
if (actualReturnKind === undefined) {
return;
}
var functionReturningFrom = Lint.ancestorWhere(node, isFunctionLike);
if (functionReturningFrom === undefined) {
// Return outside of function is invalid
return;
}
var returnKindFromType = getReturnKind(functionReturningFrom, checker);
if (returnKindFromType !== undefined && returnKindFromType !== actualReturnKind) {
ctx.addFailureAtNode(node, returnKindFromType === ReturnKind.Void
? Rule.FAILURE_STRING_VOID_RETURN
: Rule.FAILURE_STRING_VALUE_RETURN);
}
}
}
function returnKindFromReturn(node) {
if (node.expression === undefined) {
return ReturnKind.Void;
}
else if (tsutils_1.isIdentifier(node.expression) && node.expression.text === "undefined") {
return ReturnKind.Value;
}
else {
return undefined;
}
}
var ReturnKind;
(function (ReturnKind) {
ReturnKind[ReturnKind["Void"] = 0] = "Void";
ReturnKind[ReturnKind["Value"] = 1] = "Value";
})(ReturnKind || (ReturnKind = {}));
function getReturnKind(node, checker) {
switch (node.kind) {
case ts.SyntaxKind.Constructor:
case ts.SyntaxKind.SetAccessor:
return ReturnKind.Void;
case ts.SyntaxKind.GetAccessor:
return ReturnKind.Value;
}
// Handle generator functions/methods:
if (node.asteriskToken !== undefined) {
return ReturnKind.Void;
}
var contextual = isFunctionExpressionLike(node) && node.type === undefined
? tryGetReturnType(checker.getContextualType(node), checker)
: undefined;
var returnType = contextual !== undefined
? contextual
: tryGetReturnType(checker.getTypeAtLocation(node), checker);
if (returnType === undefined || tsutils_1.isTypeFlagSet(returnType, ts.TypeFlags.Any)) {
return undefined;
}
if ((tsutils_1.hasModifier(node.modifiers, ts.SyntaxKind.AsyncKeyword)
? isEffectivelyVoidPromise
: isEffectivelyVoid)(returnType)) {
return ReturnKind.Void;
}
return ReturnKind.Value;
}
/** True for `void`, `undefined`, Promise<void>, or `void | undefined | Promise<void>`. */
function isEffectivelyVoidPromise(type) {
// Would need access to `checker.getPromisedTypeOfPromise` to do this properly.
// Assume that the return type is the global Promise (since this is an async function) and get its type argument.
return (
// tslint:disable-next-line:no-bitwise
tsutils_1.isTypeFlagSet(type, ts.TypeFlags.Void | ts.TypeFlags.Undefined) ||
(tsutils_1.isUnionType(type) && type.types.every(isEffectivelyVoidPromise)) ||
(tsutils_1.isTypeReference(type) &&
type.typeArguments !== undefined &&
type.typeArguments.length === 1 &&
isEffectivelyVoidPromise(type.typeArguments[0])));
}
/** True for `void`, `undefined`, or `void | undefined`. */
function isEffectivelyVoid(type) {
return (
// tslint:disable-next-line:no-bitwise
tsutils_1.isTypeFlagSet(type, ts.TypeFlags.Void | ts.TypeFlags.Undefined) ||
(tsutils_1.isUnionType(type) && type.types.every(isEffectivelyVoid)));
}
function tryGetReturnType(fnType, checker) {
if (fnType === undefined) {
return undefined;
}
var sigs = checker.getSignaturesOfType(fnType, ts.SignatureKind.Call);
if (sigs.length !== 1) {
return undefined;
}
return checker.getReturnTypeOfSignature(sigs[0]);
}
function isFunctionLike(node) {
switch (node.kind) {
case ts.SyntaxKind.FunctionDeclaration:
case ts.SyntaxKind.FunctionExpression:
case ts.SyntaxKind.ArrowFunction:
case ts.SyntaxKind.MethodDeclaration:
case ts.SyntaxKind.Constructor:
case ts.SyntaxKind.GetAccessor:
case ts.SyntaxKind.SetAccessor:
return true;
default:
return false;
}
}
function isFunctionExpressionLike(node) {
return (node.kind === ts.SyntaxKind.FunctionExpression || node.kind === ts.SyntaxKind.ArrowFunction);
}