Move NGConstraintSpace utility methods to a separate file

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

+// Copyright 2017 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_space_utils.h"
+
+namespace blink {
+namespace {
+
+// Returns max of 2 {@code WTF::Optional} values.
+template <typename T>
+WTF::Optional<T> OptionalMax(const WTF::Optional<T>& value1,
+                             const WTF::Optional<T>& value2) {
+  if (value1 && value2) {
+    return std::max(value1.value(), value2.value());
+  } else if (value1) {
+    return value1;
+  }
+  return value2;
+}
+
+}  // namespace
+
+bool IsNewFormattingContextForInFlowBlockLevelChild(
+    const NGConstraintSpace& space,
+    const ComputedStyle& style) {
+  // TODO(layout-dev): This doesn't capture a few cases which can't be computed
+  // directly from style yet:
+  //  - The child is a <fieldset>.
+  //  - "column-span: all" is set on the child (requires knowledge that we are
+  //    in a multi-col formatting context).
+  //    (https://drafts.csswg.org/css-multicol-1/#valdef-column-span-all)
+
+  if (style.specifiesColumns() || style.containsPaint() ||
+      style.containsLayout())
+    return true;
+
+  if (!style.isOverflowVisible())
+    return true;
+
+  EDisplay display = style.display();
+  if (display == EDisplay::kGrid || display == EDisplay::kFlex ||
+      display == EDisplay::kWebkitBox)
+    return true;
+
+  if (space.WritingMode() != FromPlatformWritingMode(style.getWritingMode()))
+    return true;
+
+  return false;
+}
+
+WTF::Optional<LayoutUnit> GetClearanceOffset(
+    const std::shared_ptr<NGExclusions>& exclusions,
+    const ComputedStyle& style) {
+  const NGExclusion* right_exclusion = exclusions->last_right_float;
+  const NGExclusion* left_exclusion = exclusions->last_left_float;
+
+  WTF::Optional<LayoutUnit> left_offset;
+  if (left_exclusion) {
+    left_offset = left_exclusion->rect.BlockEndOffset();
+  }
+  WTF::Optional<LayoutUnit> right_offset;
+  if (right_exclusion) {
+    right_offset = right_exclusion->rect.BlockEndOffset();
+  }
+
+  switch (style.clear()) {
+    case EClear::kNone:
+      return WTF::nullopt;  // nothing to do here.
+    case EClear::kLeft:
+      return left_offset;
+    case EClear::kRight:
+      return right_offset;
+    case EClear::kBoth:
+      return OptionalMax<LayoutUnit>(left_offset, right_offset);
+    default:
+      ASSERT_NOT_REACHED();
+  }
+  return WTF::nullopt;
+}
+
+}  // namespace blink