Tighten up the yamilizer so it stops eliding empty sequences if the embedded empty sequence is the first key/value in a map which is itself in a sequence.

Patch with help from Nick Kledzik.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@188508 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 4 insertions, 2 deletions

diff --git a/include/llvm/Support/YAMLTraits.h b/include/llvm/Support/YAMLTraits.h
index 0f57f44..98964fc 100644
--- a/include/llvm/Support/YAMLTraits.h
+++ b/include/llvm/Support/YAMLTraits.h
@@ -323,6 +323,7 @@ public:
   virtual bool preflightElement(unsigned, void *&) = 0;
   virtual void postflightElement(void*) = 0;
   virtual void endSequence() = 0;
+  virtual bool canElideEmptySequence() = 0;
 
   virtual unsigned beginFlowSequence() = 0;
   virtual bool preflightFlowElement(unsigned, void *&) = 0;
@@ -388,7 +389,7 @@ public:
   typename llvm::enable_if_c<has_SequenceTraits<T>::value,void>::type
   mapOptional(const char* Key, T& Val) {
     // omit key/value instead of outputting empty sequence
-    if ( this->outputting() && !(Val.begin() != Val.end()) )
+    if ( this->canElideEmptySequence() && !(Val.begin() != Val.end()) )
       return;
     this->processKey(Key, Val, false);
   }
@@ -715,6 +716,7 @@ private:
   virtual void endBitSetScalar();
   virtual void scalarString(StringRef &);
   virtual void setError(const Twine &message);
+  virtual bool canElideEmptySequence();
 
   class HNode {
   public:
@@ -837,7 +839,7 @@ public:
   virtual void endBitSetScalar();
   virtual void scalarString(StringRef &);
   virtual void setError(const Twine &message);
-
+  virtual bool canElideEmptySequence();
 public:
   // These are only used by operator<<. They could be private
   // if that templated operator could be made a friend.