Make signature cache optional

src/script/sigcache.h

@@ -0,0 +1,34 @@
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2013 The Bitcoin developers
+// Distributed under the MIT/X11 software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef H_BITCOIN_SCRIPT_SIGCACHE
+#define H_BITCOIN_SCRIPT_SIGCACHE
+
+#include "script/interpreter.h"
+
+#include <vector>
+
+class CPubKey;
+
+class CachingSignatureChecker : public SignatureChecker
+{
+public:
+    CachingSignatureChecker(const CTransaction& txToIn, unsigned int nInIn) : SignatureChecker(txToIn, nInIn) {}
+
+    bool VerifySignature(const std::vector<unsigned char>& vchSig, const CPubKey& vchPubKey, const uint256& sighash, int flags) const;
+};
+
+// Wrappers using a default SignatureChecker.
+bool inline EvalScript(std::vector<std::vector<unsigned char> >& stack, const CScript& script, const CTransaction& txTo, unsigned int nIn, unsigned int flags)
+{
+    return EvalScript(stack, script, flags, CachingSignatureChecker(txTo, nIn));
+}
+
+bool inline VerifyScript(const CScript& scriptSig, const CScript& scriptPubKey, const CTransaction& txTo, unsigned int nIn, unsigned int flags)
+{
+    return VerifyScript(scriptSig, scriptPubKey, flags, CachingSignatureChecker(txTo, nIn));
+}
+
+#endif