Merge #12752: [MOVEONLY] Move compressor utility functions out of class

76a9aac Move compressor utility functions out of class (Pieter Wuille)

Pull request description:

  This is a refactor from #10785 with no functionality change.

  Move the compresion utility functions out of CScriptCompressor, as a preparation for making the class templated. I'm submitting it as a separate PR as I think it's a general improvement to code readability, and to reduce the diff further on.

Tree-SHA512: 3b3d17c2b96e43f752f512dd573296a6bb15cae165fbe3c79212a0970f5196a62a59a821d5100f29638af1e7461c9171f3dccb8112f005ee08da0ec7fe0073fd

Author: laanwj

src/compressor.cpp

@@ -9,7 +9,15 @@
 #include <pubkey.h>
 #include <script/standard.h>
 
-bool CScriptCompressor::IsToKeyID(CKeyID &hash) const
+/*
+ * These check for scripts for which a special case with a shorter encoding is defined.
+ * They are implemented separately from the CScript test, as these test for exact byte
+ * sequence correspondences, and are more strict. For example, IsToPubKey also verifies
+ * whether the public key is valid (as invalid ones cannot be represented in compressed
+ * form).
+ */
+
+static bool IsToKeyID(const CScript& script, CKeyID &hash)
 {
     if (script.size() == 25 && script[0] == OP_DUP && script[1] == OP_HASH160
                             && script[2] == 20 && script[23] == OP_EQUALVERIFY
@@ -20,7 +28,7 @@ bool CScriptCompressor::IsToKeyID(CKeyID &hash) const
     return false;
 }
 
-bool CScriptCompressor::IsToScriptID(CScriptID &hash) const
+static bool IsToScriptID(const CScript& script, CScriptID &hash)
 {
     if (script.size() == 23 && script[0] == OP_HASH160 && script[1] == 20
                             && script[22] == OP_EQUAL) {
@@ -30,7 +38,7 @@ bool CScriptCompressor::IsToScriptID(CScriptID &hash) const
     return false;
 }
 
-bool CScriptCompressor::IsToPubKey(CPubKey &pubkey) const
+static bool IsToPubKey(const CScript& script, CPubKey &pubkey)
 {
     if (script.size() == 35 && script[0] == 33 && script[34] == OP_CHECKSIG
                             && (script[1] == 0x02 || script[1] == 0x03)) {
@@ -45,24 +53,24 @@ bool CScriptCompressor::IsToPubKey(CPubKey &pubkey) const
     return false;
 }
 
-bool CScriptCompressor::Compress(std::vector<unsigned char> &out) const
+bool CompressScript(const CScript& script, std::vector<unsigned char> &out)
 {
     CKeyID keyID;
-    if (IsToKeyID(keyID)) {
+    if (IsToKeyID(script, keyID)) {
         out.resize(21);
         out[0] = 0x00;
         memcpy(&out[1], &keyID, 20);
         return true;
     }
     CScriptID scriptID;
-    if (IsToScriptID(scriptID)) {
+    if (IsToScriptID(script, scriptID)) {
         out.resize(21);
         out[0] = 0x01;
         memcpy(&out[1], &scriptID, 20);
         return true;
     }
     CPubKey pubkey;
-    if (IsToPubKey(pubkey)) {
+    if (IsToPubKey(script, pubkey)) {
         out.resize(33);
         memcpy(&out[1], &pubkey[1], 32);
         if (pubkey[0] == 0x02 || pubkey[0] == 0x03) {
@@ -76,7 +84,7 @@ bool CScriptCompressor::Compress(std::vector<unsigned char> &out) const
     return false;
 }
 
-unsigned int CScriptCompressor::GetSpecialSize(unsigned int nSize) const
+unsigned int GetSpecialScriptSize(unsigned int nSize)
 {
     if (nSize == 0 || nSize == 1)
         return 20;
@@ -85,7 +93,7 @@ unsigned int CScriptCompressor::GetSpecialSize(unsigned int nSize) const
     return 0;
 }
 
-bool CScriptCompressor::Decompress(unsigned int nSize, const std::vector<unsigned char> &in)
+bool DecompressScript(CScript& script, unsigned int nSize, const std::vector<unsigned char> &in)
 {
     switch(nSize) {
     case 0x00:
@@ -139,7 +147,7 @@ bool CScriptCompressor::Decompress(unsigned int nSize, const std::vector<unsigne
 // * if e==9, we only know the resulting number is not zero, so output 1 + 10*(n - 1) + 9
 // (this is decodable, as d is in [1-9] and e is in [0-9])
 
-uint64_t CTxOutCompressor::CompressAmount(uint64_t n)
+uint64_t CompressAmount(uint64_t n)
 {
     if (n == 0)
         return 0;
@@ -158,7 +166,7 @@ uint64_t CTxOutCompressor::CompressAmount(uint64_t n)
     }
 }
 
-uint64_t CTxOutCompressor::DecompressAmount(uint64_t x)
+uint64_t DecompressAmount(uint64_t x)
 {
     // x = 0  OR  x = 1+10*(9*n + d - 1) + e  OR  x = 1+10*(n - 1) + 9
     if (x == 0)

src/compressor.h

@@ -14,6 +14,13 @@ class CKeyID;
 class CPubKey;
 class CScriptID;
 
+bool CompressScript(const CScript& script, std::vector<unsigned char> &out);
+unsigned int GetSpecialScriptSize(unsigned int nSize);
+bool DecompressScript(CScript& script, unsigned int nSize, const std::vector<unsigned char> &out);
+
+uint64_t CompressAmount(uint64_t nAmount);
+uint64_t DecompressAmount(uint64_t nAmount);
+
 /** Compact serializer for scripts.
  *
  *  It detects common cases and encodes them much more efficiently.
@@ -37,28 +44,13 @@ class CScriptCompressor
     static const unsigned int nSpecialScripts = 6;
 
     CScript &script;
-protected:
-    /**
-     * These check for scripts for which a special case with a shorter encoding is defined.
-     * They are implemented separately from the CScript test, as these test for exact byte
-     * sequence correspondences, and are more strict. For example, IsToPubKey also verifies
-     * whether the public key is valid (as invalid ones cannot be represented in compressed
-     * form).
-     */
-    bool IsToKeyID(CKeyID &hash) const;
-    bool IsToScriptID(CScriptID &hash) const;
-    bool IsToPubKey(CPubKey &pubkey) const;
-
-    bool Compress(std::vector<unsigned char> &out) const;
-    unsigned int GetSpecialSize(unsigned int nSize) const;
-    bool Decompress(unsigned int nSize, const std::vector<unsigned char> &out);
 public:
     explicit CScriptCompressor(CScript &scriptIn) : script(scriptIn) { }
 
     template<typename Stream>
     void Serialize(Stream &s) const {
         std::vector<unsigned char> compr;
-        if (Compress(compr)) {
+        if (CompressScript(script, compr)) {
             s << CFlatData(compr);
             return;
         }
@@ -72,9 +64,9 @@ class CScriptCompressor
         unsigned int nSize = 0;
         s >> VARINT(nSize);
         if (nSize < nSpecialScripts) {
-            std::vector<unsigned char> vch(GetSpecialSize(nSize), 0x00);
+            std::vector<unsigned char> vch(GetSpecialScriptSize(nSize), 0x00);
             s >> CFlatData(vch);
-            Decompress(nSize, vch);
+            DecompressScript(script, nSize, vch);
             return;
         }
         nSize -= nSpecialScripts;
@@ -96,9 +88,6 @@ class CTxOutCompressor
     CTxOut &txout;
 
 public:
-    static uint64_t CompressAmount(uint64_t nAmount);
-    static uint64_t DecompressAmount(uint64_t nAmount);
-
     explicit CTxOutCompressor(CTxOut &txoutIn) : txout(txoutIn) { }
 
     ADD_SERIALIZE_METHODS;

src/test/compress_tests.cpp

@@ -25,16 +25,16 @@
 BOOST_FIXTURE_TEST_SUITE(compress_tests, BasicTestingSetup)
 
 bool static TestEncode(uint64_t in) {
-    return in == CTxOutCompressor::DecompressAmount(CTxOutCompressor::CompressAmount(in));
+    return in == DecompressAmount(CompressAmount(in));
 }
 
 bool static TestDecode(uint64_t in) {
-    return in == CTxOutCompressor::CompressAmount(CTxOutCompressor::DecompressAmount(in));
+    return in == CompressAmount(DecompressAmount(in));
 }
 
 bool static TestPair(uint64_t dec, uint64_t enc) {
-    return CTxOutCompressor::CompressAmount(dec) == enc &&
-           CTxOutCompressor::DecompressAmount(enc) == dec;
+    return CompressAmount(dec) == enc &&
+           DecompressAmount(enc) == dec;
 }
 
 BOOST_AUTO_TEST_CASE(compress_amounts)