Move my ostream_string function to the IO library

include/boost/io/ostream_put.hpp

@@ -0,0 +1,97 @@
+/*
+Copyright 2019 Glen Joseph Fernandes
+(glenjofe@gmail.com)
+
+Distributed under the Boost Software License, Version 1.0.
+(http://www.boost.org/LICENSE_1_0.txt)
+*/
+#ifndef BOOST_IO_OSTREAM_PUT_HPP
+#define BOOST_IO_OSTREAM_PUT_HPP
+
+#include <boost/config.hpp>
+#include <iosfwd>
+#include <cstddef>
+
+namespace boost {
+namespace io {
+namespace detail {
+
+template<class charT, class traits>
+inline std::size_t
+osp_put(std::basic_ostream<charT, traits>& os, const charT* data,
+    std::size_t size)
+{
+    return static_cast<std::size_t>(os.rdbuf()->sputn(data, size));
+}
+
+template<class charT, class traits>
+inline bool
+osp_fill(std::basic_ostream<charT, traits>& os, std::size_t size)
+{
+    charT c = os.fill();
+    charT fill[] = { c, c, c, c, c, c, c, c };
+    enum {
+        chunk = sizeof fill / sizeof(charT)
+    };
+    for (; size > chunk; size -= chunk) {
+        if (boost::io::detail::osp_put(os, fill, chunk) != chunk) {
+            return false;
+        }
+    }
+    return boost::io::detail::osp_put(os, fill, size) == size;
+}
+
+template<class charT, class traits>
+class osp_guard {
+public:
+    explicit osp_guard(std::basic_ostream<charT, traits>& os) BOOST_NOEXCEPT
+        : os_(&os) { }
+    ~osp_guard() BOOST_NOEXCEPT_IF(false) {
+        if (os_) {
+            os_->setstate(std::basic_ostream<charT, traits>::badbit);
+        }
+    }
+    void release() BOOST_NOEXCEPT {
+        os_ = 0;
+    }
+private:
+    osp_guard(const osp_guard&);
+    osp_guard& operator=(const osp_guard&);
+    std::basic_ostream<charT, traits>* os_;
+};
+
+} /* detail */
+
+template<class charT, class traits>
+inline std::basic_ostream<charT, traits>&
+ostream_put(std::basic_ostream<charT, traits>& os, const charT* data,
+    std::size_t size)
+{
+    typedef std::basic_ostream<charT, traits> stream;
+    detail::osp_guard<charT, traits> guard(os);
+    typename stream::sentry entry(os);
+    if (entry) {
+        std::size_t width = static_cast<std::size_t>(os.width());
+        if (width <= size) {
+            if (detail::osp_put(os, data, size) != size) {
+                return os;
+            }
+        } else if ((os.flags() & stream::adjustfield) == stream::left) {
+            if (detail::osp_put(os, data, size) != size ||
+                !detail::osp_fill(os, width - size)) {
+                return os;
+            }
+        } else if (!detail::osp_fill(os, width - size) ||
+            detail::osp_put(os, data, size) != size) {
+            return os;
+        }
+        os.width(0);
+    }
+    guard.release();
+    return os;
+}
+
+} /* io */
+} /* boost */
+
+#endif