refactor, indexof, map/set overloads

std/assembly/index.d.ts

@@ -882,7 +882,9 @@ declare namespace v8x16 {
 }
 /** Macro type evaluating to the underlying native WebAssembly type. */
 declare type native<T> = T;
-/** Special type evaluating the value type of a collection. */
+/** Special type evaluating the indexed access index type. */
+declare type indexof<T extends unknown[]> = keyof T;
+/** Special type evaluating the indexed access value type. */
 declare type valueof<T extends unknown[]> = T[0];
 
 /** Pseudo-class representing the backing class of integer types. */

std/assembly/map.ts

@@ -1,6 +1,7 @@
 /// <reference path="./rt/index.d.ts" />
 
 import { HASH } from "./util/hash";
+import { E_KEYNOTFOUND } from "util/error";
 
 // A deterministic hash map based on CloseTable from https://github.com/jorendorff/dht
 
@@ -96,11 +97,14 @@ export class Map<K,V> {
     return this.find(key, HASH<K>(key)) !== null;
   }
 
+  @operator("[]")
   get(key: K): V {
     var entry = this.find(key, HASH<K>(key));
-    return entry ? entry.value : <V>unreachable();
+    if (!entry) throw new Error(E_KEYNOTFOUND); // cannot represent `undefined`
+    return entry.value;
   }
 
+  @operator("[]=")
   set(key: K, value: V): void {
     var hashCode = HASH<K>(key);
     var entry = this.find(key, hashCode); // unmanaged!

std/assembly/set.ts

@@ -88,6 +88,7 @@ export class Set<T> {
     return null;
   }
 
+  @operator("[]")
   has(key: T): bool {
     return this.find(key, HASH<T>(key)) !== null;
   }
@@ -117,6 +118,12 @@ export class Set<T> {
     }
   }
 
+  @operator("[]=")
+  private __set(key: T, value: bool): void {
+    if (value) this.add(key);
+    else this.delete(key);
+  }
+
   delete(key: T): bool {
     var entry = this.find(key, HASH<T>(key)); // unmanaged!
     if (!entry) return false;

std/assembly/util/error.ts

@@ -20,3 +20,7 @@ export const E_HOLEYARRAY: string = "Element type must be nullable if array is h
 // @ts-ignore: decorator
 @lazy @inline
 export const E_NOTIMPLEMENTED: string = "Not implemented";
+
+// @ts-ignore: decorator
+@lazy @inline
+export const E_KEYNOTFOUND: string = "Key does not exist";

std/portable/index.d.ts

@@ -28,7 +28,9 @@ declare type usize = number;
 declare type f32 = number;
 declare type f64 = number;
 
-/** Special type evaluating the value type of a collection. */
+/** Special type evaluating the indexed access index type. */
+declare type indexof<T extends unknown[]> = keyof T;
+/** Special type evaluating the indexed access value type. */
 declare type valueof<T extends unknown[]> = T[0];
 
 // Compiler hints