feat: Add Deno.core.encodeBinaryString() (denoland#558)

Closes denoland#556

core/01_core.js

@@ -404,6 +404,7 @@
     op_destructure_error,
     op_dispatch_exception,
     op_encode,
+    op_encode_binary_string,
     op_eval_context,
     op_event_loop_has_more_work,
     op_get_promise_details,
@@ -591,6 +592,7 @@
     ) => op_eval_context(source, specifier),
     hostObjectBrand,
     encode: (text) => op_encode(text),
+    encodeBinaryString: (buffer) => op_encode_binary_string(buffer),
     decode: (buffer) => op_decode(buffer),
     serialize: (
       value,

core/lib.deno_core.d.ts

@@ -324,6 +324,8 @@ declare namespace Deno {
 
     function createCancelHandle(): number;
 
+    function encodeBinaryString(data: Uint8Array): string;
+
     const build: {
       target: string;
       arch: string;

core/ops_builtin.rs

@@ -16,6 +16,7 @@ use crate::OpState;
 use crate::Resource;
 use anyhow::Error;
 use bytes::BytesMut;
+use serde_v8::ByteString;
 use std::cell::RefCell;
 use std::io::stderr;
 use std::io::stdout;
@@ -56,6 +57,7 @@ builtin_ops! {
   op_str_byte_length,
   op_panic,
   op_cancel_handle,
+  op_encode_binary_string,
   ops_builtin_types::op_is_any_array_buffer,
   ops_builtin_types::op_is_arguments_object,
   ops_builtin_types::op_is_array_buffer,
@@ -381,3 +383,9 @@ fn op_str_byte_length(
 pub fn op_cancel_handle(state: &mut OpState) -> u32 {
   state.resource_table.add(CancelHandle::new())
 }
+
+#[op2]
+#[serde]
+fn op_encode_binary_string(#[buffer] s: &[u8]) -> ByteString {
+  ByteString::from(s)
+}

testing/unit/encode_decode_test.ts

@@ -57,3 +57,39 @@ test(function testStringTooLarge() {
   }
   assert(thrown);
 });
+
+test(function binaryEncode() {
+  function asBinaryString(bytes: Uint8Array): string {
+    return Array.from(bytes).map(
+      (v: number) => String.fromCodePoint(v),
+    ).join("");
+  }
+
+  function decodeBinary(binaryString: string) {
+    const chars: string[] = Array.from(binaryString);
+    return chars.map((v: string): number | undefined => v.codePointAt(0));
+  }
+
+  // invalid utf-8 code points
+  const invalid = new Uint8Array([0xC0]);
+  assertArrayEquals(
+    Deno.core.encodeBinaryString(invalid),
+    asBinaryString(invalid),
+  );
+
+  const invalid2 = new Uint8Array([0xC1]);
+  assertArrayEquals(
+    Deno.core.encodeBinaryString(invalid2),
+    asBinaryString(invalid2),
+  );
+
+  for (let i = 0, j = 255; i <= 255; i++, j--) {
+    const bytes = new Uint8Array([i, j]);
+    const binaryString = Deno.core.encodeBinaryString(bytes);
+    assertArrayEquals(
+      binaryString,
+      asBinaryString(bytes),
+    );
+    assertArrayEquals(Array.from(bytes), decodeBinary(binaryString));
+  }
+});