Simplify strHex:

Problem:
- There are several specific overloads with some custom code that can be
  easily replaced using Boost.Hex.

Solution:
- Introduce `strHex(itr, itr)` to return a string given a begin and end
  iterator.
- Remove `strHex(itr, size)` in favor of the `strHex(T)` where T is
  something that has a `begin()` member function. This allows us to
  remove the strHex overloads for `std::string`, Blob, and Slice.

src/ripple/basics/Buffer.h

@@ -39,6 +39,8 @@ private:
     std::size_t size_ = 0;
 
 public:
+    using const_iterator = std::uint8_t const*;
+
     Buffer() = default;
 
     /** Create an uninitialized buffer with the given size. */
@@ -191,6 +193,30 @@ public:
     {
         return alloc(n);
     }
+
+    const_iterator
+    begin() const noexcept
+    {
+        return p_.get();
+    }
+
+    const_iterator
+    cbegin() const noexcept
+    {
+        return p_.get();
+    }
+
+    const_iterator
+    end() const noexcept
+    {
+        return p_.get() + size_;
+    }
+
+    const_iterator
+    cend() const noexcept
+    {
+        return p_.get() + size_;
+    }
 };
 
 inline bool operator==(Buffer const& lhs, Buffer const& rhs) noexcept

src/ripple/basics/Slice.h

@@ -47,6 +47,8 @@ private:
     std::size_t size_ = 0;
 
 public:
+    using const_iterator = std::uint8_t const*;
+
     /** Default constructed Slice has length 0. */
     Slice() noexcept = default;
 
@@ -114,6 +116,31 @@ public:
         return temp += n;
     }
     /** @} */
+
+
+    const_iterator
+    begin() const noexcept
+    {
+        return data_;
+    }
+
+    const_iterator
+    cbegin() const noexcept
+    {
+        return data_;
+    }
+
+    const_iterator
+    end() const noexcept
+    {
+        return data_ + size_;
+    }
+
+    const_iterator
+    cend() const noexcept
+    {
+        return data_ + size_;
+    }
 };
 
 //------------------------------------------------------------------------------
@@ -159,7 +186,7 @@ operator< (Slice const& lhs, Slice const& rhs) noexcept
 template <class Stream>
 Stream& operator<<(Stream& s, Slice const& v)
 {
-    s << strHex(v.data(), v.size());
+    s << strHex(v);
     return s;
 }
 
@@ -192,9 +219,6 @@ makeSlice (std::basic_string<char, Traits, Alloc> const& s)
     return Slice(s.data(), s.size());
 }
 
-std::string
-strHex (Slice const& slice);
-
 } // ripple
 
 #endif

src/ripple/basics/StringUtilities.h

@@ -22,32 +22,13 @@
 
 #include <ripple/basics/Blob.h>
 #include <ripple/basics/strHex.h>
-#include <boost/endian/conversion.hpp>
+
 #include <boost/format.hpp>
 #include <boost/optional.hpp>
 #include <sstream>
 #include <string>
 
 namespace ripple {
-
-// NIKB TODO Remove the need for all these overloads. Move them out of here.
-inline const std::string strHex (std::string const& strSrc)
-{
-    return strHex (strSrc.begin (), strSrc.size ());
-}
-
-inline std::string strHex (Blob const& vucData)
-{
-    return strHex (vucData.begin (), vucData.size ());
-}
-
-inline std::string strHex (const std::uint64_t uiHost)
-{
-    uint64_t    uBig    = boost::endian::native_to_big (uiHost);
-
-    return strHex ((unsigned char*) &uBig, sizeof (uBig));
-}
-
 inline static std::string sqlEscape (std::string const& strSrc)
 {
     static boost::format f ("X'%s'");

src/ripple/basics/base_uint.h

@@ -510,7 +510,7 @@ inline const base_uint<Bits, Tag> operator+ (
 template <std::size_t Bits, class Tag>
 inline std::string to_string (base_uint<Bits, Tag> const& a)
 {
-    return strHex (a.begin (), a.size ());
+    return strHex (a.cbegin (), a.cend ());
 }
 
 // Function templates that return a base_uint given text in hexadecimal.

src/ripple/basics/impl/strHex.cpp

@@ -17,9 +17,9 @@
 */
 //==============================================================================
 
-#include <ripple/basics/Slice.h>
 #include <ripple/basics/strHex.h>
 #include <algorithm>
+#include <string>
 
 namespace ripple {
 
@@ -51,10 +51,4 @@ int charUnHex (unsigned char c)
     return xtab[c];
 }
 
-std::string
-strHex(Slice const& slice)
-{
-    return strHex(slice.data(), slice.size());
-}
-
 }

src/ripple/basics/strHex.h

@@ -28,6 +28,9 @@
 #include <cassert>
 #include <string>
 
+#include <boost/algorithm/hex.hpp>
+#include <boost/endian/conversion.hpp>
+
 namespace ripple {
 
 /** Converts an integer to the corresponding hex digit
@@ -62,22 +65,35 @@ charUnHex (char c)
 }
 /** @} */
 
-// NIKB TODO cleanup this function and reduce the need for the many overloads
-//           it has in various places.
 template <class FwdIt>
-std::string strHex (FwdIt first, int size)
+std::string
+strHex(FwdIt begin, FwdIt end)
 {
-    std::string s;
-    s.resize (size * 2);
-    for (int i = 0; i < size; i++)
-    {
-        unsigned char c = *first++;
-        s[i * 2]     = charHex (c >> 4);
-        s[i * 2 + 1] = charHex (c & 15);
-    }
-    return s;
+    static_assert(
+        std::is_convertible<
+            typename std::iterator_traits<FwdIt>::iterator_category,
+            std::forward_iterator_tag>::value,
+        "FwdIt must be a forward iterator");
+    std::string result;
+    result.reserve(2 * std::distance(begin, end));
+    boost::algorithm::hex(begin, end, std::back_inserter(result));
+    return result;
 }
 
+template <class T, class = decltype(std::declval<T>().begin())>
+std::string strHex(T const& from)
+{
+    return strHex(from.begin(), from.end());
+}
+
+inline std::string strHex (const std::uint64_t uiHost)
+{
+    uint64_t uBig    = boost::endian::native_to_big (uiHost);
+
+    auto const begin = (unsigned char*) &uBig;
+    auto const end   = begin + sizeof(uBig);
+    return strHex(begin, end);
+}
 }
 
 #endif

src/ripple/protocol/PublicKey.h

@@ -63,6 +63,8 @@ protected:
     std::uint8_t buf_[33]; // should be large enough
 
 public:
+    using const_iterator = std::uint8_t const*;
+
     PublicKey() = default;
     PublicKey (PublicKey const& other);
     PublicKey& operator= (PublicKey const& other);
@@ -87,6 +89,30 @@ public:
         return size_;
     }
 
+    const_iterator
+    begin() const noexcept
+    {
+        return buf_;
+    }
+
+    const_iterator
+    cbegin() const noexcept
+    {
+        return buf_;
+    }
+
+    const_iterator
+    end() const noexcept
+    {
+        return buf_ + size_;
+    }
+
+    const_iterator
+    cend() const noexcept
+    {
+        return buf_ + size_;
+    }
+
     bool
     empty() const noexcept
     {

src/ripple/protocol/STPathSet.h

@@ -120,7 +120,7 @@ public:
     STPathElement(STPathElement const&) = default;
     STPathElement& operator=(STPathElement const&) = default;
 
-    int
+    auto
     getNodeType () const
     {
         return mType;

src/ripple/protocol/SecretKey.h

@@ -38,6 +38,8 @@ private:
     std::uint8_t buf_[32];
 
 public:
+    using const_iterator = std::uint8_t const*;
+
     SecretKey() = default;
     SecretKey (SecretKey const&) = default;
     SecretKey& operator= (SecretKey const&) = default;
@@ -66,6 +68,30 @@ public:
     */
     std::string
     to_string() const;
+
+    const_iterator
+    begin() const noexcept
+    {
+        return buf_;
+    }
+
+    const_iterator
+    cbegin() const noexcept
+    {
+        return buf_;
+    }
+
+    const_iterator
+    end() const noexcept
+    {
+        return buf_ + sizeof(buf_);
+    }
+
+    const_iterator
+    cend() const noexcept
+    {
+        return buf_ + sizeof(buf_);
+    }
 };
 
 inline

src/ripple/protocol/Seed.h

@@ -35,6 +35,8 @@ private:
     std::array<uint8_t, 16> buf_;
 
 public:
+    using const_iterator = std::array<uint8_t, 16>::const_iterator;
+
     Seed() = delete;
 
     Seed (Seed const&) = default;
@@ -62,6 +64,30 @@ public:
     {
         return buf_.size();
     }
+
+    const_iterator
+    begin() const noexcept
+    {
+        return buf_.begin();
+    }
+
+    const_iterator
+    cbegin() const noexcept
+    {
+        return buf_.cbegin();
+    }
+
+    const_iterator
+    end() const noexcept
+    {
+        return buf_.end();
+    }
+
+    const_iterator
+    cend() const noexcept
+    {
+        return buf_.cend();
+    }
 };
 
 //------------------------------------------------------------------------------

src/ripple/protocol/impl/PublicKey.cpp

@@ -31,7 +31,7 @@ namespace ripple {
 std::ostream&
 operator<<(std::ostream& os, PublicKey const& pk)
 {
-    os << strHex(pk.data(), pk.size());
+    os << strHex(pk);
     return os;
 }
 

src/ripple/protocol/impl/STBlob.cpp

@@ -31,7 +31,7 @@ STBlob::STBlob (SerialIter& st, SField const& name)
 std::string
 STBlob::getText () const
 {
-    return strHex (value_.data (), value_.size ());
+    return strHex (value_);
 }
 
 bool

src/ripple/protocol/impl/STPathSet.cpp

@@ -156,7 +156,7 @@ STPath::getJson (int) const
     for (auto it: mPath)
     {
         Json::Value elem (Json::objectValue);
-        int         iType   = it.getNodeType ();
+        auto const iType   = it.getNodeType ();
 
         elem[jss::type]      = iType;
         elem[jss::type_hex]  = strHex (iType);

src/ripple/protocol/impl/SecretKey.cpp

@@ -51,7 +51,7 @@ SecretKey::SecretKey (Slice const& slice)
 std::string
 SecretKey::to_string() const
 {
-    return strHex(data(), size());
+    return strHex(*this);
 }
 
 //------------------------------------------------------------------------------

src/ripple/protocol/impl/UintTypes.cpp

@@ -61,7 +61,7 @@ std::string to_string(Currency const& currency)
         }
     }
 
-    return strHex (currency.begin (), currency.size ());
+    return strHex (currency);
 }
 
 bool to_currency(Currency& currency, std::string const& code)

src/ripple/rpc/handlers/WalletPropose.cpp

@@ -108,7 +108,7 @@ Json::Value walletPropose (Json::Value const& params)
     Json::Value obj (Json::objectValue);
 
     auto const seed1751 = seedAs1751 (*seed);
-    auto const seedHex = strHex (seed->data(), seed->size());
+    auto const seedHex = strHex (*seed);
     auto const seedBase58 = toBase58 (*seed);
 
     obj[jss::master_seed] = seedBase58;
@@ -117,7 +117,7 @@ Json::Value walletPropose (Json::Value const& params)
     obj[jss::account_id] = toBase58(calcAccountID(publicKey));
     obj[jss::public_key] = toBase58(TokenType::AccountPublic, publicKey);
     obj[jss::key_type] = to_string (keyType);
-    obj[jss::public_key_hex] = strHex (publicKey.data(), publicKey.size());
+    obj[jss::public_key_hex] = strHex (publicKey);
 
     // If a passphrase was specified, and it was hashed and used as a seed
     // run a quick entropy check and add an appropriate warning, because

src/test/rpc/AccountSet_test.cpp

@@ -212,7 +212,8 @@ public:
         env(jt);
         BEAST_EXPECT(! env.le(alice)->isFieldPresent(sfMessageKey));
 
-        jt[sfMessageKey.fieldName] = strHex("NOT_REALLY_A_PUBKEY");
+        using namespace std::string_literals;
+        jt[sfMessageKey.fieldName] = strHex("NOT_REALLY_A_PUBKEY"s);
         env(jt, ter(telBAD_PUBLIC_KEY));
     }