From 1ef2d90be84feedabc36a83b433af51a6c11ef24 Mon Sep 17 00:00:00 2001
From: Pieter Wuille <pieter.wuille@gmail.com>
Date: Wed, 4 Apr 2018 12:40:10 -0700
Subject: [PATCH] Support serializing Span<unsigned char> and use that instead
 of FLATDATA

---
 src/compressor.h |  9 +++++----
 src/netaddress.h |  8 ++++++--
 src/serialize.h  | 48 +++++-------------------------------------------
 3 files changed, 16 insertions(+), 49 deletions(-)

diff --git a/src/compressor.h b/src/compressor.h
index 65ea6be0dd76b..a2ced07df35d2 100644
--- a/src/compressor.h
+++ b/src/compressor.h
@@ -10,6 +10,7 @@
 #include "primitives/transaction.h"
 #include "script/script.h"
 #include "serialize.h"
+#include "span.h"
 
 class CKeyID;
 class CPubKey;
@@ -63,12 +64,12 @@ class CScriptCompressor
     {
         std::vector<unsigned char> compr;
         if (Compress(compr)) {
-            s << CFlatData(compr);
+            s << MakeSpan(compr);
             return;
         }
         unsigned int nSize = script.size() + nSpecialScripts;
         s << VARINT(nSize);
-        s << CFlatData(script);
+        s << MakeSpan(script);
     }
 
     template <typename Stream>
@@ -78,7 +79,7 @@ class CScriptCompressor
         s >> VARINT(nSize);
         if (nSize < nSpecialScripts) {
             std::vector<unsigned char> vch(GetSpecialSize(nSize), 0x00);
-            s >> CFlatData(vch);
+            s >> MakeSpan(vch);
             Decompress(nSize, vch);
             return;
         }
@@ -89,7 +90,7 @@ class CScriptCompressor
             s.ignore(nSize);
         } else {
             script.resize(nSize);
-            s >> CFlatData(script);
+            s >> MakeSpan(script);
         }
     }
 };
diff --git a/src/netaddress.h b/src/netaddress.h
index e5f3ef6e19a52..f3dfc6fc1fd7f 100644
--- a/src/netaddress.h
+++ b/src/netaddress.h
@@ -12,6 +12,7 @@
 
 #include "compat.h"
 #include "serialize.h"
+#include "span.h"
 
 #include <stdint.h>
 #include <string>
@@ -171,10 +172,13 @@ class CService : public CNetAddr
     inline void SerializationOp(Stream& s, Operation ser_action)
     {
         READWRITE(ip);
+
+        // TODO: introduce native support for BE serialization in serialize.h
         unsigned short portN = htons(port);
-        READWRITE(FLATDATA(portN));
-        if (ser_action.ForRead())
+        READWRITE(Span<unsigned char>((unsigned char*)&portN, 2));
+        if (ser_action.ForRead()) {
             port = ntohs(portN);
+        }
     }
 };
 
diff --git a/src/serialize.h b/src/serialize.h
index dde4883be959a..5fc811a2b6c5d 100644
--- a/src/serialize.h
+++ b/src/serialize.h
@@ -27,6 +27,7 @@
 #include "libzerocoin/SpendType.h"
 #include "optional.h"
 #include "prevector.h"
+#include "span.h"
 #include "sporkid.h"
 
 class CScript;
@@ -49,7 +50,7 @@ constexpr deserialize_type deserialize {};
 
 /**
  * Used to bypass the rule against non-const reference to temporary
- * where it makes sense with wrappers such as CFlatData or CTxDB
+ * where it makes sense with wrappers.
  */
 template <typename T>
 inline T& REF(const T& val)
@@ -203,6 +204,8 @@ template<typename Stream> inline void Serialize(Stream& s, float a   ) { ser_wri
 template<typename Stream> inline void Serialize(Stream& s, double a  ) { ser_writedata64(s, ser_double_to_uint64(a)); }
 template<typename Stream, int N> inline void Serialize(Stream& s, const char (&a)[N]) { s.write(a, N); }
 template<typename Stream, int N> inline void Serialize(Stream& s, const unsigned char (&a)[N]) { s.write(CharCast(a), N); }
+template<typename Stream> inline void Serialize(Stream& s, const Span<const unsigned char>& span) { s.write(CharCast(span.data()), span.size()); }
+template<typename Stream> inline void Serialize(Stream& s, const Span<unsigned char>& span) { s.write(CharCast(span.data()), span.size()); }
 
 template<typename Stream> inline void Unserialize(Stream& s, char& a    ) { a = ser_readdata8(s); } // TODO Get rid of bare char
 template<typename Stream> inline void Unserialize(Stream& s, int8_t& a  ) { a = ser_readdata8(s); }
@@ -217,6 +220,7 @@ template<typename Stream> inline void Unserialize(Stream& s, float& a   ) { a =
 template<typename Stream> inline void Unserialize(Stream& s, double& a  ) { a = ser_uint64_to_double(ser_readdata64(s)); }
 template<typename Stream, int N> inline void Unserialize(Stream& s, char (&a)[N]) { s.read(a, N); }
 template<typename Stream, int N> inline void Unserialize(Stream& s, unsigned char (&a)[N]) { s.read(CharCast(a), N); }
+template<typename Stream> inline void Unserialize(Stream& s, Span<unsigned char>& span) { s.read(CharCast(span.data()), span.size()); }
 
 template<typename Stream> inline void Serialize(Stream& s, bool a)    { char f=a; ser_writedata8(s, f); }
 template<typename Stream> inline void Unserialize(Stream& s, bool& a) { char f=ser_readdata8(s); a=f; }
@@ -433,52 +437,10 @@ I ReadVarInt(Stream& is)
     }
 }
 
-#define FLATDATA(obj) CFlatData((char*)&(obj), (char*)&(obj) + sizeof(obj))
 #define VARINT(obj, ...) WrapVarInt<__VA_ARGS__>(REF(obj))
 #define COMPACTSIZE(obj) CCompactSize(REF(obj))
 #define LIMITED_STRING(obj,n) LimitedString< n >(REF(obj))
 
-/**
- * Wrapper for serializing arrays and POD.
- */
-class CFlatData
-{
-protected:
-    char* pbegin;
-    char* pend;
-
-public:
-    CFlatData(void* pbeginIn, void* pendIn) : pbegin((char*)pbeginIn), pend((char*)pendIn) {}
-    template <class T, class TAl>
-    explicit CFlatData(std::vector<T, TAl>& v)
-    {
-        pbegin = (char*)v.data();
-        pend = (char*)(v.data() + v.size());
-    }
-    template <unsigned int N, typename T, typename S, typename D>
-    explicit CFlatData(prevector<N, T, S, D> &v)
-    {
-        pbegin = (char*)v.data();
-        pend = (char*)(v.data() + v.size());
-    }
-    char* begin() { return pbegin; }
-    const char* begin() const { return pbegin; }
-    char* end() { return pend; }
-    const char* end() const { return pend; }
-
-    template <typename Stream>
-    void Serialize(Stream& s) const
-    {
-        s.write(pbegin, pend - pbegin);
-    }
-
-    template <typename Stream>
-    void Unserialize(Stream& s)
-    {
-        s.read(pbegin, pend - pbegin);
-    }
-};
-
 template<VarIntMode Mode, typename I>
 class CVarInt
 {