Merge #19660: refactor: Make HexStr take a span

0a8aa626dd69a357e1b798b07b64cf4177a464a3 refactor: Make HexStr take a span (Wladimir J. van der Laan)

Pull request description:

  Make `HexSt`r take a span of bytes, instead of an awkward pair of templated iterators. This simplifies most of the uses.

ACKs for top commit:
  elichai:
    Code review ACK 0a8aa626dd69a357e1b798b07b64cf4177a464a3
  hebasto:
    re-ACK 0a8aa626dd69a357e1b798b07b64cf4177a464a3
  jonatack:
    re-ACK 0a8aa626dd69a357e1b798b07b64cf4177a464a3

Tree-SHA512: 6e178ece5cbac62119c857a10299b1e85422938084c3f03063e17119a5129e0c28016e05a6fabaa4c271a7e0a37c7cd89fa47c435ee19b38a5acfe80d00de992

2 files changed, 19 insertions, 21 deletions

diff --git a/src/util/strencodings.cpp b/src/util/strencodings.cpp
index 3a903b6897..d10f92ffe6 100644
--- a/src/util/strencodings.cpp
+++ b/src/util/strencodings.cpp
@@ -569,3 +569,16 @@ std::string Capitalize(std::string str)
     str[0] = ToUpper(str.front());
     return str;
 }
+
+std::string HexStr(const Span<const uint8_t> s)
+{
+    std::string rv;
+    static constexpr char hexmap[16] = { '0', '1', '2', '3', '4', '5', '6', '7',
+                                         '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
+    rv.reserve(s.size() * 2);
+    for (uint8_t v: s) {
+        rv.push_back(hexmap[v >> 4]);
+        rv.push_back(hexmap[v & 15]);
+    }
+    return rv;
+}
diff --git a/src/util/strencodings.h b/src/util/strencodings.h
index bd988f1410..eaa0fa9992 100644
--- a/src/util/strencodings.h
+++ b/src/util/strencodings.h
@@ -10,6 +10,7 @@
 #define BITCOIN_UTIL_STRENCODINGS_H
 
 #include <attributes.h>
+#include <span.h>
 
 #include <cstdint>
 #include <iterator>
@@ -119,27 +120,11 @@ NODISCARD bool ParseUInt64(const std::string& str, uint64_t *out);
  */
 NODISCARD bool ParseDouble(const std::string& str, double *out);
 
-template<typename T>
-std::string HexStr(const T itbegin, const T itend)
-{
-    std::string rv;
-    static const char hexmap[16] = { '0', '1', '2', '3', '4', '5', '6', '7',
-                                     '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
-    rv.reserve(std::distance(itbegin, itend) * 2);
-    for(T it = itbegin; it < itend; ++it)
-    {
-        unsigned char val = (unsigned char)(*it);
-        rv.push_back(hexmap[val>>4]);
-        rv.push_back(hexmap[val&15]);
-    }
-    return rv;
-}
-
-template<typename T>
-inline std::string HexStr(const T& vch)
-{
-    return HexStr(vch.begin(), vch.end());
-}
+/**
+ * Convert a span of bytes to a lower-case hexadecimal string.
+ */
+std::string HexStr(const Span<const uint8_t> s);
+inline std::string HexStr(const Span<const char> s) { return HexStr(MakeUCharSpan(s)); }
 
 /**
  * Format a paragraph of text to a fixed width, adding spaces for