cmDefinitions: Implement in terms of cmLinkedTree.

Store the definitions in a cmLinkedTree in the cmMakefile.  This can
be moved to cmState and then the tree will provide snapshotting
possibilities.  It will also make the Closure copy created at
the start of each cmMakefile unnecesarry.

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();

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.

Source/cmMakefile.cxx

@@ -47,70 +47,73 @@
 class cmMakefile::Internals
 {
 public:
-  std::list<cmDefinitions> VarStack;
+  cmLinkedTree<cmDefinitions> VarTree;
+  cmLinkedTree<cmDefinitions>::iterator VarTreeIter;
   bool IsSourceFileTryCompile;
 
   void PushDefinitions()
   {
-    this->VarStack.push_back(cmDefinitions());
+    assert(this->VarTreeIter.IsValid());
+    this->VarTreeIter = this->VarTree.Extend(this->VarTreeIter);
   }
 
   void InitializeVarScope()
   {
+    this->VarTreeIter = this->VarTree.Root();
     this->PushDefinitions();
   }
 
   void InitializeDefinitions(cmMakefile* parent)
   {
-    this->VarStack.back() =
-        cmDefinitions::MakeClosure(parent->Internal->VarStack.rbegin(),
-                                   parent->Internal->VarStack.rend());
+    *this->VarTreeIter =
+        cmDefinitions::MakeClosure(parent->Internal->VarTreeIter,
+                                   parent->Internal->VarTree.Root());
   }
 
   const char* GetDefinition(std::string const& name)
   {
-    return cmDefinitions::Get(name, this->VarStack.rbegin(),
-                                    this->VarStack.rend());
+    assert(this->VarTreeIter != this->VarTree.Root());
+    return cmDefinitions::Get(name,
+                              this->VarTreeIter, this->VarTree.Root());
   }
 
   bool IsInitialized(std::string const& name)
   {
-    return cmDefinitions::HasKey(name, this->VarStack.rbegin(),
-                                 this->VarStack.rend());
+    return cmDefinitions::HasKey(name,
+                                 this->VarTreeIter, this->VarTree.Root());
   }
 
   void SetDefinition(std::string const& name, std::string const& value)
   {
-    this->VarStack.back().Set(name, value.c_str());
+    this->VarTreeIter->Set(name, value.c_str());
   }
 
   void RemoveDefinition(std::string const& name)
   {
-    this->VarStack.back().Set(name, 0);
+    this->VarTreeIter->Set(name, 0);
   }
 
   std::vector<std::string> UnusedKeys() const
   {
-    return this->VarStack.back().UnusedKeys();
+    return this->VarTreeIter->UnusedKeys();
   }
 
   std::vector<std::string> ClosureKeys() const
   {
-    return cmDefinitions::ClosureKeys(this->VarStack.rbegin(),
-                                      this->VarStack.rend());
+    return cmDefinitions::ClosureKeys(this->VarTreeIter, this->VarTree.Root());
   }
 
   void PopDefinitions()
   {
-    this->VarStack.pop_back();
+    ++this->VarTreeIter;
   }
 
   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());
+    cmLinkedTree<cmDefinitions>::iterator it = this->VarTreeIter;
+    assert(it != this->VarTree.Root());
     ++it;
-    if(it == this->VarStack.rend())
+    if(it == this->VarTree.Root())
       {
       cmLocalGenerator* plg = mf->LocalGenerator->GetParent();
       if(!plg)
@@ -132,7 +135,7 @@ public:
       return true;
       }
     // First localize the definition in the current scope.
-    cmDefinitions::Raise(var, this->VarStack.rbegin(), this->VarStack.rend());
+    cmDefinitions::Raise(var, this->VarTreeIter, this->VarTree.Root());
 
     // Now update the definition in the parent scope.
     it->Set(var, varDef);