Upstream Chrome on iOS source code [2/11].

ios/chrome/browser/tabs/tab_model_order_controller.mm

+// Copyright 2012 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.
+
+#import "ios/chrome/browser/tabs/tab_model_order_controller.h"
+
+#include "base/logging.h"
+
+@implementation TabModelOrderController
+
+@synthesize insertionPolicy = insertionPolicy_;
+
+- (id)initWithTabModel:(TabModel*)model {
+  DCHECK(model);
+  self = [super init];
+  if (self) {
+    model_ = model;
+    insertionPolicy_ = TabModelOrderConstants::kInsertAfter;
+  }
+  return self;
+}
+
+- (NSUInteger)insertionIndexForTab:(Tab*)newTab
+                        transition:(ui::PageTransition)transition
+                            opener:(Tab*)parentTab
+                         adjacency:(TabModelOrderConstants::InsertionAdjacency)
+                                       adjacency {
+  if (model_.isEmpty)
+    return 0;
+
+  if (PageTransitionCoreTypeIs(transition, ui::PAGE_TRANSITION_LINK) &&
+      parentTab) {
+    NSUInteger referenceIndex = [model_ indexOfTab:parentTab];
+    Tab* openLocation = nil;
+    if (insertionPolicy_ == TabModelOrderConstants::kInsertAfter) {
+      openLocation = [model_ lastTabWithOpener:parentTab];
+    } else {
+      openLocation = [model_ firstTabWithOpener:parentTab];
+    }
+    if (openLocation)
+      referenceIndex = [model_ indexOfTab:openLocation];
+
+    // If the reference tab is no longer in the model (e.g., it was closed
+    // before the open request was handled), fall through to default behavior.
+    if (referenceIndex != NSNotFound) {
+      BOOL insertAfter =
+          insertionPolicy_ == TabModelOrderConstants::kInsertAfter ||
+          adjacency == TabModelOrderConstants::kAdjacentAfter;
+      NSUInteger delta = insertAfter ? 1 : 0;
+      return referenceIndex + delta;
+    }
+  }
+  // In other cases, such as a normal new tab, open at the end.
+  return [self insertionIndexForAppending];
+}
+
+- (NSUInteger)insertionIndexForAppending {
+  return insertionPolicy_ == TabModelOrderConstants::kInsertAfter ? model_.count
+                                                                  : 0;
+}
+
+- (Tab*)determineNewSelectedTabFromRemovedTab:(Tab*)removedTab {
+  // While the desktop version of this code deals in indices, this deals in
+  // actual tabs. As a result, the tab only needs to change iff the selection
+  // is the tab that's removed.
+  if (removedTab != model_.currentTab)
+    return model_.currentTab;
+
+  const NSUInteger numberOfTabs = model_.count;
+  if (numberOfTabs < 2)
+    return nil;
+  DCHECK(numberOfTabs >= 2);
+  DCHECK(removedTab == model_.currentTab);
+
+  // First see if the tab being removed has any "child" tabs. If it does, we
+  // want to select the first in that child group, not the next tab in the same
+  // group of the removed tab.
+  Tab* firstChild = [model_ nextTabWithOpener:removedTab afterTab:nil];
+  if (firstChild)
+    return firstChild;
+  Tab* parentTab = [model_ openerOfTab:removedTab];
+  if (parentTab) {
+    // If the tab was in a group, shift selection to the next tab in the group.
+    Tab* nextTab = [model_ nextTabWithOpener:parentTab afterTab:removedTab];
+    if (nextTab)
+      return nextTab;
+
+    // If we can't find a subsequent group member, just fall back to the
+    // parentTab itself. Note that we use "group" here since opener is
+    // reset by select operations.
+    return parentTab;
+  }
+
+  // No opener set, fall through to the default handler...
+  NSUInteger selectedIndex = [model_ indexOfTab:removedTab];
+  DCHECK(selectedIndex <= numberOfTabs - 1);
+  // Is the closing tab the last one? If so, return the penultimate tab.
+  if (selectedIndex == numberOfTabs - 1)
+    return [model_ tabAtIndex:selectedIndex - 1];
+  // Otherwise return the next tab after the current tab.
+  return [model_ tabAtIndex:selectedIndex + 1];
+}
+
+@end