cmState: Split auxiliary classes into separate files

Port dependents to the new locations as needed.

Leave behind a cmState.h include in cmListFileCache to reduce noise. It
is removed in a following commit.

Source/CMakeLists.txt

@@ -360,6 +360,10 @@ set(SRCS
   cmSourceGroup.h
   cmState.cxx
   cmState.h
+  cmStateDirectory.cxx
+  cmStateDirectory.h
+  cmStateSnapshot.cxx
+  cmStateSnapshot.h
   cmStateTypes.h
   cmSystemTools.cxx
   cmSystemTools.h

Source/cmCommonTargetGenerator.cxx

@@ -17,6 +17,7 @@
 #include "cmLocalGenerator.h"
 #include "cmMakefile.h"
 #include "cmSourceFile.h"
+#include "cmStateDirectory.h"
 #include "cmStateTypes.h"
 
 cmCommonTargetGenerator::cmCommonTargetGenerator(cmGeneratorTarget* gt)

Source/cmDependsFortran.cxx

@@ -7,6 +7,7 @@
 #include "cmLocalGenerator.h"
 #include "cmMakefile.h"
 #include "cmOutputConverter.h"
+#include "cmStateDirectory.h"
 #include "cmSystemTools.h"
 
 #include <assert.h>

Source/cmGlobalGenerator.h

@@ -6,7 +6,8 @@
 #include <cmConfigure.h>
 
 #include "cmExportSetMap.h"
-#include "cmState.h"
+#include "cmStateDirectory.h"
+#include "cmStateSnapshot.h"
 #include "cmSystemTools.h"
 #include "cmTarget.h"
 #include "cmTargetDepend.h"

Source/cmGlobalUnixMakefileGenerator3.cxx

@@ -12,6 +12,8 @@
 #include "cmMakefile.h"
 #include "cmMakefileTargetGenerator.h"
 #include "cmOutputConverter.h"
+#include "cmState.h"
+#include "cmStateDirectory.h"
 #include "cmSystemTools.h"
 #include "cmTarget.h"
 #include "cmTargetDepend.h"

Source/cmLinkLineComputer.cxx

@@ -5,6 +5,7 @@
 #include "cmComputeLinkInformation.h"
 #include "cmGeneratorTarget.h"
 #include "cmOutputConverter.h"
+#include "cmStateDirectory.h"
 
 cmLinkLineComputer::cmLinkLineComputer(cmOutputConverter* outputConverter,
                                        cmStateDirectory stateDir)

Source/cmLinkLineComputer.h

@@ -4,7 +4,7 @@
 #ifndef cmLinkLineComputer_h
 #define cmLinkLineComputer_h
 
-#include "cmState.h"
+#include "cmStateDirectory.h"
 
 class cmComputeLinkInformation;
 class cmOutputConverter;

Source/cmListFileCache.h

@@ -10,6 +10,7 @@
 #include <vector>
 
 #include "cmState.h"
+#include "cmStateSnapshot.h"
 
 /** \class cmListFileCache
  * \brief A class to cache list file contents.

Source/cmLocalGenerator.cxx

@@ -16,6 +16,8 @@
 #include "cmMakefile.h"
 #include "cmRulePlaceholderExpander.h"
 #include "cmSourceFile.h"
+#include "cmState.h"
+#include "cmStateDirectory.h"
 #include "cmSystemTools.h"
 #include "cmTarget.h"
 #include "cmTestGenerator.h"

Source/cmLocalUnixMakefileGenerator3.cxx

@@ -16,6 +16,8 @@
 #include "cmOutputConverter.h"
 #include "cmRulePlaceholderExpander.h"
 #include "cmSourceFile.h"
+#include "cmState.h"
+#include "cmStateDirectory.h"
 #include "cmStateTypes.h"
 #include "cmSystemTools.h"
 #include "cmVersion.h"

Source/cmMakefile.cxx

@@ -17,6 +17,8 @@
 #include "cmListFileCache.h"
 #include "cmSourceFile.h"
 #include "cmSourceFileLocation.h"
+#include "cmState.h"
+#include "cmStateDirectory.h"
 #include "cmStateTypes.h"
 #include "cmSystemTools.h"
 #include "cmTest.h"

Source/cmMakefile.h

@@ -9,7 +9,7 @@
 #include "cmListFileCache.h"
 #include "cmNewLineStyle.h"
 #include "cmPolicies.h"
-#include "cmState.h"
+#include "cmStateSnapshot.h"
 #include "cmTarget.h"
 #include "cmTargetLinkLibraryType.h"
 #include "cmake.h"

Source/cmOutputConverter.cxx

@@ -3,6 +3,8 @@
 #include "cmOutputConverter.h"
 
 #include "cmAlgorithms.h"
+#include "cmState.h"
+#include "cmStateDirectory.h"
 #include "cmSystemTools.h"
 
 #include <algorithm>

Source/cmOutputConverter.h

@@ -5,7 +5,7 @@
 
 #include <cmConfigure.h> // IWYU pragma: keep
 
-#include "cmState.h"
+#include "cmStateSnapshot.h"
 
 #include <string>
 #include <vector>

Source/cmQtAutoGenerators.cxx

@@ -7,6 +7,8 @@
 #include "cmGlobalGenerator.h"
 #include "cmMakefile.h"
 #include "cmOutputConverter.h"
+#include "cmState.h"
+#include "cmStateDirectory.h"
 #include "cmStateTypes.h"
 #include "cmSystemTools.h"
 #include "cm_auto_ptr.hxx"

Source/cmState.h

@@ -8,7 +8,6 @@
 #include "cmAlgorithms.h"
 #include "cmDefinitions.h"
 #include "cmLinkedTree.h"
-#include "cmPolicies.h"
 #include "cmProperty.h"
 #include "cmPropertyDefinitionMap.h"
 #include "cmPropertyMap.h"
@@ -186,138 +185,4 @@ private:
   bool MSYSShell;
 };
 
-class cmStateSnapshot
-{
-public:
-  cmStateSnapshot(cmState* state = CM_NULLPTR);
-  cmStateSnapshot(cmState* state, cmStateDetail::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;
-
-  std::vector<cmStateSnapshot> GetChildren();
-
-  bool IsValid() const;
-  cmStateSnapshot GetBuildsystemDirectoryParent() const;
-  cmStateSnapshot GetCallStackParent() const;
-  cmStateSnapshot GetCallStackBottom() const;
-  cmStateEnums::SnapshotType GetType() const;
-
-  void SetPolicy(cmPolicies::PolicyID id, cmPolicies::PolicyStatus status);
-  cmPolicies::PolicyStatus GetPolicy(cmPolicies::PolicyID id) const;
-  bool HasDefinedPolicyCMP0011();
-  void PushPolicy(cmPolicies::PolicyMap entry, bool weak);
-  bool PopPolicy();
-  bool CanPopPolicyScope();
-
-  cmState* GetState() const;
-
-  cmStateDirectory GetDirectory() const;
-
-  void SetProjectName(std::string const& name);
-  std::string GetProjectName() const;
-
-  void InitializeFromParent_ForSubdirsCommand();
-
-  struct StrictWeakOrder
-  {
-    bool operator()(const cmStateSnapshot& lhs,
-                    const cmStateSnapshot& rhs) const;
-  };
-
-  void SetDirectoryDefinitions();
-  void SetDefaultDefinitions();
-
-private:
-  friend bool operator==(const cmStateSnapshot& lhs,
-                         const cmStateSnapshot& rhs);
-  friend bool operator!=(const cmStateSnapshot& lhs,
-                         const cmStateSnapshot& rhs);
-  friend class cmState;
-  friend class cmStateDirectory;
-  friend struct StrictWeakOrder;
-
-  void InitializeFromParent();
-
-  cmState* State;
-  cmStateDetail::PositionType Position;
-};
-
-class cmStateDirectory
-{
-  cmStateDirectory(
-    cmLinkedTree<cmStateDetail::BuildsystemDirectoryStateType>::iterator iter,
-    cmStateSnapshot const& snapshot);
-
-public:
-  const char* GetCurrentSource() const;
-  void SetCurrentSource(std::string const& dir);
-  const char* GetCurrentBinary() const;
-  void SetCurrentBinary(std::string const& dir);
-
-  const char* GetRelativePathTopSource() const;
-  const char* GetRelativePathTopBinary() const;
-  void SetRelativePathTopSource(const char* dir);
-  void SetRelativePathTopBinary(const char* dir);
-
-  cmStringRange GetIncludeDirectoriesEntries() const;
-  cmBacktraceRange GetIncludeDirectoriesEntryBacktraces() const;
-  void AppendIncludeDirectoriesEntry(std::string const& vec,
-                                     cmListFileBacktrace const& lfbt);
-  void PrependIncludeDirectoriesEntry(std::string const& vec,
-                                      cmListFileBacktrace const& lfbt);
-  void SetIncludeDirectories(std::string const& vec,
-                             cmListFileBacktrace const& lfbt);
-  void ClearIncludeDirectories();
-
-  cmStringRange GetCompileDefinitionsEntries() const;
-  cmBacktraceRange GetCompileDefinitionsEntryBacktraces() const;
-  void AppendCompileDefinitionsEntry(std::string const& vec,
-                                     cmListFileBacktrace const& lfbt);
-  void SetCompileDefinitions(std::string const& vec,
-                             cmListFileBacktrace const& lfbt);
-  void ClearCompileDefinitions();
-
-  cmStringRange GetCompileOptionsEntries() const;
-  cmBacktraceRange GetCompileOptionsEntryBacktraces() const;
-  void AppendCompileOptionsEntry(std::string const& vec,
-                                 cmListFileBacktrace const& lfbt);
-  void SetCompileOptions(std::string const& vec,
-                         cmListFileBacktrace const& lfbt);
-  void ClearCompileOptions();
-
-  void SetProperty(const std::string& prop, const char* value,
-                   cmListFileBacktrace const& lfbt);
-  void AppendProperty(const std::string& prop, const char* value,
-                      bool asString, cmListFileBacktrace const& lfbt);
-  const char* GetProperty(const std::string& prop) const;
-  const char* GetProperty(const std::string& prop, bool chain) const;
-  bool GetPropertyAsBool(const std::string& prop) const;
-  std::vector<std::string> GetPropertyKeys() const;
-
-  void AddNormalTargetName(std::string const& name);
-
-private:
-  void ComputeRelativePathTopSource();
-  void ComputeRelativePathTopBinary();
-
-private:
-  cmLinkedTree<cmStateDetail::BuildsystemDirectoryStateType>::iterator
-    DirectoryState;
-  cmStateSnapshot Snapshot_;
-  friend class cmStateSnapshot;
-};
-
-bool operator==(const cmStateSnapshot& lhs, const cmStateSnapshot& rhs);
-bool operator!=(const cmStateSnapshot& lhs, const cmStateSnapshot& rhs);
-
 #endif

Source/cmStateDirectory.cxx

@@ -0,0 +1,518 @@
+/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+   file Copyright.txt or https://cmake.org/licensing for details.  */
+
+#include "cmStateDirectory.h"
+#include "cmState.h"
+#include "cmStatePrivate.h"
+#include "cmSystemTools.h"
+
+static std::string const kBINARY_DIR = "BINARY_DIR";
+static std::string const kBUILDSYSTEM_TARGETS = "BUILDSYSTEM_TARGETS";
+static std::string const kSOURCE_DIR = "SOURCE_DIR";
+static std::string const kSUBDIRECTORIES = "SUBDIRECTORIES";
+
+void cmStateDirectory::ComputeRelativePathTopSource()
+{
+  // Relative path conversion inside the source tree is not used to
+  // construct relative paths passed to build tools so it is safe to use
+  // even when the source is a network path.
+
+  cmStateSnapshot snapshot = this->Snapshot_;
+  std::vector<cmStateSnapshot> snapshots;
+  snapshots.push_back(snapshot);
+  while (true) {
+    snapshot = snapshot.GetBuildsystemDirectoryParent();
+    if (snapshot.IsValid()) {
+      snapshots.push_back(snapshot);
+    } else {
+      break;
+    }
+  }
+
+  std::string result = snapshots.front().GetDirectory().GetCurrentSource();
+
+  for (std::vector<cmStateSnapshot>::const_iterator it = snapshots.begin() + 1;
+       it != snapshots.end(); ++it) {
+    std::string currentSource = it->GetDirectory().GetCurrentSource();
+    if (cmSystemTools::IsSubDirectory(result, currentSource)) {
+      result = currentSource;
+    }
+  }
+  this->DirectoryState->RelativePathTopSource = result;
+}
+
+void cmStateDirectory::ComputeRelativePathTopBinary()
+{
+  cmStateSnapshot snapshot = this->Snapshot_;
+  std::vector<cmStateSnapshot> snapshots;
+  snapshots.push_back(snapshot);
+  while (true) {
+    snapshot = snapshot.GetBuildsystemDirectoryParent();
+    if (snapshot.IsValid()) {
+      snapshots.push_back(snapshot);
+    } else {
+      break;
+    }
+  }
+
+  std::string result = snapshots.front().GetDirectory().GetCurrentBinary();
+
+  for (std::vector<cmStateSnapshot>::const_iterator it = snapshots.begin() + 1;
+       it != snapshots.end(); ++it) {
+    std::string currentBinary = it->GetDirectory().GetCurrentBinary();
+    if (cmSystemTools::IsSubDirectory(result, currentBinary)) {
+      result = currentBinary;
+    }
+  }
+
+  // The current working directory on Windows cannot be a network
+  // path.  Therefore relative paths cannot work when the binary tree
+  // is a network path.
+  if (result.size() < 2 || result.substr(0, 2) != "//") {
+    this->DirectoryState->RelativePathTopBinary = result;
+  } else {
+    this->DirectoryState->RelativePathTopBinary = "";
+  }
+}
+
+const char* cmStateDirectory::GetCurrentSource() const
+{
+  return this->DirectoryState->Location.c_str();
+}
+
+void cmStateDirectory::SetCurrentSource(std::string const& dir)
+{
+  std::string& loc = this->DirectoryState->Location;
+  loc = dir;
+  cmSystemTools::ConvertToUnixSlashes(loc);
+  loc = cmSystemTools::CollapseFullPath(loc);
+
+  this->ComputeRelativePathTopSource();
+
+  this->Snapshot_.SetDefinition("CMAKE_CURRENT_SOURCE_DIR", loc);
+}
+
+const char* cmStateDirectory::GetCurrentBinary() const
+{
+  return this->DirectoryState->OutputLocation.c_str();
+}
+
+void cmStateDirectory::SetCurrentBinary(std::string const& dir)
+{
+  std::string& loc = this->DirectoryState->OutputLocation;
+  loc = dir;
+  cmSystemTools::ConvertToUnixSlashes(loc);
+  loc = cmSystemTools::CollapseFullPath(loc);
+
+  this->ComputeRelativePathTopBinary();
+
+  this->Snapshot_.SetDefinition("CMAKE_CURRENT_BINARY_DIR", loc);
+}
+
+const char* cmStateDirectory::GetRelativePathTopSource() const
+{
+  return this->DirectoryState->RelativePathTopSource.c_str();
+}
+
+const char* cmStateDirectory::GetRelativePathTopBinary() const
+{
+  return this->DirectoryState->RelativePathTopBinary.c_str();
+}
+
+void cmStateDirectory::SetRelativePathTopSource(const char* dir)
+{
+  this->DirectoryState->RelativePathTopSource = dir;
+}
+
+void cmStateDirectory::SetRelativePathTopBinary(const char* dir)
+{
+  this->DirectoryState->RelativePathTopBinary = dir;
+}
+
+cmStateDirectory::cmStateDirectory(
+  cmLinkedTree<cmStateDetail::BuildsystemDirectoryStateType>::iterator iter,
+  const cmStateSnapshot& snapshot)
+  : DirectoryState(iter)
+  , Snapshot_(snapshot)
+{
+}
+
+template <typename T, typename U>
+cmStringRange GetPropertyContent(T const& content, U contentEndPosition)
+{
+  std::vector<std::string>::const_iterator end =
+    content.begin() + contentEndPosition;
+
+  std::vector<std::string>::const_reverse_iterator rbegin =
+    cmMakeReverseIterator(end);
+  rbegin = std::find(rbegin, content.rend(), cmPropertySentinal);
+
+  return cmMakeRange(rbegin.base(), end);
+}
+
+template <typename T, typename U, typename V>
+cmBacktraceRange GetPropertyBacktraces(T const& content, U const& backtraces,
+                                       V contentEndPosition)
+{
+  std::vector<std::string>::const_iterator entryEnd =
+    content.begin() + contentEndPosition;
+
+  std::vector<std::string>::const_reverse_iterator rbegin =
+    cmMakeReverseIterator(entryEnd);
+  rbegin = std::find(rbegin, content.rend(), cmPropertySentinal);
+
+  std::vector<cmListFileBacktrace>::const_iterator it =
+    backtraces.begin() + std::distance(content.begin(), rbegin.base());
+
+  std::vector<cmListFileBacktrace>::const_iterator end = backtraces.end();
+  return cmMakeRange(it, end);
+}
+
+template <typename T, typename U, typename V>
+void AppendEntry(T& content, U& backtraces, V& endContentPosition,
+                 const std::string& value, const cmListFileBacktrace& lfbt)
+{
+  if (value.empty()) {
+    return;
+  }
+
+  assert(endContentPosition == content.size());
+
+  content.push_back(value);
+  backtraces.push_back(lfbt);
+
+  endContentPosition = content.size();
+}
+
+template <typename T, typename U, typename V>
+void SetContent(T& content, U& backtraces, V& endContentPosition,
+                const std::string& vec, const cmListFileBacktrace& lfbt)
+{
+  assert(endContentPosition == content.size());
+
+  content.resize(content.size() + 2);
+  backtraces.resize(backtraces.size() + 2);
+
+  content.back() = vec;
+  backtraces.back() = lfbt;
+
+  endContentPosition = content.size();
+}
+
+template <typename T, typename U, typename V>
+void ClearContent(T& content, U& backtraces, V& endContentPosition)
+{
+  assert(endContentPosition == content.size());
+
+  content.resize(content.size() + 1);
+  backtraces.resize(backtraces.size() + 1);
+
+  endContentPosition = content.size();
+}
+
+cmStringRange cmStateDirectory::GetIncludeDirectoriesEntries() const
+{
+  return GetPropertyContent(
+    this->DirectoryState->IncludeDirectories,
+    this->Snapshot_.Position->IncludeDirectoryPosition);
+}
+
+cmBacktraceRange cmStateDirectory::GetIncludeDirectoriesEntryBacktraces() const
+{
+  return GetPropertyBacktraces(
+    this->DirectoryState->IncludeDirectories,
+    this->DirectoryState->IncludeDirectoryBacktraces,
+    this->Snapshot_.Position->IncludeDirectoryPosition);
+}
+
+void cmStateDirectory::AppendIncludeDirectoriesEntry(
+  const std::string& vec, const cmListFileBacktrace& lfbt)
+{
+  AppendEntry(this->DirectoryState->IncludeDirectories,
+              this->DirectoryState->IncludeDirectoryBacktraces,
+              this->Snapshot_.Position->IncludeDirectoryPosition, vec, lfbt);
+}
+
+void cmStateDirectory::PrependIncludeDirectoriesEntry(
+  const std::string& vec, const cmListFileBacktrace& lfbt)
+{
+  std::vector<std::string>::iterator entryEnd =
+    this->DirectoryState->IncludeDirectories.begin() +
+    this->Snapshot_.Position->IncludeDirectoryPosition;
+
+  std::vector<std::string>::reverse_iterator rend =
+    this->DirectoryState->IncludeDirectories.rend();
+  std::vector<std::string>::reverse_iterator rbegin =
+    cmMakeReverseIterator(entryEnd);
+  rbegin = std::find(rbegin, rend, cmPropertySentinal);
+
+  std::vector<std::string>::iterator entryIt = rbegin.base();
+  std::vector<std::string>::iterator entryBegin =
+    this->DirectoryState->IncludeDirectories.begin();
+
+  std::vector<cmListFileBacktrace>::iterator btIt =
+    this->DirectoryState->IncludeDirectoryBacktraces.begin() +
+    std::distance(entryBegin, entryIt);
+
+  this->DirectoryState->IncludeDirectories.insert(entryIt, vec);
+  this->DirectoryState->IncludeDirectoryBacktraces.insert(btIt, lfbt);
+
+  this->Snapshot_.Position->IncludeDirectoryPosition =
+    this->DirectoryState->IncludeDirectories.size();
+}
+
+void cmStateDirectory::SetIncludeDirectories(const std::string& vec,
+                                             const cmListFileBacktrace& lfbt)
+{
+  SetContent(this->DirectoryState->IncludeDirectories,
+             this->DirectoryState->IncludeDirectoryBacktraces,
+             this->Snapshot_.Position->IncludeDirectoryPosition, vec, lfbt);
+}
+
+void cmStateDirectory::ClearIncludeDirectories()
+{
+  ClearContent(this->DirectoryState->IncludeDirectories,
+               this->DirectoryState->IncludeDirectoryBacktraces,
+               this->Snapshot_.Position->IncludeDirectoryPosition);
+}
+
+cmStringRange cmStateDirectory::GetCompileDefinitionsEntries() const
+{
+  return GetPropertyContent(
+    this->DirectoryState->CompileDefinitions,
+    this->Snapshot_.Position->CompileDefinitionsPosition);
+}
+
+cmBacktraceRange cmStateDirectory::GetCompileDefinitionsEntryBacktraces() const
+{
+  return GetPropertyBacktraces(
+    this->DirectoryState->CompileDefinitions,
+    this->DirectoryState->CompileDefinitionsBacktraces,
+    this->Snapshot_.Position->CompileDefinitionsPosition);
+}
+
+void cmStateDirectory::AppendCompileDefinitionsEntry(
+  const std::string& vec, const cmListFileBacktrace& lfbt)
+{
+  AppendEntry(this->DirectoryState->CompileDefinitions,
+              this->DirectoryState->CompileDefinitionsBacktraces,
+              this->Snapshot_.Position->CompileDefinitionsPosition, vec, lfbt);
+}
+
+void cmStateDirectory::SetCompileDefinitions(const std::string& vec,
+                                             const cmListFileBacktrace& lfbt)
+{
+  SetContent(this->DirectoryState->CompileDefinitions,
+             this->DirectoryState->CompileDefinitionsBacktraces,
+             this->Snapshot_.Position->CompileDefinitionsPosition, vec, lfbt);
+}
+
+void cmStateDirectory::ClearCompileDefinitions()
+{
+  ClearContent(this->DirectoryState->CompileDefinitions,
+               this->DirectoryState->CompileDefinitionsBacktraces,
+               this->Snapshot_.Position->CompileDefinitionsPosition);
+}
+
+cmStringRange cmStateDirectory::GetCompileOptionsEntries() const
+{
+  return GetPropertyContent(this->DirectoryState->CompileOptions,
+                            this->Snapshot_.Position->CompileOptionsPosition);
+}
+
+cmBacktraceRange cmStateDirectory::GetCompileOptionsEntryBacktraces() const
+{
+  return GetPropertyBacktraces(
+    this->DirectoryState->CompileOptions,
+    this->DirectoryState->CompileOptionsBacktraces,
+    this->Snapshot_.Position->CompileOptionsPosition);
+}
+
+void cmStateDirectory::AppendCompileOptionsEntry(
+  const std::string& vec, const cmListFileBacktrace& lfbt)
+{
+  AppendEntry(this->DirectoryState->CompileOptions,
+              this->DirectoryState->CompileOptionsBacktraces,
+              this->Snapshot_.Position->CompileOptionsPosition, vec, lfbt);
+}
+
+void cmStateDirectory::SetCompileOptions(const std::string& vec,
+                                         const cmListFileBacktrace& lfbt)
+{
+  SetContent(this->DirectoryState->CompileOptions,
+             this->DirectoryState->CompileOptionsBacktraces,
+             this->Snapshot_.Position->CompileOptionsPosition, vec, lfbt);
+}
+
+void cmStateDirectory::ClearCompileOptions()
+{
+  ClearContent(this->DirectoryState->CompileOptions,
+               this->DirectoryState->CompileOptionsBacktraces,
+               this->Snapshot_.Position->CompileOptionsPosition);
+}
+
+void cmStateDirectory::SetProperty(const std::string& prop, const char* value,
+                                   cmListFileBacktrace const& lfbt)
+{
+  if (prop == "INCLUDE_DIRECTORIES") {
+    if (!value) {
+      this->ClearIncludeDirectories();
+      return;
+    }
+    this->SetIncludeDirectories(value, lfbt);
+    return;
+  }
+  if (prop == "COMPILE_OPTIONS") {
+    if (!value) {
+      this->ClearCompileOptions();
+      return;
+    }
+    this->SetCompileOptions(value, lfbt);
+    return;
+  }
+  if (prop == "COMPILE_DEFINITIONS") {
+    if (!value) {
+      this->ClearCompileDefinitions();
+      return;
+    }
+    this->SetCompileDefinitions(value, lfbt);
+    return;
+  }
+
+  this->DirectoryState->Properties.SetProperty(prop, value);
+}
+
+void cmStateDirectory::AppendProperty(const std::string& prop,
+                                      const char* value, bool asString,
+                                      cmListFileBacktrace const& lfbt)
+{
+  if (prop == "INCLUDE_DIRECTORIES") {
+    this->AppendIncludeDirectoriesEntry(value, lfbt);
+    return;
+  }
+  if (prop == "COMPILE_OPTIONS") {
+    this->AppendCompileOptionsEntry(value, lfbt);
+    return;
+  }
+  if (prop == "COMPILE_DEFINITIONS") {
+    this->AppendCompileDefinitionsEntry(value, lfbt);
+    return;
+  }
+
+  this->DirectoryState->Properties.AppendProperty(prop, value, asString);
+}
+
+const char* cmStateDirectory::GetProperty(const std::string& prop) const
+{
+  const bool chain =
+    this->Snapshot_.State->IsPropertyChained(prop, cmProperty::DIRECTORY);
+  return this->GetProperty(prop, chain);
+}
+
+const char* cmStateDirectory::GetProperty(const std::string& prop,
+                                          bool chain) const
+{
+  static std::string output;
+  output = "";
+  if (prop == "PARENT_DIRECTORY") {
+    cmStateSnapshot parent = this->Snapshot_.GetBuildsystemDirectoryParent();
+    if (parent.IsValid()) {
+      return parent.GetDirectory().GetCurrentSource();
+    }
+    return "";
+  }
+  if (prop == kBINARY_DIR) {
+    output = this->GetCurrentBinary();
+    return output.c_str();
+  }
+  if (prop == kSOURCE_DIR) {
+    output = this->GetCurrentSource();
+    return output.c_str();
+  }
+  if (prop == kSUBDIRECTORIES) {
+    std::vector<std::string> child_dirs;
+    std::vector<cmStateSnapshot> const& children =
+      this->DirectoryState->Children;
+    for (std::vector<cmStateSnapshot>::const_iterator ci = children.begin();
+         ci != children.end(); ++ci) {
+      child_dirs.push_back(ci->GetDirectory().GetCurrentSource());
+    }
+    output = cmJoin(child_dirs, ";");
+    return output.c_str();
+  }
+  if (prop == kBUILDSYSTEM_TARGETS) {
+    output = cmJoin(this->DirectoryState->NormalTargetNames, ";");
+    return output.c_str();
+  }
+
+  if (prop == "LISTFILE_STACK") {
+    std::vector<std::string> listFiles;
+    cmStateSnapshot snp = this->Snapshot_;
+    while (snp.IsValid()) {
+      listFiles.push_back(snp.GetExecutionListFile());
+      snp = snp.GetCallStackParent();
+    }
+    std::reverse(listFiles.begin(), listFiles.end());
+    output = cmJoin(listFiles, ";");
+    return output.c_str();
+  }
+  if (prop == "CACHE_VARIABLES") {
+    output = cmJoin(this->Snapshot_.State->GetCacheEntryKeys(), ";");
+    return output.c_str();
+  }
+  if (prop == "VARIABLES") {
+    std::vector<std::string> res = this->Snapshot_.ClosureKeys();
+    std::vector<std::string> cacheKeys =
+      this->Snapshot_.State->GetCacheEntryKeys();
+    res.insert(res.end(), cacheKeys.begin(), cacheKeys.end());
+    std::sort(res.begin(), res.end());
+    output = cmJoin(res, ";");
+    return output.c_str();
+  }
+  if (prop == "INCLUDE_DIRECTORIES") {
+    output = cmJoin(this->GetIncludeDirectoriesEntries(), ";");
+    return output.c_str();
+  }
+  if (prop == "COMPILE_OPTIONS") {
+    output = cmJoin(this->GetCompileOptionsEntries(), ";");
+    return output.c_str();
+  }
+  if (prop == "COMPILE_DEFINITIONS") {
+    output = cmJoin(this->GetCompileDefinitionsEntries(), ";");
+    return output.c_str();
+  }
+
+  const char* retVal = this->DirectoryState->Properties.GetPropertyValue(prop);
+  if (!retVal && chain) {
+    cmStateSnapshot parentSnapshot =
+      this->Snapshot_.GetBuildsystemDirectoryParent();
+    if (parentSnapshot.IsValid()) {
+      return parentSnapshot.GetDirectory().GetProperty(prop, chain);
+    }
+    return this->Snapshot_.State->GetGlobalProperty(prop);
+  }
+
+  return retVal;
+}
+
+bool cmStateDirectory::GetPropertyAsBool(const std::string& prop) const
+{
+  return cmSystemTools::IsOn(this->GetProperty(prop));
+}
+
+std::vector<std::string> cmStateDirectory::GetPropertyKeys() const
+{
+  std::vector<std::string> keys;
+  keys.reserve(this->DirectoryState->Properties.size());
+  for (cmPropertyMap::const_iterator it =
+         this->DirectoryState->Properties.begin();
+       it != this->DirectoryState->Properties.end(); ++it) {
+    keys.push_back(it->first);
+  }
+  return keys;
+}
+
+void cmStateDirectory::AddNormalTargetName(std::string const& name)
+{
+  this->DirectoryState->NormalTargetNames.push_back(name);
+}

Source/cmStateDirectory.h

@@ -0,0 +1,82 @@
+/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+   file Copyright.txt or https://cmake.org/licensing for details.  */
+
+#ifndef cmStateDirectory_h
+#define cmStateDirectory_h
+
+#include <cmConfigure.h> // IWYU pragma: keep
+
+#include <string>
+#include <vector>
+
+#include "cmAlgorithms.h"
+#include "cmListFileCache.h"
+#include "cmStateSnapshot.h"
+#include "cmStateTypes.h"
+
+class cmStateDirectory
+{
+  cmStateDirectory(
+    cmLinkedTree<cmStateDetail::BuildsystemDirectoryStateType>::iterator iter,
+    cmStateSnapshot const& snapshot);
+
+public:
+  const char* GetCurrentSource() const;
+  void SetCurrentSource(std::string const& dir);
+  const char* GetCurrentBinary() const;
+  void SetCurrentBinary(std::string const& dir);
+
+  const char* GetRelativePathTopSource() const;
+  const char* GetRelativePathTopBinary() const;
+  void SetRelativePathTopSource(const char* dir);
+  void SetRelativePathTopBinary(const char* dir);
+
+  cmStringRange GetIncludeDirectoriesEntries() const;
+  cmBacktraceRange GetIncludeDirectoriesEntryBacktraces() const;
+  void AppendIncludeDirectoriesEntry(std::string const& vec,
+                                     cmListFileBacktrace const& lfbt);
+  void PrependIncludeDirectoriesEntry(std::string const& vec,
+                                      cmListFileBacktrace const& lfbt);
+  void SetIncludeDirectories(std::string const& vec,
+                             cmListFileBacktrace const& lfbt);
+  void ClearIncludeDirectories();
+
+  cmStringRange GetCompileDefinitionsEntries() const;
+  cmBacktraceRange GetCompileDefinitionsEntryBacktraces() const;
+  void AppendCompileDefinitionsEntry(std::string const& vec,
+                                     cmListFileBacktrace const& lfbt);
+  void SetCompileDefinitions(std::string const& vec,
+                             cmListFileBacktrace const& lfbt);
+  void ClearCompileDefinitions();
+
+  cmStringRange GetCompileOptionsEntries() const;
+  cmBacktraceRange GetCompileOptionsEntryBacktraces() const;
+  void AppendCompileOptionsEntry(std::string const& vec,
+                                 cmListFileBacktrace const& lfbt);
+  void SetCompileOptions(std::string const& vec,
+                         cmListFileBacktrace const& lfbt);
+  void ClearCompileOptions();
+
+  void SetProperty(const std::string& prop, const char* value,
+                   cmListFileBacktrace const& lfbt);
+  void AppendProperty(const std::string& prop, const char* value,
+                      bool asString, cmListFileBacktrace const& lfbt);
+  const char* GetProperty(const std::string& prop) const;
+  const char* GetProperty(const std::string& prop, bool chain) const;
+  bool GetPropertyAsBool(const std::string& prop) const;
+  std::vector<std::string> GetPropertyKeys() const;
+
+  void AddNormalTargetName(std::string const& name);
+
+private:
+  void ComputeRelativePathTopSource();
+  void ComputeRelativePathTopBinary();
+
+private:
+  cmLinkedTree<cmStateDetail::BuildsystemDirectoryStateType>::iterator
+    DirectoryState;
+  cmStateSnapshot Snapshot_;
+  friend class cmStateSnapshot;
+};
+
+#endif

Source/cmStatePrivate.h

@@ -0,0 +1,94 @@
+/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+   file Copyright.txt or https://cmake.org/licensing for details.  */
+
+#ifndef cmStatePrivate_h
+#define cmStatePrivate_h
+
+#include <cmConfigure.h> // IWYU pragma: keep
+
+#include <string>
+#include <vector>
+
+#include "cmDefinitions.h"
+#include "cmLinkedTree.h"
+#include "cmListFileCache.h"
+#include "cmPropertyMap.h"
+#include "cmStateTypes.h"
+
+static const std::string cmPropertySentinal = std::string();
+
+struct cmStateDetail::SnapshotDataType
+{
+  cmStateDetail::PositionType ScopeParent;
+  cmStateDetail::PositionType DirectoryParent;
+  cmLinkedTree<cmStateDetail::PolicyStackEntry>::iterator Policies;
+  cmLinkedTree<cmStateDetail::PolicyStackEntry>::iterator PolicyRoot;
+  cmLinkedTree<cmStateDetail::PolicyStackEntry>::iterator PolicyScope;
+  cmStateEnums::SnapshotType SnapshotType;
+  bool Keep;
+  cmLinkedTree<std::string>::iterator ExecutionListFile;
+  cmLinkedTree<cmStateDetail::BuildsystemDirectoryStateType>::iterator
+    BuildSystemDirectory;
+  cmLinkedTree<cmDefinitions>::iterator Vars;
+  cmLinkedTree<cmDefinitions>::iterator Root;
+  cmLinkedTree<cmDefinitions>::iterator Parent;
+  std::vector<std::string>::size_type IncludeDirectoryPosition;
+  std::vector<std::string>::size_type CompileDefinitionsPosition;
+  std::vector<std::string>::size_type CompileOptionsPosition;
+};
+
+struct cmStateDetail::PolicyStackEntry : public cmPolicies::PolicyMap
+{
+  typedef cmPolicies::PolicyMap derived;
+  PolicyStackEntry(bool w = false)
+    : derived()
+    , Weak(w)
+  {
+  }
+  PolicyStackEntry(derived const& d, bool w)
+    : derived(d)
+    , Weak(w)
+  {
+  }
+  PolicyStackEntry(PolicyStackEntry const& r)
+    : derived(r)
+    , Weak(r.Weak)
+  {
+  }
+  bool Weak;
+};
+
+struct cmStateDetail::BuildsystemDirectoryStateType
+{
+  cmStateDetail::PositionType DirectoryEnd;
+
+  std::string Location;
+  std::string OutputLocation;
+
+  // The top-most directories for relative path conversion.  Both the
+  // source and destination location of a relative path conversion
+  // must be underneath one of these directories (both under source or
+  // both under binary) in order for the relative path to be evaluated
+  // safely by the build tools.
+  std::string RelativePathTopSource;
+  std::string RelativePathTopBinary;
+
+  std::vector<std::string> IncludeDirectories;
+  std::vector<cmListFileBacktrace> IncludeDirectoryBacktraces;
+
+  std::vector<std::string> CompileDefinitions;
+  std::vector<cmListFileBacktrace> CompileDefinitionsBacktraces;
+
+  std::vector<std::string> CompileOptions;
+  std::vector<cmListFileBacktrace> CompileOptionsBacktraces;
+
+  std::vector<std::string> NormalTargetNames;
+
+  std::string ProjectName;
+
+  cmPropertyMap Properties;
+
+  std::vector<cmStateSnapshot> Children;
+};
+
+#endif

Source/cmStateSnapshot.cxx

@@ -0,0 +1,415 @@
+/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+   file Copyright.txt or https://cmake.org/licensing for details.  */
+
+#include "cmStateSnapshot.h"
+
+#include "cmState.h"
+#include "cmStateDirectory.h"
+#include "cmStatePrivate.h"
+#include "cmSystemTools.h"
+#include "cmVersion.h"
+#include "cmake.h"
+
+cmStateSnapshot::cmStateSnapshot(cmState* state)
+  : State(state)
+  , Position()
+{
+}
+
+std::vector<cmStateSnapshot> cmStateSnapshot::GetChildren()
+{
+  return this->Position->BuildSystemDirectory->Children;
+}
+
+cmStateSnapshot::cmStateSnapshot(cmState* state,
+                                 cmStateDetail::PositionType position)
+  : State(state)
+  , Position(position)
+{
+}
+
+cmStateEnums::SnapshotType cmStateSnapshot::GetType() const
+{
+  return this->Position->SnapshotType;
+}
+
+void cmStateSnapshot::SetListFile(const std::string& listfile)
+{
+  *this->Position->ExecutionListFile = listfile;
+}
+
+std::string cmStateSnapshot::GetExecutionListFile() const
+{
+  return *this->Position->ExecutionListFile;
+}
+
+bool cmStateSnapshot::IsValid() const
+{
+  return this->State && this->Position.IsValid()
+    ? this->Position != this->State->SnapshotData.Root()
+    : false;
+}
+
+cmStateSnapshot cmStateSnapshot::GetBuildsystemDirectoryParent() const
+{
+  cmStateSnapshot snapshot;
+  if (!this->State || this->Position == this->State->SnapshotData.Root()) {
+    return snapshot;
+  }
+  cmStateDetail::PositionType parentPos = this->Position->DirectoryParent;
+  if (parentPos != this->State->SnapshotData.Root()) {
+    snapshot = cmStateSnapshot(this->State,
+                               parentPos->BuildSystemDirectory->DirectoryEnd);
+  }
+
+  return snapshot;
+}
+
+cmStateSnapshot cmStateSnapshot::GetCallStackParent() const
+{
+  assert(this->State);
+  assert(this->Position != this->State->SnapshotData.Root());
+
+  cmStateSnapshot snapshot;
+  cmStateDetail::PositionType parentPos = this->Position;
+  while (parentPos->SnapshotType == cmStateEnums::PolicyScopeType ||
+         parentPos->SnapshotType == cmStateEnums::VariableScopeType) {
+    ++parentPos;
+  }
+  if (parentPos->SnapshotType == cmStateEnums::BuildsystemDirectoryType ||
+      parentPos->SnapshotType == cmStateEnums::BaseType) {
+    return snapshot;
+  }
+
+  ++parentPos;
+  while (parentPos->SnapshotType == cmStateEnums::PolicyScopeType ||
+         parentPos->SnapshotType == cmStateEnums::VariableScopeType) {
+    ++parentPos;
+  }
+
+  if (parentPos == this->State->SnapshotData.Root()) {
+    return snapshot;
+  }
+
+  snapshot = cmStateSnapshot(this->State, parentPos);
+  return snapshot;
+}
+
+cmStateSnapshot cmStateSnapshot::GetCallStackBottom() const
+{
+  assert(this->State);
+  assert(this->Position != this->State->SnapshotData.Root());
+
+  cmStateDetail::PositionType pos = this->Position;
+  while (pos->SnapshotType != cmStateEnums::BaseType &&
+         pos->SnapshotType != cmStateEnums::BuildsystemDirectoryType &&
+         pos != this->State->SnapshotData.Root()) {
+    ++pos;
+  }
+  return cmStateSnapshot(this->State, pos);
+}
+
+void cmStateSnapshot::PushPolicy(cmPolicies::PolicyMap entry, bool weak)
+{
+  cmStateDetail::PositionType pos = this->Position;
+  pos->Policies = this->State->PolicyStack.Push(
+    pos->Policies, cmStateDetail::PolicyStackEntry(entry, weak));
+}
+
+bool cmStateSnapshot::PopPolicy()
+{
+  cmStateDetail::PositionType pos = this->Position;
+  if (pos->Policies == pos->PolicyScope) {
+    return false;
+  }
+  pos->Policies = this->State->PolicyStack.Pop(pos->Policies);
+  return true;
+}
+
+bool cmStateSnapshot::CanPopPolicyScope()
+{
+  return this->Position->Policies == this->Position->PolicyScope;
+}
+
+void cmStateSnapshot::SetPolicy(cmPolicies::PolicyID id,
+                                cmPolicies::PolicyStatus status)
+{
+  // Update the policy stack from the top to the top-most strong entry.
+  bool previous_was_weak = true;
+  for (cmLinkedTree<cmStateDetail::PolicyStackEntry>::iterator psi =
+         this->Position->Policies;
+       previous_was_weak && psi != this->Position->PolicyRoot; ++psi) {
+    psi->Set(id, status);
+    previous_was_weak = psi->Weak;
+  }
+}
+
+cmPolicies::PolicyStatus cmStateSnapshot::GetPolicy(
+  cmPolicies::PolicyID id) const
+{
+  cmPolicies::PolicyStatus status = cmPolicies::GetPolicyStatus(id);
+
+  if (status == cmPolicies::REQUIRED_ALWAYS ||
+      status == cmPolicies::REQUIRED_IF_USED) {
+    return status;
+  }
+
+  cmLinkedTree<cmStateDetail::BuildsystemDirectoryStateType>::iterator dir =
+    this->Position->BuildSystemDirectory;
+
+  while (true) {
+    assert(dir.IsValid());
+    cmLinkedTree<cmStateDetail::PolicyStackEntry>::iterator leaf =
+      dir->DirectoryEnd->Policies;
+    cmLinkedTree<cmStateDetail::PolicyStackEntry>::iterator root =
+      dir->DirectoryEnd->PolicyRoot;
+    for (; leaf != root; ++leaf) {
+      if (leaf->IsDefined(id)) {
+        status = leaf->Get(id);
+        return status;
+      }
+    }
+    cmStateDetail::PositionType e = dir->DirectoryEnd;
+    cmStateDetail::PositionType p = e->DirectoryParent;
+    if (p == this->State->SnapshotData.Root()) {
+      break;
+    }
+    dir = p->BuildSystemDirectory;
+  }
+  return status;
+}
+
+bool cmStateSnapshot::HasDefinedPolicyCMP0011()
+{
+  return !this->Position->Policies->IsEmpty();
+}
+
+const char* cmStateSnapshot::GetDefinition(std::string const& name) const
+{
+  assert(this->Position->Vars.IsValid());
+  return cmDefinitions::Get(name, this->Position->Vars, this->Position->Root);
+}
+
+bool cmStateSnapshot::IsInitialized(std::string const& name) const
+{
+  return cmDefinitions::HasKey(name, this->Position->Vars,
+                               this->Position->Root);
+}
+
+void cmStateSnapshot::SetDefinition(std::string const& name,
+                                    std::string const& value)
+{
+  this->Position->Vars->Set(name, value.c_str());
+}
+
+void cmStateSnapshot::RemoveDefinition(std::string const& name)
+{
+  this->Position->Vars->Set(name, CM_NULLPTR);
+}
+
+std::vector<std::string> cmStateSnapshot::UnusedKeys() const
+{
+  return this->Position->Vars->UnusedKeys();
+}
+
+std::vector<std::string> cmStateSnapshot::ClosureKeys() const
+{
+  return cmDefinitions::ClosureKeys(this->Position->Vars,
+                                    this->Position->Root);
+}
+
+bool cmStateSnapshot::RaiseScope(std::string const& var, const char* varDef)
+{
+  if (this->Position->ScopeParent == this->Position->DirectoryParent) {
+    cmStateSnapshot 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;
+}
+
+template <typename T, typename U, typename V>
+void InitializeContentFromParent(T& parentContent, T& thisContent,
+                                 U& parentBacktraces, U& thisBacktraces,
+                                 V& contentEndPosition)
+{
+  std::vector<std::string>::const_iterator parentBegin = parentContent.begin();
+  std::vector<std::string>::const_iterator parentEnd = parentContent.end();
+
+  std::vector<std::string>::const_reverse_iterator parentRbegin =
+    cmMakeReverseIterator(parentEnd);
+  std::vector<std::string>::const_reverse_iterator parentRend =
+    parentContent.rend();
+  parentRbegin = std::find(parentRbegin, parentRend, cmPropertySentinal);
+  std::vector<std::string>::const_iterator parentIt = parentRbegin.base();
+
+  thisContent = std::vector<std::string>(parentIt, parentEnd);
+
+  std::vector<cmListFileBacktrace>::const_iterator btIt =
+    parentBacktraces.begin() + std::distance(parentBegin, parentIt);
+  std::vector<cmListFileBacktrace>::const_iterator btEnd =
+    parentBacktraces.end();
+
+  thisBacktraces = std::vector<cmListFileBacktrace>(btIt, btEnd);
+
+  contentEndPosition = thisContent.size();
+}
+
+void cmStateSnapshot::SetDefaultDefinitions()
+{
+/* Up to CMake 2.4 here only WIN32, UNIX and APPLE were set.
+  With CMake must separate between target and host platform. In most cases
+  the tests for WIN32, UNIX and APPLE will be for the target system, so an
+  additional set of variables for the host system is required ->
+  CMAKE_HOST_WIN32, CMAKE_HOST_UNIX, CMAKE_HOST_APPLE.
+  WIN32, UNIX and APPLE are now set in the platform files in
+  Modules/Platforms/.
+  To keep cmake scripts (-P) and custom language and compiler modules
+  working, these variables are still also set here in this place, but they
+  will be reset in CMakeSystemSpecificInformation.cmake before the platform
+  files are executed. */
+#if defined(_WIN32)
+  this->SetDefinition("WIN32", "1");
+  this->SetDefinition("CMAKE_HOST_WIN32", "1");
+#else
+  this->SetDefinition("UNIX", "1");
+  this->SetDefinition("CMAKE_HOST_UNIX", "1");
+#endif
+#if defined(__CYGWIN__)
+  std::string legacy;
+  if (cmSystemTools::GetEnv("CMAKE_LEGACY_CYGWIN_WIN32", legacy) &&
+      cmSystemTools::IsOn(legacy.c_str())) {
+    this->SetDefinition("WIN32", "1");
+    this->SetDefinition("CMAKE_HOST_WIN32", "1");
+  }
+#endif
+#if defined(__APPLE__)
+  this->SetDefinition("APPLE", "1");
+  this->SetDefinition("CMAKE_HOST_APPLE", "1");
+#endif
+#if defined(__sun__)
+  this->SetDefinition("CMAKE_HOST_SOLARIS", "1");
+#endif
+
+  char temp[1024];
+  sprintf(temp, "%d", cmVersion::GetMinorVersion());
+  this->SetDefinition("CMAKE_MINOR_VERSION", temp);
+  sprintf(temp, "%d", cmVersion::GetMajorVersion());
+  this->SetDefinition("CMAKE_MAJOR_VERSION", temp);
+  sprintf(temp, "%d", cmVersion::GetPatchVersion());
+  this->SetDefinition("CMAKE_PATCH_VERSION", temp);
+  sprintf(temp, "%d", cmVersion::GetTweakVersion());
+  this->SetDefinition("CMAKE_TWEAK_VERSION", temp);
+  this->SetDefinition("CMAKE_VERSION", cmVersion::GetCMakeVersion());
+
+  this->SetDefinition("CMAKE_FILES_DIRECTORY",
+                      cmake::GetCMakeFilesDirectory());
+
+  // Setup the default include file regular expression (match everything).
+  this->Position->BuildSystemDirectory->Properties.SetProperty(
+    "INCLUDE_REGULAR_EXPRESSION", "^.*$");
+}
+
+void cmStateSnapshot::SetDirectoryDefinitions()
+{
+  this->SetDefinition("CMAKE_SOURCE_DIR", this->State->GetSourceDirectory());
+  this->SetDefinition("CMAKE_CURRENT_SOURCE_DIR",
+                      this->State->GetSourceDirectory());
+  this->SetDefinition("CMAKE_BINARY_DIR", this->State->GetBinaryDirectory());
+  this->SetDefinition("CMAKE_CURRENT_BINARY_DIR",
+                      this->State->GetBinaryDirectory());
+}
+
+void cmStateSnapshot::InitializeFromParent()
+{
+  cmStateDetail::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,
+    parent->BuildSystemDirectory->IncludeDirectoryBacktraces,
+    this->Position->BuildSystemDirectory->IncludeDirectoryBacktraces,
+    this->Position->IncludeDirectoryPosition);
+
+  InitializeContentFromParent(
+    parent->BuildSystemDirectory->CompileDefinitions,
+    this->Position->BuildSystemDirectory->CompileDefinitions,
+    parent->BuildSystemDirectory->CompileDefinitionsBacktraces,
+    this->Position->BuildSystemDirectory->CompileDefinitionsBacktraces,
+    this->Position->CompileDefinitionsPosition);
+
+  InitializeContentFromParent(
+    parent->BuildSystemDirectory->CompileOptions,
+    this->Position->BuildSystemDirectory->CompileOptions,
+    parent->BuildSystemDirectory->CompileOptionsBacktraces,
+    this->Position->BuildSystemDirectory->CompileOptionsBacktraces,
+    this->Position->CompileOptionsPosition);
+}
+
+cmState* cmStateSnapshot::GetState() const
+{
+  return this->State;
+}
+
+cmStateDirectory cmStateSnapshot::GetDirectory() const
+{
+  return cmStateDirectory(this->Position->BuildSystemDirectory, *this);
+}
+
+void cmStateSnapshot::SetProjectName(const std::string& name)
+{
+  this->Position->BuildSystemDirectory->ProjectName = name;
+}
+
+std::string cmStateSnapshot::GetProjectName() const
+{
+  return this->Position->BuildSystemDirectory->ProjectName;
+}
+
+void cmStateSnapshot::InitializeFromParent_ForSubdirsCommand()
+{
+  std::string currentSrcDir = this->GetDefinition("CMAKE_CURRENT_SOURCE_DIR");
+  std::string currentBinDir = this->GetDefinition("CMAKE_CURRENT_BINARY_DIR");
+  this->InitializeFromParent();
+  this->SetDefinition("CMAKE_SOURCE_DIR", this->State->GetSourceDirectory());
+  this->SetDefinition("CMAKE_BINARY_DIR", this->State->GetBinaryDirectory());
+
+  this->SetDefinition("CMAKE_CURRENT_SOURCE_DIR", currentSrcDir);
+  this->SetDefinition("CMAKE_CURRENT_BINARY_DIR", currentBinDir);
+}
+
+bool cmStateSnapshot::StrictWeakOrder::operator()(
+  const cmStateSnapshot& lhs, const cmStateSnapshot& rhs) const
+{
+  return lhs.Position.StrictWeakOrdered(rhs.Position);
+}
+
+bool operator==(const cmStateSnapshot& lhs, const cmStateSnapshot& rhs)
+{
+  return lhs.Position == rhs.Position;
+}
+
+bool operator!=(const cmStateSnapshot& lhs, const cmStateSnapshot& rhs)
+{
+  return lhs.Position != rhs.Position;
+}

Source/cmStateSnapshot.h

@@ -0,0 +1,88 @@
+/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+   file Copyright.txt or https://cmake.org/licensing for details.  */
+
+#ifndef cmStateSnapshot_h
+#define cmStateSnapshot_h
+
+#include <cmConfigure.h> // IWYU pragma: keep
+
+#include <map>
+#include <string>
+#include <vector>
+
+#include "cmPolicies.h"
+#include "cmStateTypes.h"
+
+class cmState;
+class cmStateDirectory;
+
+class cmStateSnapshot
+{
+public:
+  cmStateSnapshot(cmState* state = CM_NULLPTR);
+  cmStateSnapshot(cmState* state, cmStateDetail::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;
+
+  std::vector<cmStateSnapshot> GetChildren();
+
+  bool IsValid() const;
+  cmStateSnapshot GetBuildsystemDirectoryParent() const;
+  cmStateSnapshot GetCallStackParent() const;
+  cmStateSnapshot GetCallStackBottom() const;
+  cmStateEnums::SnapshotType GetType() const;
+
+  void SetPolicy(cmPolicies::PolicyID id, cmPolicies::PolicyStatus status);
+  cmPolicies::PolicyStatus GetPolicy(cmPolicies::PolicyID id) const;
+  bool HasDefinedPolicyCMP0011();
+  void PushPolicy(cmPolicies::PolicyMap entry, bool weak);
+  bool PopPolicy();
+  bool CanPopPolicyScope();
+
+  cmState* GetState() const;
+
+  cmStateDirectory GetDirectory() const;
+
+  void SetProjectName(std::string const& name);
+  std::string GetProjectName() const;
+
+  void InitializeFromParent_ForSubdirsCommand();
+
+  struct StrictWeakOrder
+  {
+    bool operator()(const cmStateSnapshot& lhs,
+                    const cmStateSnapshot& rhs) const;
+  };
+
+  void SetDirectoryDefinitions();
+  void SetDefaultDefinitions();
+
+private:
+  friend bool operator==(const cmStateSnapshot& lhs,
+                         const cmStateSnapshot& rhs);
+  friend bool operator!=(const cmStateSnapshot& lhs,
+                         const cmStateSnapshot& rhs);
+  friend class cmState;
+  friend class cmStateDirectory;
+  friend struct StrictWeakOrder;
+
+  void InitializeFromParent();
+
+  cmState* State;
+  cmStateDetail::PositionType Position;
+};
+
+bool operator==(const cmStateSnapshot& lhs, const cmStateSnapshot& rhs);
+bool operator!=(const cmStateSnapshot& lhs, const cmStateSnapshot& rhs);
+
+#endif

Source/cmake.h

@@ -7,7 +7,7 @@
 
 #include "cmInstalledFile.h"
 #include "cmListFileCache.h"
-#include "cmState.h"
+#include "cmStateSnapshot.h"
 
 #include <map>
 #include <set>

Source/cmcmd.cxx

@@ -7,7 +7,7 @@
 #include "cmLocalGenerator.h"
 #include "cmMakefile.h"
 #include "cmQtAutoGenerators.h"
-#include "cmState.h"
+#include "cmStateDirectory.h"
 #include "cmSystemTools.h"
 #include "cmUtils.hxx"
 #include "cmVersion.h"

bootstrap

@@ -292,6 +292,8 @@ CMAKE_CXX_SOURCES="\
   cmSourceFile \
   cmSourceFileLocation \
   cmState \
+  cmStateDirectory \
+  cmStateSnapshot \
   cmSystemTools \
   cmTestGenerator \
   cmVersion \