diff --git a/Source/cmDefinitions.cxx b/Source/cmDefinitions.cxx
index 2dab169ef..b06fb5c0b 100644
--- a/Source/cmDefinitions.cxx
+++ b/Source/cmDefinitions.cxx
@@ -56,9 +56,9 @@ void cmDefinitions::Raise(const std::string& key,
 }
 
 bool cmDefinitions::HasKey(const std::string& key,
-                           StackConstIter begin, StackConstIter end)
+                           StackIter begin, StackIter end)
 {
-  for (StackConstIter it = begin; it != end; ++it)
+  for (StackIter it = begin; it != end; ++it)
     {
     MapType::const_iterator i = it->Map.find(key);
     if (i != it->Map.end())
@@ -94,12 +94,12 @@ std::vector<std::string> cmDefinitions::UnusedKeys() const
 }
 
 //----------------------------------------------------------------------------
-cmDefinitions cmDefinitions::MakeClosure(StackConstIter begin,
-                                         StackConstIter end)
+cmDefinitions cmDefinitions::MakeClosure(StackIter begin,
+                                         StackIter end)
 {
   cmDefinitions closure;
   std::set<std::string> undefined;
-  for (StackConstIter it = begin; it != end; ++it)
+  for (StackIter it = begin; it != end; ++it)
     {
     // Consider local definitions.
     for(MapType::const_iterator mi = it->Map.begin();
@@ -125,12 +125,12 @@ cmDefinitions cmDefinitions::MakeClosure(StackConstIter begin,
 
 //----------------------------------------------------------------------------
 std::vector<std::string>
-cmDefinitions::ClosureKeys(StackConstIter begin, StackConstIter end)
+cmDefinitions::ClosureKeys(StackIter begin, StackIter end)
 {
   std::set<std::string> bound;
   std::vector<std::string> defined;
 
-  for (StackConstIter it = begin; it != end; ++it)
+  for (StackIter it = begin; it != end; ++it)
     {
     defined.reserve(defined.size() + it->Map.size());
     for(MapType::const_iterator mi = it->Map.begin();
diff --git a/Source/cmDefinitions.h b/Source/cmDefinitions.h
index 5fdcaab72..411867c52 100644
--- a/Source/cmDefinitions.h
+++ b/Source/cmDefinitions.h
@@ -13,6 +13,9 @@
 #define cmDefinitions_h
 
 #include "cmStandardIncludes.h"
+
+#include "cmLinkedTree.h"
+
 #if defined(CMAKE_BUILD_WITH_CMAKE)
 #ifdef CMake_HAVE_CXX11_UNORDERED_MAP
 #include <unordered_map>
@@ -32,26 +35,26 @@
  */
 class cmDefinitions
 {
-  typedef std::list<cmDefinitions>::reverse_iterator StackIter;
-  typedef std::list<cmDefinitions>::const_reverse_iterator StackConstIter;
+  typedef cmLinkedTree<cmDefinitions>::iterator StackIter;
 public:
   static const char* Get(const std::string& key,
                          StackIter begin, StackIter end);
 
-  static void Raise(const std::string& key, StackIter begin, StackIter end);
+  static void Raise(const std::string& key,
+                    StackIter begin, StackIter end);
 
   static bool HasKey(const std::string& key,
-                     StackConstIter begin, StackConstIter end);
+                     StackIter begin, StackIter end);
 
   /** Set (or unset if null) a value associated with a key.  */
   void Set(const std::string& key, const char* value);
 
   std::vector<std::string> UnusedKeys() const;
 
-  static std::vector<std::string> ClosureKeys(StackConstIter begin,
-                                              StackConstIter end);
+  static std::vector<std::string> ClosureKeys(StackIter begin,
+                                              StackIter end);
 
-  static cmDefinitions MakeClosure(StackConstIter begin, StackConstIter end);
+  static cmDefinitions MakeClosure(StackIter begin, StackIter end);
 
 private:
   // String with existence boolean.
diff --git a/Source/cmMakefile.cxx b/Source/cmMakefile.cxx
index 6e43b5230..7ad37e60e 100644
--- a/Source/cmMakefile.cxx
+++ b/Source/cmMakefile.cxx
@@ -31,7 +31,6 @@
 #endif
 #include "cmInstallGenerator.h"
 #include "cmTestGenerator.h"
-#include "cmDefinitions.h"
 #include "cmAlgorithms.h"
 #include "cmake.h"
 #include <stdlib.h> // required for atoi
@@ -47,92 +46,7 @@
 class cmMakefile::Internals
 {
 public:
-  std::list<cmDefinitions> VarStack;
   bool IsSourceFileTryCompile;
-
-  void PushDefinitions()
-  {
-    this->VarStack.push_back(cmDefinitions());
-  }
-
-  void InitializeDefinitions(cmMakefile* parent)
-  {
-    this->VarStack.back() =
-        cmDefinitions::MakeClosure(parent->Internal->VarStack.rbegin(),
-                                   parent->Internal->VarStack.rend());
-  }
-
-  const char* GetDefinition(std::string const& name)
-  {
-    return cmDefinitions::Get(name, this->VarStack.rbegin(),
-                                    this->VarStack.rend());
-  }
-
-  bool IsInitialized(std::string const& name)
-  {
-    return cmDefinitions::HasKey(name, this->VarStack.rbegin(),
-                                 this->VarStack.rend());
-  }
-
-  void SetDefinition(std::string const& name, std::string const& value)
-  {
-    this->VarStack.back().Set(name, value.c_str());
-  }
-
-  void RemoveDefinition(std::string const& name)
-  {
-    this->VarStack.back().Set(name, 0);
-  }
-
-  std::vector<std::string> UnusedKeys() const
-  {
-    return this->VarStack.back().UnusedKeys();
-  }
-
-  std::vector<std::string> ClosureKeys() const
-  {
-    return cmDefinitions::ClosureKeys(this->VarStack.rbegin(),
-                                      this->VarStack.rend());
-  }
-
-  void PopDefinitions()
-  {
-    this->VarStack.pop_back();
-  }
-
-  bool RaiseScope(std::string const& var, const char* varDef, cmMakefile* mf)
-  {
-    std::list<cmDefinitions>::reverse_iterator it = this->VarStack.rbegin();
-    assert(it != this->VarStack.rend());
-    ++it;
-    if(it == this->VarStack.rend())
-      {
-      cmLocalGenerator* plg = mf->LocalGenerator->GetParent();
-      if(!plg)
-        {
-        return false;
-        }
-      // Update the definition in the parent directory top scope.  This
-      // directory's scope was initialized by the closure of the parent
-      // scope, so we do not need to localize the definition first.
-      cmMakefile* parent = plg->GetMakefile();
-      if (varDef)
-        {
-        parent->AddDefinition(var, varDef);
-        }
-      else
-        {
-        parent->RemoveDefinition(var);
-        }
-      return true;
-      }
-    // First localize the definition in the current scope.
-    cmDefinitions::Raise(var, this->VarStack.rbegin(), this->VarStack.rend());
-
-    // Now update the definition in the parent scope.
-    it->Set(var, varDef);
-    return true;
-  }
 };
 
 // default is not to be building executables
@@ -141,7 +55,6 @@ cmMakefile::cmMakefile(cmLocalGenerator* localGenerator)
     LocalGenerator(localGenerator),
     StateSnapshot(localGenerator->GetStateSnapshot())
 {
-  this->Internal->PushDefinitions();
   this->Internal->IsSourceFileTryCompile = false;
 
   // Initialize these first since AddDefaultDefinitions calls AddDefinition
@@ -1567,9 +1480,6 @@ void cmMakefile::AddLinkLibrary(const std::string& lib)
 
 void cmMakefile::InitializeFromParent(cmMakefile* parent)
 {
-  // Initialize definitions with the closure of the parent scope.
-  this->Internal->InitializeDefinitions(parent);
-
   this->StateSnapshot.InitializeFromParent();
 
   this->AddDefinition("CMAKE_CURRENT_SOURCE_DIR",
@@ -1634,8 +1544,6 @@ void cmMakefile::PushFunctionScope(std::string const& fileName,
         fileName);
   assert(this->StateSnapshot.IsValid());
 
-  this->Internal->PushDefinitions();
-
   this->PushLoopBlockBarrier();
 
 #if defined(CMAKE_BUILD_WITH_CMAKE)
@@ -1662,8 +1570,6 @@ void cmMakefile::PopFunctionScope(bool reportError)
   this->PopLoopBlockBarrier();
 
   this->CheckForUnusedVariables();
-
-  this->Internal->PopDefinitions();
 }
 
 void cmMakefile::PushMacroScope(std::string const& fileName,
@@ -1967,7 +1873,7 @@ void cmMakefile::AddDefinition(const std::string& name, const char* value)
     {
     this->LogUnused("changing definition", name);
     }
-  this->Internal->SetDefinition(name, value);
+  this->StateSnapshot.SetDefinition(name, value);
 
 #ifdef CMAKE_BUILD_WITH_CMAKE
   cmVariableWatch* vv = this->GetVariableWatch();
@@ -2030,7 +1936,7 @@ void cmMakefile::AddCacheDefinition(const std::string& name, const char* value,
   this->GetState()->AddCacheEntry(name, haveVal ? val.c_str() : 0,
                                           doc, type);
   // if there was a definition then remove it
-  this->Internal->RemoveDefinition(name);
+  this->StateSnapshot.RemoveDefinition(name);
 }
 
 
@@ -2040,7 +1946,9 @@ void cmMakefile::AddDefinition(const std::string& name, bool value)
     {
     this->LogUnused("changing definition", name);
     }
-  this->Internal->SetDefinition(name, value ? "ON" : "OFF");
+
+  this->StateSnapshot.SetDefinition(name, value ? "ON" : "OFF");
+
 #ifdef CMAKE_BUILD_WITH_CMAKE
   cmVariableWatch* vv = this->GetVariableWatch();
   if ( vv )
@@ -2057,7 +1965,7 @@ void cmMakefile::CheckForUnusedVariables() const
     {
     return;
     }
-  const std::vector<std::string>& unused = this->Internal->UnusedKeys();
+  const std::vector<std::string>& unused = this->StateSnapshot.UnusedKeys();
   std::vector<std::string>::const_iterator it = unused.begin();
   for (; it != unused.end(); ++it)
     {
@@ -2067,12 +1975,12 @@ void cmMakefile::CheckForUnusedVariables() const
 
 void cmMakefile::MarkVariableAsUsed(const std::string& var)
 {
-  this->Internal->GetDefinition(var);
+  this->StateSnapshot.GetDefinition(var);
 }
 
 bool cmMakefile::VariableInitialized(const std::string& var) const
 {
-  return this->Internal->IsInitialized(var);
+  return this->StateSnapshot.IsInitialized(var);
 }
 
 void cmMakefile::LogUnused(const char* reason,
@@ -2120,7 +2028,7 @@ void cmMakefile::RemoveDefinition(const std::string& name)
     {
     this->LogUnused("unsetting", name);
     }
-  this->Internal->RemoveDefinition(name);
+  this->StateSnapshot.RemoveDefinition(name);
 #ifdef CMAKE_BUILD_WITH_CMAKE
   cmVariableWatch* vv = this->GetVariableWatch();
   if ( vv )
@@ -2598,7 +2506,7 @@ const char* cmMakefile::GetRequiredDefinition(const std::string& name) const
 
 bool cmMakefile::IsDefinitionSet(const std::string& name) const
 {
-  const char* def = this->Internal->GetDefinition(name);
+  const char* def = this->StateSnapshot.GetDefinition(name);
   if(!def)
     {
     def = this->GetState()->GetInitializedCacheValue(name);
@@ -2619,7 +2527,7 @@ bool cmMakefile::IsDefinitionSet(const std::string& name) const
 
 const char* cmMakefile::GetDefinition(const std::string& name) const
 {
-  const char* def = this->Internal->GetDefinition(name);
+  const char* def = this->StateSnapshot.GetDefinition(name);
   if(!def)
     {
     def = this->GetState()->GetInitializedCacheValue(name);
@@ -2655,7 +2563,7 @@ const char* cmMakefile::GetSafeDefinition(const std::string& def) const
 
 std::vector<std::string> cmMakefile::GetDefinitions() const
 {
-  std::vector<std::string> res = this->Internal->ClosureKeys();
+  std::vector<std::string> res = this->StateSnapshot.ClosureKeys();
   std::vector<std::string> cacheKeys = this->GetState()->GetCacheEntryKeys();
   res.insert(res.end(), cacheKeys.begin(), cacheKeys.end());
   std::sort(res.begin(), res.end());
@@ -4434,8 +4342,17 @@ std::string cmMakefile::FormatListFileStack() const
 
 void cmMakefile::PushScope()
 {
-  this->Internal->PushDefinitions();
-
+  std::string commandName;
+  long line = 0;
+  if (!this->ContextStack.empty())
+    {
+    commandName = this->ContextStack.back()->Name;
+    line = this->ContextStack.back()->Line;
+    }
+  this->StateSnapshot = this->GetState()->CreateVariableScopeSnapshot(
+        this->StateSnapshot,
+        commandName,
+        line);
   this->PushLoopBlockBarrier();
 
 #if defined(CMAKE_BUILD_WITH_CMAKE)
@@ -4453,7 +4370,9 @@ void cmMakefile::PopScope()
 
   this->CheckForUnusedVariables();
 
-  this->Internal->PopDefinitions();
+  this->StateSnapshot =
+      this->GetState()->Pop(this->StateSnapshot);
+  assert(this->StateSnapshot.IsValid());
 }
 
 void cmMakefile::RaiseScope(const std::string& var, const char *varDef)
@@ -4463,7 +4382,7 @@ void cmMakefile::RaiseScope(const std::string& var, const char *varDef)
     return;
     }
 
-  if (!this->Internal->RaiseScope(var, varDef, this))
+  if (!this->StateSnapshot.RaiseScope(var, varDef))
     {
     std::ostringstream m;
     m << "Cannot set \"" << var << "\": current scope has no parent.";
diff --git a/Source/cmState.cxx b/Source/cmState.cxx
index 84d87838e..336ff78aa 100644
--- a/Source/cmState.cxx
+++ b/Source/cmState.cxx
@@ -15,11 +15,13 @@
 #include "cmCacheManager.h"
 #include "cmCommand.h"
 #include "cmAlgorithms.h"
+#include "cmDefinitions.h"
 
 #include <assert.h>
 
 struct cmState::SnapshotDataType
 {
+  cmState::PositionType ScopeParent;
   cmState::PositionType DirectoryParent;
   cmLinkedTree<cmState::PolicyStackEntry>::iterator Policies;
   cmLinkedTree<cmState::PolicyStackEntry>::iterator PolicyRoot;
@@ -28,6 +30,9 @@ struct cmState::SnapshotDataType
   cmLinkedTree<std::string>::iterator ExecutionListFile;
   cmLinkedTree<cmState::BuildsystemDirectoryStateType>::iterator
                                                           BuildSystemDirectory;
+  cmLinkedTree<cmDefinitions>::iterator Vars;
+  cmLinkedTree<cmDefinitions>::iterator Root;
+  cmLinkedTree<cmDefinitions>::iterator Parent;
   std::string EntryPointCommand;
   long EntryPointLine;
   std::vector<std::string>::size_type IncludeDirectoryPosition;
@@ -274,6 +279,10 @@ cmState::Snapshot cmState::Reset()
   pos->PolicyScope = this->PolicyStack.Root();
   assert(pos->Policies.IsValid());
   assert(pos->PolicyRoot.IsValid());
+  this->VarTree.Clear();
+  pos->Vars = this->VarTree.Extend(this->VarTree.Root());
+  pos->Parent = this->VarTree.Root();
+  pos->Root = this->VarTree.Root();
 
   this->DefineProperty
     ("RULE_LAUNCH_COMPILE", cmProperty::DIRECTORY,
@@ -736,7 +745,8 @@ cmState::Snapshot cmState::CreateBaseSnapshot()
 {
   PositionType pos = this->SnapshotData.Extend(this->SnapshotData.Root());
   pos->DirectoryParent = this->SnapshotData.Root();
-  pos->SnapshotType = BuildsystemDirectoryType;
+  pos->ScopeParent = this->SnapshotData.Root();
+  pos->SnapshotType = BaseType;
   pos->BuildSystemDirectory =
       this->BuildsystemDirectory.Extend(this->BuildsystemDirectory.Root());
   pos->ExecutionListFile =
@@ -750,6 +760,10 @@ cmState::Snapshot cmState::CreateBaseSnapshot()
   pos->PolicyScope = this->PolicyStack.Root();
   assert(pos->Policies.IsValid());
   assert(pos->PolicyRoot.IsValid());
+  pos->Vars = this->VarTree.Extend(this->VarTree.Root());
+  assert(pos->Vars.IsValid());
+  pos->Parent = this->VarTree.Root();
+  pos->Root = this->VarTree.Root();
   return cmState::Snapshot(this, pos);
 }
 
@@ -763,6 +777,7 @@ cmState::CreateBuildsystemDirectorySnapshot(Snapshot originSnapshot,
   pos->EntryPointLine = entryPointLine;
   pos->EntryPointCommand = entryPointCommand;
   pos->DirectoryParent = originSnapshot.Position;
+  pos->ScopeParent = originSnapshot.Position;
   pos->SnapshotType = BuildsystemDirectoryType;
   pos->BuildSystemDirectory =
       this->BuildsystemDirectory.Extend(
@@ -776,6 +791,12 @@ cmState::CreateBuildsystemDirectorySnapshot(Snapshot originSnapshot,
   pos->PolicyScope = originSnapshot.Position->Policies;
   assert(pos->Policies.IsValid());
   assert(pos->PolicyRoot.IsValid());
+
+  cmLinkedTree<cmDefinitions>::iterator origin =
+      originSnapshot.Position->Vars;
+  pos->Parent = origin;
+  pos->Root = origin;
+  pos->Vars = this->VarTree.Extend(origin);
   return cmState::Snapshot(this, pos);
 }
 
@@ -787,6 +808,7 @@ cmState::CreateFunctionCallSnapshot(cmState::Snapshot originSnapshot,
 {
   PositionType pos = this->SnapshotData.Extend(originSnapshot.Position,
                                                *originSnapshot.Position);
+  pos->ScopeParent = originSnapshot.Position;
   pos->EntryPointLine = entryPointLine;
   pos->EntryPointCommand = entryPointCommand;
   pos->SnapshotType = FunctionCallType;
@@ -794,6 +816,11 @@ cmState::CreateFunctionCallSnapshot(cmState::Snapshot originSnapshot,
         originSnapshot.Position->ExecutionListFile, fileName);
   pos->BuildSystemDirectory->DirectoryEnd = pos;
   pos->PolicyScope = originSnapshot.Position->Policies;
+  assert(originSnapshot.Position->Vars.IsValid());
+  cmLinkedTree<cmDefinitions>::iterator origin =
+      originSnapshot.Position->Vars;
+  pos->Parent = origin;
+  pos->Vars = this->VarTree.Extend(origin);
   return cmState::Snapshot(this, pos);
 }
 
@@ -811,6 +838,7 @@ cmState::CreateMacroCallSnapshot(cmState::Snapshot originSnapshot,
   pos->SnapshotType = MacroCallType;
   pos->ExecutionListFile = this->ExecutionListFiles.Extend(
         originSnapshot.Position->ExecutionListFile, fileName);
+  assert(originSnapshot.Position->Vars.IsValid());
   pos->BuildSystemDirectory->DirectoryEnd = pos;
   pos->PolicyScope = originSnapshot.Position->Policies;
   return cmState::Snapshot(this, pos);
@@ -829,11 +857,33 @@ cmState::CreateCallStackSnapshot(cmState::Snapshot originSnapshot,
   pos->SnapshotType = CallStackType;
   pos->ExecutionListFile = this->ExecutionListFiles.Extend(
         originSnapshot.Position->ExecutionListFile, fileName);
+  assert(originSnapshot.Position->Vars.IsValid());
   pos->BuildSystemDirectory->DirectoryEnd = pos;
   pos->PolicyScope = originSnapshot.Position->Policies;
   return cmState::Snapshot(this, pos);
 }
 
+cmState::Snapshot
+cmState::CreateVariableScopeSnapshot(cmState::Snapshot originSnapshot,
+                                     std::string const& entryPointCommand,
+                                     long entryPointLine)
+{
+  PositionType pos = this->SnapshotData.Extend(originSnapshot.Position,
+                                               *originSnapshot.Position);
+  pos->ScopeParent = originSnapshot.Position;
+  pos->EntryPointLine = entryPointLine;
+  pos->EntryPointCommand = entryPointCommand;
+  pos->SnapshotType = VariableScopeType;
+  assert(originSnapshot.Position->Vars.IsValid());
+
+  cmLinkedTree<cmDefinitions>::iterator origin =
+      originSnapshot.Position->Vars;
+  pos->Parent = origin;
+  pos->Vars = this->VarTree.Extend(origin);
+  assert(pos->Vars.IsValid());
+  return cmState::Snapshot(this, pos);
+}
+
 cmState::Snapshot
 cmState::CreateInlineListFileSnapshot(cmState::Snapshot originSnapshot,
                                       const std::string& entryPointCommand,
@@ -1019,7 +1069,8 @@ cmState::Snapshot cmState::Snapshot::GetCallStackParent() const
     {
     ++parentPos;
     }
-  if (parentPos->SnapshotType == cmState::BuildsystemDirectoryType)
+  if (parentPos->SnapshotType == cmState::BuildsystemDirectoryType
+      || parentPos->SnapshotType == cmState::BaseType)
     {
     return snapshot;
     }
@@ -1121,6 +1172,72 @@ bool cmState::Snapshot::HasDefinedPolicyCMP0011()
   return !this->Position->Policies->IsEmpty();
 }
 
+const char* cmState::Snapshot::GetDefinition(std::string const& name) const
+{
+  assert(this->Position->Vars.IsValid());
+  return cmDefinitions::Get(name, this->Position->Vars,
+                    this->Position->Root);
+}
+
+bool cmState::Snapshot::IsInitialized(std::string const& name) const
+{
+  return cmDefinitions::HasKey(name, this->Position->Vars,
+                               this->Position->Root);
+}
+
+void cmState::Snapshot::SetDefinition(std::string const& name,
+                                      std::string const& value)
+{
+  this->Position->Vars->Set(name, value.c_str());
+}
+
+void cmState::Snapshot::RemoveDefinition(std::string const& name)
+{
+  this->Position->Vars->Set(name, 0);
+}
+
+std::vector<std::string> cmState::Snapshot::UnusedKeys() const
+{
+  return this->Position->Vars->UnusedKeys();
+}
+
+std::vector<std::string> cmState::Snapshot::ClosureKeys() const
+{
+  return cmDefinitions::ClosureKeys(this->Position->Vars,
+                                    this->Position->Root);
+}
+
+bool cmState::Snapshot::RaiseScope(std::string const& var, const char* varDef)
+{
+  if(this->Position->ScopeParent == this->Position->DirectoryParent)
+    {
+    Snapshot parentDir = this->GetBuildsystemDirectoryParent();
+    if(!parentDir.IsValid())
+      {
+      return false;
+      }
+    // Update the definition in the parent directory top scope.  This
+    // directory's scope was initialized by the closure of the parent
+    // scope, so we do not need to localize the definition first.
+    if (varDef)
+      {
+      parentDir.SetDefinition(var, varDef);
+      }
+    else
+      {
+      parentDir.RemoveDefinition(var);
+      }
+    return true;
+    }
+  // First localize the definition in the current scope.
+  cmDefinitions::Raise(var, this->Position->Vars,
+                       this->Position->Root);
+
+  // Now update the definition in the parent scope.
+  this->Position->Parent->Set(var, varDef);
+  return true;
+}
+
 static const std::string cmPropertySentinal = std::string();
 
 template<typename T, typename U, typename V>
@@ -1157,6 +1274,11 @@ void InitializeContentFromParent(T& parentContent,
 void cmState::Snapshot::InitializeFromParent()
 {
   PositionType parent = this->Position->DirectoryParent;
+  assert(this->Position->Vars.IsValid());
+  assert(parent->Vars.IsValid());
+
+  *this->Position->Vars =
+      cmDefinitions::MakeClosure(parent->Vars, parent->Root);
 
   InitializeContentFromParent(parent->BuildSystemDirectory->IncludeDirectories,
               this->Position->BuildSystemDirectory->IncludeDirectories,
diff --git a/Source/cmState.h b/Source/cmState.h
index 3132d1b8e..86945f663 100644
--- a/Source/cmState.h
+++ b/Source/cmState.h
@@ -21,6 +21,8 @@
 
 class cmake;
 class cmCommand;
+class cmDefinitions;
+class cmListFileBacktrace;
 
 class cmState
 {
@@ -35,12 +37,14 @@ public:
 
   enum SnapshotType
   {
+    BaseType,
     BuildsystemDirectoryType,
     FunctionCallType,
     MacroCallType,
     CallStackType,
     InlineListFileType,
-    PolicyScopeType
+    PolicyScopeType,
+    VariableScopeType
   };
 
   class Directory;
@@ -50,6 +54,14 @@ public:
     Snapshot(cmState* state = 0);
     Snapshot(cmState* state, PositionType position);
 
+    const char* GetDefinition(std::string const& name) const;
+    bool IsInitialized(std::string const& name) const;
+    void SetDefinition(std::string const& name, std::string const& value);
+    void RemoveDefinition(std::string const& name);
+    std::vector<std::string> UnusedKeys() const;
+    std::vector<std::string> ClosureKeys() const;
+    bool RaiseScope(std::string const& var, const char* varDef);
+
     void SetListFile(std::string const& listfile);
 
     std::string GetExecutionListFile() const;
@@ -161,6 +173,9 @@ public:
                                    std::string const& entryPointCommand,
                                    long entryPointLine,
                                    std::string const& fileName);
+  Snapshot CreateVariableScopeSnapshot(Snapshot originSnapshot,
+                                       std::string const& entryPointCommand,
+                                       long entryPointLine);
   Snapshot CreateInlineListFileSnapshot(Snapshot originSnapshot,
                                         const std::string& entryPointCommand,
                                         long entryPointLine,
@@ -275,6 +290,7 @@ private:
 
   cmLinkedTree<PolicyStackEntry> PolicyStack;
   cmLinkedTree<SnapshotDataType> SnapshotData;
+  cmLinkedTree<cmDefinitions> VarTree;
 
   std::vector<std::string> SourceDirectoryComponents;
   std::vector<std::string> BinaryDirectoryComponents;