[MarkersIntersectingRange #2.05] Add DocumentMarkerList::FirstMarkerIntersectingRange()

third_party/WebKit/Source/core/editing/markers/DocumentMarkerListEditor.cpp

 // 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/editing/markers/DocumentMarkerListEditor.h"
 
 #include "core/editing/markers/SpellCheckMarkerListImpl.h"
 
 namespace blink {
 
@@ skipping 148 matching lines @@
       marker.SetStartOffset(result.value().start_offset);
       marker.SetEndOffset(result.value().end_offset);
     }
   }
 
   list->erase(erase_range_begin - list->begin(),
               erase_range_end - erase_range_begin);
   return did_shift_marker;
 }
 
+DocumentMarker* DocumentMarkerListEditor::FirstMarkerIntersectingRange(
+    const MarkerList& list,
+    unsigned start_offset,
+    unsigned end_offset) {
+  DCHECK_LE(start_offset, end_offset);
+
+  const auto& marker_it =
+      std::lower_bound(list.begin(), list.end(), start_offset,
+                       [](const DocumentMarker* marker, unsigned start_offset) {
+                         return marker->EndOffset() <= start_offset;
+                       });
+  if (marker_it == list.end())
+    return nullptr;
+
+  DocumentMarker* marker = *marker_it;
+  if (marker->StartOffset() >= end_offset)
+    return nullptr;
+  return marker;
+}
+
 HeapVector<Member<DocumentMarker>>
 DocumentMarkerListEditor::MarkersIntersectingRange(const MarkerList& list,
                                                    unsigned start_offset,
                                                    unsigned end_offset) {
   DCHECK_LE(start_offset, end_offset);
 
   const auto& start_it =
       std::lower_bound(list.begin(), list.end(), start_offset,
                        [](const DocumentMarker* marker, unsigned start_offset) {
                          return marker->EndOffset() <= start_offset;
                        });
   const auto& end_it =
       std::upper_bound(list.begin(), list.end(), end_offset,
                        [](unsigned end_offset, const DocumentMarker* marker) {
                          return end_offset <= marker->StartOffset();
                        });
 
   HeapVector<Member<DocumentMarker>> results;
   std::copy(start_it, end_it, std::back_inserter(results));
   return results;
 }
 
 }  // namespace blink