perf: Optimize TextEncoder and TextDecoder

cli/js/web/text_encoding.ts

@@ -26,7 +26,7 @@
 import * as base64 from "./base64.ts";
 import { decodeUtf8 } from "./decode_utf8.ts";
 import * as domTypes from "./dom_types.ts";
-import { encodeUtf8 } from "./encode_utf8.ts";
+import { core } from "../core.ts";
 
 const CONTINUE = null;
 const END_OF_STREAM = -1;
@@ -352,6 +352,15 @@ export class TextDecoder {
  bytes = new Uint8Array(0);
  }
 
+ // For simple utf-8 decoding "Deno.core.decode" can be used for performance
+ if (
+ this._encoding === "utf-8" &&
+ this.fatal === false &&
+ this.ignoreBOM === false
+ ) {
+ return core.decode(bytes);
+ }
+
  // For performance reasons we utilise a highly optimised decoder instead of
  // the general decoder.
  if (this._encoding === "utf-8") {
@@ -396,10 +405,9 @@ interface TextEncoderEncodeIntoResult {
 export class TextEncoder {
  readonly encoding = "utf-8";
  encode(input = ""): Uint8Array {
- // For performance reasons we utilise a highly optimised decoder instead of
- // the general decoder.
+ // Deno.core.encode() provides very efficient utf-8 encoding
  if (this.encoding === "utf-8") {
- return encodeUtf8(input);
+ return core.encode(input);
  }
 
  const encoder = new UTF8Encoder();

core/bindings.rs

@@ -632,7 +632,20 @@ fn encode(
  };
  let text_str = text.to_rust_string_lossy(scope);
  let text_bytes = text_str.as_bytes().to_vec().into_boxed_slice();
- let buf = boxed_slice_to_uint8array(scope, text_bytes);
+
+ let buf = if text_bytes.is_empty() {
+ let ab = v8::ArrayBuffer::new(scope, 0);
+ v8::Uint8Array::new(ab, 0, 0).expect("Failed to create UintArray8")
+ } else {
+ let buf_len = text_bytes.len();
+ let backing_store =
+ v8::ArrayBuffer::new_backing_store_from_boxed_slice(text_bytes);
+ let mut backing_store_shared = backing_store.make_shared();
+ let ab =
+ v8::ArrayBuffer::with_backing_store(scope, &mut backing_store_shared);
+ v8::Uint8Array::new(ab, 0, buf_len).expect("Failed to create UintArray8")
+ };
+
  rv.set(buf.into())
 }
 

core/encode_decode_test.js

@@ -27,12 +27,18 @@ function main() {
  108, 100 
  ];
 
+ const empty = Deno.core.encode("");
+ if (empty.length !== 0) throw new Error("assert");
+
  assertArrayEquals(Array.from(Deno.core.encode("𝓽𝓮𝔁𝓽")), fixture1);
  assertArrayEquals(
  Array.from(Deno.core.encode("Hello \udc12\ud834 World")),
  fixture2
  );
 
+ const emptyBuf = Deno.core.decode(new Uint8Array(0));
+ if (emptyBuf !== "") throw new Error("assert");
+
  assert(Deno.core.decode(new Uint8Array(fixture1)) === "𝓽𝓮𝔁𝓽");
  assert(Deno.core.decode(new Uint8Array(fixture2)) === "Hello �� World");
 }