Bug 1249443 - add AllChildrenIterator::GetPreviousChild, r=bz

dom/base/ChildIterator.cpp

@@ -314,24 +314,25 @@ ExplicitChildIterator::GetPreviousChild()
 bool
 AllChildrenIterator::Seek(nsIContent* aChildToFind)
 {
-  if (mPhase == eNeedBeforeKid) {
+  if (mPhase == eAtBegin || mPhase == eAtBeforeKid) {
-    mPhase = eNeedExplicitKids;
+    mPhase = eAtExplicitKids;
     nsIFrame* frame = mOriginalContent->GetPrimaryFrame();
     if (frame) {
       nsIFrame* beforeFrame = nsLayoutUtils::GetBeforeFrame(frame);
       if (beforeFrame) {
         if (beforeFrame->GetContent() == aChildToFind) {
+          mPhase = eAtBeforeKid;
           return true;
         }
       }
     }
   }
 
-  if (mPhase == eNeedExplicitKids) {
+  if (mPhase == eAtExplicitKids) {
     if (ExplicitChildIterator::Seek(aChildToFind)) {
       return true;
     }
-    mPhase = eNeedAnonKids;
+    mPhase = eAtAnonKids;
   }
 
   nsIContent* child = nullptr;
@@ -345,59 +346,124 @@ AllChildrenIterator::Seek(nsIContent* aChildToFind)
 nsIContent*
 AllChildrenIterator::GetNextChild()
 {
-  if (mPhase == eNeedBeforeKid) {
+  if (mPhase == eAtBegin) {
-    mPhase = eNeedExplicitKids;
+    mPhase = eAtExplicitKids;
     nsIFrame* frame = mOriginalContent->GetPrimaryFrame();
     if (frame) {
       nsIFrame* beforeFrame = nsLayoutUtils::GetBeforeFrame(frame);
       if (beforeFrame) {
+        mPhase = eAtBeforeKid;
         return beforeFrame->GetContent();
       }
     }
   }
 
-  if (mPhase == eNeedExplicitKids) {
+  if (mPhase == eAtBeforeKid) {
+    // Advance into our explicit kids.
+    mPhase = eAtExplicitKids;
+  }
+
+  if (mPhase == eAtExplicitKids) {
     nsIContent* kid = ExplicitChildIterator::GetNextChild();
     if (kid) {
       return kid;
     }
-
+    mPhase = eAtAnonKids;
-    mPhase = eNeedAnonKids;
   }
 
-  if (mPhase == eNeedAnonKids) {
+  if (mPhase == eAtAnonKids) {
     if (mAnonKids.IsEmpty()) {
+      MOZ_ASSERT(mAnonKidsIdx == UINT32_MAX);
       nsIAnonymousContentCreator* ac =
         do_QueryFrame(mOriginalContent->GetPrimaryFrame());
       if (ac) {
         ac->AppendAnonymousContentTo(mAnonKids, mFlags);
       }
+      mAnonKidsIdx = 0;
     }
-
+    else {
-    if (!mAnonKids.IsEmpty()) {
+      if (mAnonKidsIdx == UINT32_MAX) {
-      nsIContent* nextKid = mAnonKids[0];
+        mAnonKidsIdx = 0;
-      mAnonKids.RemoveElementAt(0);
+      }
-      if (mAnonKids.IsEmpty()) {
+      else {
-        mPhase = eNeedAfterKid;
+        mAnonKidsIdx++;
       }
-
-      return nextKid;
     }
 
-    mPhase = eNeedAfterKid;
+    if (mAnonKidsIdx < mAnonKids.Length()) {
-  }
+      return mAnonKids[mAnonKidsIdx];
+    }
 
-  if (mPhase == eNeedAfterKid) {
-    mPhase = eDone;
     nsIFrame* frame = mOriginalContent->GetPrimaryFrame();
     if (frame) {
       nsIFrame* afterFrame = nsLayoutUtils::GetAfterFrame(frame);
       if (afterFrame) {
+        mPhase = eAtAfterKid;
         return afterFrame->GetContent();
       }
     }
   }
 
+  mPhase = eAtEnd;
+  return nullptr;
+}
+
+nsIContent*
+AllChildrenIterator::GetPreviousChild()
+{
+  if (mPhase == eAtEnd) {
+    MOZ_ASSERT(mAnonKidsIdx == mAnonKids.Length());
+    mPhase = eAtAnonKids;
+    nsIFrame* frame = mOriginalContent->GetPrimaryFrame();
+    if (frame) {
+      nsIFrame* afterFrame = nsLayoutUtils::GetAfterFrame(frame);
+      if (afterFrame) {
+        mPhase = eAtAfterKid;
+        return afterFrame->GetContent();
+      }
+    }
+  }
+
+  if (mPhase == eAtAfterKid) {
+    mPhase = eAtAnonKids;
+  }
+
+  if (mPhase == eAtAnonKids) {
+    if (mAnonKids.IsEmpty()) {
+      nsIAnonymousContentCreator* ac =
+        do_QueryFrame(mOriginalContent->GetPrimaryFrame());
+      if (ac) {
+        ac->AppendAnonymousContentTo(mAnonKids, mFlags);
+        mAnonKidsIdx = mAnonKids.Length();
+      }
+    }
+
+    // If 0 then it turns into UINT32_MAX, which indicates the iterator is
+    // before the anonymous children.
+    --mAnonKidsIdx;
+    if (mAnonKidsIdx < mAnonKids.Length()) {
+      return mAnonKids[mAnonKidsIdx];
+    }
+    mPhase = eAtExplicitKids;
+  }
+
+  if (mPhase == eAtExplicitKids) {
+    nsIContent* kid = ExplicitChildIterator::GetPreviousChild();
+    if (kid) {
+      return kid;
+    }
+
+    nsIFrame* frame = mOriginalContent->GetPrimaryFrame();
+    if (frame) {
+      nsIFrame* beforeFrame = nsLayoutUtils::GetBeforeFrame(frame);
+      if (beforeFrame) {
+        mPhase = eAtBeforeKid;
+        return beforeFrame->GetContent();
+      }
+    }
+  }
+
+  mPhase = eAtBegin;
   return nullptr;
 }
 

dom/base/ChildIterator.h

@@ -182,14 +182,14 @@ class AllChildrenIterator : private FlattenedChildIterator
 public:
   AllChildrenIterator(nsIContent* aNode, uint32_t aFlags, bool aStartAtBeginning = true) :
     FlattenedChildIterator(aNode, aFlags, aStartAtBeginning),
-    mOriginalContent(aNode), mFlags(aFlags),
+    mOriginalContent(aNode), mAnonKidsIdx(aStartAtBeginning ? UINT32_MAX : 0),
-    mPhase(eNeedBeforeKid) {}
+    mFlags(aFlags), mPhase(aStartAtBeginning ? eAtBegin : eAtEnd) { }
 
   AllChildrenIterator(AllChildrenIterator&& aOther)
     : FlattenedChildIterator(Move(aOther)),
       mOriginalContent(aOther.mOriginalContent),
-      mAnonKids(Move(aOther.mAnonKids)), mFlags(aOther.mFlags),
+      mAnonKids(Move(aOther.mAnonKids)), mAnonKidsIdx(aOther.mAnonKidsIdx),
-      mPhase(aOther.mPhase)
+      mFlags(aOther.mFlags), mPhase(aOther.mPhase)
 #ifdef DEBUG
       , mMutationGuard(aOther.mMutationGuard)
 #endif
@@ -202,20 +202,31 @@ public:
   bool Seek(nsIContent* aChildToFind);
 
   nsIContent* GetNextChild();
+  nsIContent* GetPreviousChild();
   nsIContent* Parent() const { return mOriginalContent; }
 
 private:
   enum IteratorPhase
   {
-    eNeedBeforeKid,
+    eAtBegin,
-    eNeedExplicitKids,
+    eAtBeforeKid,
-    eNeedAnonKids,
+    eAtExplicitKids,
-    eNeedAfterKid,
+    eAtAnonKids,
-    eDone
+    eAtAfterKid,
+    eAtEnd
   };
 
   nsIContent* mOriginalContent;
+
+  // mAnonKids is an array of native anonymous children, mAnonKidsIdx is index
+  // in the array. If mAnonKidsIdx < mAnonKids.Length() and mPhase is
+  // eAtAnonKids then the iterator points at a child at mAnonKidsIdx index. If
+  // mAnonKidsIdx == mAnonKids.Length() then the iterator is somewhere after
+  // the last native anon child. If mAnonKidsIdx == UINT32_MAX then the iterator
+  // is somewhere before the first native anon child.
   nsTArray<nsIContent*> mAnonKids;
+  uint32_t mAnonKidsIdx;
+
   uint32_t mFlags;
   IteratorPhase mPhase;
 #ifdef DEBUG