Added "PreprocessorFactory", an interface for lazily creating Preprocessor objects on-demand.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@49868 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/clang/Lex/Preprocessor.h b/include/clang/Lex/Preprocessor.h
index 98edf5a..5fc4642 100644
--- a/include/clang/Lex/Preprocessor.h
+++ b/include/clang/Lex/Preprocessor.h
@@ -524,6 +524,14 @@
   void HandlePragmaDependency(Token &DependencyTok);
 };
 
+/// PreprocessorFactory - A generic factory interface for lazily creating
+///  Preprocessor objects on-demand when they are needed.
+class PreprocessorFactory {
+public:
+  virtual ~PreprocessorFactory();
+  virtual Preprocessor* CreatePreprocessor() = 0;  
+};
+  
 }  // end namespace clang
 
 #endif
diff --git a/lib/Lex/Preprocessor.cpp b/lib/Lex/Preprocessor.cpp
index ebd3072..6d08a36 100644
--- a/lib/Lex/Preprocessor.cpp
+++ b/lib/Lex/Preprocessor.cpp
@@ -40,6 +40,8 @@
 
 //===----------------------------------------------------------------------===//
 
+PreprocessorFactory::~PreprocessorFactory() {}
+
 Preprocessor::Preprocessor(Diagnostic &diags, const LangOptions &opts,
                            TargetInfo &target, SourceManager &SM, 
                            HeaderSearch &Headers)