feat: Deno.core.{encode,decode}; standalone UTF-8 encoding/decoding (#4349)

This commits add two new methods to "Deno.core" namespace: "encode" and "decode".

Those methods are bound in Rust to provide a) fast b) generally available of encoding and decoding UTF-8 strings. 

Both methods are now used in "cli/js/dispatch_json.ts".

4 files changed, 74 insertions, 3 deletions

diff --git a/cli/js/globals.ts b/cli/js/globals.ts
index 8d122878f..21ce7e619 100644
--- a/cli/js/globals.ts
+++ b/cli/js/globals.ts
@@ -97,6 +97,9 @@ declare global {
     evalContext(code: string): [any, EvalErrorInfo | null];
 
     formatError: (e: Error) => string;
+
+    decode(bytes: Uint8Array): string;
+    encode(text: string): Uint8Array;
   }
 
   // Only `var` variables show up in the `globalThis` type when doing a global
diff --git a/cli/js/ops/dispatch_json.ts b/cli/js/ops/dispatch_json.ts
index 4aa1f6b8b..9ff0f13f5 100644
--- a/cli/js/ops/dispatch_json.ts
+++ b/cli/js/ops/dispatch_json.ts
@@ -1,6 +1,5 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
 import * as util from "../util.ts";
-import { TextEncoder, TextDecoder } from "../web/text_encoding.ts";
 import { core } from "../core.ts";
 import { OPS_CACHE } from "../runtime.ts";
 import { ErrorKind, getErrorClass } from "../errors.ts";
@@ -30,13 +29,13 @@ function nextPromiseId(): number {
 }
 
 function decode(ui8: Uint8Array): JsonResponse {
-  const s = new TextDecoder().decode(ui8);
+  const s = core.decode(ui8);
   return JSON.parse(s) as JsonResponse;
 }
 
 function encode(args: object): Uint8Array {
   const s = JSON.stringify(args);
-  return new TextEncoder().encode(s);
+  return core.encode(s);
 }
 
 function unwrapResponse(res: JsonResponse): Ok {
diff --git a/cli/tests/core_decode_perf.js b/cli/tests/core_decode_perf.js
new file mode 100644
index 000000000..fc00b8996
--- /dev/null
+++ b/cli/tests/core_decode_perf.js
@@ -0,0 +1,37 @@
+const mixed = new TextEncoder().encode("@Ā๐😀");
+
+function generateRandom(bytes) {
+  const result = new Uint8Array(bytes);
+  let i = 0;
+  while (i < bytes) {
+    const toAdd = Math.floor(Math.random() * Math.min(4, bytes - i));
+    switch (toAdd) {
+      case 0:
+        result[i] = mixed[0];
+        i++;
+        break;
+      case 1:
+        result[i] = mixed[1];
+        result[i + 1] = mixed[2];
+        i += 2;
+        break;
+      case 2:
+        result[i] = mixed[3];
+        result[i + 1] = mixed[4];
+        result[i + 2] = mixed[5];
+        i += 3;
+        break;
+      case 3:
+        result[i] = mixed[6];
+        result[i + 1] = mixed[7];
+        result[i + 2] = mixed[8];
+        result[i + 3] = mixed[9];
+        i += 4;
+        break;
+    }
+  }
+  return result;
+}
+
+const randomData = generateRandom(1024);
+for (let i = 0; i < 10_000; i++) Deno.core.decode(randomData);
diff --git a/cli/tests/core_encode_perf.js b/cli/tests/core_encode_perf.js
new file mode 100644
index 000000000..5cde81c7a
--- /dev/null
+++ b/cli/tests/core_encode_perf.js
@@ -0,0 +1,32 @@
+const mixed = "@Ā๐😀";
+
+function generateRandom(bytes) {
+  let result = "";
+  let i = 0;
+  while (i < bytes) {
+    const toAdd = Math.floor(Math.random() * Math.min(4, bytes - i));
+    switch (toAdd) {
+      case 0:
+        result += mixed[0];
+        i++;
+        break;
+      case 1:
+        result += mixed[1];
+        i++;
+        break;
+      case 2:
+        result += mixed[2];
+        i++;
+        break;
+      case 3:
+        result += mixed[3];
+        result += mixed[4];
+        i += 2;
+        break;
+    }
+  }
+  return result;
+}
+
+const randomData = generateRandom(1024);
+for (let i = 0; i < 10_000; i++) Deno.core.encode(randomData);