Change NULL to nullptr (#805)

include/yaml-cpp/contrib/graphbuilder.h

@@ -15,7 +15,7 @@ class Parser;
 
 // GraphBuilderInterface
 // . Abstraction of node creation
-// . pParentNode is always NULL or the return value of one of the NewXXX()
+// . pParentNode is always nullptr or the return value of one of the NewXXX()
 //   functions.
 class GraphBuilderInterface {
  public:
@@ -73,9 +73,9 @@ class GraphBuilder : public GraphBuilderInterface {
   typedef typename Impl::Map Map;
 
   GraphBuilder(Impl &impl) : m_impl(impl) {
-    Map *pMap = NULL;
-    Sequence *pSeq = NULL;
-    Node *pNode = NULL;
+    Map *pMap = nullptr;
+    Sequence *pSeq = nullptr;
+    Node *pNode = nullptr;
 
     // Type consistency checks
     pNode = pMap;

include/yaml-cpp/node/detail/node.h

@@ -119,7 +119,7 @@ class node {
   template <typename Key>
   node* get(const Key& key, shared_memory_holder pMemory) const {
     // NOTE: this returns a non-const node so that the top-level Node can wrap
-    // it, and returns a pointer so that it can be NULL (if there is no such
+    // it, and returns a pointer so that it can be nullptr (if there is no such
     // key).
     return static_cast<const node_ref&>(*m_pRef).get(key, pMemory);
   }
@@ -136,7 +136,7 @@ class node {
 
   node* get(node& key, shared_memory_holder pMemory) const {
     // NOTE: this returns a non-const node so that the top-level Node can wrap
-    // it, and returns a pointer so that it can be NULL (if there is no such
+    // it, and returns a pointer so that it can be nullptr (if there is no such
     // key).
     return static_cast<const node_ref&>(*m_pRef).get(key, pMemory);
   }