src: small modification to NgHeader

This is separated out of the QUIC PR. It is not specific to QUIC but
provides a new base class that is used there as an abstraction of
the actual implementation. This is a purely internal implementation
detail that has no outward functional changes (so no need for tests)

Signed-off-by: James M Snell <jasnell@gmail.com>

PR-URL: #33289
Reviewed-By: Sam Roberts <vieuxtech@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: David Carlier <devnexen@gmail.com>

src/node_http_common-inl.h

@@ -76,6 +76,14 @@ size_t GetServerMaxHeaderPairs(size_t max_header_pairs) {
   return std::max(max_header_pairs, min_header_pairs);
 }
 
+template <typename allocator_t>
+std::string NgHeaderBase<allocator_t>::ToString() const {
+  std::string ret = name();
+  ret += " = ";
+  ret += value();
+  return ret;
+}
+
 template <typename T>
 bool NgHeader<T>::IsZeroLength(
     NgHeader<T>::rcbuf_t* name,
@@ -132,6 +140,12 @@ NgHeader<T>::NgHeader(NgHeader<T>&& other) noexcept
   other.env_ = nullptr;
 }
 
+template <typename T>
+void NgHeader<T>::MemoryInfo(MemoryTracker* tracker) const {
+  tracker->TrackField("name", name_);
+  tracker->TrackField("value", value_);
+}
+
 template <typename T>
 v8::MaybeLocal<v8::String> NgHeader<T>::GetName(
     NgHeader<T>::allocator_t* allocator) const {

src/node_http_common.h

@@ -453,6 +453,16 @@ class NgRcBufPointer : public MemoryRetainer {
   bool internalizable_ = false;
 };
 
+template <typename allocator_t>
+struct NgHeaderBase : public MemoryRetainer {
+  virtual v8::MaybeLocal<v8::String> GetName(allocator_t* allocator) const = 0;
+  virtual v8::MaybeLocal<v8::String> GetValue(allocator_t* allocator) const = 0;
+  virtual std::string name() const = 0;
+  virtual std::string value() const = 0;
+  virtual size_t length() const = 0;
+  virtual std::string ToString() const;
+};
+
 // The ng libraries use nearly identical structs to represent
 // received http headers. The NgHeader class wraps those in a
 // consistent way and allows converting the name and value to
@@ -461,7 +471,7 @@ class NgRcBufPointer : public MemoryRetainer {
 // memory tracking, and implementation of static utility functions.
 // See Http2HeaderTraits in node_http2.h for an example.
 template <typename T>
-class NgHeader : public MemoryRetainer {
+class NgHeader final : public NgHeaderBase<typename T::allocator_t> {
  public:
   typedef typename T::rcbufferpointer_t rcbufferpointer_t;
   typedef typename T::rcbufferpointer_t::rcbuf_t rcbuf_t;
@@ -487,28 +497,20 @@ class NgHeader : public MemoryRetainer {
   // object to the v8 string. Once the v8 string is garbage collected,
   // the reference counter will be decremented.
 
-  inline v8::MaybeLocal<v8::String> GetName(allocator_t* allocator) const;
-  inline v8::MaybeLocal<v8::String> GetValue(allocator_t* allocator) const;
+  inline v8::MaybeLocal<v8::String> GetName(
+      allocator_t* allocator) const override;
+  inline v8::MaybeLocal<v8::String> GetValue(
+      allocator_t* allocator) const override;
 
-  inline std::string name() const;
-  inline std::string value() const;
-  inline size_t length() const;
+  inline std::string name() const override;
+  inline std::string value() const override;
+  inline size_t length() const override;
 
-  void MemoryInfo(MemoryTracker* tracker) const override {
-    tracker->TrackField("name", name_);
-    tracker->TrackField("value", value_);
-  }
+  void MemoryInfo(MemoryTracker* tracker) const override;
 
   SET_MEMORY_INFO_NAME(NgHeader)
   SET_SELF_SIZE(NgHeader)
 
-  std::string ToString() const {
-    std::string ret = name();
-    ret += " = ";
-    ret += value();
-    return ret;
-  }
-
  private:
   Environment* env_;
   rcbufferpointer_t name_;