Improvements for epee binary to hex functions:

  - Performance improvements
  - Added `span` for zero-copy pointer+length arguments
  - Added `std::ostream` overload for direct writing to output buffers
  - Removal of unused `string_tools::buff_to_hex`

1 files changed, 82 insertions, 0 deletions

diff --git a/contrib/epee/src/hex.cpp b/contrib/epee/src/hex.cpp
new file mode 100644
index 000000000..6a698b5a9
--- /dev/null
+++ b/contrib/epee/src/hex.cpp
@@ -0,0 +1,82 @@
+// Copyright (c) 2017, The Monero Project
+//
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without modification, are
+// permitted provided that the following conditions are met:
+//
+// 1. Redistributions of source code must retain the above copyright notice, this list of
+//    conditions and the following disclaimer.
+//
+// 2. Redistributions in binary form must reproduce the above copyright notice, this list
+//    of conditions and the following disclaimer in the documentation and/or other
+//    materials provided with the distribution.
+//
+// 3. Neither the name of the copyright holder nor the names of its contributors may be
+//    used to endorse or promote products derived from this software without specific
+//    prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include "hex.h"
+
+#include <iterator>
+#include <limits>
+#include <ostream>
+#include <stdexcept>
+
+namespace epee
+{
+  namespace
+  {
+    template<typename T>
+    void write_hex(T&& out, const view<std::uint8_t> src)
+    {
+      static constexpr const char hex[] = u8"0123456789abcdef";
+      static_assert(sizeof(hex) == 17, "bad string size");
+      for (const std::uint8_t byte : src)
+      {
+        *out = hex[byte >> 4];
+        ++out;
+        *out = hex[byte & 0x0F];
+        ++out;
+      }
+    }
+  }
+
+  std::string to_hex::string(const view<std::uint8_t> src)
+  {
+    if (std::numeric_limits<std::size_t>::max() / 2 < src.size())
+      throw std::range_error("hex_view::to_string exceeded maximum size");
+
+    std::string out{};
+    out.resize(src.size() * 2);
+    buffer_unchecked(std::addressof(out[0]), src);
+    return out;
+  }
+
+  void to_hex::buffer(std::ostream& out, const view<std::uint8_t> src)
+  {
+    write_hex(std::ostreambuf_iterator<char>{out}, src);
+  }
+
+  void to_hex::formatted(std::ostream& out, const view<std::uint8_t> src)
+  {
+    out.put('<');
+    buffer(out, src);
+    out.put('>');
+  }
+
+  void to_hex::buffer_unchecked(char* out, const view<std::uint8_t> src) noexcept
+  {
+    return write_hex(out, src);
+  }
+}