84 lines
1.8 KiB
TypeScript
84 lines
1.8 KiB
TypeScript
// @target: es5
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// @declaration: true
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// There's a 'File' class in the stdlib, wrap with a namespace to avoid collision
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namespace Test {
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export class FileSystemObject {
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isFSO: this is FileSystemObject;
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get isFile(): this is File {
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return this instanceof File;
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}
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set isFile(param) {
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// noop
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}
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get isDirectory(): this is Directory {
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return this instanceof Directory;
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}
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isNetworked: this is (Networked & this);
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constructor(public path: string) {}
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}
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export class File extends FileSystemObject {
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constructor(path: string, public content: string) { super(path); }
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}
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export class Directory extends FileSystemObject {
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children: FileSystemObject[];
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}
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export interface Networked {
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host: string;
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}
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let file: FileSystemObject = new File("foo/bar.txt", "foo");
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file.isNetworked = false;
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file.isFSO = file.isFile;
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file.isFile = true;
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let x = file.isFile;
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if (file.isFile) {
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file.content;
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if (file.isNetworked) {
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file.host;
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file.content;
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}
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}
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else if (file.isDirectory) {
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file.children;
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}
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else if (file.isNetworked) {
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file.host;
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}
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interface GenericLeadGuard<T> extends GenericGuard<T> {
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lead(): void;
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}
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interface GenericFollowerGuard<T> extends GenericGuard<T> {
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follow(): void;
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}
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interface GenericGuard<T> {
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target: T;
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isLeader: this is (GenericLeadGuard<T>);
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isFollower: this is GenericFollowerGuard<T>;
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}
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let guard: GenericGuard<File>;
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if (guard.isLeader) {
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guard.lead();
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}
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else if (guard.isFollower) {
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guard.follow();
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}
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interface SpecificGuard {
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isMoreSpecific: this is MoreSpecificGuard;
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}
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interface MoreSpecificGuard extends SpecificGuard {
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do(): void;
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}
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let general: SpecificGuard;
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if (general.isMoreSpecific) {
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general.do();
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}
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}
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