Export: Factor out file generation steps into helpers

Do not actually generate any content in the driving code paths.
Use helpers for that.

Source/cmExportFileGenerator.cxx

@@ -96,24 +96,8 @@ bool cmExportFileGenerator::GenerateImportFile()
   }
   std::ostream& os = *foutPtr;
 
-  // Protect that file against use with older CMake versions.
-  /* clang-format off */
-  os << "# Generated by CMake\n\n";
-  os << "if(\"${CMAKE_MAJOR_VERSION}.${CMAKE_MINOR_VERSION}\" LESS 2.5)\n"
-     << "   message(FATAL_ERROR \"CMake >= 2.6.0 required\")\n"
-     << "endif()\n";
-  /* clang-format on */
-
-  // Isolate the file policy level.
-  // We use 2.6 here instead of the current version because newer
-  // versions of CMake should be able to export files imported by 2.6
-  // until the import format changes.
-  /* clang-format off */
-  os << "cmake_policy(PUSH)\n"
-     << "cmake_policy(VERSION 2.6)\n";
-  /* clang-format on */
-
   // Start with the import file header.
+  this->GeneratePolicyHeaderCode(os);
   this->GenerateImportHeaderCode(os);
 
   // Create all the imported targets.
@@ -121,7 +105,7 @@ bool cmExportFileGenerator::GenerateImportFile()
 
   // End with the import file footer.
   this->GenerateImportFooterCode(os);
-  os << "cmake_policy(POP)\n";
+  this->GeneratePolicyFooterCode(os);
 
   return result;
 }
@@ -832,6 +816,31 @@ void cmExportFileGenerator::SetImportLinkProperty(
   properties[prop] = link_entries;
 }
 
+void cmExportFileGenerator::GeneratePolicyHeaderCode(std::ostream& os)
+{
+  // Protect that file against use with older CMake versions.
+  /* clang-format off */
+  os << "# Generated by CMake\n\n";
+  os << "if(\"${CMAKE_MAJOR_VERSION}.${CMAKE_MINOR_VERSION}\" LESS 2.5)\n"
+     << "   message(FATAL_ERROR \"CMake >= 2.6.0 required\")\n"
+     << "endif()\n";
+  /* clang-format on */
+
+  // Isolate the file policy level.
+  // We use 2.6 here instead of the current version because newer
+  // versions of CMake should be able to export files imported by 2.6
+  // until the import format changes.
+  /* clang-format off */
+  os << "cmake_policy(PUSH)\n"
+     << "cmake_policy(VERSION 2.6)\n";
+  /* clang-format on */
+}
+
+void cmExportFileGenerator::GeneratePolicyFooterCode(std::ostream& os)
+{
+  os << "cmake_policy(POP)\n";
+}
+
 void cmExportFileGenerator::GenerateImportHeaderCode(std::ostream& os,
                                                      const std::string& config)
 {

Source/cmExportFileGenerator.h

@@ -78,6 +78,8 @@ protected:
                             std::vector<std::string>& missingTargets);
 
   // Methods to implement export file code generation.
+  void GeneratePolicyHeaderCode(std::ostream& os);
+  void GeneratePolicyFooterCode(std::ostream& os);
   void GenerateImportHeaderCode(std::ostream& os,
                                 const std::string& config = "");
   void GenerateImportFooterCode(std::ostream& os);

Source/cmExportInstallFileGenerator.cxx

@@ -75,58 +75,8 @@ bool cmExportInstallFileGenerator::GenerateMainFile(std::ostream& os)
     this->GenerateExpectedTargetsCode(os, expectedTargets);
   }
 
-  // Set an _IMPORT_PREFIX variable for import location properties
+  // Compute the relative import prefix for the file
-  // to reference if they are relative to the install prefix.
+  this->GenerateImportPrefix(os);
-  std::string installPrefix =
-    this->IEGen->GetLocalGenerator()->GetMakefile()->GetSafeDefinition(
-      "CMAKE_INSTALL_PREFIX");
-  std::string const& expDest = this->IEGen->GetDestination();
-  if (cmSystemTools::FileIsFullPath(expDest)) {
-    // The export file is being installed to an absolute path so the
-    // package is not relocatable.  Use the configured install prefix.
-    /* clang-format off */
-    os <<
-      "# The installation prefix configured by this project.\n"
-      "set(_IMPORT_PREFIX \"" << installPrefix << "\")\n"
-      "\n";
-    /* clang-format on */
-  } else {
-    // Add code to compute the installation prefix relative to the
-    // import file location.
-    std::string absDest = installPrefix + "/" + expDest;
-    std::string absDestS = absDest + "/";
-    os << "# Compute the installation prefix relative to this file.\n"
-       << "get_filename_component(_IMPORT_PREFIX"
-       << " \"${CMAKE_CURRENT_LIST_FILE}\" PATH)\n";
-    if (cmHasLiteralPrefix(absDestS.c_str(), "/lib/") ||
-        cmHasLiteralPrefix(absDestS.c_str(), "/lib64/") ||
-        cmHasLiteralPrefix(absDestS.c_str(), "/usr/lib/") ||
-        cmHasLiteralPrefix(absDestS.c_str(), "/usr/lib64/")) {
-      // Handle "/usr move" symlinks created by some Linux distros.
-      /* clang-format off */
-      os <<
-        "# Use original install prefix when loaded through a\n"
-        "# cross-prefix symbolic link such as /lib -> /usr/lib.\n"
-        "get_filename_component(_realCurr \"${_IMPORT_PREFIX}\" REALPATH)\n"
-        "get_filename_component(_realOrig \"" << absDest << "\" REALPATH)\n"
-        "if(_realCurr STREQUAL _realOrig)\n"
-        "  set(_IMPORT_PREFIX \"" << absDest << "\")\n"
-        "endif()\n"
-        "unset(_realOrig)\n"
-        "unset(_realCurr)\n";
-      /* clang-format on */
-    }
-    std::string dest = expDest;
-    while (!dest.empty()) {
-      os << "get_filename_component(_IMPORT_PREFIX \"${_IMPORT_PREFIX}\" "
-            "PATH)\n";
-      dest = cmSystemTools::GetFilenamePath(dest);
-    }
-    os << "if(_IMPORT_PREFIX STREQUAL \"/\")\n"
-       << "  set(_IMPORT_PREFIX \"\")\n"
-       << "endif()\n"
-       << "\n";
-  }
 
   std::vector<std::string> missingTargets;
 
@@ -204,24 +154,9 @@ bool cmExportInstallFileGenerator::GenerateMainFile(std::ostream& os)
     this->GenerateRequiredCMakeVersion(os, "2.8.12");
   }
 
-  // Now load per-configuration properties for them.
+  this->LoadConfigFiles(os);
-  /* clang-format off */
-  os << "# Load information for each installed configuration.\n"
-     << "get_filename_component(_DIR \"${CMAKE_CURRENT_LIST_FILE}\" PATH)\n"
-     << "file(GLOB CONFIG_FILES \"${_DIR}/"
-     << this->GetConfigImportFileGlob() << "\")\n"
-     << "foreach(f ${CONFIG_FILES})\n"
-     << "  include(${f})\n"
-     << "endforeach()\n"
-     << "\n";
-  /* clang-format on */
 
-  // Cleanup the import prefix variable.
+  this->CleanupTemporaryVariables(os);
-  /* clang-format off */
-  os << "# Cleanup temporary variables.\n"
-     << "set(_IMPORT_PREFIX)\n"
-     << "\n";
-  /* clang-format on */
   this->GenerateImportedFileCheckLoop(os);
 
   bool result = true;
@@ -242,6 +177,86 @@ bool cmExportInstallFileGenerator::GenerateMainFile(std::ostream& os)
   return result;
 }
 
+void cmExportInstallFileGenerator::GenerateImportPrefix(std::ostream& os)
+{
+  // Set an _IMPORT_PREFIX variable for import location properties
+  // to reference if they are relative to the install prefix.
+  std::string installPrefix =
+    this->IEGen->GetLocalGenerator()->GetMakefile()->GetSafeDefinition(
+      "CMAKE_INSTALL_PREFIX");
+  std::string const& expDest = this->IEGen->GetDestination();
+  if (cmSystemTools::FileIsFullPath(expDest)) {
+    // The export file is being installed to an absolute path so the
+    // package is not relocatable.  Use the configured install prefix.
+    /* clang-format off */
+    os <<
+      "# The installation prefix configured by this project.\n"
+      "set(_IMPORT_PREFIX \"" << installPrefix << "\")\n"
+      "\n";
+    /* clang-format on */
+  } else {
+    // Add code to compute the installation prefix relative to the
+    // import file location.
+    std::string absDest = installPrefix + "/" + expDest;
+    std::string absDestS = absDest + "/";
+    os << "# Compute the installation prefix relative to this file.\n"
+       << "get_filename_component(_IMPORT_PREFIX"
+       << " \"${CMAKE_CURRENT_LIST_FILE}\" PATH)\n";
+    if (cmHasLiteralPrefix(absDestS.c_str(), "/lib/") ||
+        cmHasLiteralPrefix(absDestS.c_str(), "/lib64/") ||
+        cmHasLiteralPrefix(absDestS.c_str(), "/usr/lib/") ||
+        cmHasLiteralPrefix(absDestS.c_str(), "/usr/lib64/")) {
+      // Handle "/usr move" symlinks created by some Linux distros.
+      /* clang-format off */
+      os <<
+        "# Use original install prefix when loaded through a\n"
+        "# cross-prefix symbolic link such as /lib -> /usr/lib.\n"
+        "get_filename_component(_realCurr \"${_IMPORT_PREFIX}\" REALPATH)\n"
+        "get_filename_component(_realOrig \"" << absDest << "\" REALPATH)\n"
+        "if(_realCurr STREQUAL _realOrig)\n"
+        "  set(_IMPORT_PREFIX \"" << absDest << "\")\n"
+        "endif()\n"
+        "unset(_realOrig)\n"
+        "unset(_realCurr)\n";
+      /* clang-format on */
+    }
+    std::string dest = expDest;
+    while (!dest.empty()) {
+      os << "get_filename_component(_IMPORT_PREFIX \"${_IMPORT_PREFIX}\" "
+            "PATH)\n";
+      dest = cmSystemTools::GetFilenamePath(dest);
+    }
+    os << "if(_IMPORT_PREFIX STREQUAL \"/\")\n"
+       << "  set(_IMPORT_PREFIX \"\")\n"
+       << "endif()\n"
+       << "\n";
+  }
+}
+
+void cmExportInstallFileGenerator::CleanupTemporaryVariables(std::ostream& os)
+{
+  /* clang-format off */
+  os << "# Cleanup temporary variables.\n"
+     << "set(_IMPORT_PREFIX)\n"
+     << "\n";
+  /* clang-format on */
+}
+
+void cmExportInstallFileGenerator::LoadConfigFiles(std::ostream& os)
+{
+  // Now load per-configuration properties for them.
+  /* clang-format off */
+  os << "# Load information for each installed configuration.\n"
+     << "get_filename_component(_DIR \"${CMAKE_CURRENT_LIST_FILE}\" PATH)\n"
+     << "file(GLOB CONFIG_FILES \"${_DIR}/"
+     << this->GetConfigImportFileGlob() << "\")\n"
+     << "foreach(f ${CONFIG_FILES})\n"
+     << "  include(${f})\n"
+     << "endforeach()\n"
+     << "\n";
+  /* clang-format on */
+}
+
 void cmExportInstallFileGenerator::ReplaceInstallPrefix(std::string& input)
 {
   std::string::size_type pos = 0;

Source/cmExportInstallFileGenerator.h

@@ -80,6 +80,14 @@ protected:
   std::vector<std::string> FindNamespaces(cmGlobalGenerator* gg,
                                           const std::string& name);
 
+  /** Generate the relative import prefix.  */
+  void GenerateImportPrefix(std::ostream&);
+
+  /** Generate the relative import prefix.  */
+  void LoadConfigFiles(std::ostream&);
+
+  void CleanupTemporaryVariables(std::ostream&);
+
   /** Generate a per-configuration file for the targets.  */
   bool GenerateImportFileConfig(const std::string& config,
                                 std::vector<std::string>& missingTargets);