util: use @@toStringTag

uses @@toStringTag when creating the "tag" for an inspected value

PR-URL: https://github.com/nodejs/node/pull/16956
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Timothy Gu <timothygu99@gmail.com>
Reviewed-By: Brian White <mscdex@mscdex.net>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>

1 files changed, 29 insertions, 23 deletions

diff --git a/lib/util.js b/lib/util.js
index 058b5ed6bd..da8d1f0f9b 100644
--- a/lib/util.js
+++ b/lib/util.js
@@ -56,7 +56,7 @@ const {
 const {
   customInspectSymbol,
   deprecate,
-  getConstructorOf,
+  getIdentificationOf,
   isError,
   promisify,
   join
@@ -429,9 +429,15 @@ function formatValue(ctx, value, recurseTimes, ln) {
   }
 
   const keyLength = keys.length + symbols.length;
-  const constructor = getConstructorOf(value);
-  const ctorName = constructor && constructor.name ?
-    `${constructor.name} ` : '';
+
+  const { constructor, tag } = getIdentificationOf(value);
+  var prefix = '';
+  if (constructor && tag && constructor !== tag)
+    prefix = `${constructor} [${tag}] `;
+  else if (constructor)
+    prefix = `${constructor} `;
+  else if (tag)
+    prefix = `[${tag}] `;
 
   var base = '';
   var formatter = formatObject;
@@ -444,28 +450,28 @@ function formatValue(ctx, value, recurseTimes, ln) {
     noIterator = false;
     if (Array.isArray(value)) {
       // Only set the constructor for non ordinary ("Array [...]") arrays.
-      braces = [`${ctorName === 'Array ' ? '' : ctorName}[`, ']'];
+      braces = [`${prefix === 'Array ' ? '' : prefix}[`, ']'];
       if (value.length === 0 && keyLength === 0)
         return `${braces[0]}]`;
       formatter = formatArray;
     } else if (isSet(value)) {
       if (value.size === 0 && keyLength === 0)
-        return `${ctorName}{}`;
-      braces = [`${ctorName}{`, '}'];
+        return `${prefix}{}`;
+      braces = [`${prefix}{`, '}'];
       formatter = formatSet;
     } else if (isMap(value)) {
       if (value.size === 0 && keyLength === 0)
-        return `${ctorName}{}`;
-      braces = [`${ctorName}{`, '}'];
+        return `${prefix}{}`;
+      braces = [`${prefix}{`, '}'];
       formatter = formatMap;
     } else if (isTypedArray(value)) {
-      braces = [`${ctorName}[`, ']'];
+      braces = [`${prefix}[`, ']'];
       formatter = formatTypedArray;
     } else if (isMapIterator(value)) {
-      braces = ['MapIterator {', '}'];
+      braces = [`[${tag}] {`, '}'];
       formatter = formatMapIterator;
     } else if (isSetIterator(value)) {
-      braces = ['SetIterator {', '}'];
+      braces = [`[${tag}] {`, '}'];
       formatter = formatSetIterator;
     } else {
       // Check for boxed strings with valueOf()
@@ -491,12 +497,13 @@ function formatValue(ctx, value, recurseTimes, ln) {
   }
   if (noIterator) {
     braces = ['{', '}'];
-    if (ctorName === 'Object ') {
+    if (prefix === 'Object ') {
       // Object fast path
       if (keyLength === 0)
         return '{}';
     } else if (typeof value === 'function') {
-      const name = `${constructor.name}${value.name ? `: ${value.name}` : ''}`;
+      const name =
+        `${constructor || tag}${value.name ? `: ${value.name}` : ''}`;
       if (keyLength === 0)
         return ctx.stylize(`[${name}]`, 'special');
       base = ` [${name}]`;
@@ -523,16 +530,16 @@ function formatValue(ctx, value, recurseTimes, ln) {
       // Can't do the same for DataView because it has a non-primitive
       // .buffer property that we need to recurse for.
       if (keyLength === 0)
-        return ctorName +
+        return prefix +
               `{ byteLength: ${formatNumber(ctx.stylize, value.byteLength)} }`;
-      braces[0] = `${ctorName}{`;
+      braces[0] = `${prefix}{`;
       keys.unshift('byteLength');
     } else if (isDataView(value)) {
-      braces[0] = `${ctorName}{`;
+      braces[0] = `${prefix}{`;
       // .buffer goes last, it's not a primitive like the others.
       keys.unshift('byteLength', 'byteOffset', 'buffer');
     } else if (isPromise(value)) {
-      braces[0] = `${ctorName}{`;
+      braces[0] = `${prefix}{`;
       formatter = formatPromise;
     } else {
       // Check boxed primitives other than string with valueOf()
@@ -560,22 +567,21 @@ function formatValue(ctx, value, recurseTimes, ln) {
       } else if (keyLength === 0) {
         if (isExternal(value))
           return ctx.stylize('[External]', 'special');
-        return `${ctorName}{}`;
+        return `${prefix}{}`;
       } else {
-        braces[0] = `${ctorName}{`;
+        braces[0] = `${prefix}{`;
       }
     }
   }
 
   // Using an array here is actually better for the average case than using
-  // a Set. `seen` will only check for the depth and will never grow to large.
+  // a Set. `seen` will only check for the depth and will never grow too large.
   if (ctx.seen.indexOf(value) !== -1)
     return ctx.stylize('[Circular]', 'special');
 
   if (recurseTimes != null) {
     if (recurseTimes < 0)
-      return ctx.stylize(`[${constructor ? constructor.name : 'Object'}]`,
-                         'special');
+      return ctx.stylize(`[${constructor || tag || 'Object'}]`, 'special');
     recurseTimes -= 1;
   }