Merge branch 'handle-reference-cycles-in-pretty-print-function' into 'master'

Handle reference cycles in pretty print function

Closes #469

See merge request GNOME/gjs!739

2 files changed, 52 insertions, 7 deletions

diff --git a/installed-tests/js/testPrint.js b/installed-tests/js/testPrint.js
index 50a4ebc2..f6d27405 100644
--- a/installed-tests/js/testPrint.js
+++ b/installed-tests/js/testPrint.js
@@ -48,12 +48,29 @@ describe('prettyPrint', function () {
         log({greeting: 'hi'});
     });
 
+    it('property value is object reference', function () {
+        GLib.test_expect_message('Gjs', GLib.LogLevelFlags.LEVEL_MESSAGE,
+            'JS LOG: { a: 5, b: [Circular] }');
+        let obj = {a: 5};
+        obj.b = obj;
+        log(obj);
+    });
+
     it('more than one property', function () {
         GLib.test_expect_message('Gjs', GLib.LogLevelFlags.LEVEL_MESSAGE,
             'JS LOG: { a: 1, b: 2, c: 3 }');
         log({a: 1, b: 2, c: 3});
     });
 
+    it('add property value after property value object reference', function () {
+        GLib.test_expect_message('Gjs', GLib.LogLevelFlags.LEVEL_MESSAGE,
+            'JS LOG: { a: 5, b: [Circular], c: 4 }');
+        let obj = {a: 5};
+        obj.b = obj;
+        obj.c = 4;
+        log(obj);
+    });
+
     it('array', function () {
         GLib.test_expect_message('Gjs', GLib.LogLevelFlags.LEVEL_MESSAGE,
             'JS LOG: [1, 2, 3, 4, 5]');
@@ -66,6 +83,24 @@ describe('prettyPrint', function () {
         log({arr: [1, 2, 3, 4, 5]});
     });
 
+    it('array reference is the only array element', function () {
+        GLib.test_expect_message('Gjs', GLib.LogLevelFlags.LEVEL_MESSAGE,
+            'JS LOG: [[Circular]]');
+        let arr = [];
+        arr.push(arr);
+        log(arr);
+    });
+
+    it('array reference is one of multiple array elements', function () {
+        GLib.test_expect_message('Gjs', GLib.LogLevelFlags.LEVEL_MESSAGE,
+            'JS LOG: [4, [Circular], 5]');
+        let arr = [];
+        arr.push(4);
+        arr.push(arr);
+        arr.push(5);
+        log(arr);
+    });
+
     it('nested array', function () {
         GLib.test_expect_message('Gjs', GLib.LogLevelFlags.LEVEL_MESSAGE,
             'JS LOG: [1, 2, [3, 4], 5]');
diff --git a/modules/script/_bootstrap/default.js b/modules/script/_bootstrap/default.js
index e5953bf3..8c211a5a 100644
--- a/modules/script/_bootstrap/default.js
+++ b/modules/script/_bootstrap/default.js
@@ -24,9 +24,10 @@
     }
 
     function prettyPrint(value) {
+        const printedObjects = new WeakSet();
         switch (typeof value) {
         case 'object':
-            return formatObject(value);
+            return formatObject(value, printedObjects);
         case 'function':
             return formatFunction(value);
         default:
@@ -34,9 +35,11 @@
         }
     }
 
-    function formatObject(obj) {
+    function formatObject(obj, printedObjects) {
+        printedObjects.add(obj);
         if (Array.isArray(obj))
-            return formatArray(obj).toString();
+            return formatArray(obj, printedObjects).toString();
+
         if (obj instanceof Date)
             return formatDate(obj);
 
@@ -44,7 +47,10 @@
         for (const [key, value] of Object.entries(obj)) {
             switch (typeof value) {
             case 'object':
-                formattedObject.push(`${key}: ${formatObject(value)}`);
+                if (printedObjects.has(value))
+                    formattedObject.push(`${key}: [Circular]`);
+                else
+                    formattedObject.push(`${key}: ${formatObject(value, printedObjects)}`);
                 break;
             case 'function':
                 formattedObject.push(`${key}: ${formatFunction(value)}`);
@@ -60,10 +66,14 @@
         return `{ ${formattedObject.join(', ')} }`;
     }
 
-    function formatArray(arr) {
+    function formatArray(arr, printedObjects) {
         const formattedArray = [];
-        for (const [key, value] of arr.entries())
-            formattedArray[key] = prettyPrint(value);
+        for (const [key, value] of arr.entries()) {
+            if (printedObjects.has(value))
+                formattedArray[key] = '[Circular]';
+            else
+                formattedArray[key] = prettyPrint(value);
+        }
         return `[${formattedArray.join(', ')}]`;
     }