Insert interception point onStartOfTranslationUnit.

Often users of the ASTMatchers want to add tasks that are done once per
translation unit, for example, cleaning up caches. Combined with the
interception point for the end of source file one can add to the factory
creation, this covers the cases we've seen users need.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@167271 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 38 insertions, 0 deletions

diff --git a/include/clang/ASTMatchers/ASTMatchFinder.h b/include/clang/ASTMatchers/ASTMatchFinder.h
index ba8e0a7ecc..30b4050e1c 100644
--- a/include/clang/ASTMatchers/ASTMatchFinder.h
+++ b/include/clang/ASTMatchers/ASTMatchFinder.h
@@ -85,7 +85,14 @@ public:
   class MatchCallback {
   public:
     virtual ~MatchCallback();
+
+    /// \brief Called on every match by the \c MatchFinder.
     virtual void run(const MatchResult &Result) = 0;
+
+    /// \brief Called at the start of each translation unit.
+    ///
+    /// Optionally override to do per translation unit tasks.
+    virtual void onStartOfTranslationUnit() {}
   };
 
   /// \brief Called when parsing is finished. Intended for testing only.
diff --git a/lib/ASTMatchers/ASTMatchFinder.cpp b/lib/ASTMatchers/ASTMatchFinder.cpp
index b081f5426e..8ecb26e8c1 100644
--- a/lib/ASTMatchers/ASTMatchFinder.cpp
+++ b/lib/ASTMatchers/ASTMatchFinder.cpp
@@ -315,6 +315,15 @@ public:
        ActiveASTContext(NULL) {
   }
 
+  void onStartOfTranslationUnit() {
+    for (std::vector<std::pair<const internal::DynTypedMatcher*,
+                               MatchCallback*> >::const_iterator
+             I = MatcherCallbackPairs->begin(), E = MatcherCallbackPairs->end();
+         I != E; ++I) {
+      I->second->onStartOfTranslationUnit();
+    }
+  }
+
   void set_active_ast_context(ASTContext *NewActiveASTContext) {
     ActiveASTContext = NewActiveASTContext;
   }
@@ -649,6 +658,7 @@ private:
       ParsingDone->run();
     }
     Visitor.set_active_ast_context(&Context);
+    Visitor.onStartOfTranslationUnit();
     Visitor.TraverseDecl(Context.getTranslationUnitDecl());
     Visitor.set_active_ast_context(NULL);
   }
diff --git a/unittests/ASTMatchers/ASTMatchersTest.cpp b/unittests/ASTMatchers/ASTMatchersTest.cpp
index 8861881efa..ad5469348d 100644
--- a/unittests/ASTMatchers/ASTMatchersTest.cpp
+++ b/unittests/ASTMatchers/ASTMatchersTest.cpp
@@ -3366,5 +3366,26 @@ TEST(MatchFinder, CanMatchStatementsRecursively) {
     new VerifyRecursiveMatch<clang::Stmt>("if", declStmt())));
 }
 
+class VerifyStartOfTranslationUnit : public MatchFinder::MatchCallback {
+public:
+  VerifyStartOfTranslationUnit() : Called(false) {}
+  virtual void run(const MatchFinder::MatchResult &Result) {
+    EXPECT_TRUE(Called);
+  }
+  virtual void onStartOfTranslationUnit() {
+    Called = true;
+  }
+  bool Called;
+};
+
+TEST(MatchFinder, InterceptsStartOfTranslationUnit) {
+  MatchFinder Finder;
+  VerifyStartOfTranslationUnit VerifyCallback;
+  Finder.addMatcher(decl(), &VerifyCallback);
+  OwningPtr<FrontendActionFactory> Factory(newFrontendActionFactory(&Finder));
+  ASSERT_TRUE(tooling::runToolOnCode(Factory->create(), "int x;"));
+  EXPECT_TRUE(VerifyCallback.Called);
+}
+
 } // end namespace ast_matchers
 } // end namespace clang