Overloaded __pad_and_output on ostreambuf_iterator and in this overload call sputn instead of dereferencing the iterator which calls sputc. This is intended to be purely a performance optimization, especially for clients who may have overloaded the virtual function xsputn.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@164241 91177308-0d34-0410-b5e6-96231b3b80d8

include/iterator

@@ -881,6 +881,14 @@ public:
     _LIBCPP_INLINE_VISIBILITY ostreambuf_iterator& operator++()    {return *this;}
     _LIBCPP_INLINE_VISIBILITY ostreambuf_iterator& operator++(int) {return *this;}
     _LIBCPP_INLINE_VISIBILITY bool failed() const _NOEXCEPT {return __sbuf_ == 0;}
+
+    template <class _Ch, class _Tr>
+    friend
+    _LIBCPP_HIDDEN
+    ostreambuf_iterator<_Ch, _Tr>
+    __pad_and_output(ostreambuf_iterator<_Ch, _Tr> __s,
+                     const _Ch* __ob, const _Ch* __op, const _Ch* __oe,
+                     ios_base& __iob, _Ch __fl);
 };
 
 template <class _Iter>

include/locale

@@ -1587,6 +1587,52 @@ __pad_and_output(_OutputIterator __s,
     return __s;
 }
 
+template <class _CharT, class _Traits>
+_LIBCPP_HIDDEN
+ostreambuf_iterator<_CharT, _Traits>
+__pad_and_output(ostreambuf_iterator<_CharT, _Traits> __s,
+                 const _CharT* __ob, const _CharT* __op, const _CharT* __oe,
+                 ios_base& __iob, _CharT __fl)
+{
+    if (__s.__sbuf_ == nullptr)
+        return __s;
+    streamsize __sz = __oe - __ob;
+    streamsize __ns = __iob.width();
+    if (__ns > __sz)
+        __ns -= __sz;
+    else
+        __ns = 0;
+    streamsize __np = __op - __ob;
+    if (__np > 0)
+    {
+        if (__s.__sbuf_->sputn(__ob, __np) != __np)
+        {
+            __s.__sbuf_ = nullptr;
+            return __s;
+        }
+    }
+    if (__ns > 0)
+    {
+        basic_string<_CharT, _Traits> __sp(__ns, __fl);
+        if (__s.__sbuf_->sputn(__sp.data(), __ns) != __ns)
+        {
+            __s.__sbuf_ = nullptr;
+            return __s;
+        }
+    }
+    __np = __oe - __op;
+    if (__np > 0)
+    {
+        if (__s.__sbuf_->sputn(__op, __np) != __np)
+        {
+            __s.__sbuf_ = nullptr;
+            return __s;
+        }
+    }
+    __iob.width(0);
+    return __s;
+}
+
 template <class _CharT, class _OutputIterator>
 _OutputIterator
 num_put<_CharT, _OutputIterator>::do_put(iter_type __s, ios_base& __iob,