// print
type PrintStart = {
type: "print";
subtype: "start";
attributes: {
controlsId: string;
tabId: number;
};
}
type PrintAbort = {
type: "print";
subtype: "abort";
attributes: {
controlsId: string;
};
}
type PrintLoading = {
type: "print";
subtype: "loading";
attributes: {
controlsId: string;
};
}
type Print = PrintLoading | PrintAbort | PrintStart
// chat
type ChatConnected = {
timestamp?: number | undefined;
type: "chat";
subtype: "connected";
attributes: {
controlsId: string;
component: string;
};
}
type ChatLoading = {
timestamp?: number | undefined;
type: "chat";
subtype: "loading";
attributes: {
controlsId: string;
component: string;
};
}
type ChatUpload = {
timestamp?: number | undefined;
type: "chat";
subtype: "unload";
attributes: {
controlsId: string;
component: string;
};
}
type Chat = ChatUpload | ChatLoading | ChatConnected
// Union of message
type Message = Print | Chat
What we want is that
function sendEncodeMessage(type, subtype, msg) {}
When we give `type` and `subtype`, the `msg` should be narrow down to the exact type
const printStart: PrintStart = {
type: 'print',
subtype: 'start',
attributes: {
tabId: 123,
controlsId: '123',
},
}
function sendEncodeMessage<
Type extends Message['type'],
Sub extends GetMessageSubtypes<Type>,
Msg extends GetMessage<Type, Sub>,
>(type: Type, subtype: Sub, msg: Msg) {}
sendEncodeMessage('print', 'start', printStart) // works
Helpers
export type GetMessagesByType<Type extends Message['type']> = Message extends infer Msg
? Msg extends { type: Type }
? Message
: never
: never
export type GetMessageSubtypes<Type extends Message['type']> = Type extends Message['type']
? GetMessagesByType<Type>['subtype']
: never
export type GetMessage<
Type extends Message['type'],
Subtype extends GetMessageSubtypes<Type>,
> = Message extends infer Msg ? (Msg extends { type: Type; subtype: Subtype } ? Message : never) : never
export type GetMessageAttr<Type extends Message['type'], Subtype extends GetMessageSubtypes<Type>> = GetMessage<
Type,
Subtype
> extends {
attributes: infer Attr
}
? Attr
: never
标签:Typescript,string,subtype,full,extends,attributes,type,controlsId From: https://www.cnblogs.com/Answer1215/p/17023841.html