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//// [typeGuardOfFormThisMember.ts]
// There's a 'File' class in the stdlib, wrap with a namespace to avoid collision
namespace Test {
export class FileSystemObject {
isFSO: this is FileSystemObject;
get isFile(): this is File {
return this instanceof File;
}
set isFile(param) {
// noop
}
get isDirectory(): this is Directory {
return this instanceof Directory;
}
isNetworked: this is (Networked & this);
constructor(public path: string) {}
}
export class File extends FileSystemObject {
constructor(path: string, public content: string) { super(path); }
}
export class Directory extends FileSystemObject {
children: FileSystemObject[];
}
export interface Networked {
host: string;
}
let file: FileSystemObject = new File("foo/bar.txt", "foo");
file.isNetworked = false;
file.isFSO = file.isFile;
file.isFile = true;
let x = file.isFile;
if (file.isFile) {
file.content;
if (file.isNetworked) {
file.host;
file.content;
}
}
else if (file.isDirectory) {
file.children;
}
else if (file.isNetworked) {
file.host;
}
interface GenericLeadGuard<T> extends GenericGuard<T> {
lead(): void;
}
interface GenericFollowerGuard<T> extends GenericGuard<T> {
follow(): void;
}
interface GenericGuard<T> {
target: T;
isLeader: this is (GenericLeadGuard<T>);
isFollower: this is GenericFollowerGuard<T>;
}
let guard: GenericGuard<File>;
if (guard.isLeader) {
guard.lead();
}
else if (guard.isFollower) {
guard.follow();
}
interface SpecificGuard {
isMoreSpecific: this is MoreSpecificGuard;
}
interface MoreSpecificGuard extends SpecificGuard {
do(): void;
}
let general: SpecificGuard;
if (general.isMoreSpecific) {
general.do();
}
}
//// [typeGuardOfFormThisMember.js]
var __extends = (this && this.__extends) || (function () {
var extendStatics = function (d, b) {
extendStatics = Object.setPrototypeOf ||
({ __proto__: [] } instanceof Array && function (d, b) { d.__proto__ = b; }) ||
function (d, b) { for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p]; };
return extendStatics(d, b);
};
return function (d, b) {
extendStatics(d, b);
function __() { this.constructor = d; }
d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
};
})();
// There's a 'File' class in the stdlib, wrap with a namespace to avoid collision
var Test;
(function (Test) {
var FileSystemObject = /** @class */ (function () {
function FileSystemObject(path) {
this.path = path;
}
Object.defineProperty(FileSystemObject.prototype, "isFile", {
get: function () {
return this instanceof File;
},
set: function (param) {
// noop
},
enumerable: true,
configurable: true
});
Object.defineProperty(FileSystemObject.prototype, "isDirectory", {
get: function () {
return this instanceof Directory;
},
enumerable: true,
configurable: true
});
return FileSystemObject;
}());
Test.FileSystemObject = FileSystemObject;
var File = /** @class */ (function (_super) {
__extends(File, _super);
function File(path, content) {
var _this = _super.call(this, path) || this;
_this.content = content;
return _this;
}
return File;
}(FileSystemObject));
Test.File = File;
var Directory = /** @class */ (function (_super) {
__extends(Directory, _super);
function Directory() {
return _super !== null && _super.apply(this, arguments) || this;
}
return Directory;
}(FileSystemObject));
Test.Directory = Directory;
var file = new File("foo/bar.txt", "foo");
file.isNetworked = false;
file.isFSO = file.isFile;
file.isFile = true;
var x = file.isFile;
if (file.isFile) {
file.content;
if (file.isNetworked) {
file.host;
file.content;
}
}
else if (file.isDirectory) {
file.children;
}
else if (file.isNetworked) {
file.host;
}
var guard;
if (guard.isLeader) {
guard.lead();
}
else if (guard.isFollower) {
guard.follow();
}
var general;
if (general.isMoreSpecific) {
general.do();
}
})(Test || (Test = {}));
//// [typeGuardOfFormThisMember.d.ts]
declare namespace Test {
class FileSystemObject {
path: string;
isFSO: this is FileSystemObject;
isFile: this is File;
readonly isDirectory: this is Directory;
isNetworked: this is (Networked & this);
constructor(path: string);
}
class File extends FileSystemObject {
content: string;
constructor(path: string, content: string);
}
class Directory extends FileSystemObject {
children: FileSystemObject[];
}
interface Networked {
host: string;
}
}
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