Bug 1316302 - Part 3: Create EditActionResult class for making the methods which return nsresult, handled and canceled with out params

In a lot of places, edit action handlers and their helper methods return nsresult and aHandled and aCanceled with out params. However, the out params cause the code complicated since:

* it's not unclear if the method will overwrite aHandled and aCanceled value.
* callers need to create temporary variable event if some of them are not necessary.

This patch rewrites the helper methods of HTMLEditRules::WillDeleteSelection() with it.

Tag #1563

1 files changed, 113 insertions, 0 deletions

diff --git a/editor/libeditor/EditorUtils.h b/editor/libeditor/EditorUtils.h
index 34286da8a..15ec0b62d 100644
--- a/editor/libeditor/EditorUtils.h
+++ b/editor/libeditor/EditorUtils.h
@@ -31,6 +31,119 @@ class Selection;
 } // namespace dom
 
 /***************************************************************************
+ * EditActionResult is useful to return multiple results of an editor
+ * action handler without out params.
+ * Note that when you return an anonymous instance from a method, you should
+ * use EditActionIgnored(), EditActionHandled() or EditActionCanceled() for
+ * easier to read.  In other words, EditActionResult should be used when
+ * declaring return type of a method, being an argument or defined as a local
+ * variable.
+ */
+class MOZ_STACK_CLASS EditActionResult final
+{
+public:
+  bool Succeeded() const { return NS_SUCCEEDED(mRv); }
+  bool Failed() const { return NS_FAILED(mRv); }
+  nsresult Rv() const { return mRv; }
+  bool Canceled() const { return mCanceled; }
+  bool Handled() const { return mHandled; }
+
+  EditActionResult SetResult(nsresult aRv)
+  {
+    mRv = aRv;
+    return *this;
+  }
+  EditActionResult MarkAsCanceled()
+  {
+    mCanceled = true;
+    return *this;
+  }
+  EditActionResult MarkAsHandled()
+  {
+    mHandled = true;
+    return *this;
+  }
+
+  explicit EditActionResult(nsresult aRv)
+    : mRv(aRv)
+    , mCanceled(false)
+    , mHandled(false)
+  {
+  }
+
+  EditActionResult& operator|=(const EditActionResult& aOther)
+  {
+    mCanceled |= aOther.mCanceled;
+    mHandled |= aOther.mHandled;
+    // When both result are same, keep the result.
+    if (mRv == aOther.mRv) {
+      return *this;
+    }
+    // If one of the results is error, use NS_ERROR_FAILURE.
+    if (Failed() || aOther.Failed()) {
+      mRv = NS_ERROR_FAILURE;
+    } else {
+      // Otherwise, use generic success code, NS_OK.
+      mRv = NS_OK;
+    }
+    return *this;
+  }
+
+private:
+  nsresult mRv;
+  bool mCanceled;
+  bool mHandled;
+
+  EditActionResult(nsresult aRv, bool aCanceled, bool aHandled)
+    : mRv(aRv)
+    , mCanceled(aCanceled)
+    , mHandled(aHandled)
+  {
+  }
+
+  EditActionResult()
+    : mRv(NS_ERROR_NOT_INITIALIZED)
+    , mCanceled(false)
+    , mHandled(false)
+  {
+  }
+
+  friend EditActionResult EditActionIgnored(nsresult aRv);
+  friend EditActionResult EditActionHandled(nsresult aRv);
+  friend EditActionResult EditActionCanceled(nsresult aRv);
+};
+
+/***************************************************************************
+ * When an edit action handler (or its helper) does nothing,
+ * EditActionIgnored should be returned.
+ */
+inline EditActionResult
+EditActionIgnored(nsresult aRv = NS_OK)
+{
+  return EditActionResult(aRv, false, false);
+}
+
+/***************************************************************************
+ * When an edit action handler (or its helper) handled and not canceled,
+ * EditActionHandled should be returned.
+ */
+inline EditActionResult
+EditActionHandled(nsresult aRv = NS_OK)
+{
+  return EditActionResult(aRv, false, true);
+}
+
+/***************************************************************************
+ * When an edit action handler (or its helper) handled and canceled,
+ * EditActionHandled should be returned.
+ */
+inline EditActionResult
+EditActionCanceled(nsresult aRv = NS_OK)
+{
+  return EditActionResult(aRv, true, true);
+}
+
+/***************************************************************************
  * stack based helper class for batching a collection of txns inside a
  * placeholder txn.
  */