Add string that optimized for integer positive values serialization.

1 files changed, 64 insertions, 0 deletions

diff --git a/coding/value_opt_string.hpp b/coding/value_opt_string.hpp
new file mode 100644
index 0000000000..7bbdf5cd24
--- /dev/null
+++ b/coding/value_opt_string.hpp
@@ -0,0 +1,64 @@
+#pragma once
+
+#include "varint.hpp"
+
+#include "../base/string_utils.hpp"
+#include "../base/assert.hpp"
+
+#include "../std/string.hpp"
+
+
+class StringNumericOptimal
+{
+  string m_s;
+
+  static const uint8_t numeric_bit = 1;
+
+public:
+  inline void Set(string const & s)
+  {
+    CHECK ( !s.empty(), () );
+    m_s = s;
+  }
+  inline void Set(char const * p)
+  {
+    m_s = p;
+    CHECK ( !m_s.empty(), () );
+  }
+  template <class T> void Set(T const & s)
+  {
+    m_s = utils::to_string(s);
+    CHECK ( !m_s.empty(), () );
+  }
+
+  inline string Get() const { return m_s; }
+
+  template <class TSink> void Write(TSink & sink)
+  {
+    int n;
+    if (utils::to_int(m_s, n) && n >= 0)
+      WriteVarUint(sink, static_cast<uint32_t>((n << 1) | numeric_bit));
+    else
+    {
+      size_t const sz = m_s.size();
+      ASSERT_GREATER ( sz, 0, () );
+
+      WriteVarUint(sink, static_cast<uint32_t>((sz-1) << 1));
+      sink.Write(m_s.c_str(), sz);
+    }
+  }
+
+  template <class TSource> void Read(TSource & src)
+  {
+    uint32_t sz = ReadVarUint<uint32_t>(src);
+
+    if ((sz & numeric_bit) != 0)
+      m_s = utils::to_string(sz >> 1);
+    else
+    {
+      sz = (sz >> 1) + 1;
+      m_s.resize(sz);
+      src.Read(&m_s[0], sz);
+    }
+  }
+};