FixedArray experimentation

std/assembly/fixedarray.ts

@@ -0,0 +1,48 @@
+import { ALLOCATE, REGISTER, MAX_BYTELENGTH, HEADER, HEADER_SIZE, LINK } from "./runtime";
+
+// NOTE: DO NOT USE YET!
+
+// TODO: FixedArray<T,S> with S being the static size, i.e. `new FixedArray<i32,10>`.
+// Then hard-wire this special type to the compiler and do static length checks instead :)
+
+export class FixedArray<T> {
+  [key: number]: T;
+
+  constructor(length: i32) {
+    if (<u32>length > <u32>MAX_BYTELENGTH >>> alignof<T>()) throw new RangeError("Invalid length");
+    var outSize = <usize>length << alignof<T>();
+    var out = ALLOCATE(outSize);
+    memory.fill(out, 0, outSize);
+    return REGISTER<FixedArray<T>>(out);
+  }
+
+  get length(): i32 {
+    return changetype<HEADER>(changetype<usize>(this) - HEADER_SIZE).payloadSize >>> alignof<T>();
+  }
+
+  @operator("[]") private __get(index: i32): T {
+    if (<u32>index >= <u32>this.length) throw new RangeError("Offset out of bounds");
+    return load<T>(changetype<usize>(this) + (<usize>index << alignof<T>()));
+  }
+
+  @operator("[]=") private __set(index: i32, value: T): void {
+    if (<u32>index >= <u32>this.length) throw new RangeError("Offset out of bounds");
+    store<T>(changetype<usize>(this) + (<usize>index << alignof<T>()),
+      isManaged<T>()
+        ? LINK<T,this>(value, this)
+        : value
+    );
+  }
+
+  @operator("{}") private __unchecked_get(index: i32): T {
+    return load<T>(changetype<usize>(this) + (<usize>index << alignof<T>()));
+  }
+
+  @operator("{}=") private __unchecked_set(index: i32, value: T): void {
+    store<T>(changetype<usize>(this) + (<usize>index << alignof<T>()),
+      isManaged<T>()
+        ? LINK<T,this>(value, this)
+        : value
+    );
+  }
+}