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[Implement] Naive basic EventEmitter class #18

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92c8656
[Implement] Naive basic EventEmitter class
jtenner Jul 25, 2019
a99518d
[Implement] idof<Callback<T>>() for runtime callback type checking
jtenner Jul 25, 2019
5f12802
[Implement] Multiple Parameter Callbacks with
jtenner Jul 26, 2019
1ff2d68
[Fix] Veryify function type is void, obtain function parameter length
jtenner Jul 30, 2019
9da090e
[Update] experimental builtins in assemblyscript package
jtenner Jul 31, 2019
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[Implement] idof<Callback<T>>() for runtime callback type checking
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@jtenner
jtenner committed Jul 25, 2019
commit a99518de1a5b810f1a469c373fa2d9a577d183e1
68 changes: 31 additions & 37 deletions assembly/events/index.ts
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Original file line number Diff line number Diff line change
@@ -1,56 +1,50 @@
import { BLOCK_MAXSIZE, BLOCK, BLOCK_OVERHEAD } from "rt/common";
import { E_INVALIDLENGTH } from "util/error";
import { BLOCK_OVERHEAD, BLOCK } from "rt/common";

class EventList {
count: usize;

// adapted from https://github.com/AssemblyScript/assemblyscript/blob/master/std/assembly/array.ts#L11
ensureSize(minSize: usize): EventList {
let currentSize = changetype<BLOCK>(changetype<usize>(this) - BLOCK_OVERHEAD).rtSize;
let byteLength = (minSize + 2) << alignof<usize>();
if (byteLength > currentSize) {
if (byteLength > BLOCK_MAXSIZE) throw new RangeError(E_INVALIDLENGTH);
let oldData = changetype<usize>(this);
let newData = __realloc(oldData, byteLength);
// don't need to fill because they won't be used
// memory.fill(newData + currentSize, 0, byteLength - currentSize);
return changetype<EventList>(newData);
}
return this;
}
}
class Callback<T> {}
class Dummy {}

export class EventEmitter {
private _events: Map<string, EventList> = new Map<string, EventList>();

private _ensureEvent(event: string): void {
if (!this._events.has(event)) {
let byteLength = offsetof<EventList>() + (sizeof<usize>() << 2);
let list = changetype<EventList>(__alloc(byteLength, idof<EventList>()));
this._events.set(event, list);
public static EventMap: Map<i32, Map<string, i32>> = new Map<i32, Map<string, i32>>();
public static registerEventCallback<T, U>(event: string): void {
if (!isFunction<U>()) {
ERROR("Cannot register event callback of type U where U is not a function.");
}
if (!EventEmitter.EventMap.has(idof<T>())) {
EventEmitter.EventMap.set(idof<T>(), new Map<string, i32>());
}
let ClassEvents = EventEmitter.EventMap.get(idof<T>());
if (ClassEvents.has(event)) {
throw new Error("EventMap already contains a definition for event: " + event);
}
ClassEvents.set(event, idof<Callback<U>>());
}

private _events: Map<string, u32[]> = new Map<string, u32[]>();

public on<T>(event: string, callback: T): EventEmitter {
if (!isFunction<T>()) {
ERROR("EventEmitter#on can only be called with a callback of type T where T is a static function.");
}
this._ensureEvent(event);
let list = this._events.get(event);
list.count += 1;
list = list.ensureSize(list.count);
store<usize>(changetype<usize>(list) + ((list.count) << alignof<usize>()), changetype<usize>(callback));
let rtId = changetype<BLOCK>(changetype<usize>(this) - BLOCK_OVERHEAD).rtId;
let EventMap = EventEmitter.EventMap;
if (!EventMap.has(rtId)) throw new Error("Cannot attach events to an EventEmitter with no EventMap definitions.");
let ClassEvents = EventMap.get(rtId);
if (!ClassEvents.has(event)) throw new Error("Event does not exist: " + event);
let cbId = idof<Callback<T>>();
let classEventCallbackID = ClassEvents.get(event);
assert(cbId == classEventCallbackID);
if (!this._events.has(event)) this._events.set(event, new Array<u32>());
let eventList = this._events.get(event);
eventList.push(changetype<u32>(callback));
return this;
}

public emit<T>(event: string, data: T): EventEmitter {
if (this._events.has(event)) {
let list = this._events.get(event);
let count = list.count;
let start = changetype<usize>(list) + sizeof<usize>();
for (let i: usize = 0; i < count; i++) {
call_indirect(<u32>load<usize>(start), data);
start += sizeof<usize>();
let length = list.length;
for (let i: i32 = 0; i < length; i++) {
call_indirect(unchecked(list[i]), data);
}
}
return this;
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8 changes: 6 additions & 2 deletions tests/events.spec.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -4,10 +4,14 @@ let calls: i32 = 0;

type i32Callback = (value: i32) => void;

class CustomEventEmitter extends EventEmitter {}

EventEmitter.registerEventCallback<CustomEventEmitter, i32Callback>("data");

describe("events", () => {
test("events", () => {
let t = new EventEmitter();
t.on<i32Callback>("data", (value: i32) => {
let t = new CustomEventEmitter();
t.on<i32Callback>("data", <i32Callback>(value: i32) => {
calls += 1;
expect<i32>(value).toBe(42);
});
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