util: handle circular maps and sets in inspect()

Handle maps and sets with circular references in `util.inspect()` the way objects and arrays are treated in this case. Fixes: nodejs#14758
aqrln · Aug 11, 2017 · 566b5f5 · 566b5f5
1 parent 7307839
commit 566b5f5
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Showing 2 changed files with 49 additions and 9 deletions.
diff --git a/lib/util.js b/lib/util.js
@@ -737,9 +737,7 @@ function formatTypedArray(ctx, value, recurseTimes, visibleKeys, keys) {
 function formatSet(ctx, value, recurseTimes, visibleKeys, keys) {
   var output = [];
   value.forEach(function(v) {
-    var nextRecurseTimes = recurseTimes === null ? null : recurseTimes - 1;
-    var str = formatValue(ctx, v, nextRecurseTimes);
-    output.push(str);
+    output.push(formatMapSetValue(ctx, v, recurseTimes));
   });
   for (var n = 0; n < keys.length; n++) {
     output.push(formatProperty(ctx, value, recurseTimes, visibleKeys,
@@ -752,11 +750,11 @@ function formatSet(ctx, value, recurseTimes, visibleKeys, keys) {
 function formatMap(ctx, value, recurseTimes, visibleKeys, keys) {
   var output = [];
   value.forEach(function(v, k) {
-    var nextRecurseTimes = recurseTimes === null ? null : recurseTimes - 1;
-    var str = formatValue(ctx, k, nextRecurseTimes);
-    str += ' => ';
-    str += formatValue(ctx, v, nextRecurseTimes);
-    output.push(str);
+    output.push(
+      formatMapSetValue(ctx, k, recurseTimes) +
+      ' => ' +
+      formatMapSetValue(ctx, v, recurseTimes)
+    );
   });
   for (var n = 0; n < keys.length; n++) {
     output.push(formatProperty(ctx, value, recurseTimes, visibleKeys,
@@ -765,6 +763,14 @@ function formatMap(ctx, value, recurseTimes, visibleKeys, keys) {
   return output;
 }
 
+function formatMapSetValue(ctx, value, recurseTimes) {
+  if (ctx.seen.includes(value)) {
+    return formatCircular(ctx);
+  }
+  const nextRecurseTimes = recurseTimes === null ? null : recurseTimes - 1;
+  return formatValue(ctx, value, nextRecurseTimes);
+}
+
 function formatCollectionIterator(ctx, value, recurseTimes, visibleKeys, keys) {
   ensureDebugIsInitialized();
   const mirror = Debug.MakeMirror(value, true);
@@ -836,7 +842,7 @@ function formatProperty(ctx, value, recurseTimes, visibleKeys, key, array) {
         }
       }
     } else {
-      str = ctx.stylize('[Circular]', 'special');
+      str = formatCircular(ctx);
     }
   }
   if (name === undefined) {
@@ -859,6 +865,9 @@ function formatProperty(ctx, value, recurseTimes, visibleKeys, key, array) {
   return `${name}: ${str}`;
 }
 
+function formatCircular(ctx) {
+  return ctx.stylize('[Circular]', 'special');
+}
 
 function reduceToSingleString(output, base, braces, breakLength) {
   var length = output.reduce(function(prev, cur) {

diff --git a/test/parallel/test-util-inspect.js b/test/parallel/test-util-inspect.js
@@ -794,6 +794,37 @@ if (typeof Symbol !== 'undefined') {
                      'Map { \'foo\' => null, [size]: 1, bar: 42 }');
 }
 
+// Test maps and sets with circular references
+{
+  const circularKeyMap = new Map();
+  circularKeyMap.set(circularKeyMap, 'value');
+  assert.strictEqual(
+    util.inspect(circularKeyMap),
+    'Map { [Circular] => \'value\' }'
+  );
+
+  const circularValueMap = new Map();
+  circularValueMap.set('key', circularValueMap);
+  assert.strictEqual(
+    util.inspect(circularValueMap),
+    'Map { \'key\' => [Circular] }'
+  );
+
+  const circularKeyValueMap = new Map();
+  circularKeyValueMap.set(circularKeyValueMap, circularKeyValueMap);
+  assert.strictEqual(
+    util.inspect(circularKeyValueMap),
+    'Map { [Circular] => [Circular] }'
+  );
+
+  const circularSet = new Set();
+  circularSet.add(circularSet);
+  assert.strictEqual(
+    util.inspect(circularSet),
+    'Set { [Circular] }'
+  );
+}
+
 // test Promise
 {
   const resolved = Promise.resolve(3);