Refactor LayoutCurrentChild

third_party/WebKit/Source/core/layout/ng/ng_block_layout_algorithm.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/layout/ng/ng_block_layout_algorithm.h"
 
 #include "core/layout/ng/ng_constraint_space.h"
 #include "core/layout/ng/ng_fragment_builder.h"
 #include "core/layout/ng/ng_fragment.h"
 #include "core/layout/ng/ng_layout_opportunity_iterator.h"
@@ skipping 167 matching lines @@
       builder_ = new NGFragmentBuilder(NGPhysicalFragmentBase::FragmentBox);
       builder_->SetDirection(constraint_space->Direction());
       builder_->SetWritingMode(constraint_space->WritingMode());
       builder_->SetInlineSize(inline_size).SetBlockSize(block_size);
       current_child_ = first_child_;
       state_ = kStateChildLayout;
       return false;
     }
     case kStateChildLayout: {
       if (current_child_) {
-        constraint_space_for_children_->SetIsNewFormattingContext(
-            IsNewFormattingContextForInFlowBlockLevelChild(
-                *constraint_space, *current_child_->Style()));
-
-        NGFragment* fragment;
-        if (!current_child_->Layout(constraint_space_for_children_, &fragment))
+        if (!LayoutCurrentChild(constraint_space))
           return false;
-
-        NGBoxStrut child_margins = ComputeMargins(
-            *constraint_space_for_children_, *current_child_->Style(),
-            constraint_space_for_children_->WritingMode(),
-            constraint_space_for_children_->Direction());
-
-        NGLogicalOffset fragment_offset;
-        if (current_child_->Style()->isFloating()) {
-          fragment_offset = PositionFloatFragment(*fragment, child_margins);
-        } else {
-          ApplyAutoMargins(*constraint_space_for_children_,
-                           *current_child_->Style(), *fragment, &child_margins);
-          fragment_offset =
-              PositionFragment(*fragment, child_margins, *constraint_space);
-        }
-        builder_->AddChild(fragment, fragment_offset);
-
         current_child_ = current_child_->NextSibling();
         if (current_child_)
           return false;
       }
       state_ = kStateFinalize;
       return false;
     }
     case kStateFinalize: {
       content_size_ += border_and_padding_.block_end;
 
       // Recompute the block-axis size now that we know our content size.
       LayoutUnit block_size = ComputeBlockSizeForFragment(
           *constraint_space, Style(), content_size_);
 
       builder_->SetBlockSize(block_size)
           .SetInlineOverflow(max_inline_size_)
           .SetBlockOverflow(content_size_);
       *out = builder_->ToFragment();
       state_ = kStateInit;
       return true;
     }
   };
   NOTREACHED();
   *out = nullptr;
   return true;
 }
 
+bool NGBlockLayoutAlgorithm::LayoutCurrentChild(
+    const NGConstraintSpace* constraint_space) {
+  constraint_space_for_children_->SetIsNewFormattingContext(
+      IsNewFormattingContextForInFlowBlockLevelChild(*constraint_space,
+                                                     *current_child_->Style()));
+
+  NGFragment* fragment;
+  if (!current_child_->Layout(constraint_space_for_children_, &fragment))
+    return false;
+
+  NGBoxStrut child_margins =
+      ComputeMargins(*constraint_space_for_children_, *current_child_->Style(),
+                     constraint_space_for_children_->WritingMode(),
+                     constraint_space_for_children_->Direction());
+
+  NGLogicalOffset fragment_offset;
+  if (current_child_->Style()->isFloating()) {
+    fragment_offset = PositionFloatFragment(*fragment, child_margins);
+  } else {
+    // TODO(layout-ng): move ApplyAutoMargins to PositionFragment
+    ApplyAutoMargins(*constraint_space_for_children_, *current_child_->Style(),
+                     *fragment, &child_margins);
+    fragment_offset =
+        PositionFragment(*fragment, child_margins, *constraint_space);
+  }
+  builder_->AddChild(fragment, fragment_offset);
+  return true;
+}
+
 NGBoxStrut NGBlockLayoutAlgorithm::CollapseMargins(
     const NGConstraintSpace& space,
     const NGBoxStrut& margins,
     const NGFragment& fragment) {
   bool is_zero_height_box = !fragment.BlockSize() && margins.IsEmpty() &&
                             fragment.MarginStrut().IsEmpty();
   // Create the current child's margin strut from its children's margin strut or
   // use margin strut from the the last non-empty child.
   NGMarginStrut curr_margin_strut =
       is_zero_height_box ? prev_child_margin_strut_ : fragment.MarginStrut();
@@ skipping 97 matching lines @@
 }
 
 void NGBlockLayoutAlgorithm::UpdateMarginStrut(const NGMarginStrut& from) {
   if (!is_fragment_margin_strut_block_start_updated_) {
     builder_->SetMarginStrutBlockStart(from);
     is_fragment_margin_strut_block_start_updated_ = true;
   }
   builder_->SetMarginStrutBlockEnd(from);
 }
 
+DEFINE_TRACE(NGBlockLayoutAlgorithm) {
+  NGLayoutAlgorithm::trace(visitor);
+  visitor->trace(first_child_);
+  visitor->trace(builder_);
+  visitor->trace(constraint_space_for_children_);
+  visitor->trace(current_child_);
+}
+
 }  // namespace blink