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+// Copyright (C) 2006 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// contained_range_map.h: Hierarchically-organized range maps.
+//
+// A contained range map is similar to a standard range map, except it allows
+// objects to be organized hierarchically.  A contained range map allows
+// objects to contain other objects.  It is not sensitive to the order that
+// objects are added to the map: larger, more general, containing objects
+// may be added either before or after smaller, more specific, contained
+// ones.
+//
+// Contained range maps guarantee that each object may only contain smaller
+// objects than itself, and that a parent object may only contain child
+// objects located entirely within the parent's address space.  Attempts
+// to introduce objects (via StoreRange) that violate these rules will fail.
+// Retrieval (via RetrieveRange) always returns the most specific (smallest)
+// object that contains the address being queried.  Note that while it is
+// not possible to insert two objects into a map that have exactly the same
+// geometry (base address and size), it is possible to completely mask a
+// larger object by inserting smaller objects that entirely fill the larger
+// object's address space.
+//
+// Internally, contained range maps are implemented as a tree.  Each tree
+// node except for the root node describes an object in the map.  Each node
+// maintains its list of children in a map similar to a standard range map,
+// keyed by the highest address that each child occupies.  Each node's
+// children occupy address ranges entirely within the node.  The root node
+// is the only node directly accessible to the user, and represents the
+// entire address space.
+//
+// Author: Mark Mentovai
+
+#ifndef PROCESSOR_CONTAINED_RANGE_MAP_H__
+#define PROCESSOR_CONTAINED_RANGE_MAP_H__
+
+
+#include <map>
+
+
+namespace google_airbag {
+
+
+template<typename AddressType, typename EntryType>
+class ContainedRangeMap {
+ public:
+  // The default constructor creates a ContainedRangeMap with no geometry
+  // and no entry, and as such is only suitable for the root node of a
+  // ContainedRangeMap tree.
+  ContainedRangeMap() : base_(), entry_(), map_(NULL) {}
+
+  ~ContainedRangeMap();
+
+  // Inserts a range into the map.  If the new range is encompassed by
+  // an existing child range, the new range is passed into the child range's
+  // StoreRange method.  If the new range encompasses any existing child
+  // ranges, those child ranges are moved to the new range, becoming
+  // grandchildren of this ContainedRangeMap.  Returns false for a
+  // parameter error, or if the ContainedRangeMap hierarchy guarantees
+  // would be violated.
+  bool StoreRange(const AddressType &base,
+                  const AddressType &size,
+                  const EntryType &entry);
+  
+  // Retrieves the most specific (smallest) descendant range encompassing
+  // the specified address.  This method will only return entries held by
+  // child ranges, and not the entry contained by |this|.  This is necessary
+  // to support a sparsely-populated root range.  If no descendant range
+  // encompasses the address, or if there is a parameter error, returns
+  // false.
+  bool RetrieveRange(const AddressType &address, EntryType *entry) const;
+
+  // Removes all children.  Note that Clear only removes descendants,
+  // leaving the node on which it is called intact.  Because the only
+  // meaningful things contained by a root node are descendants, this
+  // is sufficient to restore an entire ContainedRangeMap to its initial
+  // empty state when called on the root node.
+  void Clear();
+
+ private:
+  // AddressToRangeMap stores pointers.  This makes reparenting simpler in
+  // StoreRange, because it doesn't need to copy entire objects.
+  typedef std::map<AddressType, ContainedRangeMap *> AddressToRangeMap;
+  typedef typename AddressToRangeMap::const_iterator MapConstIterator;
+  typedef typename AddressToRangeMap::iterator MapIterator;
+  typedef typename AddressToRangeMap::value_type MapValue;
+
+  // Creates a new ContainedRangeMap with the specified base address, entry,
+  // and initial child map, which may be NULL.  This is only used internally
+  // by ContainedRangeMap when it creates a new child.
+  ContainedRangeMap(const AddressType &base, const EntryType &entry,
+                    AddressToRangeMap *map)
+      : base_(base), entry_(entry), map_(map) {}
+
+  // The base address of this range.  The high address does not need to
+  // be stored, because it is used as the key to an object in its parent's
+  // map, and all ContainedRangeMaps except for the root range are contained
+  // within maps.  The root range does not actually contain an entry, so its
+  // base_ field is meaningless, and the fact that it has no parent and thus
+  // no key is unimportant.  For this reason, the base_ field should only be
+  // is accessed on child ContainedRangeMap objects, and never on |this|.
+  const AddressType base_;
+
+  // The entry corresponding to this range.  The root range does not
+  // actually contain an entry, so its entry_ field is meaningless.  For
+  // this reason, the entry_ field should only be accessed on child
+  // ContainedRangeMap objects, and never on |this|.
+  const EntryType entry_;
+
+  // The map containing child ranges, keyed by each child range's high
+  // address.  This is a pointer to avoid allocating map structures for
+  // leaf nodes, where they are not needed.
+  AddressToRangeMap *map_;
+};
+
+
+}  // namespace google_airbag
+
+
+#endif  // PROCESSOR_CONTAINED_RANGE_MAP_H__