Bug 1596665 - P2. Add ability to copy all property bag contents to another. r=mattwoodrow

Add static CopyFrom method which is to be used in a follow-up patch. The static method takes a nsIWritablePropertyBag so that we don't need to cast to the concrete class.

Differential Revision: https://phabricator.services.mozilla.com/D53923

--HG--
extra : moz-landing-system : lando

netwerk/base/nsBaseChannel.cpp

@@ -137,11 +137,8 @@ nsresult nsBaseChannel::Redirect(nsIChannel* newChannel, uint32_t redirectFlags,
     }
   }
 
-  nsCOMPtr<nsIWritablePropertyBag> bag = ::do_QueryInterface(newChannel);
-  if (bag) {
-    for (auto iter = mPropertyHash.Iter(); !iter.Done(); iter.Next()) {
-      bag->SetProperty(iter.Key(), iter.UserData());
-    }
+  if (nsCOMPtr<nsIWritablePropertyBag> bag = ::do_QueryInterface(newChannel)) {
+    nsHashPropertyBag::CopyFrom(bag, static_cast<nsIPropertyBag2*>(this));
   }
 
   // Notify consumer, giving chance to cancel redirect.

netwerk/dns/mdns/libmdns/nsDNSServiceInfo.cpp

@@ -44,35 +44,8 @@ nsDNSServiceInfo::nsDNSServiceInfo(nsIDNSServiceInfo* aServiceInfo) {
 
   nsCOMPtr<nsIPropertyBag2> attributes;  // deep copy
   if (NS_SUCCEEDED(aServiceInfo->GetAttributes(getter_AddRefs(attributes)))) {
-    nsCOMPtr<nsISimpleEnumerator> enumerator;
-    if (NS_WARN_IF(
-            NS_FAILED(attributes->GetEnumerator(getter_AddRefs(enumerator))))) {
-      return;
-    }
-
-    nsCOMPtr<nsIWritablePropertyBag2> newAttributes = new nsHashPropertyBag();
-
-    bool hasMoreElements;
-    while (NS_SUCCEEDED(enumerator->HasMoreElements(&hasMoreElements)) &&
-           hasMoreElements) {
-      nsCOMPtr<nsISupports> element;
-      Unused << NS_WARN_IF(
-          NS_FAILED(enumerator->GetNext(getter_AddRefs(element))));
-      nsCOMPtr<nsIProperty> property = do_QueryInterface(element);
-      MOZ_ASSERT(property);
-
-      nsAutoString name;
-      nsCOMPtr<nsIVariant> value;
-      Unused << NS_WARN_IF(NS_FAILED(property->GetName(name)));
-      Unused << NS_WARN_IF(
-          NS_FAILED(property->GetValue(getter_AddRefs(value))));
-      nsAutoCString valueStr;
-      Unused << NS_WARN_IF(NS_FAILED(value->GetAsACString(valueStr)));
-
-      Unused << NS_WARN_IF(
-          NS_FAILED(newAttributes->SetPropertyAsACString(name, valueStr)));
-    }
-
+    RefPtr<nsHashPropertyBag> newAttributes = new nsHashPropertyBag();
+    newAttributes->CopyFrom(attributes);
     Unused << NS_WARN_IF(NS_FAILED(SetAttributes(newAttributes)));
   }
 }

xpcom/ds/nsHashPropertyBag.cpp

@@ -5,14 +5,16 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "nsHashPropertyBag.h"
-#include "nsArray.h"
-#include "nsArrayEnumerator.h"
-#include "nsIVariant.h"
-#include "nsIProperty.h"
-#include "nsThreadUtils.h"
-#include "nsVariant.h"
+
 #include "mozilla/Attributes.h"
 #include "mozilla/Move.h"
+#include "mozilla/SimpleEnumerator.h"
+#include "nsArray.h"
+#include "nsArrayEnumerator.h"
+#include "nsIProperty.h"
+#include "nsIVariant.h"
+#include "nsThreadUtils.h"
+#include "nsVariant.h"
 
 extern "C" {
 
@@ -228,6 +230,37 @@ nsHashPropertyBagBase::SetPropertyAsInterface(const nsAString& aProp,
   return SetProperty(aProp, var);
 }
 
+void nsHashPropertyBagBase::CopyFrom(const nsHashPropertyBagBase* aOther) {
+  for (auto iter = aOther->mPropertyHash.ConstIter(); !iter.Done();
+       iter.Next()) {
+    SetProperty(iter.Key(), iter.UserData());
+  }
+}
+
+void nsHashPropertyBagBase::CopyFrom(nsIPropertyBag* aOther) {
+  CopyFrom(this, aOther);
+}
+
+/* static */ void nsHashPropertyBagBase::CopyFrom(nsIWritablePropertyBag* aTo,
+                                                  nsIPropertyBag* aFrom) {
+  if (aTo && aFrom) {
+    nsCOMPtr<nsISimpleEnumerator> enumerator;
+    if (NS_SUCCEEDED(aFrom->GetEnumerator(getter_AddRefs(enumerator)))) {
+      for (auto& property : SimpleEnumerator<nsIProperty>(enumerator)) {
+        nsString name;
+        nsCOMPtr<nsIVariant> value;
+        Unused << NS_WARN_IF(NS_FAILED(property->GetName(name)));
+        Unused << NS_WARN_IF(
+            NS_FAILED(property->GetValue(getter_AddRefs(value))));
+        Unused << NS_WARN_IF(
+            NS_FAILED(aTo->SetProperty(std::move(name), value)));
+      }
+    } else {
+      NS_WARNING("Unable to copy nsIPropertyBag");
+    }
+  }
+}
+
 /*
  * nsHashPropertyBag implementation.
  */

xpcom/ds/nsHashPropertyBag.h

@@ -17,7 +17,11 @@
 class nsHashPropertyBagBase : public nsIWritablePropertyBag,
                               public nsIWritablePropertyBag2 {
  public:
-  nsHashPropertyBagBase() {}
+  nsHashPropertyBagBase() = default;
+
+  void CopyFrom(const nsHashPropertyBagBase* aOther);
+  void CopyFrom(nsIPropertyBag* aOther);
+  static void CopyFrom(nsIWritablePropertyBag* aTo, nsIPropertyBag* aFrom);
 
   NS_DECL_NSIPROPERTYBAG
   NS_DECL_NSIPROPERTYBAG2
@@ -47,12 +51,12 @@ class nsHashPropertyBag : public nsHashPropertyBagBase {
 /* A cycle collected nsHashPropertyBag for main-thread-only use. */
 class nsHashPropertyBagCC final : public nsHashPropertyBagBase {
  public:
-  nsHashPropertyBagCC() {}
+  nsHashPropertyBagCC() = default;
   NS_DECL_CYCLE_COLLECTING_ISUPPORTS
   NS_DECL_CYCLE_COLLECTION_CLASS_AMBIGUOUS(nsHashPropertyBagCC,
                                            nsIWritablePropertyBag)
  protected:
-  virtual ~nsHashPropertyBagCC() {}
+  virtual ~nsHashPropertyBagCC() = default;
 };
 
 inline nsISupports* ToSupports(nsHashPropertyBagBase* aPropertyBag) {