Address review comments

src/libdredd/include_private/include/libdredd/mutate_visitor.h

@@ -172,10 +172,13 @@ class MutateVisitor : public clang::RecursiveASTVisitor<MutateVisitor> {
   // this special case, so that it can be ignored.
   bool IsConversionOfEnumToConstructor(const clang::Expr& expr) const;
 
-  // It is safe to Dredd's prelude before the first function we encounter in a
-  // file as Dredd only makes source code modifications inside functions.
+  // It is safe to put Dredd's prelude before the first function we encounter in
+  // a file as Dredd only makes source code modifications inside functions.
   void UpdateStartLocationOfFirstFunctionInSourceFile();
 
+  // TODO(JLJ): Add comment
+  void AddMutation(std::unique_ptr<Mutation> mutation);
+
   const clang::CompilerInstance* compiler_instance_;
   bool optimise_mutations_;
 

src/libdredd/src/mutate_visitor.cc

@@ -342,10 +342,9 @@ void MutateVisitor::HandleUnaryOperator(clang::UnaryOperator* unary_operator) {
     }
   }
 
-  mutation_tree_path_.back()->AddMutation(
-      std::make_unique<MutationReplaceUnaryOperator>(
-          *unary_operator, compiler_instance_->getPreprocessor(),
-          compiler_instance_->getASTContext()));
+  AddMutation(std::make_unique<MutationReplaceUnaryOperator>(
+      *unary_operator, compiler_instance_->getPreprocessor(),
+      compiler_instance_->getASTContext()));
 }
 
 void MutateVisitor::HandleBinaryOperator(
@@ -405,10 +404,9 @@ void MutateVisitor::HandleBinaryOperator(
     return;
   }
 
-  mutation_tree_path_.back()->AddMutation(
-      std::make_unique<MutationReplaceBinaryOperator>(
-          *binary_operator, compiler_instance_->getPreprocessor(),
-          compiler_instance_->getASTContext()));
+  AddMutation(std::make_unique<MutationReplaceBinaryOperator>(
+      *binary_operator, compiler_instance_->getPreprocessor(),
+      compiler_instance_->getASTContext()));
 }
 
 void MutateVisitor::HandleExpr(clang::Expr* expr) {
@@ -477,7 +475,7 @@ void MutateVisitor::HandleExpr(clang::Expr* expr) {
     }
   }
 
-  mutation_tree_path_.back()->AddMutation(std::make_unique<MutationReplaceExpr>(
+  AddMutation(std::make_unique<MutationReplaceExpr>(
       *expr, compiler_instance_->getPreprocessor(),
       compiler_instance_->getASTContext()));
 }
@@ -588,15 +586,18 @@ bool MutateVisitor::TraverseCompoundStmt(clang::CompoundStmt* compound_stmt) {
     assert(!enclosing_decls_.empty() &&
            "Statements can only be removed if they are nested in some "
            "declaration.");
-    UpdateStartLocationOfFirstFunctionInSourceFile();
-    mutation_tree_path_.back()->AddMutation(
-        std::make_unique<MutationRemoveStmt>(
-            *target_stmt, compiler_instance_->getPreprocessor(),
-            compiler_instance_->getASTContext()));
+    AddMutation(std::make_unique<MutationRemoveStmt>(
+        *target_stmt, compiler_instance_->getPreprocessor(),
+        compiler_instance_->getASTContext()));
   }
   return true;
 }
 
+void MutateVisitor::AddMutation(std::unique_ptr<Mutation> mutation) {
+  UpdateStartLocationOfFirstFunctionInSourceFile();
+  mutation_tree_path_.back()->AddMutation(std::move(mutation));
+}
+
 bool MutateVisitor::VisitVarDecl(clang::VarDecl* var_decl) {
   var_decl_source_locations_.insert(var_decl->getLocation());
   return true;