25 files changed, 4227 insertions, 61 deletions

diff --git a/Source/CMakeLists.txt b/Source/CMakeLists.txt
index 464d6f3..91c45bc 100644
--- a/Source/CMakeLists.txt
+++ b/Source/CMakeLists.txt
@@ -207,6 +207,14 @@ set(SRCS
   cmExtraKateGenerator.h
   cmExtraSublimeTextGenerator.cxx
   cmExtraSublimeTextGenerator.h
+  cmFileAPI.cxx
+  cmFileAPI.h
+  cmFileAPICache.cxx
+  cmFileAPICache.h
+  cmFileAPICodemodel.cxx
+  cmFileAPICodemodel.h
+  cmFileAPICMakeFiles.cxx
+  cmFileAPICMakeFiles.h
   cmFileLock.cxx
   cmFileLock.h
   cmFileLockPool.cxx
@@ -375,6 +383,9 @@ set(SRCS
   cmXMLWriter.h
   cmake.cxx
   cmake.h
+  cm_string_view.cxx
+  cm_string_view.hxx
+  cm_static_string_view.hxx
 
   cmCommand.cxx
   cmCommand.h
@@ -566,6 +577,8 @@ set(SRCS
   cmSiteNameCommand.h
   cmSourceGroupCommand.cxx
   cmSourceGroupCommand.h
+  cmString.cxx
+  cmString.hxx
   cmStringReplaceHelper.cxx
   cmStringCommand.cxx
   cmStringCommand.h
diff --git a/Source/CMakeVersion.cmake b/Source/CMakeVersion.cmake
index 7abab01..b43f9fd 100644
--- a/Source/CMakeVersion.cmake
+++ b/Source/CMakeVersion.cmake
@@ -1,5 +1,5 @@
 # CMake version number components.
 set(CMake_VERSION_MAJOR 3)
 set(CMake_VERSION_MINOR 13)
-set(CMake_VERSION_PATCH 20181212)
+set(CMake_VERSION_PATCH 20181213)
 #set(CMake_VERSION_RC 1)
diff --git a/Source/cmFileAPI.cxx b/Source/cmFileAPI.cxx
new file mode 100644
index 0000000..89bd258
--- /dev/null
+++ b/Source/cmFileAPI.cxx
@@ -0,0 +1,800 @@
+/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+   file Copyright.txt or https://cmake.org/licensing for details.  */
+#include "cmFileAPI.h"
+
+#include "cmAlgorithms.h"
+#include "cmCryptoHash.h"
+#include "cmFileAPICMakeFiles.h"
+#include "cmFileAPICache.h"
+#include "cmFileAPICodemodel.h"
+#include "cmGlobalGenerator.h"
+#include "cmSystemTools.h"
+#include "cmTimestamp.h"
+#include "cmake.h"
+#include "cmsys/Directory.hxx"
+#include "cmsys/FStream.hxx"
+
+#include <algorithm>
+#include <cassert>
+#include <chrono>
+#include <ctime>
+#include <iomanip>
+#include <sstream>
+#include <utility>
+
+cmFileAPI::cmFileAPI(cmake* cm)
+  : CMakeInstance(cm)
+{
+  this->APIv1 =
+    this->CMakeInstance->GetHomeOutputDirectory() + "/.cmake/api/v1";
+
+  Json::CharReaderBuilder rbuilder;
+  rbuilder["collectComments"] = false;
+  rbuilder["failIfExtra"] = true;
+  rbuilder["rejectDupKeys"] = false;
+  rbuilder["strictRoot"] = true;
+  this->JsonReader =
+    std::unique_ptr<Json::CharReader>(rbuilder.newCharReader());
+
+  Json::StreamWriterBuilder wbuilder;
+  wbuilder["indentation"] = "\t";
+  this->JsonWriter =
+    std::unique_ptr<Json::StreamWriter>(wbuilder.newStreamWriter());
+}
+
+void cmFileAPI::ReadQueries()
+{
+  std::string const query_dir = this->APIv1 + "/query";
+  this->QueryExists = cmSystemTools::FileIsDirectory(query_dir);
+  if (!this->QueryExists) {
+    return;
+  }
+
+  // Load queries at the top level.
+  std::vector<std::string> queries = cmFileAPI::LoadDir(query_dir);
+
+  // Read the queries and save for later.
+  for (std::string& query : queries) {
+    if (cmHasLiteralPrefix(query, "client-")) {
+      this->ReadClient(query);
+    } else if (!cmFileAPI::ReadQuery(query, this->TopQuery.Known)) {
+      this->TopQuery.Unknown.push_back(std::move(query));
+    }
+  }
+}
+
+void cmFileAPI::WriteReplies()
+{
+  if (this->QueryExists) {
+    cmSystemTools::MakeDirectory(this->APIv1 + "/reply");
+    this->WriteJsonFile(this->BuildReplyIndex(), "index", ComputeSuffixTime);
+  }
+
+  this->RemoveOldReplyFiles();
+}
+
+std::vector<std::string> cmFileAPI::LoadDir(std::string const& dir)
+{
+  std::vector<std::string> files;
+  cmsys::Directory d;
+  d.Load(dir);
+  for (unsigned long i = 0; i < d.GetNumberOfFiles(); ++i) {
+    std::string f = d.GetFile(i);
+    if (f != "." && f != "..") {
+      files.push_back(std::move(f));
+    }
+  }
+  std::sort(files.begin(), files.end());
+  return files;
+}
+
+void cmFileAPI::RemoveOldReplyFiles()
+{
+  std::string const reply_dir = this->APIv1 + "/reply";
+  std::vector<std::string> files = this->LoadDir(reply_dir);
+  for (std::string const& f : files) {
+    if (this->ReplyFiles.find(f) == this->ReplyFiles.end()) {
+      std::string file = reply_dir + "/" + f;
+      cmSystemTools::RemoveFile(file);
+    }
+  }
+}
+
+bool cmFileAPI::ReadJsonFile(std::string const& file, Json::Value& value,
+                             std::string& error)
+{
+  std::vector<char> content;
+
+  cmsys::ifstream fin;
+  if (!cmSystemTools::FileIsDirectory(file)) {
+    fin.open(file.c_str(), std::ios::binary);
+  }
+  auto finEnd = fin.rdbuf()->pubseekoff(0, std::ios::end);
+  if (finEnd > 0) {
+    size_t finSize = finEnd;
+    try {
+      // Allocate a buffer to read the whole file.
+      content.resize(finSize);
+
+      // Now read the file from the beginning.
+      fin.seekg(0, std::ios::beg);
+      fin.read(content.data(), finSize);
+    } catch (...) {
+      fin.setstate(std::ios::failbit);
+    }
+  }
+  fin.close();
+  if (!fin) {
+    value = Json::Value();
+    error = "failed to read from file";
+    return false;
+  }
+
+  // Parse our buffer as json.
+  if (!this->JsonReader->parse(content.data(), content.data() + content.size(),
+                               &value, &error)) {
+    value = Json::Value();
+    return false;
+  }
+
+  return true;
+}
+
+std::string cmFileAPI::WriteJsonFile(
+  Json::Value const& value, std::string const& prefix,
+  std::string (*computeSuffix)(std::string const&))
+{
+  std::string fileName;
+
+  // Write the json file with a temporary name.
+  std::string const& tmpFile = this->APIv1 + "/tmp.json";
+  cmsys::ofstream ftmp(tmpFile.c_str());
+  this->JsonWriter->write(value, &ftmp);
+  ftmp << "\n";
+  ftmp.close();
+  if (!ftmp) {
+    cmSystemTools::RemoveFile(tmpFile);
+    return fileName;
+  }
+
+  // Compute the final name for the file.
+  fileName = prefix + "-" + computeSuffix(tmpFile) + ".json";
+
+  // Create the destination.
+  std::string file = this->APIv1 + "/reply";
+  cmSystemTools::MakeDirectory(file);
+  file += "/";
+  file += fileName;
+
+  // If the final name already exists then assume it has proper content.
+  // Otherwise, atomically place the reply file at its final name
+  if (cmSystemTools::FileExists(file, true) ||
+      !cmSystemTools::RenameFile(tmpFile.c_str(), file.c_str())) {
+    cmSystemTools::RemoveFile(tmpFile);
+  }
+
+  // Record this among files we have just written.
+  this->ReplyFiles.insert(fileName);
+
+  return fileName;
+}
+
+Json::Value cmFileAPI::MaybeJsonFile(Json::Value in, std::string const& prefix)
+{
+  Json::Value out;
+  if (in.isObject() || in.isArray()) {
+    out = Json::objectValue;
+    out["jsonFile"] = this->WriteJsonFile(in, prefix);
+  } else {
+    out = std::move(in);
+  }
+  return out;
+}
+
+std::string cmFileAPI::ComputeSuffixHash(std::string const& file)
+{
+  cmCryptoHash hasher(cmCryptoHash::AlgoSHA3_256);
+  std::string hash = hasher.HashFile(file);
+  hash.resize(20, '0');
+  return hash;
+}
+
+std::string cmFileAPI::ComputeSuffixTime(std::string const&)
+{
+  std::chrono::milliseconds ms =
+    std::chrono::duration_cast<std::chrono::milliseconds>(
+      std::chrono::system_clock::now().time_since_epoch());
+  std::chrono::seconds s =
+    std::chrono::duration_cast<std::chrono::seconds>(ms);
+
+  std::time_t ts = s.count();
+  std::size_t tms = ms.count() % 1000;
+
+  cmTimestamp cmts;
+  std::ostringstream ss;
+  ss << cmts.CreateTimestampFromTimeT(ts, "%Y-%m-%dT%H-%M-%S", true) << '-'
+     << std::setfill('0') << std::setw(4) << tms;
+  return ss.str();
+}
+
+bool cmFileAPI::ReadQuery(std::string const& query,
+                          std::vector<Object>& objects)
+{
+  // Parse the "<kind>-" syntax.
+  std::string::size_type sep_pos = query.find('-');
+  if (sep_pos == std::string::npos) {
+    return false;
+  }
+  std::string kindName = query.substr(0, sep_pos);
+  std::string verStr = query.substr(sep_pos + 1);
+  if (kindName == ObjectKindName(ObjectKind::CodeModel)) {
+    Object o;
+    o.Kind = ObjectKind::CodeModel;
+    if (verStr == "v2") {
+      o.Version = 2;
+    } else {
+      return false;
+    }
+    objects.push_back(o);
+    return true;
+  }
+  if (kindName == ObjectKindName(ObjectKind::Cache)) {
+    Object o;
+    o.Kind = ObjectKind::Cache;
+    if (verStr == "v2") {
+      o.Version = 2;
+    } else {
+      return false;
+    }
+    objects.push_back(o);
+    return true;
+  }
+  if (kindName == ObjectKindName(ObjectKind::CMakeFiles)) {
+    Object o;
+    o.Kind = ObjectKind::CMakeFiles;
+    if (verStr == "v1") {
+      o.Version = 1;
+    } else {
+      return false;
+    }
+    objects.push_back(o);
+    return true;
+  }
+  if (kindName == ObjectKindName(ObjectKind::InternalTest)) {
+    Object o;
+    o.Kind = ObjectKind::InternalTest;
+    if (verStr == "v1") {
+      o.Version = 1;
+    } else if (verStr == "v2") {
+      o.Version = 2;
+    } else {
+      return false;
+    }
+    objects.push_back(o);
+    return true;
+  }
+  return false;
+}
+
+void cmFileAPI::ReadClient(std::string const& client)
+{
+  // Load queries for the client.
+  std::string clientDir = this->APIv1 + "/query/" + client;
+  std::vector<std::string> queries = this->LoadDir(clientDir);
+
+  // Read the queries and save for later.
+  ClientQuery& clientQuery = this->ClientQueries[client];
+  for (std::string& query : queries) {
+    if (query == "query.json") {
+      clientQuery.HaveQueryJson = true;
+      this->ReadClientQuery(client, clientQuery.QueryJson);
+    } else if (!this->ReadQuery(query, clientQuery.DirQuery.Known)) {
+      clientQuery.DirQuery.Unknown.push_back(std::move(query));
+    }
+  }
+}
+
+void cmFileAPI::ReadClientQuery(std::string const& client, ClientQueryJson& q)
+{
+  // Read the query.json file.
+  std::string queryFile = this->APIv1 + "/query/" + client + "/query.json";
+  Json::Value query;
+  if (!this->ReadJsonFile(queryFile, query, q.Error)) {
+    return;
+  }
+  if (!query.isObject()) {
+    q.Error = "query root is not an object";
+    return;
+  }
+
+  Json::Value const& clientValue = query["client"];
+  if (!clientValue.isNull()) {
+    q.ClientValue = clientValue;
+  }
+  q.RequestsValue = std::move(query["requests"]);
+  q.Requests = this->BuildClientRequests(q.RequestsValue);
+}
+
+Json::Value cmFileAPI::BuildReplyIndex()
+{
+  Json::Value index(Json::objectValue);
+
+  // Report information about this version of CMake.
+  index["cmake"] = this->BuildCMake();
+
+  // Reply to all queries that we loaded.
+  Json::Value& reply = index["reply"] = this->BuildReply(this->TopQuery);
+  for (auto const& client : this->ClientQueries) {
+    std::string const& clientName = client.first;
+    ClientQuery const& clientQuery = client.second;
+    reply[clientName] = this->BuildClientReply(clientQuery);
+  }
+
+  // Move our index of generated objects into its field.
+  Json::Value& objects = index["objects"] = Json::arrayValue;
+  for (auto& entry : this->ReplyIndexObjects) {
+    objects.append(std::move(entry.second)); // NOLINT(*)
+  }
+
+  return index;
+}
+
+Json::Value cmFileAPI::BuildCMake()
+{
+  Json::Value cmake = Json::objectValue;
+  cmake["version"] = this->CMakeInstance->ReportVersionJson();
+  Json::Value& cmake_paths = cmake["paths"] = Json::objectValue;
+  cmake_paths["cmake"] = cmSystemTools::GetCMakeCommand();
+  cmake_paths["ctest"] = cmSystemTools::GetCTestCommand();
+  cmake_paths["cpack"] = cmSystemTools::GetCPackCommand();
+  cmake_paths["root"] = cmSystemTools::GetCMakeRoot();
+  cmake["generator"] = this->CMakeInstance->GetGlobalGenerator()->GetJson();
+  return cmake;
+}
+
+Json::Value cmFileAPI::BuildReply(Query const& q)
+{
+  Json::Value reply = Json::objectValue;
+  for (Object const& o : q.Known) {
+    std::string const& name = ObjectName(o);
+    reply[name] = this->AddReplyIndexObject(o);
+  }
+
+  for (std::string const& name : q.Unknown) {
+    reply[name] = cmFileAPI::BuildReplyError("unknown query file");
+  }
+  return reply;
+}
+
+Json::Value cmFileAPI::BuildReplyError(std::string const& error)
+{
+  Json::Value e = Json::objectValue;
+  e["error"] = error;
+  return e;
+}
+
+Json::Value const& cmFileAPI::AddReplyIndexObject(Object const& o)
+{
+  Json::Value& indexEntry = this->ReplyIndexObjects[o];
+  if (!indexEntry.isNull()) {
+    // The reply object has already been generated.
+    return indexEntry;
+  }
+
+  // Generate this reply object.
+  Json::Value const& object = this->BuildObject(o);
+  assert(object.isObject());
+
+  // Populate this index entry.
+  indexEntry = Json::objectValue;
+  indexEntry["kind"] = object["kind"];
+  indexEntry["version"] = object["version"];
+  indexEntry["jsonFile"] = this->WriteJsonFile(object, ObjectName(o));
+  return indexEntry;
+}
+
+const char* cmFileAPI::ObjectKindName(ObjectKind kind)
+{
+  // Keep in sync with ObjectKind enum.
+  static const char* objectKindNames[] = {
+    "codemodel",  //
+    "cache",      //
+    "cmakeFiles", //
+    "__test"      //
+  };
+  return objectKindNames[size_t(kind)];
+}
+
+std::string cmFileAPI::ObjectName(Object const& o)
+{
+  std::string name = ObjectKindName(o.Kind);
+  name += "-v";
+  name += std::to_string(o.Version);
+  return name;
+}
+
+Json::Value cmFileAPI::BuildObject(Object const& object)
+{
+  Json::Value value;
+
+  switch (object.Kind) {
+    case ObjectKind::CodeModel:
+      value = this->BuildCodeModel(object);
+      break;
+    case ObjectKind::Cache:
+      value = this->BuildCache(object);
+      break;
+    case ObjectKind::CMakeFiles:
+      value = this->BuildCMakeFiles(object);
+      break;
+    case ObjectKind::InternalTest:
+      value = this->BuildInternalTest(object);
+      break;
+  }
+
+  return value;
+}
+
+cmFileAPI::ClientRequests cmFileAPI::BuildClientRequests(
+  Json::Value const& requests)
+{
+  ClientRequests result;
+  if (requests.isNull()) {
+    result.Error = "'requests' member missing";
+    return result;
+  }
+  if (!requests.isArray()) {
+    result.Error = "'requests' member is not an array";
+    return result;
+  }
+
+  result.reserve(requests.size());
+  for (Json::Value const& request : requests) {
+    result.emplace_back(this->BuildClientRequest(request));
+  }
+
+  return result;
+}
+
+cmFileAPI::ClientRequest cmFileAPI::BuildClientRequest(
+  Json::Value const& request)
+{
+  ClientRequest r;
+
+  if (!request.isObject()) {
+    r.Error = "request is not an object";
+    return r;
+  }
+
+  Json::Value const& kind = request["kind"];
+  if (kind.isNull()) {
+    r.Error = "'kind' member missing";
+    return r;
+  }
+  if (!kind.isString()) {
+    r.Error = "'kind' member is not a string";
+    return r;
+  }
+  std::string const& kindName = kind.asString();
+
+  if (kindName == this->ObjectKindName(ObjectKind::CodeModel)) {
+    r.Kind = ObjectKind::CodeModel;
+  } else if (kindName == this->ObjectKindName(ObjectKind::Cache)) {
+    r.Kind = ObjectKind::Cache;
+  } else if (kindName == this->ObjectKindName(ObjectKind::CMakeFiles)) {
+    r.Kind = ObjectKind::CMakeFiles;
+  } else if (kindName == this->ObjectKindName(ObjectKind::InternalTest)) {
+    r.Kind = ObjectKind::InternalTest;
+  } else {
+    r.Error = "unknown request kind '" + kindName + "'";
+    return r;
+  }
+
+  Json::Value const& version = request["version"];
+  if (version.isNull()) {
+    r.Error = "'version' member missing";
+    return r;
+  }
+  std::vector<RequestVersion> versions;
+  if (!cmFileAPI::ReadRequestVersions(version, versions, r.Error)) {
+    return r;
+  }
+
+  switch (r.Kind) {
+    case ObjectKind::CodeModel:
+      this->BuildClientRequestCodeModel(r, versions);
+      break;
+    case ObjectKind::Cache:
+      this->BuildClientRequestCache(r, versions);
+      break;
+    case ObjectKind::CMakeFiles:
+      this->BuildClientRequestCMakeFiles(r, versions);
+      break;
+    case ObjectKind::InternalTest:
+      this->BuildClientRequestInternalTest(r, versions);
+      break;
+  }
+
+  return r;
+}
+
+Json::Value cmFileAPI::BuildClientReply(ClientQuery const& q)
+{
+  Json::Value reply = this->BuildReply(q.DirQuery);
+
+  if (!q.HaveQueryJson) {
+    return reply;
+  }
+
+  Json::Value& reply_query_json = reply["query.json"];
+  ClientQueryJson const& qj = q.QueryJson;
+
+  if (!qj.Error.empty()) {
+    reply_query_json = this->BuildReplyError(qj.Error);
+    return reply;
+  }
+
+  if (!qj.ClientValue.isNull()) {
+    reply_query_json["client"] = qj.ClientValue;
+  }
+
+  if (!qj.RequestsValue.isNull()) {
+    reply_query_json["requests"] = qj.RequestsValue;
+  }
+
+  reply_query_json["responses"] = this->BuildClientReplyResponses(qj.Requests);
+
+  return reply;
+}
+
+Json::Value cmFileAPI::BuildClientReplyResponses(
+  ClientRequests const& requests)
+{
+  Json::Value responses;
+
+  if (!requests.Error.empty()) {
+    responses = this->BuildReplyError(requests.Error);
+    return responses;
+  }
+
+  responses = Json::arrayValue;
+  for (ClientRequest const& request : requests) {
+    responses.append(this->BuildClientReplyResponse(request));
+  }
+
+  return responses;
+}
+
+Json::Value cmFileAPI::BuildClientReplyResponse(ClientRequest const& request)
+{
+  Json::Value response;
+  if (!request.Error.empty()) {
+    response = this->BuildReplyError(request.Error);
+    return response;
+  }
+  response = this->AddReplyIndexObject(request);
+  return response;
+}
+
+bool cmFileAPI::ReadRequestVersions(Json::Value const& version,
+                                    std::vector<RequestVersion>& versions,
+                                    std::string& error)
+{
+  if (version.isArray()) {
+    for (Json::Value const& v : version) {
+      if (!ReadRequestVersion(v, /*inArray=*/true, versions, error)) {
+        return false;
+      }
+    }
+  } else {
+    if (!ReadRequestVersion(version, /*inArray=*/false, versions, error)) {
+      return false;
+    }
+  }
+  return true;
+}
+
+bool cmFileAPI::ReadRequestVersion(Json::Value const& version, bool inArray,
+                                   std::vector<RequestVersion>& result,
+                                   std::string& error)
+{
+  if (version.isUInt()) {
+    RequestVersion v;
+    v.Major = version.asUInt();
+    result.push_back(v);
+    return true;
+  }
+
+  if (!version.isObject()) {
+    if (inArray) {
+      error = "'version' array entry is not a non-negative integer or object";
+    } else {
+      error =
+        "'version' member is not a non-negative integer, object, or array";
+    }
+    return false;
+  }
+
+  Json::Value const& major = version["major"];
+  if (major.isNull()) {
+    error = "'version' object 'major' member missing";
+    return false;
+  }
+  if (!major.isUInt()) {
+    error = "'version' object 'major' member is not a non-negative integer";
+    return false;
+  }
+
+  RequestVersion v;
+  v.Major = major.asUInt();
+
+  Json::Value const& minor = version["minor"];
+  if (minor.isUInt()) {
+    v.Minor = minor.asUInt();
+  } else if (!minor.isNull()) {
+    error = "'version' object 'minor' member is not a non-negative integer";
+    return false;
+  }
+
+  result.push_back(v);
+
+  return true;
+}
+
+std::string cmFileAPI::NoSupportedVersion(
+  std::vector<RequestVersion> const& versions)
+{
+  std::ostringstream msg;
+  msg << "no supported version specified";
+  if (!versions.empty()) {
+    msg << " among:";
+    for (RequestVersion const& v : versions) {
+      msg << " " << v.Major << "." << v.Minor;
+    }
+  }
+  return msg.str();
+}
+
+// The "codemodel" object kind.
+
+static unsigned int const CodeModelV2Minor = 0;
+
+void cmFileAPI::BuildClientRequestCodeModel(
+  ClientRequest& r, std::vector<RequestVersion> const& versions)
+{
+  // Select a known version from those requested.
+  for (RequestVersion const& v : versions) {
+    if ((v.Major == 2 && v.Minor <= CodeModelV2Minor)) {
+      r.Version = v.Major;
+      break;
+    }
+  }
+  if (!r.Version) {
+    r.Error = NoSupportedVersion(versions);
+  }
+}
+
+Json::Value cmFileAPI::BuildCodeModel(Object const& object)
+{
+  using namespace std::placeholders;
+  Json::Value codemodel = cmFileAPICodemodelDump(*this, object.Version);
+  codemodel["kind"] = this->ObjectKindName(object.Kind);
+
+  Json::Value& version = codemodel["version"] = Json::objectValue;
+  if (object.Version == 2) {
+    version["major"] = 2;
+    version["minor"] = CodeModelV2Minor;
+  } else {
+    return codemodel; // should be unreachable
+  }
+
+  return codemodel;
+}
+
+// The "cache" object kind.
+
+static unsigned int const CacheV2Minor = 0;
+
+void cmFileAPI::BuildClientRequestCache(
+  ClientRequest& r, std::vector<RequestVersion> const& versions)
+{
+  // Select a known version from those requested.
+  for (RequestVersion const& v : versions) {
+    if ((v.Major == 2 && v.Minor <= CacheV2Minor)) {
+      r.Version = v.Major;
+      break;
+    }
+  }
+  if (!r.Version) {
+    r.Error = NoSupportedVersion(versions);
+  }
+}
+
+Json::Value cmFileAPI::BuildCache(Object const& object)
+{
+  using namespace std::placeholders;
+  Json::Value cache = cmFileAPICacheDump(*this, object.Version);
+  cache["kind"] = this->ObjectKindName(object.Kind);
+
+  Json::Value& version = cache["version"] = Json::objectValue;
+  if (object.Version == 2) {
+    version["major"] = 2;
+    version["minor"] = CacheV2Minor;
+  } else {
+    return cache; // should be unreachable
+  }
+
+  return cache;
+}
+
+// The "cmakeFiles" object kind.
+
+static unsigned int const CMakeFilesV1Minor = 0;
+
+void cmFileAPI::BuildClientRequestCMakeFiles(
+  ClientRequest& r, std::vector<RequestVersion> const& versions)
+{
+  // Select a known version from those requested.
+  for (RequestVersion const& v : versions) {
+    if ((v.Major == 1 && v.Minor <= CMakeFilesV1Minor)) {
+      r.Version = v.Major;
+      break;
+    }
+  }
+  if (!r.Version) {
+    r.Error = NoSupportedVersion(versions);
+  }
+}
+
+Json::Value cmFileAPI::BuildCMakeFiles(Object const& object)
+{
+  using namespace std::placeholders;
+  Json::Value cmakeFiles = cmFileAPICMakeFilesDump(*this, object.Version);
+  cmakeFiles["kind"] = this->ObjectKindName(object.Kind);
+
+  Json::Value& version = cmakeFiles["version"] = Json::objectValue;
+  if (object.Version == 1) {
+    version["major"] = 1;
+    version["minor"] = CMakeFilesV1Minor;
+  } else {
+    return cmakeFiles; // should be unreachable
+  }
+
+  return cmakeFiles;
+}
+
+// The "__test" object kind is for internal testing of CMake.
+
+static unsigned int const InternalTestV1Minor = 3;
+static unsigned int const InternalTestV2Minor = 0;
+
+void cmFileAPI::BuildClientRequestInternalTest(
+  ClientRequest& r, std::vector<RequestVersion> const& versions)
+{
+  // Select a known version from those requested.
+  for (RequestVersion const& v : versions) {
+    if ((v.Major == 1 && v.Minor <= InternalTestV1Minor) || //
+        (v.Major == 2 && v.Minor <= InternalTestV2Minor)) {
+      r.Version = v.Major;
+      break;
+    }
+  }
+  if (!r.Version) {
+    r.Error = NoSupportedVersion(versions);
+  }
+}
+
+Json::Value cmFileAPI::BuildInternalTest(Object const& object)
+{
+  Json::Value test = Json::objectValue;
+  test["kind"] = this->ObjectKindName(object.Kind);
+  Json::Value& version = test["version"] = Json::objectValue;
+  if (object.Version == 2) {
+    version["major"] = 2;
+    version["minor"] = InternalTestV2Minor;
+  } else {
+    version["major"] = 1;
+    version["minor"] = InternalTestV1Minor;
+  }
+  return test;
+}
diff --git a/Source/cmFileAPI.h b/Source/cmFileAPI.h
new file mode 100644
index 0000000..341b072
--- /dev/null
+++ b/Source/cmFileAPI.h
@@ -0,0 +1,204 @@
+/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+   file Copyright.txt or https://cmake.org/licensing for details.  */
+#ifndef cmFileAPI_h
+#define cmFileAPI_h
+
+#include "cmConfigure.h" // IWYU pragma: keep
+
+#include "cm_jsoncpp_reader.h"
+#include "cm_jsoncpp_value.h"
+#include "cm_jsoncpp_writer.h"
+
+#include <map>
+#include <memory> // IWYU pragma: keep
+#include <string>
+#include <unordered_set>
+#include <vector>
+
+class cmake;
+
+class cmFileAPI
+{
+public:
+  cmFileAPI(cmake* cm);
+
+  /** Read fileapi queries from disk.  */
+  void ReadQueries();
+
+  /** Write fileapi replies to disk.  */
+  void WriteReplies();
+
+  /** Get the "cmake" instance with which this was constructed.  */
+  cmake* GetCMakeInstance() const { return this->CMakeInstance; }
+
+  /** Convert a JSON object or array into an object with a single
+      "jsonFile" member specifying a file named with the given prefix
+      and holding the original object.  Other JSON types are unchanged.  */
+  Json::Value MaybeJsonFile(Json::Value in, std::string const& prefix);
+
+private:
+  cmake* CMakeInstance;
+
+  /** The api/v1 directory location.  */
+  std::string APIv1;
+
+  /** The set of files we have just written to the reply directory.  */
+  std::unordered_set<std::string> ReplyFiles;
+
+  static std::vector<std::string> LoadDir(std::string const& dir);
+  void RemoveOldReplyFiles();
+
+  // Keep in sync with ObjectKindName.
+  enum class ObjectKind
+  {
+    CodeModel,
+    Cache,
+    CMakeFiles,
+    InternalTest
+  };
+
+  /** Identify one object kind and major version.  */
+  struct Object
+  {
+    ObjectKind Kind;
+    unsigned long Version = 0;
+    friend bool operator<(Object const& l, Object const& r)
+    {
+      if (l.Kind != r.Kind) {
+        return l.Kind < r.Kind;
+      }
+      return l.Version < r.Version;
+    }
+  };
+
+  /** Represent content of a query directory.  */
+  struct Query
+  {
+    /** Known object kind-version pairs.  */
+    std::vector<Object> Known;
+    /** Unknown object kind names.  */
+    std::vector<std::string> Unknown;
+  };
+
+  /** Represent one request in a client 'query.json'.  */
+  struct ClientRequest : public Object
+  {
+    /** Empty if request is valid, else the error string.  */
+    std::string Error;
+  };
+
+  /** Represent the "requests" in a client 'query.json'.  */
+  struct ClientRequests : public std::vector<ClientRequest>
+  {
+    /** Empty if requests field is valid, else the error string.  */
+    std::string Error;
+  };
+
+  /** Represent the content of a client query.json file.  */
+  struct ClientQueryJson
+  {
+    /** The error string if parsing failed, else empty.  */
+    std::string Error;
+
+    /** The 'query.json' object "client" member if it exists, else null.  */
+    Json::Value ClientValue;
+
+    /** The 'query.json' object "requests" member if it exists, else null.  */
+    Json::Value RequestsValue;
+
+    /** Requests extracted from 'query.json'.  */
+    ClientRequests Requests;
+  };
+
+  /** Represent content of a client query directory.  */
+  struct ClientQuery
+  {
+    /** The content of the client query directory except 'query.json'.  */
+    Query DirQuery;
+
+    /** True if 'query.json' exists.  */
+    bool HaveQueryJson = false;
+
+    /** The 'query.json' content.  */
+    ClientQueryJson QueryJson;
+  };
+
+  /** Whether the top-level query directory exists at all.  */
+  bool QueryExists = false;
+
+  /** The content of the top-level query directory.  */
+  Query TopQuery;
+
+  /** The content of each "client-$client" query directory.  */
+  std::map<std::string, ClientQuery> ClientQueries;
+
+  /** Reply index object generated for object kind/version.
+      This populates the "objects" field of the reply index.  */
+  std::map<Object, Json::Value> ReplyIndexObjects;
+
+  std::unique_ptr<Json::CharReader> JsonReader;
+  std::unique_ptr<Json::StreamWriter> JsonWriter;
+
+  bool ReadJsonFile(std::string const& file, Json::Value& value,
+                    std::string& error);
+
+  std::string WriteJsonFile(
+    Json::Value const& value, std::string const& prefix,
+    std::string (*computeSuffix)(std::string const&) = ComputeSuffixHash);
+  static std::string ComputeSuffixHash(std::string const&);
+  static std::string ComputeSuffixTime(std::string const&);
+
+  static bool ReadQuery(std::string const& query,
+                        std::vector<Object>& objects);
+  void ReadClient(std::string const& client);
+  void ReadClientQuery(std::string const& client, ClientQueryJson& q);
+
+  Json::Value BuildReplyIndex();
+  Json::Value BuildCMake();
+  Json::Value BuildReply(Query const& q);
+  static Json::Value BuildReplyError(std::string const& error);
+  Json::Value const& AddReplyIndexObject(Object const& o);
+
+  static const char* ObjectKindName(ObjectKind kind);
+  static std::string ObjectName(Object const& o);
+
+  Json::Value BuildObject(Object const& object);
+
+  ClientRequests BuildClientRequests(Json::Value const& requests);
+  ClientRequest BuildClientRequest(Json::Value const& request);
+  Json::Value BuildClientReply(ClientQuery const& q);
+  Json::Value BuildClientReplyResponses(ClientRequests const& requests);
+  Json::Value BuildClientReplyResponse(ClientRequest const& request);
+
+  struct RequestVersion
+  {
+    unsigned int Major = 0;
+    unsigned int Minor = 0;
+  };
+  static bool ReadRequestVersions(Json::Value const& version,
+                                  std::vector<RequestVersion>& versions,
+                                  std::string& error);
+  static bool ReadRequestVersion(Json::Value const& version, bool inArray,
+                                 std::vector<RequestVersion>& result,
+                                 std::string& error);
+  static std::string NoSupportedVersion(
+    std::vector<RequestVersion> const& versions);
+
+  void BuildClientRequestCodeModel(
+    ClientRequest& r, std::vector<RequestVersion> const& versions);
+  Json::Value BuildCodeModel(Object const& object);
+
+  void BuildClientRequestCache(ClientRequest& r,
+                               std::vector<RequestVersion> const& versions);
+  Json::Value BuildCache(Object const& object);
+
+  void BuildClientRequestCMakeFiles(
+    ClientRequest& r, std::vector<RequestVersion> const& versions);
+  Json::Value BuildCMakeFiles(Object const& object);
+
+  void BuildClientRequestInternalTest(
+    ClientRequest& r, std::vector<RequestVersion> const& versions);
+  Json::Value BuildInternalTest(Object const& object);
+};
+
+#endif
diff --git a/Source/cmFileAPICMakeFiles.cxx b/Source/cmFileAPICMakeFiles.cxx
new file mode 100644
index 0000000..799a047
--- /dev/null
+++ b/Source/cmFileAPICMakeFiles.cxx
@@ -0,0 +1,113 @@
+/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+   file Copyright.txt or https://cmake.org/licensing for details.  */
+#include "cmFileAPICMakeFiles.h"
+
+#include "cmFileAPI.h"
+#include "cmGlobalGenerator.h"
+#include "cmLocalGenerator.h"
+#include "cmMakefile.h"
+#include "cmSystemTools.h"
+#include "cmake.h"
+
+#include "cm_jsoncpp_value.h"
+
+#include <string>
+
+namespace {
+
+class CMakeFiles
+{
+  cmFileAPI& FileAPI;
+  unsigned long Version;
+  std::string CMakeModules;
+  std::string const& TopSource;
+  std::string const& TopBuild;
+  bool OutOfSource;
+
+  Json::Value DumpPaths();
+  Json::Value DumpInputs();
+  Json::Value DumpInput(std::string const& file);
+
+public:
+  CMakeFiles(cmFileAPI& fileAPI, unsigned long version);
+  Json::Value Dump();
+};
+
+CMakeFiles::CMakeFiles(cmFileAPI& fileAPI, unsigned long version)
+  : FileAPI(fileAPI)
+  , Version(version)
+  , CMakeModules(cmSystemTools::GetCMakeRoot() + "/Modules")
+  , TopSource(this->FileAPI.GetCMakeInstance()->GetHomeDirectory())
+  , TopBuild(this->FileAPI.GetCMakeInstance()->GetHomeOutputDirectory())
+  , OutOfSource(TopBuild != TopSource)
+{
+  static_cast<void>(this->Version);
+}
+
+Json::Value CMakeFiles::Dump()
+{
+  Json::Value cmakeFiles = Json::objectValue;
+  cmakeFiles["paths"] = this->DumpPaths();
+  cmakeFiles["inputs"] = DumpInputs();
+  return cmakeFiles;
+}
+
+Json::Value CMakeFiles::DumpPaths()
+{
+  Json::Value paths = Json::objectValue;
+  paths["source"] = this->TopSource;
+  paths["build"] = this->TopBuild;
+  return paths;
+}
+
+Json::Value CMakeFiles::DumpInputs()
+{
+  Json::Value inputs = Json::arrayValue;
+
+  cmGlobalGenerator* gg =
+    this->FileAPI.GetCMakeInstance()->GetGlobalGenerator();
+  for (cmLocalGenerator const* lg : gg->GetLocalGenerators()) {
+    cmMakefile const* mf = lg->GetMakefile();
+    for (std::string const& file : mf->GetListFiles()) {
+      inputs.append(this->DumpInput(file));
+    }
+  }
+
+  return inputs;
+}
+
+Json::Value CMakeFiles::DumpInput(std::string const& file)
+{
+  Json::Value input = Json::objectValue;
+
+  bool const isCMake = cmSystemTools::IsSubDirectory(file, this->CMakeModules);
+  if (isCMake) {
+    input["isCMake"] = true;
+  }
+
+  if (!cmSystemTools::IsSubDirectory(file, this->TopSource) &&
+      !cmSystemTools::IsSubDirectory(file, this->TopBuild)) {
+    input["isExternal"] = true;
+  }
+
+  if (this->OutOfSource &&
+      cmSystemTools::IsSubDirectory(file, this->TopBuild)) {
+    input["isGenerated"] = true;
+  }
+
+  std::string path = file;
+  if (!isCMake && cmSystemTools::IsSubDirectory(path, this->TopSource)) {
+    // Use a relative path within the source directory.
+    path = cmSystemTools::RelativePath(this->TopSource, path);
+  }
+  input["path"] = path;
+
+  return input;
+}
+}
+
+Json::Value cmFileAPICMakeFilesDump(cmFileAPI& fileAPI, unsigned long version)
+{
+  CMakeFiles cmakeFiles(fileAPI, version);
+  return cmakeFiles.Dump();
+}
diff --git a/Source/cmFileAPICMakeFiles.h b/Source/cmFileAPICMakeFiles.h
new file mode 100644
index 0000000..a851c32
--- /dev/null
+++ b/Source/cmFileAPICMakeFiles.h
@@ -0,0 +1,15 @@
+/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+   file Copyright.txt or https://cmake.org/licensing for details.  */
+#ifndef cmFileAPICMakeFiles_h
+#define cmFileAPICMakeFiles_h
+
+#include "cmConfigure.h" // IWYU pragma: keep
+
+#include "cm_jsoncpp_value.h"
+
+class cmFileAPI;
+
+extern Json::Value cmFileAPICMakeFilesDump(cmFileAPI& fileAPI,
+                                           unsigned long version);
+
+#endif
diff --git a/Source/cmFileAPICache.cxx b/Source/cmFileAPICache.cxx
new file mode 100644
index 0000000..074994a
--- /dev/null
+++ b/Source/cmFileAPICache.cxx
@@ -0,0 +1,105 @@
+/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+   file Copyright.txt or https://cmake.org/licensing for details.  */
+#include "cmFileAPICache.h"
+
+#include "cmFileAPI.h"
+#include "cmState.h"
+#include "cmake.h"
+
+#include "cm_jsoncpp_value.h"
+
+#include <algorithm>
+#include <string>
+#include <vector>
+
+namespace {
+
+class Cache
+{
+  cmFileAPI& FileAPI;
+  unsigned long Version;
+  cmState* State;
+
+  Json::Value DumpEntries();
+  Json::Value DumpEntry(std::string const& name);
+  Json::Value DumpEntryProperties(std::string const& name);
+  Json::Value DumpEntryProperty(std::string const& name,
+                                std::string const& prop);
+
+public:
+  Cache(cmFileAPI& fileAPI, unsigned long version);
+  Json::Value Dump();
+};
+
+Cache::Cache(cmFileAPI& fileAPI, unsigned long version)
+  : FileAPI(fileAPI)
+  , Version(version)
+  , State(this->FileAPI.GetCMakeInstance()->GetState())
+{
+  static_cast<void>(this->Version);
+}
+
+Json::Value Cache::Dump()
+{
+  Json::Value cache = Json::objectValue;
+  cache["entries"] = DumpEntries();
+  return cache;
+}
+
+Json::Value Cache::DumpEntries()
+{
+  Json::Value entries = Json::arrayValue;
+
+  std::vector<std::string> names = this->State->GetCacheEntryKeys();
+  std::sort(names.begin(), names.end());
+
+  for (std::string const& name : names) {
+    entries.append(this->DumpEntry(name));
+  }
+
+  return entries;
+}
+
+Json::Value Cache::DumpEntry(std::string const& name)
+{
+  Json::Value entry = Json::objectValue;
+  entry["name"] = name;
+  entry["type"] =
+    cmState::CacheEntryTypeToString(this->State->GetCacheEntryType(name));
+  entry["value"] = this->State->GetCacheEntryValue(name);
+
+  Json::Value properties = this->DumpEntryProperties(name);
+  if (!properties.empty()) {
+    entry["properties"] = std::move(properties);
+  }
+
+  return entry;
+}
+
+Json::Value Cache::DumpEntryProperties(std::string const& name)
+{
+  Json::Value properties = Json::arrayValue;
+  std::vector<std::string> props =
+    this->State->GetCacheEntryPropertyList(name);
+  std::sort(props.begin(), props.end());
+  for (std::string const& prop : props) {
+    properties.append(this->DumpEntryProperty(name, prop));
+  }
+  return properties;
+}
+
+Json::Value Cache::DumpEntryProperty(std::string const& name,
+                                     std::string const& prop)
+{
+  Json::Value property = Json::objectValue;
+  property["name"] = prop;
+  property["value"] = this->State->GetCacheEntryProperty(name, prop);
+  return property;
+}
+}
+
+Json::Value cmFileAPICacheDump(cmFileAPI& fileAPI, unsigned long version)
+{
+  Cache cache(fileAPI, version);
+  return cache.Dump();
+}
diff --git a/Source/cmFileAPICache.h b/Source/cmFileAPICache.h
new file mode 100644
index 0000000..09d9e1c
--- /dev/null
+++ b/Source/cmFileAPICache.h
@@ -0,0 +1,15 @@
+/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+   file Copyright.txt or https://cmake.org/licensing for details.  */
+#ifndef cmFileAPICache_h
+#define cmFileAPICache_h
+
+#include "cmConfigure.h" // IWYU pragma: keep
+
+#include "cm_jsoncpp_value.h"
+
+class cmFileAPI;
+
+extern Json::Value cmFileAPICacheDump(cmFileAPI& fileAPI,
+                                      unsigned long version);
+
+#endif
diff --git a/Source/cmFileAPICodemodel.cxx b/Source/cmFileAPICodemodel.cxx
new file mode 100644
index 0000000..078d1d5
--- /dev/null
+++ b/Source/cmFileAPICodemodel.cxx
@@ -0,0 +1,1247 @@
+/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+   file Copyright.txt or https://cmake.org/licensing for details.  */
+#include "cmFileAPICodemodel.h"
+
+#include "cmCryptoHash.h"
+#include "cmFileAPI.h"
+#include "cmGeneratorExpression.h"
+#include "cmGeneratorTarget.h"
+#include "cmGlobalGenerator.h"
+#include "cmInstallGenerator.h"
+#include "cmInstallSubdirectoryGenerator.h"
+#include "cmInstallTargetGenerator.h"
+#include "cmLinkLineComputer.h"
+#include "cmListFileCache.h"
+#include "cmLocalGenerator.h"
+#include "cmMakefile.h"
+#include "cmSourceFile.h"
+#include "cmSourceGroup.h"
+#include "cmState.h"
+#include "cmStateDirectory.h"
+#include "cmStateSnapshot.h"
+#include "cmStateTypes.h"
+#include "cmSystemTools.h"
+#include "cmTarget.h"
+#include "cmTargetDepend.h"
+#include "cmake.h"
+
+#include "cm_jsoncpp_value.h"
+
+#include <algorithm>
+#include <cassert>
+#include <map>
+#include <set>
+#include <string>
+#include <unordered_map>
+#include <utility>
+#include <vector>
+
+namespace {
+
+class Codemodel
+{
+  cmFileAPI& FileAPI;
+  unsigned long Version;
+
+  Json::Value DumpPaths();
+  Json::Value DumpConfigurations();
+  Json::Value DumpConfiguration(std::string const& config);
+
+public:
+  Codemodel(cmFileAPI& fileAPI, unsigned long version);
+  Json::Value Dump();
+};
+
+class CodemodelConfig
+{
+  cmFileAPI& FileAPI;
+  unsigned long Version;
+  std::string const& Config;
+  std::string TopSource;
+  std::string TopBuild;
+
+  struct Directory
+  {
+    cmStateSnapshot Snapshot;
+    cmLocalGenerator const* LocalGenerator = nullptr;
+    Json::Value TargetIndexes = Json::arrayValue;
+    Json::ArrayIndex ProjectIndex;
+    bool HasInstallRule = false;
+  };
+  std::map<cmStateSnapshot, Json::ArrayIndex, cmStateSnapshot::StrictWeakOrder>
+    DirectoryMap;
+  std::vector<Directory> Directories;
+
+  struct Project
+  {
+    cmStateSnapshot Snapshot;
+    static const Json::ArrayIndex NoParentIndex =
+      static_cast<Json::ArrayIndex>(-1);
+    Json::ArrayIndex ParentIndex = NoParentIndex;
+    Json::Value ChildIndexes = Json::arrayValue;
+    Json::Value DirectoryIndexes = Json::arrayValue;
+    Json::Value TargetIndexes = Json::arrayValue;
+  };
+  std::map<cmStateSnapshot, Json::ArrayIndex, cmStateSnapshot::StrictWeakOrder>
+    ProjectMap;
+  std::vector<Project> Projects;
+
+  void ProcessDirectories();
+
+  Json::ArrayIndex GetDirectoryIndex(cmLocalGenerator const* lg);
+  Json::ArrayIndex GetDirectoryIndex(cmStateSnapshot s);
+
+  Json::ArrayIndex AddProject(cmStateSnapshot s);
+
+  Json::Value DumpTargets();
+  Json::Value DumpTarget(cmGeneratorTarget* gt, Json::ArrayIndex ti);
+
+  Json::Value DumpDirectories();
+  Json::Value DumpDirectory(Directory& d);
+
+  Json::Value DumpProjects();
+  Json::Value DumpProject(Project& p);
+
+  Json::Value DumpMinimumCMakeVersion(cmStateSnapshot s);
+
+public:
+  CodemodelConfig(cmFileAPI& fileAPI, unsigned long version,
+                  std::string const& config);
+  Json::Value Dump();
+};
+
+std::string RelativeIfUnder(std::string const& top, std::string const& in)
+{
+  std::string out;
+  if (in == top) {
+    out = ".";
+  } else if (cmSystemTools::IsSubDirectory(in, top)) {
+    out = in.substr(top.size() + 1);
+  } else {
+    out = in;
+  }
+  return out;
+}
+
+std::string TargetId(cmGeneratorTarget const* gt, std::string const& topBuild)
+{
+  cmCryptoHash hasher(cmCryptoHash::AlgoSHA3_256);
+  std::string path = RelativeIfUnder(
+    topBuild, gt->GetLocalGenerator()->GetCurrentBinaryDirectory());
+  std::string hash = hasher.HashString(path);
+  hash.resize(20, '0');
+  return gt->GetName() + CMAKE_DIRECTORY_ID_SEP + hash;
+}
+
+class BacktraceData
+{
+  std::string TopSource;
+  std::unordered_map<std::string, Json::ArrayIndex> CommandMap;
+  std::unordered_map<std::string, Json::ArrayIndex> FileMap;
+  std::unordered_map<cmListFileContext const*, Json::ArrayIndex> NodeMap;
+  Json::Value Commands = Json::arrayValue;
+  Json::Value Files = Json::arrayValue;
+  Json::Value Nodes = Json::arrayValue;
+
+  Json::ArrayIndex AddCommand(std::string const& command)
+  {
+    auto i = this->CommandMap.find(command);
+    if (i == this->CommandMap.end()) {
+      auto cmdIndex = static_cast<Json::ArrayIndex>(this->Commands.size());
+      i = this->CommandMap.emplace(command, cmdIndex).first;
+      this->Commands.append(command);
+    }
+    return i->second;
+  }
+
+  Json::ArrayIndex AddFile(std::string const& file)
+  {
+    auto i = this->FileMap.find(file);
+    if (i == this->FileMap.end()) {
+      auto fileIndex = static_cast<Json::ArrayIndex>(this->Files.size());
+      i = this->FileMap.emplace(file, fileIndex).first;
+      this->Files.append(RelativeIfUnder(this->TopSource, file));
+    }
+    return i->second;
+  }
+
+public:
+  BacktraceData(std::string const& topSource);
+  bool Add(cmListFileBacktrace const& bt, Json::ArrayIndex& index);
+  Json::Value Dump();
+};
+
+BacktraceData::BacktraceData(std::string const& topSource)
+  : TopSource(topSource)
+{
+}
+
+bool BacktraceData::Add(cmListFileBacktrace const& bt, Json::ArrayIndex& index)
+{
+  if (bt.Empty()) {
+    return false;
+  }
+  cmListFileContext const* top = &bt.Top();
+  auto found = this->NodeMap.find(top);
+  if (found != this->NodeMap.end()) {
+    index = found->second;
+    return true;
+  }
+  Json::Value entry = Json::objectValue;
+  entry["file"] = this->AddFile(top->FilePath);
+  if (top->Line) {
+    entry["line"] = static_cast<int>(top->Line);
+  }
+  if (!top->Name.empty()) {
+    entry["command"] = this->AddCommand(top->Name);
+  }
+  Json::ArrayIndex parent;
+  if (this->Add(bt.Pop(), parent)) {
+    entry["parent"] = parent;
+  }
+  index = this->NodeMap[top] = this->Nodes.size();
+  this->Nodes.append(std::move(entry)); // NOLINT(*)
+  return true;
+}
+
+Json::Value BacktraceData::Dump()
+{
+  Json::Value backtraceGraph;
+  this->CommandMap.clear();
+  this->FileMap.clear();
+  this->NodeMap.clear();
+  backtraceGraph["commands"] = std::move(this->Commands);
+  backtraceGraph["files"] = std::move(this->Files);
+  backtraceGraph["nodes"] = std::move(this->Nodes);
+  return backtraceGraph;
+}
+
+struct CompileData
+{
+  struct IncludeEntry
+  {
+    BT<std::string> Path;
+    bool IsSystem = false;
+    IncludeEntry(BT<std::string> path, bool isSystem)
+      : Path(std::move(path))
+      , IsSystem(isSystem)
+    {
+    }
+  };
+
+  void SetDefines(std::set<BT<std::string>> const& defines);
+
+  std::string Language;
+  std::string Sysroot;
+  std::vector<BT<std::string>> Flags;
+  std::vector<BT<std::string>> Defines;
+  std::vector<IncludeEntry> Includes;
+};
+
+void CompileData::SetDefines(std::set<BT<std::string>> const& defines)
+{
+  this->Defines.reserve(defines.size());
+  for (BT<std::string> const& d : defines) {
+    this->Defines.push_back(d);
+  }
+}
+
+class Target
+{
+  cmGeneratorTarget* GT;
+  std::string const& Config;
+  std::string TopSource;
+  std::string TopBuild;
+  std::vector<cmSourceGroup> SourceGroupsLocal;
+  BacktraceData Backtraces;
+
+  std::map<std::string, CompileData> CompileDataMap;
+
+  std::unordered_map<cmSourceFile const*, Json::ArrayIndex> SourceMap;
+  Json::Value Sources = Json::arrayValue;
+
+  struct SourceGroup
+  {
+    std::string Name;
+    Json::Value SourceIndexes = Json::arrayValue;
+  };
+  std::unordered_map<cmSourceGroup const*, Json::ArrayIndex> SourceGroupsMap;
+  std::vector<SourceGroup> SourceGroups;
+
+  struct CompileGroup
+  {
+    std::map<Json::Value, Json::ArrayIndex>::iterator Entry;
+    Json::Value SourceIndexes = Json::arrayValue;
+  };
+  std::map<Json::Value, Json::ArrayIndex> CompileGroupMap;
+  std::vector<CompileGroup> CompileGroups;
+
+  void ProcessLanguages();
+  void ProcessLanguage(std::string const& lang);
+
+  Json::ArrayIndex AddSourceGroup(cmSourceGroup* sg, Json::ArrayIndex si);
+  CompileData BuildCompileData(cmSourceFile* sf);
+  Json::ArrayIndex AddSourceCompileGroup(cmSourceFile* sf,
+                                         Json::ArrayIndex si);
+  void AddBacktrace(Json::Value& object, cmListFileBacktrace const& bt);
+  Json::Value DumpPaths();
+  Json::Value DumpCompileData(CompileData cd);
+  Json::Value DumpInclude(CompileData::IncludeEntry const& inc);
+  Json::Value DumpDefine(BT<std::string> const& def);
+  Json::Value DumpSources();
+  Json::Value DumpSource(cmGeneratorTarget::SourceAndKind const& sk,
+                         Json::ArrayIndex si);
+  Json::Value DumpSourceGroups();
+  Json::Value DumpSourceGroup(SourceGroup& sg);
+  Json::Value DumpCompileGroups();
+  Json::Value DumpCompileGroup(CompileGroup& cg);
+  Json::Value DumpSysroot(std::string const& path);
+  Json::Value DumpInstall();
+  Json::Value DumpInstallPrefix();
+  Json::Value DumpInstallDestinations();
+  Json::Value DumpInstallDestination(cmInstallTargetGenerator* itGen);
+  Json::Value DumpArtifacts();
+  Json::Value DumpLink();
+  Json::Value DumpArchive();
+  Json::Value DumpLinkCommandFragments();
+  Json::Value DumpCommandFragments(std::vector<BT<std::string>> const& frags);
+  Json::Value DumpCommandFragment(BT<std::string> const& frag,
+                                  std::string const& role = std::string());
+  Json::Value DumpDependencies();
+  Json::Value DumpDependency(cmTargetDepend const& td);
+  Json::Value DumpFolder();
+
+public:
+  Target(cmGeneratorTarget* gt, std::string const& config);
+  Json::Value Dump();
+};
+
+Codemodel::Codemodel(cmFileAPI& fileAPI, unsigned long version)
+  : FileAPI(fileAPI)
+  , Version(version)
+{
+}
+
+Json::Value Codemodel::Dump()
+{
+  Json::Value codemodel = Json::objectValue;
+
+  codemodel["paths"] = this->DumpPaths();
+  codemodel["configurations"] = this->DumpConfigurations();
+
+  return codemodel;
+}
+
+Json::Value Codemodel::DumpPaths()
+{
+  Json::Value paths = Json::objectValue;
+  paths["source"] = this->FileAPI.GetCMakeInstance()->GetHomeDirectory();
+  paths["build"] = this->FileAPI.GetCMakeInstance()->GetHomeOutputDirectory();
+  return paths;
+}
+
+Json::Value Codemodel::DumpConfigurations()
+{
+  std::vector<std::string> configs;
+  cmGlobalGenerator* gg =
+    this->FileAPI.GetCMakeInstance()->GetGlobalGenerator();
+  auto makefiles = gg->GetMakefiles();
+  if (!makefiles.empty()) {
+    makefiles[0]->GetConfigurations(configs);
+    if (configs.empty()) {
+      configs.emplace_back();
+    }
+  }
+  Json::Value configurations = Json::arrayValue;
+  for (std::string const& config : configs) {
+    configurations.append(this->DumpConfiguration(config));
+  }
+  return configurations;
+}
+
+Json::Value Codemodel::DumpConfiguration(std::string const& config)
+{
+  CodemodelConfig configuration(this->FileAPI, this->Version, config);
+  return configuration.Dump();
+}
+
+CodemodelConfig::CodemodelConfig(cmFileAPI& fileAPI, unsigned long version,
+                                 std::string const& config)
+  : FileAPI(fileAPI)
+  , Version(version)
+  , Config(config)
+  , TopSource(this->FileAPI.GetCMakeInstance()->GetHomeDirectory())
+  , TopBuild(this->FileAPI.GetCMakeInstance()->GetHomeOutputDirectory())
+{
+  static_cast<void>(this->Version);
+}
+
+Json::Value CodemodelConfig::Dump()
+{
+  Json::Value configuration = Json::objectValue;
+  configuration["name"] = this->Config;
+  this->ProcessDirectories();
+  configuration["targets"] = this->DumpTargets();
+  configuration["directories"] = this->DumpDirectories();
+  configuration["projects"] = this->DumpProjects();
+  return configuration;
+}
+
+void CodemodelConfig::ProcessDirectories()
+{
+  cmGlobalGenerator* gg =
+    this->FileAPI.GetCMakeInstance()->GetGlobalGenerator();
+  std::vector<cmLocalGenerator*> const& localGens = gg->GetLocalGenerators();
+
+  // Add directories in forward order to process parents before children.
+  this->Directories.reserve(localGens.size());
+  for (cmLocalGenerator* lg : localGens) {
+    auto directoryIndex =
+      static_cast<Json::ArrayIndex>(this->Directories.size());
+    this->Directories.emplace_back();
+    Directory& d = this->Directories[directoryIndex];
+    d.Snapshot = lg->GetStateSnapshot().GetBuildsystemDirectory();
+    d.LocalGenerator = lg;
+    this->DirectoryMap[d.Snapshot] = directoryIndex;
+
+    d.ProjectIndex = this->AddProject(d.Snapshot);
+    this->Projects[d.ProjectIndex].DirectoryIndexes.append(directoryIndex);
+  }
+
+  // Update directories in reverse order to process children before parents.
+  for (auto di = this->Directories.rbegin(); di != this->Directories.rend();
+       ++di) {
+    Directory& d = *di;
+
+    // Accumulate the presence of install rules on the way up.
+    for (auto gen : d.LocalGenerator->GetMakefile()->GetInstallGenerators()) {
+      if (!dynamic_cast<cmInstallSubdirectoryGenerator*>(gen)) {
+        d.HasInstallRule = true;
+        break;
+      }
+    }
+    if (!d.HasInstallRule) {
+      for (cmStateSnapshot const& child : d.Snapshot.GetChildren()) {
+        cmStateSnapshot childDir = child.GetBuildsystemDirectory();
+        Json::ArrayIndex const childIndex = this->GetDirectoryIndex(childDir);
+        if (this->Directories[childIndex].HasInstallRule) {
+          d.HasInstallRule = true;
+          break;
+        }
+      }
+    }
+  }
+}
+
+Json::ArrayIndex CodemodelConfig::GetDirectoryIndex(cmLocalGenerator const* lg)
+{
+  return this->GetDirectoryIndex(
+    lg->GetStateSnapshot().GetBuildsystemDirectory());
+}
+
+Json::ArrayIndex CodemodelConfig::GetDirectoryIndex(cmStateSnapshot s)
+{
+  auto i = this->DirectoryMap.find(s);
+  assert(i != this->DirectoryMap.end());
+  return i->second;
+}
+
+Json::ArrayIndex CodemodelConfig::AddProject(cmStateSnapshot s)
+{
+  cmStateSnapshot ps = s.GetBuildsystemDirectoryParent();
+  if (ps.IsValid() && ps.GetProjectName() == s.GetProjectName()) {
+    // This directory is part of its parent directory project.
+    Json::ArrayIndex const parentDirIndex = this->GetDirectoryIndex(ps);
+    return this->Directories[parentDirIndex].ProjectIndex;
+  }
+
+  // This directory starts a new project.
+  auto projectIndex = static_cast<Json::ArrayIndex>(this->Projects.size());
+  this->Projects.emplace_back();
+  Project& p = this->Projects[projectIndex];
+  p.Snapshot = s;
+  this->ProjectMap[s] = projectIndex;
+  if (ps.IsValid()) {
+    Json::ArrayIndex const parentDirIndex = this->GetDirectoryIndex(ps);
+    p.ParentIndex = this->Directories[parentDirIndex].ProjectIndex;
+    this->Projects[p.ParentIndex].ChildIndexes.append(projectIndex);
+  }
+  return projectIndex;
+}
+
+Json::Value CodemodelConfig::DumpTargets()
+{
+  Json::Value targets = Json::arrayValue;
+
+  std::vector<cmGeneratorTarget*> targetList;
+  cmGlobalGenerator* gg =
+    this->FileAPI.GetCMakeInstance()->GetGlobalGenerator();
+  for (cmLocalGenerator const* lg : gg->GetLocalGenerators()) {
+    std::vector<cmGeneratorTarget*> const& list = lg->GetGeneratorTargets();
+    targetList.insert(targetList.end(), list.begin(), list.end());
+  }
+  std::sort(targetList.begin(), targetList.end(),
+            [](cmGeneratorTarget* l, cmGeneratorTarget* r) {
+              return l->GetName() < r->GetName();
+            });
+
+  for (cmGeneratorTarget* gt : targetList) {
+    if (gt->GetType() == cmStateEnums::GLOBAL_TARGET ||
+        gt->GetType() == cmStateEnums::INTERFACE_LIBRARY) {
+      continue;
+    }
+
+    targets.append(this->DumpTarget(gt, targets.size()));
+  }
+
+  return targets;
+}
+
+Json::Value CodemodelConfig::DumpTarget(cmGeneratorTarget* gt,
+                                        Json::ArrayIndex ti)
+{
+  Target t(gt, this->Config);
+  std::string prefix = "target-" + gt->GetName();
+  if (!this->Config.empty()) {
+    prefix += "-" + this->Config;
+  }
+  Json::Value target = this->FileAPI.MaybeJsonFile(t.Dump(), prefix);
+  target["name"] = gt->GetName();
+  target["id"] = TargetId(gt, this->TopBuild);
+
+  // Cross-reference directory containing target.
+  Json::ArrayIndex di = this->GetDirectoryIndex(gt->GetLocalGenerator());
+  target["directoryIndex"] = di;
+  this->Directories[di].TargetIndexes.append(ti);
+
+  // Cross-reference project containing target.
+  Json::ArrayIndex pi = this->Directories[di].ProjectIndex;
+  target["projectIndex"] = pi;
+  this->Projects[pi].TargetIndexes.append(ti);
+
+  return target;
+}
+
+Json::Value CodemodelConfig::DumpDirectories()
+{
+  Json::Value directories = Json::arrayValue;
+  for (Directory& d : this->Directories) {
+    directories.append(this->DumpDirectory(d));
+  }
+  return directories;
+}
+
+Json::Value CodemodelConfig::DumpDirectory(Directory& d)
+{
+  Json::Value directory = Json::objectValue;
+
+  std::string sourceDir = d.Snapshot.GetDirectory().GetCurrentSource();
+  directory["source"] = RelativeIfUnder(this->TopSource, sourceDir);
+
+  std::string buildDir = d.Snapshot.GetDirectory().GetCurrentBinary();
+  directory["build"] = RelativeIfUnder(this->TopBuild, buildDir);
+
+  cmStateSnapshot parentDir = d.Snapshot.GetBuildsystemDirectoryParent();
+  if (parentDir.IsValid()) {
+    directory["parentIndex"] = this->GetDirectoryIndex(parentDir);
+  }
+
+  Json::Value childIndexes = Json::arrayValue;
+  for (cmStateSnapshot const& child : d.Snapshot.GetChildren()) {
+    childIndexes.append(
+      this->GetDirectoryIndex(child.GetBuildsystemDirectory()));
+  }
+  if (!childIndexes.empty()) {
+    directory["childIndexes"] = std::move(childIndexes);
+  }
+
+  directory["projectIndex"] = d.ProjectIndex;
+
+  if (!d.TargetIndexes.empty()) {
+    directory["targetIndexes"] = std::move(d.TargetIndexes);
+  }
+
+  Json::Value minimumCMakeVersion = this->DumpMinimumCMakeVersion(d.Snapshot);
+  if (!minimumCMakeVersion.isNull()) {
+    directory["minimumCMakeVersion"] = std::move(minimumCMakeVersion);
+  }
+
+  if (d.HasInstallRule) {
+    directory["hasInstallRule"] = true;
+  }
+
+  return directory;
+}
+
+Json::Value CodemodelConfig::DumpProjects()
+{
+  Json::Value projects = Json::arrayValue;
+  for (Project& p : this->Projects) {
+    projects.append(this->DumpProject(p));
+  }
+  return projects;
+}
+
+Json::Value CodemodelConfig::DumpProject(Project& p)
+{
+  Json::Value project = Json::objectValue;
+
+  project["name"] = p.Snapshot.GetProjectName();
+
+  if (p.ParentIndex != Project::NoParentIndex) {
+    project["parentIndex"] = p.ParentIndex;
+  }
+
+  if (!p.ChildIndexes.empty()) {
+    project["childIndexes"] = std::move(p.ChildIndexes);
+  }
+
+  project["directoryIndexes"] = std::move(p.DirectoryIndexes);
+
+  if (!p.TargetIndexes.empty()) {
+    project["targetIndexes"] = std::move(p.TargetIndexes);
+  }
+
+  return project;
+}
+
+Json::Value CodemodelConfig::DumpMinimumCMakeVersion(cmStateSnapshot s)
+{
+  Json::Value minimumCMakeVersion;
+  if (std::string const* def =
+        s.GetDefinition("CMAKE_MINIMUM_REQUIRED_VERSION")) {
+    minimumCMakeVersion = Json::objectValue;
+    minimumCMakeVersion["string"] = *def;
+  }
+  return minimumCMakeVersion;
+}
+
+Target::Target(cmGeneratorTarget* gt, std::string const& config)
+  : GT(gt)
+  , Config(config)
+  , TopSource(gt->GetGlobalGenerator()->GetCMakeInstance()->GetHomeDirectory())
+  , TopBuild(
+      gt->GetGlobalGenerator()->GetCMakeInstance()->GetHomeOutputDirectory())
+  , SourceGroupsLocal(this->GT->Makefile->GetSourceGroups())
+  , Backtraces(this->TopSource)
+{
+}
+
+Json::Value Target::Dump()
+{
+  Json::Value target = Json::objectValue;
+
+  cmStateEnums::TargetType const type = this->GT->GetType();
+
+  target["name"] = this->GT->GetName();
+  target["type"] = cmState::GetTargetTypeName(type);
+  target["id"] = TargetId(this->GT, this->TopBuild);
+  target["paths"] = this->DumpPaths();
+  if (this->GT->Target->GetIsGeneratorProvided()) {
+    target["isGeneratorProvided"] = true;
+  }
+
+  this->AddBacktrace(target, this->GT->GetBacktrace());
+
+  if (this->GT->Target->GetHaveInstallRule()) {
+    target["install"] = this->DumpInstall();
+  }
+
+  if (this->GT->HaveWellDefinedOutputFiles()) {
+    Json::Value artifacts = this->DumpArtifacts();
+    if (!artifacts.empty()) {
+      target["artifacts"] = std::move(artifacts);
+    }
+  }
+
+  if (type == cmStateEnums::EXECUTABLE ||
+      type == cmStateEnums::SHARED_LIBRARY ||
+      type == cmStateEnums::MODULE_LIBRARY) {
+    target["nameOnDisk"] = this->GT->GetFullName(this->Config);
+    target["link"] = this->DumpLink();
+  } else if (type == cmStateEnums::STATIC_LIBRARY) {
+    target["nameOnDisk"] = this->GT->GetFullName(this->Config);
+    target["archive"] = this->DumpArchive();
+  }
+
+  Json::Value dependencies = this->DumpDependencies();
+  if (!dependencies.empty()) {
+    target["dependencies"] = dependencies;
+  }
+
+  {
+    this->ProcessLanguages();
+
+    target["sources"] = this->DumpSources();
+
+    Json::Value folder = this->DumpFolder();
+    if (!folder.isNull()) {
+      target["folder"] = std::move(folder);
+    }
+
+    Json::Value sourceGroups = this->DumpSourceGroups();
+    if (!sourceGroups.empty()) {
+      target["sourceGroups"] = std::move(sourceGroups);
+    }
+
+    Json::Value compileGroups = this->DumpCompileGroups();
+    if (!compileGroups.empty()) {
+      target["compileGroups"] = std::move(compileGroups);
+    }
+  }
+
+  target["backtraceGraph"] = this->Backtraces.Dump();
+
+  return target;
+}
+
+void Target::ProcessLanguages()
+{
+  std::set<std::string> languages;
+  this->GT->GetLanguages(languages, this->Config);
+  for (std::string const& lang : languages) {
+    this->ProcessLanguage(lang);
+  }
+}
+
+void Target::ProcessLanguage(std::string const& lang)
+{
+  CompileData& cd = this->CompileDataMap[lang];
+  cd.Language = lang;
+  if (const char* sysrootCompile =
+        this->GT->Makefile->GetDefinition("CMAKE_SYSROOT_COMPILE")) {
+    cd.Sysroot = sysrootCompile;
+  } else if (const char* sysroot =
+               this->GT->Makefile->GetDefinition("CMAKE_SYSROOT")) {
+    cd.Sysroot = sysroot;
+  }
+  cmLocalGenerator* lg = this->GT->GetLocalGenerator();
+  {
+    // FIXME: Add flags from end section of ExpandRuleVariable,
+    // which may need to be factored out.
+    std::string flags;
+    lg->GetTargetCompileFlags(this->GT, this->Config, lang, flags);
+    cd.Flags.emplace_back(std::move(flags), cmListFileBacktrace());
+  }
+  std::set<BT<std::string>> defines =
+    lg->GetTargetDefines(this->GT, this->Config, lang);
+  cd.SetDefines(defines);
+  std::vector<BT<std::string>> includePathList =
+    lg->GetIncludeDirectories(this->GT, lang, this->Config, true);
+  for (BT<std::string> const& i : includePathList) {
+    cd.Includes.emplace_back(
+      i, this->GT->IsSystemIncludeDirectory(i.Value, this->Config, lang));
+  }
+}
+
+Json::ArrayIndex Target::AddSourceGroup(cmSourceGroup* sg, Json::ArrayIndex si)
+{
+  std::unordered_map<cmSourceGroup const*, Json::ArrayIndex>::iterator i =
+    this->SourceGroupsMap.find(sg);
+  if (i == this->SourceGroupsMap.end()) {
+    auto sgIndex = static_cast<Json::ArrayIndex>(this->SourceGroups.size());
+    i = this->SourceGroupsMap.emplace(sg, sgIndex).first;
+    SourceGroup g;
+    g.Name = sg->GetFullName();
+    this->SourceGroups.push_back(std::move(g));
+  }
+  this->SourceGroups[i->second].SourceIndexes.append(si);
+  return i->second;
+}
+
+CompileData Target::BuildCompileData(cmSourceFile* sf)
+{
+  CompileData fd;
+
+  fd.Language = sf->GetLanguage();
+  if (fd.Language.empty()) {
+    return fd;
+  }
+  CompileData const& cd = this->CompileDataMap.at(fd.Language);
+
+  fd.Sysroot = cd.Sysroot;
+
+  cmLocalGenerator* lg = this->GT->GetLocalGenerator();
+  cmGeneratorExpressionInterpreter genexInterpreter(lg, this->Config, this->GT,
+                                                    fd.Language);
+
+  fd.Flags = cd.Flags;
+  const std::string COMPILE_FLAGS("COMPILE_FLAGS");
+  if (const char* cflags = sf->GetProperty(COMPILE_FLAGS)) {
+    std::string flags = genexInterpreter.Evaluate(cflags, COMPILE_FLAGS);
+    fd.Flags.emplace_back(std::move(flags), cmListFileBacktrace());
+  }
+  const std::string COMPILE_OPTIONS("COMPILE_OPTIONS");
+  if (const char* coptions = sf->GetProperty(COMPILE_OPTIONS)) {
+    std::string flags;
+    lg->AppendCompileOptions(
+      flags, genexInterpreter.Evaluate(coptions, COMPILE_OPTIONS));
+    fd.Flags.emplace_back(std::move(flags), cmListFileBacktrace());
+  }
+
+  // Add include directories from source file properties.
+  {
+    std::vector<std::string> includes;
+    const std::string INCLUDE_DIRECTORIES("INCLUDE_DIRECTORIES");
+    if (const char* cincludes = sf->GetProperty(INCLUDE_DIRECTORIES)) {
+      const std::string& evaluatedIncludes =
+        genexInterpreter.Evaluate(cincludes, INCLUDE_DIRECTORIES);
+      lg->AppendIncludeDirectories(includes, evaluatedIncludes, *sf);
+
+      for (std::string const& include : includes) {
+        bool const isSystemInclude = this->GT->IsSystemIncludeDirectory(
+          include, this->Config, fd.Language);
+        fd.Includes.emplace_back(include, isSystemInclude);
+      }
+    }
+  }
+  fd.Includes.insert(fd.Includes.end(), cd.Includes.begin(),
+                     cd.Includes.end());
+
+  const std::string COMPILE_DEFINITIONS("COMPILE_DEFINITIONS");
+  std::set<std::string> fileDefines;
+  if (const char* defs = sf->GetProperty(COMPILE_DEFINITIONS)) {
+    lg->AppendDefines(fileDefines,
+                      genexInterpreter.Evaluate(defs, COMPILE_DEFINITIONS));
+  }
+
+  const std::string defPropName =
+    "COMPILE_DEFINITIONS_" + cmSystemTools::UpperCase(this->Config);
+  if (const char* config_defs = sf->GetProperty(defPropName)) {
+    lg->AppendDefines(
+      fileDefines,
+      genexInterpreter.Evaluate(config_defs, COMPILE_DEFINITIONS));
+  }
+
+  std::set<BT<std::string>> defines;
+  defines.insert(fileDefines.begin(), fileDefines.end());
+  defines.insert(cd.Defines.begin(), cd.Defines.end());
+
+  fd.SetDefines(defines);
+
+  return fd;
+}
+
+Json::ArrayIndex Target::AddSourceCompileGroup(cmSourceFile* sf,
+                                               Json::ArrayIndex si)
+{
+  Json::Value compileDataJson =
+    this->DumpCompileData(this->BuildCompileData(sf));
+  std::map<Json::Value, Json::ArrayIndex>::iterator i =
+    this->CompileGroupMap.find(compileDataJson);
+  if (i == this->CompileGroupMap.end()) {
+    Json::ArrayIndex cgIndex =
+      static_cast<Json::ArrayIndex>(this->CompileGroups.size());
+    i =
+      this->CompileGroupMap.emplace(std::move(compileDataJson), cgIndex).first;
+    CompileGroup g;
+    g.Entry = i;
+    this->CompileGroups.push_back(std::move(g));
+  }
+  this->CompileGroups[i->second].SourceIndexes.append(si);
+  return i->second;
+}
+
+void Target::AddBacktrace(Json::Value& object, cmListFileBacktrace const& bt)
+{
+  Json::ArrayIndex backtrace;
+  if (this->Backtraces.Add(bt, backtrace)) {
+    object["backtrace"] = backtrace;
+  }
+}
+
+Json::Value Target::DumpPaths()
+{
+  Json::Value paths = Json::objectValue;
+  cmLocalGenerator* lg = this->GT->GetLocalGenerator();
+
+  std::string const& sourceDir = lg->GetCurrentSourceDirectory();
+  paths["source"] = RelativeIfUnder(this->TopSource, sourceDir);
+
+  std::string const& buildDir = lg->GetCurrentBinaryDirectory();
+  paths["build"] = RelativeIfUnder(this->TopBuild, buildDir);
+
+  return paths;
+}
+
+Json::Value Target::DumpSources()
+{
+  Json::Value sources = Json::arrayValue;
+  cmGeneratorTarget::KindedSources const& kinded =
+    this->GT->GetKindedSources(this->Config);
+  for (cmGeneratorTarget::SourceAndKind const& sk : kinded.Sources) {
+    sources.append(this->DumpSource(sk, sources.size()));
+  }
+  return sources;
+}
+
+Json::Value Target::DumpSource(cmGeneratorTarget::SourceAndKind const& sk,
+                               Json::ArrayIndex si)
+{
+  Json::Value source = Json::objectValue;
+
+  std::string const path = sk.Source.Value->GetFullPath();
+  source["path"] = RelativeIfUnder(this->TopSource, path);
+  if (sk.Source.Value->GetPropertyAsBool("GENERATED")) {
+    source["isGenerated"] = true;
+  }
+  this->AddBacktrace(source, sk.Source.Backtrace);
+
+  if (cmSourceGroup* sg =
+        this->GT->Makefile->FindSourceGroup(path, this->SourceGroupsLocal)) {
+    source["sourceGroupIndex"] = this->AddSourceGroup(sg, si);
+  }
+
+  switch (sk.Kind) {
+    case cmGeneratorTarget::SourceKindObjectSource: {
+      source["compileGroupIndex"] =
+        this->AddSourceCompileGroup(sk.Source.Value, si);
+    } break;
+    case cmGeneratorTarget::SourceKindAppManifest:
+    case cmGeneratorTarget::SourceKindCertificate:
+    case cmGeneratorTarget::SourceKindCustomCommand:
+    case cmGeneratorTarget::SourceKindExternalObject:
+    case cmGeneratorTarget::SourceKindExtra:
+    case cmGeneratorTarget::SourceKindHeader:
+    case cmGeneratorTarget::SourceKindIDL:
+    case cmGeneratorTarget::SourceKindManifest:
+    case cmGeneratorTarget::SourceKindModuleDefinition:
+    case cmGeneratorTarget::SourceKindResx:
+    case cmGeneratorTarget::SourceKindXaml:
+      break;
+  }
+
+  return source;
+}
+
+Json::Value Target::DumpCompileData(CompileData cd)
+{
+  Json::Value result = Json::objectValue;
+
+  if (!cd.Language.empty()) {
+    result["language"] = cd.Language;
+  }
+  if (!cd.Sysroot.empty()) {
+    result["sysroot"] = this->DumpSysroot(cd.Sysroot);
+  }
+  if (!cd.Flags.empty()) {
+    result["compileCommandFragments"] = this->DumpCommandFragments(cd.Flags);
+  }
+  if (!cd.Includes.empty()) {
+    Json::Value includes = Json::arrayValue;
+    for (auto const& i : cd.Includes) {
+      includes.append(this->DumpInclude(i));
+    }
+    result["includes"] = includes;
+  }
+  if (!cd.Defines.empty()) {
+    Json::Value defines = Json::arrayValue;
+    for (BT<std::string> const& d : cd.Defines) {
+      defines.append(this->DumpDefine(d));
+    }
+    result["defines"] = std::move(defines);
+  }
+
+  return result;
+}
+
+Json::Value Target::DumpInclude(CompileData::IncludeEntry const& inc)
+{
+  Json::Value include = Json::objectValue;
+  include["path"] = inc.Path.Value;
+  if (inc.IsSystem) {
+    include["isSystem"] = true;
+  }
+  this->AddBacktrace(include, inc.Path.Backtrace);
+  return include;
+}
+
+Json::Value Target::DumpDefine(BT<std::string> const& def)
+{
+  Json::Value define = Json::objectValue;
+  define["define"] = def.Value;
+  this->AddBacktrace(define, def.Backtrace);
+  return define;
+}
+
+Json::Value Target::DumpSourceGroups()
+{
+  Json::Value sourceGroups = Json::arrayValue;
+  for (auto& sg : this->SourceGroups) {
+    sourceGroups.append(this->DumpSourceGroup(sg));
+  }
+  return sourceGroups;
+}
+
+Json::Value Target::DumpSourceGroup(SourceGroup& sg)
+{
+  Json::Value group = Json::objectValue;
+  group["name"] = sg.Name;
+  group["sourceIndexes"] = std::move(sg.SourceIndexes);
+  return group;
+}
+
+Json::Value Target::DumpCompileGroups()
+{
+  Json::Value compileGroups = Json::arrayValue;
+  for (auto& cg : this->CompileGroups) {
+    compileGroups.append(this->DumpCompileGroup(cg));
+  }
+  return compileGroups;
+}
+
+Json::Value Target::DumpCompileGroup(CompileGroup& cg)
+{
+  Json::Value group = cg.Entry->first;
+  group["sourceIndexes"] = std::move(cg.SourceIndexes);
+  return group;
+}
+
+Json::Value Target::DumpSysroot(std::string const& path)
+{
+  Json::Value sysroot = Json::objectValue;
+  sysroot["path"] = path;
+  return sysroot;
+}
+
+Json::Value Target::DumpInstall()
+{
+  Json::Value install = Json::objectValue;
+  install["prefix"] = this->DumpInstallPrefix();
+  install["destinations"] = this->DumpInstallDestinations();
+  return install;
+}
+
+Json::Value Target::DumpInstallPrefix()
+{
+  Json::Value prefix = Json::objectValue;
+  std::string p =
+    this->GT->Makefile->GetSafeDefinition("CMAKE_INSTALL_PREFIX");
+  cmSystemTools::ConvertToUnixSlashes(p);
+  prefix["path"] = p;
+  return prefix;
+}
+
+Json::Value Target::DumpInstallDestinations()
+{
+  Json::Value destinations = Json::arrayValue;
+  auto installGens = this->GT->Makefile->GetInstallGenerators();
+  for (auto iGen : installGens) {
+    auto itGen = dynamic_cast<cmInstallTargetGenerator*>(iGen);
+    if (itGen != nullptr && itGen->GetTarget() == this->GT) {
+      destinations.append(this->DumpInstallDestination(itGen));
+    }
+  }
+  return destinations;
+}
+
+Json::Value Target::DumpInstallDestination(cmInstallTargetGenerator* itGen)
+{
+  Json::Value destination = Json::objectValue;
+  destination["path"] = itGen->GetDestination(this->Config);
+  this->AddBacktrace(destination, itGen->GetBacktrace());
+  return destination;
+}
+
+Json::Value Target::DumpArtifacts()
+{
+  Json::Value artifacts = Json::arrayValue;
+
+  // Object libraries have only object files as artifacts.
+  if (this->GT->GetType() == cmStateEnums::OBJECT_LIBRARY) {
+    if (!this->GT->GetGlobalGenerator()->HasKnownObjectFileLocation(nullptr)) {
+      return artifacts;
+    }
+    std::vector<cmSourceFile const*> objectSources;
+    this->GT->GetObjectSources(objectSources, this->Config);
+    std::string const obj_dir = this->GT->GetObjectDirectory(this->Config);
+    for (cmSourceFile const* sf : objectSources) {
+      const std::string& obj = this->GT->GetObjectName(sf);
+      Json::Value artifact = Json::objectValue;
+      artifact["path"] = RelativeIfUnder(this->TopBuild, obj_dir + obj);
+      artifacts.append(std::move(artifact)); // NOLINT(*)
+    }
+    return artifacts;
+  }
+
+  // Other target types always have a "main" artifact.
+  {
+    Json::Value artifact = Json::objectValue;
+    artifact["path"] =
+      RelativeIfUnder(this->TopBuild,
+                      this->GT->GetFullPath(
+                        this->Config, cmStateEnums::RuntimeBinaryArtifact));
+    artifacts.append(std::move(artifact)); // NOLINT(*)
+  }
+
+  // Add Windows-specific artifacts produced by the linker.
+  if (this->GT->IsDLLPlatform() &&
+      this->GT->GetType() != cmStateEnums::STATIC_LIBRARY) {
+    if (this->GT->GetType() == cmStateEnums::SHARED_LIBRARY ||
+        this->GT->IsExecutableWithExports()) {
+      Json::Value artifact = Json::objectValue;
+      artifact["path"] =
+        RelativeIfUnder(this->TopBuild,
+                        this->GT->GetFullPath(
+                          this->Config, cmStateEnums::ImportLibraryArtifact));
+      artifacts.append(std::move(artifact)); // NOLINT(*)
+    }
+    cmGeneratorTarget::OutputInfo const* output =
+      this->GT->GetOutputInfo(this->Config);
+    if (output && !output->PdbDir.empty()) {
+      Json::Value artifact = Json::objectValue;
+      artifact["path"] = RelativeIfUnder(this->TopBuild,
+                                         output->PdbDir + '/' +
+                                           this->GT->GetPDBName(this->Config));
+      artifacts.append(std::move(artifact)); // NOLINT(*)
+    }
+  }
+  return artifacts;
+}
+
+Json::Value Target::DumpLink()
+{
+  Json::Value link = Json::objectValue;
+  std::string lang = this->GT->GetLinkerLanguage(this->Config);
+  link["language"] = lang;
+  {
+    Json::Value commandFragments = this->DumpLinkCommandFragments();
+    if (!commandFragments.empty()) {
+      link["commandFragments"] = std::move(commandFragments);
+    }
+  }
+  if (const char* sysrootLink =
+        this->GT->Makefile->GetDefinition("CMAKE_SYSROOT_LINK")) {
+    link["sysroot"] = this->DumpSysroot(sysrootLink);
+  } else if (const char* sysroot =
+               this->GT->Makefile->GetDefinition("CMAKE_SYSROOT")) {
+    link["sysroot"] = this->DumpSysroot(sysroot);
+  }
+  if (this->GT->IsIPOEnabled(lang, this->Config)) {
+    link["lto"] = true;
+  }
+  return link;
+}
+
+Json::Value Target::DumpArchive()
+{
+  Json::Value archive = Json::objectValue;
+  {
+    // The "link" fragments not relevant to static libraries are empty.
+    Json::Value commandFragments = this->DumpLinkCommandFragments();
+    if (!commandFragments.empty()) {
+      archive["commandFragments"] = std::move(commandFragments);
+    }
+  }
+  std::string lang = this->GT->GetLinkerLanguage(this->Config);
+  if (this->GT->IsIPOEnabled(lang, this->Config)) {
+    archive["lto"] = true;
+  }
+  return archive;
+}
+
+Json::Value Target::DumpLinkCommandFragments()
+{
+  Json::Value linkFragments = Json::arrayValue;
+
+  std::string linkLanguageFlags;
+  std::string linkFlags;
+  std::string frameworkPath;
+  std::string linkPath;
+  std::string linkLibs;
+  cmLocalGenerator* lg = this->GT->GetLocalGenerator();
+  cmLinkLineComputer linkLineComputer(lg,
+                                      lg->GetStateSnapshot().GetDirectory());
+  lg->GetTargetFlags(&linkLineComputer, this->Config, linkLibs,
+                     linkLanguageFlags, linkFlags, frameworkPath, linkPath,
+                     this->GT);
+  linkLanguageFlags = cmSystemTools::TrimWhitespace(linkLanguageFlags);
+  linkFlags = cmSystemTools::TrimWhitespace(linkFlags);
+  frameworkPath = cmSystemTools::TrimWhitespace(frameworkPath);
+  linkPath = cmSystemTools::TrimWhitespace(linkPath);
+  linkLibs = cmSystemTools::TrimWhitespace(linkLibs);
+
+  if (!linkLanguageFlags.empty()) {
+    linkFragments.append(
+      this->DumpCommandFragment(std::move(linkLanguageFlags), "flags"));
+  }
+
+  if (!linkFlags.empty()) {
+    linkFragments.append(
+      this->DumpCommandFragment(std::move(linkFlags), "flags"));
+  }
+
+  if (!frameworkPath.empty()) {
+    linkFragments.append(
+      this->DumpCommandFragment(std::move(frameworkPath), "frameworkPath"));
+  }
+
+  if (!linkPath.empty()) {
+    linkFragments.append(
+      this->DumpCommandFragment(std::move(linkPath), "libraryPath"));
+  }
+
+  if (!linkLibs.empty()) {
+    linkFragments.append(
+      this->DumpCommandFragment(std::move(linkLibs), "libraries"));
+  }
+
+  return linkFragments;
+}
+
+Json::Value Target::DumpCommandFragments(
+  std::vector<BT<std::string>> const& frags)
+{
+  Json::Value commandFragments = Json::arrayValue;
+  for (BT<std::string> const& f : frags) {
+    commandFragments.append(this->DumpCommandFragment(f));
+  }
+  return commandFragments;
+}
+
+Json::Value Target::DumpCommandFragment(BT<std::string> const& frag,
+                                        std::string const& role)
+{
+  Json::Value fragment = Json::objectValue;
+  fragment["fragment"] = frag.Value;
+  if (!role.empty()) {
+    fragment["role"] = role;
+  }
+  this->AddBacktrace(fragment, frag.Backtrace);
+  return fragment;
+}
+
+Json::Value Target::DumpDependencies()
+{
+  Json::Value dependencies = Json::arrayValue;
+  cmGlobalGenerator* gg = this->GT->GetGlobalGenerator();
+  for (cmTargetDepend const& td : gg->GetTargetDirectDepends(this->GT)) {
+    dependencies.append(this->DumpDependency(td));
+  }
+  return dependencies;
+}
+
+Json::Value Target::DumpDependency(cmTargetDepend const& td)
+{
+  Json::Value dependency = Json::objectValue;
+  dependency["id"] = TargetId(td, this->TopBuild);
+  this->AddBacktrace(dependency, td.GetBacktrace());
+  return dependency;
+}
+
+Json::Value Target::DumpFolder()
+{
+  Json::Value folder;
+  if (const char* f = this->GT->GetProperty("FOLDER")) {
+    folder = Json::objectValue;
+    folder["name"] = f;
+  }
+  return folder;
+}
+}
+
+Json::Value cmFileAPICodemodelDump(cmFileAPI& fileAPI, unsigned long version)
+{
+  Codemodel codemodel(fileAPI, version);
+  return codemodel.Dump();
+}
diff --git a/Source/cmFileAPICodemodel.h b/Source/cmFileAPICodemodel.h
new file mode 100644
index 0000000..ffbd928
--- /dev/null
+++ b/Source/cmFileAPICodemodel.h
@@ -0,0 +1,15 @@
+/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+   file Copyright.txt or https://cmake.org/licensing for details.  */
+#ifndef cmFileAPICodemodel_h
+#define cmFileAPICodemodel_h
+
+#include "cmConfigure.h" // IWYU pragma: keep
+
+#include "cm_jsoncpp_value.h"
+
+class cmFileAPI;
+
+extern Json::Value cmFileAPICodemodelDump(cmFileAPI& fileAPI,
+                                          unsigned long version);
+
+#endif
diff --git a/Source/cmGlobalGenerator.cxx b/Source/cmGlobalGenerator.cxx
index 8b20db6..35d716c 100644
--- a/Source/cmGlobalGenerator.cxx
+++ b/Source/cmGlobalGenerator.cxx
@@ -112,6 +112,15 @@ cmGlobalGenerator::~cmGlobalGenerator()
   delete this->ExtraGenerator;
 }
 
+#if defined(CMAKE_BUILD_WITH_CMAKE)
+Json::Value cmGlobalGenerator::GetJson() const
+{
+  Json::Value generator = Json::objectValue;
+  generator["name"] = this->GetName();
+  return generator;
+}
+#endif
+
 bool cmGlobalGenerator::SetGeneratorInstance(std::string const& i,
                                              cmMakefile* mf)
 {
diff --git a/Source/cmGlobalGenerator.h b/Source/cmGlobalGenerator.h
index 1ea2d24..4e6b6de 100644
--- a/Source/cmGlobalGenerator.h
+++ b/Source/cmGlobalGenerator.h
@@ -24,6 +24,7 @@
 
 #if defined(CMAKE_BUILD_WITH_CMAKE)
 #  include "cmFileLockPool.h"
+#  include "cm_jsoncpp_value.h"
 #endif
 
 #define CMAKE_DIRECTORY_ID_SEP "::@"
@@ -70,6 +71,11 @@ public:
     return codecvt::None;
   }
 
+#if defined(CMAKE_BUILD_WITH_CMAKE)
+  /** Get a JSON object describing the generator.  */
+  virtual Json::Value GetJson() const;
+#endif
+
   /** Tell the generator about the target system.  */
   virtual bool SetSystemName(std::string const&, cmMakefile*) { return true; }
 
diff --git a/Source/cmGlobalVisualStudio7Generator.cxx b/Source/cmGlobalVisualStudio7Generator.cxx
index 0b6c149..3648086 100644
--- a/Source/cmGlobalVisualStudio7Generator.cxx
+++ b/Source/cmGlobalVisualStudio7Generator.cxx
@@ -254,6 +254,15 @@ cmLocalGenerator* cmGlobalVisualStudio7Generator::CreateLocalGenerator(
   return lg;
 }
 
+#if defined(CMAKE_BUILD_WITH_CMAKE)
+Json::Value cmGlobalVisualStudio7Generator::GetJson() const
+{
+  Json::Value generator = this->cmGlobalVisualStudioGenerator::GetJson();
+  generator["platform"] = this->GetPlatformName();
+  return generator;
+}
+#endif
+
 std::string const& cmGlobalVisualStudio7Generator::GetPlatformName() const
 {
   if (!this->GeneratorPlatform.empty()) {
diff --git a/Source/cmGlobalVisualStudio7Generator.h b/Source/cmGlobalVisualStudio7Generator.h
index 251478d..59e7a98 100644
--- a/Source/cmGlobalVisualStudio7Generator.h
+++ b/Source/cmGlobalVisualStudio7Generator.h
@@ -28,6 +28,10 @@ public:
   ///! Create a local generator appropriate to this Global Generator
   cmLocalGenerator* CreateLocalGenerator(cmMakefile* mf) override;
 
+#if defined(CMAKE_BUILD_WITH_CMAKE)
+  Json::Value GetJson() const override;
+#endif
+
   bool SetSystemName(std::string const& s, cmMakefile* mf) override;
 
   bool SetGeneratorPlatform(std::string const& p, cmMakefile* mf) override;
diff --git a/Source/cmStateSnapshot.cxx b/Source/cmStateSnapshot.cxx
index c2510f3..a649f5e 100644
--- a/Source/cmStateSnapshot.cxx
+++ b/Source/cmStateSnapshot.cxx
@@ -66,6 +66,12 @@ bool cmStateSnapshot::IsValid() const
     : false;
 }
 
+cmStateSnapshot cmStateSnapshot::GetBuildsystemDirectory() const
+{
+  return cmStateSnapshot(this->State,
+                         this->Position->BuildSystemDirectory->DirectoryEnd);
+}
+
 cmStateSnapshot cmStateSnapshot::GetBuildsystemDirectoryParent() const
 {
   cmStateSnapshot snapshot;
diff --git a/Source/cmStateSnapshot.h b/Source/cmStateSnapshot.h
index 014c62e..c315f48 100644
--- a/Source/cmStateSnapshot.h
+++ b/Source/cmStateSnapshot.h
@@ -37,6 +37,7 @@ public:
   std::vector<cmStateSnapshot> GetChildren();
 
   bool IsValid() const;
+  cmStateSnapshot GetBuildsystemDirectory() const;
   cmStateSnapshot GetBuildsystemDirectoryParent() const;
   cmStateSnapshot GetCallStackParent() const;
   cmStateSnapshot GetCallStackBottom() const;
diff --git a/Source/cmString.cxx b/Source/cmString.cxx
new file mode 100644
index 0000000..2a0c125
--- /dev/null
+++ b/Source/cmString.cxx
@@ -0,0 +1,152 @@
+/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+   file Copyright.txt or https://cmake.org/licensing for details.  */
+#define _SCL_SECURE_NO_WARNINGS
+
+#include "cmString.hxx"
+
+#include <memory>
+#include <ostream>
+#include <stdexcept>
+#include <string>
+#include <type_traits>
+
+namespace cm {
+
+static std::string const empty_string_;
+
+void String::internally_mutate_to_stable_string()
+{
+  // We assume that only one thread mutates this instance at
+  // a time even if we point to a shared string buffer refernced
+  // by other threads.
+  *this = String(data(), size());
+}
+
+bool String::is_stable() const
+{
+  return str_if_stable() != nullptr;
+}
+
+void String::stabilize()
+{
+  if (is_stable()) {
+    return;
+  }
+  this->internally_mutate_to_stable_string();
+}
+
+std::string const* String::str_if_stable() const
+{
+  if (!data()) {
+    // We view no string.
+    // This is stable for the lifetime of our current value.
+    return &empty_string_;
+  }
+
+  if (string_ && data() == string_->data() && size() == string_->size()) {
+    // We view an entire string.
+    // This is stable for the lifetime of our current value.
+    return string_.get();
+  }
+
+  return nullptr;
+}
+
+std::string const& String::str()
+{
+  if (std::string const* s = str_if_stable()) {
+    return *s;
+  }
+  // Mutate to hold a std::string that is stable for the lifetime
+  // of our current value.
+  this->internally_mutate_to_stable_string();
+  return *string_;
+}
+
+const char* String::c_str()
+{
+  const char* c = data();
+  if (c == nullptr) {
+    return c;
+  }
+
+  // We always point into a null-terminated string so it is safe to
+  // access one past the end.  If it is a null byte then we can use
+  // the pointer directly.
+  if (c[size()] == '\0') {
+    return c;
+  }
+
+  // Mutate to hold a std::string so we can get a null terminator.
+  this->internally_mutate_to_stable_string();
+  c = string_->c_str();
+  return c;
+}
+
+String& String::insert(size_type index, size_type count, char ch)
+{
+  std::string s;
+  s.reserve(size() + count);
+  s.assign(data(), size());
+  s.insert(index, count, ch);
+  return *this = std::move(s);
+}
+
+String& String::erase(size_type index, size_type count)
+{
+  if (index > size()) {
+    throw std::out_of_range("Index out of range in String::erase");
+  }
+  size_type const rcount = std::min(count, size() - index);
+  size_type const rindex = index + rcount;
+  std::string s;
+  s.reserve(size() - rcount);
+  s.assign(data(), index);
+  s.append(data() + rindex, size() - rindex);
+  return *this = std::move(s);
+}
+
+String String::substr(size_type pos, size_type count) const
+{
+  if (pos > size()) {
+    throw std::out_of_range("Index out of range in String::substr");
+  }
+  return String(*this, pos, count);
+}
+
+String::String(std::string&& s, Private)
+  : string_(std::make_shared<std::string>(std::move(s)))
+  , view_(string_->data(), string_->size())
+{
+}
+
+String::size_type String::copy(char* dest, size_type count,
+                               size_type pos) const
+{
+  return view_.copy(dest, count, pos);
+}
+
+std::ostream& operator<<(std::ostream& os, String const& s)
+{
+  return os.write(s.data(), s.size());
+}
+
+std::string& operator+=(std::string& self, String const& s)
+{
+  return self += s.view();
+}
+
+String IntoString<char*>::into_string(const char* s)
+{
+  if (!s) {
+    return String();
+  }
+  return std::string(s);
+}
+
+string_view AsStringView<String>::view(String const& s)
+{
+  return s.view();
+}
+
+} // namespace cm
diff --git a/Source/cmString.hxx b/Source/cmString.hxx
new file mode 100644
index 0000000..1623a43
--- /dev/null
+++ b/Source/cmString.hxx
@@ -0,0 +1,815 @@
+/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+   file Copyright.txt or https://cmake.org/licensing for details.  */
+#ifndef cmString_hxx
+#define cmString_hxx
+
+#include "cmConfigure.h" // IWYU pragma: keep
+
+#include "cm_static_string_view.hxx"
+#include "cm_string_view.hxx"
+
+#include <algorithm>
+#include <functional>
+#include <initializer_list>
+#include <memory>
+#include <ostream>
+#include <string>
+#include <type_traits>
+
+namespace cm {
+
+class String;
+
+/**
+ * Trait to convert type T into a String.
+ * Implementations must derive from 'std::true_type'
+ * and define an 'into_string' member that accepts
+ * type T (by value or reference) and returns one of:
+ *
+ * - 'std::string' to construct an owned instance.
+ * - 'cm::string_view' to construct a borrowed or null instances.
+ *   The buffer from which the view is borrowed must outlive
+ *   all copies of the resulting String, e.g. static storage.
+ * - 'cm::String' for already-constructed instances.
+ */
+template <typename T>
+struct IntoString : std::false_type
+{
+};
+
+template <typename T>
+struct IntoString<T&> : IntoString<T>
+{
+};
+
+template <typename T>
+struct IntoString<T const> : IntoString<T>
+{
+};
+
+template <typename T>
+struct IntoString<T const*> : IntoString<T*>
+{
+};
+
+template <typename T, std::string::size_type N>
+struct IntoString<T const[N]> : IntoString<T[N]>
+{
+};
+
+template <>
+struct IntoString<char*> : std::true_type
+{
+  static String into_string(const char* s);
+};
+
+template <>
+struct IntoString<std::nullptr_t> : std::true_type
+{
+  static string_view into_string(std::nullptr_t) { return string_view(); }
+};
+
+template <std::string::size_type N>
+struct IntoString<char[N]> : std::true_type
+{
+  static std::string into_string(char const (&s)[N])
+  {
+    return std::string(s, N - 1);
+  }
+};
+
+template <>
+struct IntoString<std::string> : std::true_type
+{
+  static std::string into_string(std::string s) { return s; }
+};
+
+template <>
+struct IntoString<string_view> : std::true_type
+{
+  static std::string into_string(string_view s) { return std::string(s); }
+};
+
+template <>
+struct IntoString<static_string_view> : std::true_type
+{
+  static string_view into_string(static_string_view s) { return s; }
+};
+
+template <>
+struct IntoString<char> : std::true_type
+{
+  static std::string into_string(char const& c) { return std::string(1, c); }
+};
+
+/**
+ * Trait to convert type T into a 'cm::string_view'.
+ * Implementations must derive from 'std::true_type' and
+ * define a 'view' member that accepts type T (by reference)
+ * and returns a 'cm::string_view'.
+ */
+template <typename T>
+struct AsStringView : std::false_type
+{
+};
+
+template <typename T>
+struct AsStringView<T&> : AsStringView<T>
+{
+};
+
+template <typename T>
+struct AsStringView<T const> : AsStringView<T>
+{
+};
+
+template <typename T>
+struct AsStringView<T const*> : AsStringView<T*>
+{
+};
+
+template <typename T, std::string::size_type N>
+struct AsStringView<T const[N]> : AsStringView<T[N]>
+{
+};
+
+template <>
+struct AsStringView<char*> : std::true_type
+{
+  static string_view view(const char* s) { return s; }
+};
+
+template <std::string::size_type N>
+struct AsStringView<char[N]> : std::true_type
+{
+  static string_view view(char const (&s)[N]) { return string_view(s, N - 1); }
+};
+
+template <>
+struct AsStringView<std::string> : std::true_type
+{
+  static string_view view(std::string const& s) { return s; }
+};
+
+template <>
+struct AsStringView<char> : std::true_type
+{
+  static string_view view(const char& s) { return string_view(&s, 1); }
+};
+
+template <>
+struct AsStringView<string_view> : std::true_type
+{
+  static string_view view(string_view const& s) { return s; }
+};
+
+template <>
+struct AsStringView<static_string_view> : std::true_type
+{
+  static string_view view(static_string_view const& s) { return s; }
+};
+
+template <>
+struct AsStringView<String> : std::true_type
+{
+  static string_view view(String const& s);
+};
+
+/**
+ * \class String
+ *
+ * A custom string type that holds a view of a string buffer
+ * and optionally shares ownership of the buffer.  Instances
+ * may have one of the following states:
+ *
+ * - null: views and owns nothing.
+ *   Conversion to 'bool' is 'false'.
+ *   'data()' and 'c_str()' return nullptr.
+ *   'size()' returns 0.
+ *   'str()' returns an empty string.
+ *
+ * - borrowed: views a string but does not own it.  This is used
+ *   to bind to static storage (e.g. string literals) or for
+ *   temporary instances that do not outlive the borrowed buffer.
+ *   Copies and substrings still borrow the original buffer.
+ *   Mutation allocates a new internal string and converts to
+ *   the 'owned' state.
+ *   Conversion to 'bool' is 'true'.
+ *   'c_str()' may internally mutate to the 'owned' state.
+ *   'str()' internally mutates to the 'owned' state.
+ *
+ * - owned: views an immutable 'std::string' instance owned internally.
+ *   Copies and substrings share ownership of the internal string.
+ *   Mutation allocates a new internal string.
+ *   Conversion to 'bool' is 'true'.
+ */
+class String
+{
+  enum class Private
+  {
+  };
+
+public:
+  using traits_type = std::string::traits_type;
+  using value_type = string_view::value_type;
+  using pointer = string_view::pointer;
+  using const_pointer = string_view::const_pointer;
+  using reference = string_view::reference;
+  using const_reference = string_view::const_reference;
+  using const_iterator = string_view::const_iterator;
+  using iterator = string_view::const_iterator;
+  using const_reverse_iterator = string_view::const_reverse_iterator;
+  using reverse_iterator = string_view::const_reverse_iterator;
+  using difference_type = string_view::difference_type;
+  using size_type = string_view::size_type;
+
+  static size_type const npos = string_view::npos;
+
+  /** Construct a null string.  */
+  String() = default;
+
+  /** Construct from any type implementing the IntoString trait.  */
+  template <typename T,
+            typename = typename std::enable_if<IntoString<T>::value>::type>
+  String(T&& s)
+    : String(IntoString<T>::into_string(std::forward<T>(s)), Private())
+  {
+  }
+
+  /** Construct via std::string initializer list constructor.  */
+  String(std::initializer_list<char> il)
+    : String(std::string(il))
+  {
+  }
+
+  /** Construct by copying the specified buffer.  */
+  String(const char* d, size_type s)
+    : String(std::string(d, s))
+  {
+  }
+
+  /** Construct by copying from input iterator range.  */
+  template <typename InputIterator>
+  String(InputIterator first, InputIterator last)
+    : String(std::string(first, last))
+  {
+  }
+
+  /** Construct a string with 'n' copies of character 'c'.  */
+  String(size_type n, char c)
+    : String(std::string(n, c))
+  {
+  }
+
+  /** Construct from a substring of another String instance.
+      This shares ownership of the other string's buffer
+      but views only a substring.  */
+  String(String const& s, size_type pos, size_type count = npos)
+    : string_(s.string_)
+    , view_(s.data() + pos, std::min(count, s.size() - pos))
+  {
+  }
+
+  /** Construct by moving from another String instance.
+      The other instance is left as a null string.  */
+  String(String&& s) noexcept
+    : string_(std::move(s.string_))
+    , view_(s.view_)
+  {
+    s.view_ = string_view();
+  }
+
+  /** Construct by copying from another String instance.
+      This shares ownership of the other string's buffer.  */
+  String(String const&) noexcept = default;
+
+  ~String() = default;
+
+  /** Construct by borrowing an externally-owned buffer.  The buffer
+      must outlive the returned instance and all copies of it.  */
+  static String borrow(string_view v) { return String(v, Private()); }
+
+  /** Assign by moving from another String instance.
+      The other instance is left as a null string.  */
+  String& operator=(String&& s) noexcept
+  {
+    string_ = std::move(s.string_);
+    view_ = s.view_;
+    s.view_ = string_view();
+    return *this;
+  }
+
+  /** Assign by copying from another String instance.
+      This shares ownership of the other string's buffer.  */
+  String& operator=(String const&) noexcept = default;
+
+  /** Assign from any type implementing the IntoString trait.  */
+  template <typename T>
+  typename // NOLINT(*)
+    std::enable_if<IntoString<T>::value, String&>::type
+    operator=(T&& s)
+  {
+    *this = String(std::forward<T>(s));
+    return *this;
+  }
+
+  /** Assign via std::string initializer list constructor.  */
+  String& operator=(std::initializer_list<char> il)
+  {
+    *this = String(il);
+    return *this;
+  }
+
+  /** Return true if the instance is not a null string.  */
+  explicit operator bool() const noexcept { return data() != nullptr; }
+
+  /** Return a view of the string.  */
+  string_view view() const noexcept { return view_; }
+
+  /** Return true if the instance is an empty stringn or null string.  */
+  bool empty() const noexcept { return view_.empty(); }
+
+  /** Return a pointer to the start of the string.  */
+  const char* data() const noexcept { return view_.data(); }
+
+  /** Return the length of the string in bytes.  */
+  size_type size() const noexcept { return view_.size(); }
+  size_type length() const noexcept { return view_.length(); }
+
+  /** Return the character at the given position.
+      No bounds checking is performed.  */
+  char operator[](size_type pos) const noexcept { return view_[pos]; }
+
+  /** Return the character at the given position.
+      If the position is out of bounds, throws std::out_of_range.  */
+  char at(size_type pos) const { return view_.at(pos); }
+
+  char front() const noexcept { return view_.front(); }
+
+  char back() const noexcept { return view_.back(); }
+
+  /** Return true if this instance is stable and otherwise false.
+      An instance is stable if it is in the 'null' state or if it is
+      an 'owned' state not produced by substring operations, or
+      after a call to 'stabilize()' or 'str()'.  */
+  bool is_stable() const;
+
+  /** If 'is_stable()' does not return true, mutate so it does.  */
+  void stabilize();
+
+  /** Get a pointer to a normal std::string if 'is_stable()' returns
+      true and otherwise nullptr.  The pointer is valid until this
+      instance is mutated or destroyed.  */
+  std::string const* str_if_stable() const;
+
+  /** Get a refernce to a normal std::string.  The reference
+      is valid until this instance is mutated or destroyed.  */
+  std::string const& str();
+
+  /** Get a pointer to a C-style null-terminated string
+      containing the same value as this instance.  The pointer
+      is valid until this instance is mutated, destroyed,
+      or str() is called.  */
+  const char* c_str();
+
+  const_iterator begin() const noexcept { return view_.begin(); }
+  const_iterator end() const noexcept { return view_.end(); }
+  const_iterator cbegin() const noexcept { return begin(); }
+  const_iterator cend() const noexcept { return end(); }
+
+  const_reverse_iterator rbegin() const noexcept { return view_.rbegin(); }
+  const_reverse_iterator rend() const noexcept { return view_.rend(); }
+  const_reverse_iterator crbegin() const noexcept { return rbegin(); }
+  const_reverse_iterator crend() const noexcept { return rend(); }
+
+  /** Append to the string using any type that implements the
+      AsStringView trait.  */
+  template <typename T>
+  typename std::enable_if<AsStringView<T>::value, String&>::type operator+=(
+    T&& s)
+  {
+    string_view v = AsStringView<T>::view(std::forward<T>(s));
+    std::string r;
+    r.reserve(size() + v.size());
+    r.assign(data(), size());
+    r.append(v.data(), v.size());
+    return *this = std::move(r);
+  }
+
+  /** Assign to an empty string.  */
+  void clear() { *this = ""_s; }
+
+  /** Insert 'count' copies of 'ch' at position 'index'.  */
+  String& insert(size_type index, size_type count, char ch);
+
+  /** Erase 'count' characters starting at position 'index'.  */
+  String& erase(size_type index = 0, size_type count = npos);
+
+  void push_back(char ch)
+  {
+    std::string s;
+    s.reserve(size() + 1);
+    s.assign(data(), size());
+    s.push_back(ch);
+    *this = std::move(s);
+  }
+
+  void pop_back() { *this = String(*this, 0, size() - 1); }
+
+  template <typename T>
+  typename std::enable_if<AsStringView<T>::value, String&>::type replace(
+    size_type pos, size_type count, T&& s)
+  {
+    const_iterator first = begin() + pos;
+    const_iterator last = first + count;
+    return replace(first, last, std::forward<T>(s));
+  }
+
+  template <typename InputIterator>
+  String& replace(const_iterator first, const_iterator last,
+                  InputIterator first2, InputIterator last2)
+  {
+    std::string out;
+    out.append(view_.begin(), first);
+    out.append(first2, last2);
+    out.append(last, view_.end());
+    return *this = std::move(out);
+  }
+
+  template <typename T>
+  typename std::enable_if<AsStringView<T>::value, String&>::type replace(
+    const_iterator first, const_iterator last, T&& s)
+  {
+    string_view v = AsStringView<T>::view(std::forward<T>(s));
+    std::string out;
+    out.reserve((first - view_.begin()) + v.size() + (view_.end() - last));
+    out.append(view_.begin(), first);
+    out.append(v.data(), v.size());
+    out.append(last, view_.end());
+    return *this = std::move(out);
+  }
+
+  template <typename T>
+  typename std::enable_if<AsStringView<T>::value, String&>::type replace(
+    size_type pos, size_type count, T&& s, size_type pos2,
+    size_type count2 = npos)
+  {
+    string_view v = AsStringView<T>::view(std::forward<T>(s));
+    v = v.substr(pos2, count2);
+    return replace(pos, count, v);
+  }
+
+  String& replace(size_type pos, size_type count, size_type count2, char ch)
+  {
+    const_iterator first = begin() + pos;
+    const_iterator last = first + count;
+    return replace(first, last, count2, ch);
+  }
+
+  String& replace(const_iterator first, const_iterator last, size_type count2,
+                  char ch)
+  {
+    std::string out;
+    out.reserve((first - view_.begin()) + count2 + (view_.end() - last));
+    out.append(view_.begin(), first);
+    out.append(count2, ch);
+    out.append(last, view_.end());
+    return *this = std::move(out);
+  }
+
+  size_type copy(char* dest, size_type count, size_type pos = 0) const;
+
+  void resize(size_type count) { resize(count, char()); }
+
+  void resize(size_type count, char ch)
+  {
+    std::string s;
+    s.reserve(count);
+    if (count <= size()) {
+      s.assign(data(), count);
+    } else {
+      s.assign(data(), size());
+      s.resize(count, ch);
+    }
+    *this = std::move(s);
+  }
+
+  void swap(String& other)
+  {
+    std::swap(string_, other.string_);
+    std::swap(view_, other.view_);
+  }
+
+  /** Return a substring starting at position 'pos' and
+      consisting of at most 'count' characters.  */
+  String substr(size_type pos = 0, size_type count = npos) const;
+
+  template <typename T>
+  typename std::enable_if<AsStringView<T>::value, int>::type compare(
+    T&& s) const
+  {
+    return view_.compare(AsStringView<T>::view(std::forward<T>(s)));
+  }
+
+  int compare(size_type pos1, size_type count1, string_view v) const
+  {
+    return view_.compare(pos1, count1, v);
+  }
+
+  int compare(size_type pos1, size_type count1, string_view v, size_type pos2,
+              size_type count2) const
+  {
+    return view_.compare(pos1, count1, v, pos2, count2);
+  }
+
+  int compare(size_type pos1, size_type count1, const char* s) const
+  {
+    return view_.compare(pos1, count1, s);
+  }
+
+  int compare(size_type pos1, size_type count1, const char* s,
+              size_type count2) const
+  {
+    return view_.compare(pos1, count1, s, count2);
+  }
+
+  template <typename T>
+  typename std::enable_if<AsStringView<T>::value, size_type>::type find(
+    T&& s, size_type pos = 0) const
+  {
+    string_view v = AsStringView<T>::view(std::forward<T>(s));
+    return view_.find(v, pos);
+  }
+
+  size_type find(const char* s, size_type pos, size_type count) const
+  {
+    return view_.find(s, pos, count);
+  }
+
+  template <typename T>
+  typename std::enable_if<AsStringView<T>::value, size_type>::type rfind(
+    T&& s, size_type pos = npos) const
+  {
+    string_view v = AsStringView<T>::view(std::forward<T>(s));
+    return view_.rfind(v, pos);
+  }
+
+  size_type rfind(const char* s, size_type pos, size_type count) const
+  {
+    return view_.rfind(s, pos, count);
+  }
+
+  template <typename T>
+  typename std::enable_if<AsStringView<T>::value, size_type>::type
+  find_first_of(T&& s, size_type pos = 0) const
+  {
+    string_view v = AsStringView<T>::view(std::forward<T>(s));
+    return view_.find_first_of(v, pos);
+  }
+
+  size_type find_first_of(const char* s, size_type pos, size_type count) const
+  {
+    return view_.find_first_of(s, pos, count);
+  }
+
+  template <typename T>
+  typename std::enable_if<AsStringView<T>::value, size_type>::type
+  find_first_not_of(T&& s, size_type pos = 0) const
+  {
+    string_view v = AsStringView<T>::view(std::forward<T>(s));
+    return view_.find_first_not_of(v, pos);
+  }
+
+  size_type find_first_not_of(const char* s, size_type pos,
+                              size_type count) const
+  {
+    return view_.find_first_not_of(s, pos, count);
+  }
+
+  template <typename T>
+  typename std::enable_if<AsStringView<T>::value, size_type>::type
+  find_last_of(T&& s, size_type pos = npos) const
+  {
+    string_view v = AsStringView<T>::view(std::forward<T>(s));
+    return view_.find_last_of(v, pos);
+  }
+
+  size_type find_last_of(const char* s, size_type pos, size_type count) const
+  {
+    return view_.find_last_of(s, pos, count);
+  }
+
+  template <typename T>
+  typename std::enable_if<AsStringView<T>::value, size_type>::type
+  find_last_not_of(T&& s, size_type pos = npos) const
+  {
+    string_view v = AsStringView<T>::view(std::forward<T>(s));
+    return view_.find_last_not_of(v, pos);
+  }
+
+  size_type find_last_not_of(const char* s, size_type pos,
+                             size_type count) const
+  {
+    return view_.find_last_not_of(s, pos, count);
+  }
+
+private:
+  // Internal constructor to move from existing String.
+  String(String&& s, Private) noexcept
+    : String(std::move(s))
+  {
+  }
+
+  // Internal constructor for dynamically allocated string.
+  String(std::string&& s, Private);
+
+  // Internal constructor for view of statically allocated string.
+  String(string_view v, Private)
+    : string_()
+    , view_(v)
+  {
+  }
+
+  void internally_mutate_to_stable_string();
+
+  std::shared_ptr<std::string const> string_;
+  string_view view_;
+};
+
+template <typename L, typename R>
+typename std::enable_if<AsStringView<L>::value && AsStringView<R>::value,
+                        bool>::type
+operator==(L&& l, R&& r)
+{
+  return (AsStringView<L>::view(std::forward<L>(l)) ==
+          AsStringView<R>::view(std::forward<R>(r)));
+}
+
+template <typename L, typename R>
+typename std::enable_if<AsStringView<L>::value && AsStringView<R>::value,
+                        bool>::type
+operator!=(L&& l, R&& r)
+{
+  return (AsStringView<L>::view(std::forward<L>(l)) !=
+          AsStringView<R>::view(std::forward<R>(r)));
+}
+
+template <typename L, typename R>
+typename std::enable_if<AsStringView<L>::value && AsStringView<R>::value,
+                        bool>::type
+operator<(L&& l, R&& r)
+{
+  return (AsStringView<L>::view(std::forward<L>(l)) <
+          AsStringView<R>::view(std::forward<R>(r)));
+}
+
+template <typename L, typename R>
+typename std::enable_if<AsStringView<L>::value && AsStringView<R>::value,
+                        bool>::type
+operator<=(L&& l, R&& r)
+{
+  return (AsStringView<L>::view(std::forward<L>(l)) <=
+          AsStringView<R>::view(std::forward<R>(r)));
+}
+
+template <typename L, typename R>
+typename std::enable_if<AsStringView<L>::value && AsStringView<R>::value,
+                        bool>::type
+operator>(L&& l, R&& r)
+{
+  return (AsStringView<L>::view(std::forward<L>(l)) >
+          AsStringView<R>::view(std::forward<R>(r)));
+}
+
+template <typename L, typename R>
+typename std::enable_if<AsStringView<L>::value && AsStringView<R>::value,
+                        bool>::type
+operator>=(L&& l, R&& r)
+{
+  return (AsStringView<L>::view(std::forward<L>(l)) >=
+          AsStringView<R>::view(std::forward<R>(r)));
+}
+
+std::ostream& operator<<(std::ostream& os, String const& s);
+std::string& operator+=(std::string& self, String const& s);
+
+template <typename L, typename R>
+struct StringOpPlus
+{
+  L l;
+  R r;
+#if defined(__SUNPRO_CC)
+  StringOpPlus(L in_l, R in_r)
+    : l(in_l)
+    , r(in_r)
+  {
+  }
+#endif
+  operator std::string() const;
+  std::string::size_type size() const { return l.size() + r.size(); }
+};
+
+template <typename T>
+struct StringAdd
+{
+  static const bool value = AsStringView<T>::value;
+  typedef string_view temp_type;
+  template <typename S>
+  static temp_type temp(S&& s)
+  {
+    return AsStringView<T>::view(std::forward<S>(s));
+  }
+};
+
+template <typename L, typename R>
+struct StringAdd<StringOpPlus<L, R>> : std::true_type
+{
+  typedef StringOpPlus<L, R> const& temp_type;
+  static temp_type temp(temp_type s) { return s; }
+};
+
+template <typename L, typename R>
+StringOpPlus<L, R>::operator std::string() const
+{
+  std::string s;
+  s.reserve(size());
+  s += *this;
+  return s;
+}
+
+template <typename L, typename R>
+std::string& operator+=(std::string& s, StringOpPlus<L, R> const& a)
+{
+  s.reserve(s.size() + a.size());
+  s += a.l;
+  s += a.r;
+  return s;
+}
+
+template <typename L, typename R>
+String& operator+=(String& s, StringOpPlus<L, R> const& a)
+{
+  std::string r;
+  r.reserve(s.size() + a.size());
+  r.assign(s.data(), s.size());
+  r += a.l;
+  r += a.r;
+  s = std::move(r);
+  return s;
+}
+
+template <typename L, typename R>
+std::ostream& operator<<(std::ostream& os, StringOpPlus<L, R> const& a)
+{
+  return os << a.l << a.r;
+}
+
+template <typename L, typename R>
+struct IntoString<StringOpPlus<L, R>> : std::true_type
+{
+  static std::string into_string(StringOpPlus<L, R> const& a) { return a; }
+};
+
+template <typename L, typename R>
+typename std::enable_if<StringAdd<L>::value && StringAdd<R>::value,
+                        StringOpPlus<typename StringAdd<L>::temp_type,
+                                     typename StringAdd<R>::temp_type>>::type
+operator+(L&& l, R&& r)
+{
+  return { StringAdd<L>::temp(std::forward<L>(l)),
+           StringAdd<R>::temp(std::forward<R>(r)) };
+}
+
+template <typename LL, typename LR, typename R>
+typename std::enable_if<AsStringView<R>::value, bool>::type operator==(
+  StringOpPlus<LL, LR> const& l, R&& r)
+{
+  return std::string(l) == AsStringView<R>::view(std::forward<R>(r));
+}
+
+template <typename L, typename RL, typename RR>
+typename std::enable_if<AsStringView<L>::value, bool>::type operator==(
+  L&& l, StringOpPlus<RL, RR> const& r)
+{
+  return AsStringView<L>::view(std::forward<L>(l)) == std::string(r);
+}
+
+} // namespace cm
+
+namespace std {
+
+template <>
+struct hash<cm::String>
+{
+  typedef cm::String argument_type;
+  typedef size_t result_type;
+
+  result_type operator()(argument_type const& s) const noexcept
+  {
+    result_type const h(std::hash<cm::string_view>{}(s.view()));
+    return h;
+  }
+};
+}
+
+#endif
diff --git a/Source/cmTimestamp.h b/Source/cmTimestamp.h
index 8dd499a..2f75acb 100644
--- a/Source/cmTimestamp.h
+++ b/Source/cmTimestamp.h
@@ -23,12 +23,12 @@ public:
                                    const std::string& formatString,
                                    bool utcFlag);
 
-private:
-  time_t CreateUtcTimeTFromTm(struct tm& timeStruct) const;
-
   std::string CreateTimestampFromTimeT(time_t timeT, std::string formatString,
                                        bool utcFlag) const;
 
+private:
+  time_t CreateUtcTimeTFromTm(struct tm& timeStruct) const;
+
   std::string AddTimestampComponent(char flag, struct tm& timeStruct,
                                     time_t timeT) const;
 };
diff --git a/Source/cm_static_string_view.hxx b/Source/cm_static_string_view.hxx
new file mode 100644
index 0000000..1bef0c6
--- /dev/null
+++ b/Source/cm_static_string_view.hxx
@@ -0,0 +1,41 @@
+/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+   file Copyright.txt or https://cmake.org/licensing for details.  */
+#ifndef cm_static_string_view_hxx
+#define cm_static_string_view_hxx
+
+#include "cmConfigure.h" // IWYU pragma: keep
+
+#include "cm_string_view.hxx"
+
+#include <cstddef>
+
+namespace cm {
+
+/** A string_view that only binds to static storage.
+ *
+ * This is used together with the `""_s` user-defined literal operator
+ * to construct a type-safe abstraction of a string_view that only views
+ * statically allocated strings.  These strings are const and available
+ * for the entire lifetime of the program.
+ */
+class static_string_view : public string_view
+{
+  static_string_view(string_view v)
+    : string_view(v)
+  {
+  }
+
+  friend static_string_view operator"" _s(const char* data, size_t size);
+};
+
+/** Create a static_string_view using `""_s` literal syntax.  */
+inline static_string_view operator"" _s(const char* data, size_t size)
+{
+  return string_view(data, size);
+}
+
+} // namespace cm
+
+using cm::operator"" _s;
+
+#endif
diff --git a/Source/cm_string_view.cxx b/Source/cm_string_view.cxx
new file mode 100644
index 0000000..61fa80e
--- /dev/null
+++ b/Source/cm_string_view.cxx
@@ -0,0 +1,301 @@
+/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+   file Copyright.txt or https://cmake.org/licensing for details.  */
+
+#include "cm_string_view.hxx"
+
+#ifndef CMake_HAVE_CXX_STRING_VIEW
+
+#  include "cm_kwiml.h"
+
+#  include <algorithm>
+#  include <ostream>
+#  include <stdexcept>
+
+namespace cm {
+
+string_view::const_reference string_view::at(size_type pos) const
+{
+  if (pos >= size_) {
+    throw std::out_of_range("Index out of range in string_view::at");
+  }
+  return data_[pos];
+}
+
+string_view::size_type string_view::copy(char* dest, size_type count,
+                                         size_type pos) const
+{
+  if (pos > size_) {
+    throw std::out_of_range("Index out of range in string_view::copy");
+  }
+  size_type const rcount = std::min(count, size_ - pos);
+  traits_type::copy(dest, data_ + pos, rcount);
+  return rcount;
+}
+
+string_view string_view::substr(size_type pos, size_type count) const
+{
+  if (pos > size_) {
+    throw std::out_of_range("Index out of range in string_view::substr");
+  }
+  size_type const rcount = std::min(count, size_ - pos);
+  return string_view(data_ + pos, rcount);
+}
+
+int string_view::compare(string_view v) const noexcept
+{
+  size_type const rlen = std::min(size_, v.size_);
+  int c = traits_type::compare(data_, v.data_, rlen);
+  if (c == 0) {
+    if (size_ < v.size_) {
+      c = -1;
+    } else if (size_ > v.size_) {
+      c = 1;
+    }
+  }
+  return c;
+}
+
+int string_view::compare(size_type pos1, size_type count1, string_view v) const
+{
+  return substr(pos1, count1).compare(v);
+}
+
+int string_view::compare(size_type pos1, size_type count1, string_view v,
+                         size_type pos2, size_type count2) const
+{
+  return substr(pos1, count1).compare(v.substr(pos2, count2));
+}
+
+int string_view::compare(const char* s) const
+{
+  return compare(string_view(s));
+}
+
+int string_view::compare(size_type pos1, size_type count1, const char* s) const
+{
+  return substr(pos1, count1).compare(string_view(s));
+}
+
+int string_view::compare(size_type pos1, size_type count1, const char* s,
+                         size_type count2) const
+{
+  return substr(pos1, count1).compare(string_view(s, count2));
+}
+
+string_view::size_type string_view::find(string_view v, size_type pos) const
+  noexcept
+{
+  for (; pos + v.size_ <= size_; ++pos) {
+    if (std::char_traits<char>::compare(data_ + pos, v.data_, v.size_) == 0) {
+      return pos;
+    }
+  }
+  return npos;
+}
+
+string_view::size_type string_view::find(char c, size_type pos) const noexcept
+{
+  return find(string_view(&c, 1), pos);
+}
+
+string_view::size_type string_view::find(const char* s, size_type pos,
+                                         size_type count) const
+{
+  return find(string_view(s, count), pos);
+}
+
+string_view::size_type string_view::find(const char* s, size_type pos) const
+{
+  return find(string_view(s), pos);
+}
+
+string_view::size_type string_view::rfind(string_view v, size_type pos) const
+  noexcept
+{
+  if (size_ >= v.size_) {
+    for (pos = std::min(pos, size_ - v.size_) + 1; pos > 0;) {
+      --pos;
+      if (std::char_traits<char>::compare(data_ + pos, v.data_, v.size_) ==
+          0) {
+        return pos;
+      }
+    }
+  }
+  return npos;
+}
+
+string_view::size_type string_view::rfind(char c, size_type pos) const noexcept
+{
+  return rfind(string_view(&c, 1), pos);
+}
+
+string_view::size_type string_view::rfind(const char* s, size_type pos,
+                                          size_type count) const
+{
+  return rfind(string_view(s, count), pos);
+}
+
+string_view::size_type string_view::rfind(const char* s, size_type pos) const
+{
+  return rfind(string_view(s), pos);
+}
+
+string_view::size_type string_view::find_first_of(string_view v,
+                                                  size_type pos) const noexcept
+{
+  for (; pos < size_; ++pos) {
+    if (traits_type::find(v.data_, v.size_, data_[pos])) {
+      return pos;
+    }
+  }
+  return npos;
+}
+
+string_view::size_type string_view::find_first_of(char c, size_type pos) const
+  noexcept
+{
+  return find_first_of(string_view(&c, 1), pos);
+}
+
+string_view::size_type string_view::find_first_of(const char* s, size_type pos,
+                                                  size_type count) const
+{
+  return find_first_of(string_view(s, count), pos);
+}
+
+string_view::size_type string_view::find_first_of(const char* s,
+                                                  size_type pos) const
+{
+  return find_first_of(string_view(s), pos);
+}
+
+string_view::size_type string_view::find_last_of(string_view v,
+                                                 size_type pos) const noexcept
+{
+  if (size_ > 0) {
+    for (pos = std::min(pos, size_ - 1) + 1; pos > 0;) {
+      --pos;
+      if (traits_type::find(v.data_, v.size_, data_[pos])) {
+        return pos;
+      }
+    }
+  }
+  return npos;
+}
+
+string_view::size_type string_view::find_last_of(char c, size_type pos) const
+  noexcept
+{
+  return find_last_of(string_view(&c, 1), pos);
+}
+
+string_view::size_type string_view::find_last_of(const char* s, size_type pos,
+                                                 size_type count) const
+{
+  return find_last_of(string_view(s, count), pos);
+}
+
+string_view::size_type string_view::find_last_of(const char* s,
+                                                 size_type pos) const
+{
+  return find_last_of(string_view(s), pos);
+}
+
+string_view::size_type string_view::find_first_not_of(string_view v,
+                                                      size_type pos) const
+  noexcept
+{
+  for (; pos < size_; ++pos) {
+    if (!traits_type::find(v.data_, v.size_, data_[pos])) {
+      return pos;
+    }
+  }
+  return npos;
+}
+
+string_view::size_type string_view::find_first_not_of(char c,
+                                                      size_type pos) const
+  noexcept
+{
+  return find_first_not_of(string_view(&c, 1), pos);
+}
+
+string_view::size_type string_view::find_first_not_of(const char* s,
+                                                      size_type pos,
+                                                      size_type count) const
+{
+  return find_first_not_of(string_view(s, count), pos);
+}
+
+string_view::size_type string_view::find_first_not_of(const char* s,
+                                                      size_type pos) const
+{
+  return find_first_not_of(string_view(s), pos);
+}
+
+string_view::size_type string_view::find_last_not_of(string_view v,
+                                                     size_type pos) const
+  noexcept
+{
+  if (size_ > 0) {
+    for (pos = std::min(pos, size_ - 1) + 1; pos > 0;) {
+      --pos;
+      if (!traits_type::find(v.data_, v.size_, data_[pos])) {
+        return pos;
+      }
+    }
+  }
+  return npos;
+}
+
+string_view::size_type string_view::find_last_not_of(char c,
+                                                     size_type pos) const
+  noexcept
+{
+  return find_last_not_of(string_view(&c, 1), pos);
+}
+
+string_view::size_type string_view::find_last_not_of(const char* s,
+                                                     size_type pos,
+                                                     size_type count) const
+{
+  return find_last_not_of(string_view(s, count), pos);
+}
+
+string_view::size_type string_view::find_last_not_of(const char* s,
+                                                     size_type pos) const
+{
+  return find_last_not_of(string_view(s), pos);
+}
+
+std::ostream& operator<<(std::ostream& o, string_view v)
+{
+  return o.write(v.data(), v.size());
+}
+
+std::string& operator+=(std::string& s, string_view v)
+{
+  s.append(v.data(), v.size());
+  return s;
+}
+}
+
+std::hash<cm::string_view>::result_type std::hash<cm::string_view>::operator()(
+  argument_type const& s) const noexcept
+{
+  // FNV-1a hash.
+  static KWIML_INT_uint64_t const fnv_offset_basis = 0xcbf29ce484222325;
+  static KWIML_INT_uint64_t const fnv_prime = 0x100000001b3;
+  KWIML_INT_uint64_t h = fnv_offset_basis;
+  for (char const& c : s) {
+    h = h ^ KWIML_INT_uint64_t(KWIML_INT_uint8_t(c));
+    h = h * fnv_prime;
+  }
+  return result_type(h);
+}
+#else
+// Avoid empty translation unit.
+void cm_string_view_cxx()
+{
+}
+#endif
diff --git a/Source/cm_string_view.hxx b/Source/cm_string_view.hxx
new file mode 100644
index 0000000..d368ed8
--- /dev/null
+++ b/Source/cm_string_view.hxx
@@ -0,0 +1,217 @@
+/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+   file Copyright.txt or https://cmake.org/licensing for details.  */
+#ifndef cm_string_view_hxx
+#define cm_string_view_hxx
+
+#include "cmConfigure.h" // IWYU pragma: keep
+
+#if __cplusplus >= 201703L || defined(_MSVC_LANG) && _MSVC_LANG >= 201703L
+#  define CMake_HAVE_CXX_STRING_VIEW
+#endif
+
+#ifdef CMake_HAVE_CXX_STRING_VIEW
+#  include <string_view>
+namespace cm {
+using std::string_view;
+}
+#else
+#  include <cstddef>
+#  include <functional>
+#  include <iosfwd>
+#  include <iterator>
+#  include <string>
+
+namespace cm {
+
+class string_view
+{
+public:
+  using traits_type = std::string::traits_type;
+  using value_type = char;
+  using pointer = char*;
+  using const_pointer = const char*;
+  using reference = char&;
+  using const_reference = char const&;
+  using const_iterator = const char*;
+  using iterator = const_iterator;
+  using const_reverse_iterator = std::reverse_iterator<const_iterator>;
+  using reverse_iterator = const_reverse_iterator;
+  using size_type = std::string::size_type;
+  using difference_type = std::string::difference_type;
+
+  static size_type const npos = static_cast<size_type>(-1);
+
+  string_view() noexcept = default;
+  string_view(string_view const&) noexcept = default;
+
+  string_view(const char* s, size_t count) noexcept
+    : data_(s)
+    , size_(count)
+  {
+  }
+
+  string_view(const char* s) noexcept
+    : data_(s)
+    , size_(traits_type::length(s))
+  {
+  }
+
+  // C++17 does not define this constructor.  Instead it defines
+  // a conversion operator on std::string to create a string_view.
+  // Since this implementation is used in C++11, std::string does
+  // not have that conversion.
+  string_view(std::string const& s) noexcept
+    : data_(s.data())
+    , size_(s.size())
+  {
+  }
+
+  // C++17 does not define this conversion.  Instead it defines
+  // a constructor on std::string that can take a string_view.
+  // Since this implementation is used in C++11, std::string does
+  // not have that constructor.
+  explicit operator std::string() const { return std::string(data_, size_); }
+
+  string_view& operator=(string_view const&) = default;
+
+  const_iterator begin() const noexcept { return data_; }
+  const_iterator end() const noexcept { return data_ + size_; }
+  const_iterator cbegin() const noexcept { return begin(); }
+  const_iterator cend() const noexcept { return end(); }
+
+  const_reverse_iterator rbegin() const noexcept
+  {
+    return const_reverse_iterator(end());
+  }
+  const_reverse_iterator rend() const noexcept
+  {
+    return const_reverse_iterator(begin());
+  }
+  const_reverse_iterator crbegin() const noexcept { return rbegin(); }
+  const_reverse_iterator crend() const noexcept { return rend(); }
+
+  const_reference operator[](size_type pos) const noexcept
+  {
+    return data_[pos];
+  }
+  const_reference at(size_type pos) const;
+  const_reference front() const noexcept { return data_[0]; }
+  const_reference back() const noexcept { return data_[size_ - 1]; }
+  const_pointer data() const noexcept { return data_; }
+
+  size_type size() const noexcept { return size_; }
+  size_type length() const noexcept { return size_; }
+  size_type max_size() const noexcept { return npos - 1; }
+  bool empty() const noexcept { return size_ == 0; }
+
+  void remove_prefix(size_type n) noexcept
+  {
+    data_ += n;
+    size_ -= n;
+  }
+  void remove_suffix(size_type n) noexcept { size_ -= n; }
+  void swap(string_view& v) noexcept
+  {
+    string_view tmp = v;
+    v = *this;
+    *this = tmp;
+  }
+
+  size_type copy(char* dest, size_type count, size_type pos = 0) const;
+  string_view substr(size_type pos = 0, size_type count = npos) const;
+
+  int compare(string_view v) const noexcept;
+  int compare(size_type pos1, size_type count1, string_view v) const;
+  int compare(size_type pos1, size_type count1, string_view v, size_type pos2,
+              size_type count2) const;
+  int compare(const char* s) const;
+  int compare(size_type pos1, size_type count1, const char* s) const;
+  int compare(size_type pos1, size_type count1, const char* s,
+              size_type count2) const;
+
+  size_type find(string_view v, size_type pos = 0) const noexcept;
+  size_type find(char c, size_type pos = 0) const noexcept;
+  size_type find(const char* s, size_type pos, size_type count) const;
+  size_type find(const char* s, size_type pos = 0) const;
+
+  size_type rfind(string_view v, size_type pos = npos) const noexcept;
+  size_type rfind(char c, size_type pos = npos) const noexcept;
+  size_type rfind(const char* s, size_type pos, size_type count) const;
+  size_type rfind(const char* s, size_type pos = npos) const;
+
+  size_type find_first_of(string_view v, size_type pos = 0) const noexcept;
+  size_type find_first_of(char c, size_type pos = 0) const noexcept;
+  size_type find_first_of(const char* s, size_type pos, size_type count) const;
+  size_type find_first_of(const char* s, size_type pos = 0) const;
+
+  size_type find_last_of(string_view v, size_type pos = npos) const noexcept;
+  size_type find_last_of(char c, size_type pos = npos) const noexcept;
+  size_type find_last_of(const char* s, size_type pos, size_type count) const;
+  size_type find_last_of(const char* s, size_type pos = npos) const;
+
+  size_type find_first_not_of(string_view v, size_type pos = 0) const noexcept;
+  size_type find_first_not_of(char c, size_type pos = 0) const noexcept;
+  size_type find_first_not_of(const char* s, size_type pos,
+                              size_type count) const;
+  size_type find_first_not_of(const char* s, size_type pos = 0) const;
+
+  size_type find_last_not_of(string_view v, size_type pos = npos) const
+    noexcept;
+  size_type find_last_not_of(char c, size_type pos = npos) const noexcept;
+  size_type find_last_not_of(const char* s, size_type pos,
+                             size_type count) const;
+  size_type find_last_not_of(const char* s, size_type pos = npos) const;
+
+private:
+  const char* data_ = nullptr;
+  size_type size_ = 0;
+};
+
+std::ostream& operator<<(std::ostream& o, string_view v);
+
+std::string& operator+=(std::string& s, string_view v);
+
+inline bool operator==(string_view l, string_view r) noexcept
+{
+  return l.compare(r) == 0;
+}
+
+inline bool operator!=(string_view l, string_view r) noexcept
+{
+  return l.compare(r) != 0;
+}
+
+inline bool operator<(string_view l, string_view r) noexcept
+{
+  return l.compare(r) < 0;
+}
+
+inline bool operator<=(string_view l, string_view r) noexcept
+{
+  return l.compare(r) <= 0;
+}
+
+inline bool operator>(string_view l, string_view r) noexcept
+{
+  return l.compare(r) > 0;
+}
+
+inline bool operator>=(string_view l, string_view r) noexcept
+{
+  return l.compare(r) >= 0;
+}
+}
+
+namespace std {
+
+template <>
+struct hash<cm::string_view>
+{
+  typedef cm::string_view argument_type;
+  typedef size_t result_type;
+  result_type operator()(argument_type const& s) const noexcept;
+};
+}
+
+#endif
+#endif
diff --git a/Source/cmake.cxx b/Source/cmake.cxx
index 2ac7f4d..e81d14b 100644
--- a/Source/cmake.cxx
+++ b/Source/cmake.cxx
@@ -30,6 +30,7 @@
 #if defined(CMAKE_BUILD_WITH_CMAKE)
 #  include "cm_jsoncpp_writer.h"
 
+#  include "cmFileAPI.h"
 #  include "cmGraphVizWriter.h"
 #  include "cmVariableWatch.h"
 #  include <unordered_map>
@@ -1443,6 +1444,11 @@ int cmake::ActualConfigure()
     this->TruncateOutputLog("CMakeError.log");
   }
 
+#if defined(CMAKE_BUILD_WITH_CMAKE)
+  this->FileAPI = cm::make_unique<cmFileAPI>(this);
+  this->FileAPI->ReadQueries();
+#endif
+
   // actually do the configure
   this->GlobalGenerator->Configure();
   // Before saving the cache
@@ -1682,6 +1688,10 @@ int cmake::Generate()
   // for the Visual Studio and Xcode generators.)
   this->SaveCache(this->GetHomeOutputDirectory());
 
+#if defined(CMAKE_BUILD_WITH_CMAKE)
+  this->FileAPI->WriteReplies();
+#endif
+
   return 0;
 }
 
diff --git a/Source/cmake.h b/Source/cmake.h
index d3d0e80..d00acc7 100644
--- a/Source/cmake.h
+++ b/Source/cmake.h
@@ -6,6 +6,7 @@
 #include "cmConfigure.h" // IWYU pragma: keep
 
 #include <map>
+#include <memory> // IWYU pragma: keep
 #include <set>
 #include <string>
 #include <unordered_set>
@@ -21,6 +22,7 @@
 #endif
 
 class cmExternalMakefileProjectGeneratorFactory;
+class cmFileAPI;
 class cmFileTimeComparison;
 class cmGlobalGenerator;
 class cmGlobalGeneratorFactory;
@@ -528,6 +530,7 @@ private:
 
 #if defined(CMAKE_BUILD_WITH_CMAKE)
   cmVariableWatch* VariableWatch;
+  std::unique_ptr<cmFileAPI> FileAPI;
 #endif
 
   cmState* State;
diff --git a/Source/kwsys/SystemTools.cxx b/Source/kwsys/SystemTools.cxx
index 331f16e..c5160a9 100644
--- a/Source/kwsys/SystemTools.cxx
+++ b/Source/kwsys/SystemTools.cxx
@@ -82,6 +82,10 @@
 #  include <signal.h> /* sigprocmask */
 #endif
 
+#ifdef __linux
+#  include <linux/fs.h>
+#endif
+
 // Windows API.
 #if defined(_WIN32)
 #  include <windows.h>
@@ -2158,6 +2162,120 @@ bool SystemTools::FilesDiffer(const std::string& source,
 }
 
 /**
+ * Blockwise copy source to destination file
+ */
+static bool CopyFileContentBlockwise(const std::string& source,
+                                     const std::string& destination)
+{
+// Open files
+#if defined(_WIN32)
+  kwsys::ifstream fin(
+    Encoding::ToNarrow(Encoding::ToWindowsExtendedPath(source)).c_str(),
+    std::ios::in | std::ios::binary);
+#else
+  kwsys::ifstream fin(source.c_str(), std::ios::in | std::ios::binary);
+#endif
+  if (!fin) {
+    return false;
+  }
+
+  // try and remove the destination file so that read only destination files
+  // can be written to.
+  // If the remove fails continue so that files in read only directories
+  // that do not allow file removal can be modified.
+  SystemTools::RemoveFile(destination);
+
+#if defined(_WIN32)
+  kwsys::ofstream fout(
+    Encoding::ToNarrow(Encoding::ToWindowsExtendedPath(destination)).c_str(),
+    std::ios::out | std::ios::trunc | std::ios::binary);
+#else
+  kwsys::ofstream fout(destination.c_str(),
+                       std::ios::out | std::ios::trunc | std::ios::binary);
+#endif
+  if (!fout) {
+    return false;
+  }
+
+  // This copy loop is very sensitive on certain platforms with
+  // slightly broken stream libraries (like HPUX).  Normally, it is
+  // incorrect to not check the error condition on the fin.read()
+  // before using the data, but the fin.gcount() will be zero if an
+  // error occurred.  Therefore, the loop should be safe everywhere.
+  while (fin) {
+    const int bufferSize = 4096;
+    char buffer[bufferSize];
+
+    fin.read(buffer, bufferSize);
+    if (fin.gcount()) {
+      fout.write(buffer, fin.gcount());
+    } else {
+      break;
+    }
+  }
+
+  // Make sure the operating system has finished writing the file
+  // before closing it.  This will ensure the file is finished before
+  // the check below.
+  fout.flush();
+
+  fin.close();
+  fout.close();
+
+  if (!fout) {
+    return false;
+  }
+
+  return true;
+}
+
+/**
+ * Clone the source file to the destination file
+ *
+ * If available, the Linux FICLONE ioctl is used to create a check
+ * copy-on-write clone of the source file.
+ *
+ * The method returns false for the following cases:
+ * - The code has not been compiled on Linux or the ioctl was unknown
+ * - The source and destination is on different file systems
+ * - The underlying filesystem does not support file cloning
+ * - An unspecified error occurred
+ */
+static bool CloneFileContent(const std::string& source,
+                             const std::string& destination)
+{
+#if defined(__linux) && defined(FICLONE)
+  int in = open(source.c_str(), O_RDONLY);
+  if (in < 0) {
+    return false;
+  }
+
+  SystemTools::RemoveFile(destination);
+
+  int out =
+    open(destination.c_str(), O_WRONLY | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR);
+  if (out < 0) {
+    close(in);
+    return false;
+  }
+
+  int result = ioctl(out, FICLONE, in);
+  close(in);
+  close(out);
+
+  if (result < 0) {
+    return false;
+  }
+
+  return true;
+#else
+  (void)source;
+  (void)destination;
+  return false;
+#endif
+}
+
+/**
  * Copy a file named by "source" to the file named by "destination".
  */
 bool SystemTools::CopyFileAlways(const std::string& source,
@@ -2174,9 +2292,6 @@ bool SystemTools::CopyFileAlways(const std::string& source,
   if (SystemTools::FileIsDirectory(source)) {
     SystemTools::MakeDirectory(destination);
   } else {
-    const int bufferSize = 4096;
-    char buffer[bufferSize];
-
     // If destination is a directory, try to create a file with the same
     // name as the source in that directory.
 
@@ -2195,62 +2310,12 @@ bool SystemTools::CopyFileAlways(const std::string& source,
 
     SystemTools::MakeDirectory(destination_dir);
 
-// Open files
-#if defined(_WIN32)
-    kwsys::ifstream fin(
-      Encoding::ToNarrow(Encoding::ToWindowsExtendedPath(source)).c_str(),
-      std::ios::in | std::ios::binary);
-#else
-    kwsys::ifstream fin(source.c_str(), std::ios::in | std::ios::binary);
-#endif
-    if (!fin) {
-      return false;
-    }
-
-    // try and remove the destination file so that read only destination files
-    // can be written to.
-    // If the remove fails continue so that files in read only directories
-    // that do not allow file removal can be modified.
-    SystemTools::RemoveFile(real_destination);
-
-#if defined(_WIN32)
-    kwsys::ofstream fout(
-      Encoding::ToNarrow(Encoding::ToWindowsExtendedPath(real_destination))
-        .c_str(),
-      std::ios::out | std::ios::trunc | std::ios::binary);
-#else
-    kwsys::ofstream fout(real_destination.c_str(),
-                         std::ios::out | std::ios::trunc | std::ios::binary);
-#endif
-    if (!fout) {
-      return false;
-    }
-
-    // This copy loop is very sensitive on certain platforms with
-    // slightly broken stream libraries (like HPUX).  Normally, it is
-    // incorrect to not check the error condition on the fin.read()
-    // before using the data, but the fin.gcount() will be zero if an
-    // error occurred.  Therefore, the loop should be safe everywhere.
-    while (fin) {
-      fin.read(buffer, bufferSize);
-      if (fin.gcount()) {
-        fout.write(buffer, fin.gcount());
-      } else {
-        break;
+    if (!CloneFileContent(source, real_destination)) {
+      // if cloning did not succeed, fall back to blockwise copy
+      if (!CopyFileContentBlockwise(source, real_destination)) {
+        return false;
       }
     }
-
-    // Make sure the operating system has finished writing the file
-    // before closing it.  This will ensure the file is finished before
-    // the check below.
-    fout.flush();
-
-    fin.close();
-    fout.close();
-
-    if (!fout) {
-      return false;
-    }
   }
   if (perms) {
     if (!SystemTools::SetPermissions(real_destination, perm)) {