From cf703f3e302312e1602fe46dc2c1e32dee786e6b Mon Sep 17 00:00:00 2001
From: Karen Arutyunov <karen@codesynthesis.com>
Date: Thu, 8 Jun 2017 23:23:07 +0300
Subject: Add to_stream(duration) and to_string(duration)

---
 libbutl/timestamp.cxx | 43 ++++++++++++++++++++++++++++---------------
 libbutl/timestamp.hxx | 18 ++++++++++++++++--
 2 files changed, 44 insertions(+), 17 deletions(-)

diff --git a/libbutl/timestamp.cxx b/libbutl/timestamp.cxx
index cf84dd5..aae4622 100644
--- a/libbutl/timestamp.cxx
+++ b/libbutl/timestamp.cxx
@@ -232,7 +232,7 @@ namespace butl
   }
 
   ostream&
-  operator<< (ostream& os, const duration& d)
+  to_stream (ostream& os, const duration& d, bool ns)
   {
     if (os.width () != 0) // We always print nanosecond.
       throw runtime_error (
@@ -300,29 +300,42 @@ namespace butl
 
     using namespace chrono;
 
-    timestamp sec (system_clock::from_time_t (t));
-    nanoseconds ns (duration_cast<nanoseconds> (ts - sec));
-
-    if (ns != nanoseconds::zero ())
+    if (ns)
     {
-      if (fmt != nullptr)
+      timestamp sec (system_clock::from_time_t (t));
+      nanoseconds nsec (duration_cast<nanoseconds> (ts - sec));
+
+      if (nsec != nanoseconds::zero ())
       {
-        ostream::fmtflags fl (os.flags ());
-        char fc (os.fill ('0'));
-        os << '.' << dec << right << setw (9) << ns.count ();
-        os.fill (fc);
-        os.flags (fl);
-      }
-      else
-        os << ns.count ();
+        if (fmt != nullptr)
+        {
+          ostream::fmtflags fl (os.flags ());
+          char fc (os.fill ('0'));
+          os << '.' << dec << right << setw (9) << nsec.count ();
+          os.fill (fc);
+          os.flags (fl);
+        }
+        else
+          os << nsec.count ();
 
-      os << ' ' << unt;
+        os << ' ' << unt;
+      }
+      else if (fmt == nullptr)
+        os << '0';
     }
     else if (fmt == nullptr)
       os << '0';
 
     return os;
   }
+
+  string
+  to_string (const duration& d, bool nsec)
+  {
+    ostringstream o;
+    to_stream (o, d, nsec);
+    return o.str ();
+  }
 }
 
 // Implementation of strptime() and timegm() for Windows.
diff --git a/libbutl/timestamp.hxx b/libbutl/timestamp.hxx
index 9fb0f59..8a5c71a 100644
--- a/libbutl/timestamp.hxx
+++ b/libbutl/timestamp.hxx
@@ -88,7 +88,7 @@ namespace butl
              bool special,
              bool local);
 
-  // Same as above, but provide the result as string. Note that it is
+  // Same as above, but provide the result as a string. Note that it is
   // implemented via to_stream() and std::ostringstream.
   //
   LIBBUTL_EXPORT std::string
@@ -103,8 +103,22 @@ namespace butl
     return to_stream (os, ts, "%Y-%m-%d %H:%M:%S%[.N]", true, true);
   }
 
+  // Print human-readable representation of the duration.
+  //
   LIBBUTL_EXPORT std::ostream&
-  operator<< (std::ostream&, const duration&);
+  to_stream (std::ostream&, const duration&, bool nanoseconds);
+
+  // Same as above, but provide the result as a string. Note that it is
+  // implemented via to_stream() and std::ostringstream.
+  //
+  LIBBUTL_EXPORT std::string
+  to_string (const duration&, bool nanoseconds);
+
+  inline std::ostream&
+  operator<< (std::ostream& os, const duration& d)
+  {
+    return to_stream (os, d, true);
+  }
 
   // Parse human-readable representation of the timestamp.
   //
-- 
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