Raise the ARCMT functionality in Clang into proper FrontendActions.

These are somewhat special in that they wrap any other FrontendAction,
running various ARC transformations or checks prior to the standard
action's run. To implement them easily, this extends FrontendAction to
have a WrapperFrontendAction utility class which forwards all calls by
default to an inner action setup at construction time. This is then
subclassed to override the specific behavior needed by the different
ARCMT tools.

Finally, FrontendTool is taught how to create these wrapper actions from
the existing flags and options structures.

The result is that clangFrontend no longer depends on clangARCMigrate.
This is very important, as clangARCMigrate *heavily* depends on
clangFrontend. Fundamentally ARCMigrate is at the same layer as
a library like Rewrite, sitting firmly on top of the Frontend, but tied
together with the FrontendTool when building the clang binary itself.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@133161 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 30 insertions, 0 deletions

diff --git a/include/clang/Frontend/FrontendAction.h b/include/clang/Frontend/FrontendAction.h
index ee0863a477..2538f55aaf 100644
--- a/include/clang/Frontend/FrontendAction.h
+++ b/include/clang/Frontend/FrontendAction.h
@@ -51,6 +51,7 @@ class FrontendAction {
   llvm::OwningPtr<ASTUnit> CurrentASTUnit;
   CompilerInstance *Instance;
   friend class ASTMergeAction;
+  friend class WrapperFrontendAction;
 
 private:
   ASTConsumer* CreateWrappedASTConsumer(CompilerInstance &CI,
@@ -253,6 +254,35 @@ public:
   virtual bool usesPreprocessorOnly() const { return true; }
 };
 
+/// WrapperFrontendAction - A frontend action which simply wraps some other
+/// runtime specified frontend action. Deriving from this class allows an
+/// action to inject custom logic around some existing action's behavior. It
+/// implements every virtual method in the FrontendAction interface by
+/// forwarding to the wrapped action.
+class WrapperFrontendAction : public FrontendAction {
+  llvm::OwningPtr<FrontendAction> WrappedAction;
+
+protected:
+  virtual ASTConsumer *CreateASTConsumer(CompilerInstance &CI,
+                                         llvm::StringRef InFile);
+  virtual bool BeginSourceFileAction(CompilerInstance &CI,
+                                     llvm::StringRef Filename);
+  virtual void ExecuteAction();
+  virtual void EndSourceFileAction();
+
+public:
+  /// Construct a WrapperFrontendAction from an existing action, taking
+  /// ownership of it.
+  WrapperFrontendAction(FrontendAction *WrappedAction);
+
+  virtual bool usesPreprocessorOnly() const;
+  virtual bool usesCompleteTranslationUnit();
+  virtual bool hasPCHSupport() const;
+  virtual bool hasASTFileSupport() const;
+  virtual bool hasIRSupport() const;
+  virtual bool hasCodeCompletionSupport() const;
+};
+
 }  // end namespace clang
 
 #endif