util: Add format for SharedArrayBuffer

PR-URL: https://github.com/nodejs/node/pull/8587
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

lib/util.js

@@ -435,9 +435,10 @@ function formatValue(ctx, value, recurseTimes) {
       formatted = formatPrimitiveNoColor(ctx, raw);
       return ctx.stylize('[Boolean: ' + formatted + ']', 'boolean');
     }
-    // Fast path for ArrayBuffer.  Can't do the same for DataView because it
+    // Fast path for ArrayBuffer and SharedArrayBuffer.
-    // has a non-primitive .buffer property that we need to recurse for.
+    // Can't do the same for DataView because it has a non-primitive
-    if (binding.isArrayBuffer(value)) {
+    // .buffer property that we need to recurse for.
+    if (binding.isArrayBuffer(value) || binding.isSharedArrayBuffer(value)) {
       return `${getConstructorOf(value).name}` +
              ` { byteLength: ${formatNumber(ctx, value.byteLength)} }`;
     }
@@ -475,7 +476,8 @@ function formatValue(ctx, value, recurseTimes) {
       keys.unshift('size');
     empty = value.size === 0;
     formatter = formatMap;
-  } else if (binding.isArrayBuffer(value)) {
+  } else if (binding.isArrayBuffer(value) ||
+             binding.isSharedArrayBuffer(value)) {
     braces = ['{', '}'];
     keys.unshift('byteLength');
     visibleKeys.byteLength = true;

src/node_util.cc

@@ -20,7 +20,6 @@ using v8::Value;
 
 #define VALUE_METHOD_MAP(V)                                                   \
   V(isArrayBuffer, IsArrayBuffer)                                             \
-  V(isSharedArrayBuffer, IsSharedArrayBuffer)                                 \
   V(isDataView, IsDataView)                                                   \
   V(isDate, IsDate)                                                           \
   V(isMap, IsMap)                                                             \
@@ -29,6 +28,7 @@ using v8::Value;
   V(isRegExp, IsRegExp)                                                       \
   V(isSet, IsSet)                                                             \
   V(isSetIterator, IsSetIterator)                                             \
+  V(isSharedArrayBuffer, IsSharedArrayBuffer)                                 \
   V(isTypedArray, IsTypedArray)
 
 

test/parallel/test-util-format-shared-arraybuffer.js

@@ -0,0 +1,10 @@
+// Flags: --harmony_sharedarraybuffer
+
+'use strict';
+require('../common');
+const assert = require('assert');
+const util = require('util');
+
+/* global SharedArrayBuffer */
+const sab = new SharedArrayBuffer(4);
+assert.strictEqual(util.format(sab), 'SharedArrayBuffer { byteLength: 4 }');