From dabf53a703f70ed6bdfb6b981fc326b9e9a10226 Mon Sep 17 00:00:00 2001
From: Glen Fernandes <glen.fernandes@gmail.com>
Date: Thu, 18 Apr 2019 16:30:40 -0400
Subject: [PATCH] Refactor stream write functionality into a standalone utility

---
 doc/Jamfile.v2                           |  15 ++-
 doc/ostream_string.qbk                   |  62 +++++++++++
 include/boost/utility/ostream_string.hpp |  95 ++++++++++++++++
 include/boost/utility/string_ref.hpp     |  68 +-----------
 include/boost/utility/string_view.hpp    |  68 +-----------
 index.html                               |   1 +
 test/Jamfile.v2                          |   2 +
 test/ostream_string_test.cpp             | 136 +++++++++++++++++++++++
 8 files changed, 314 insertions(+), 133 deletions(-)
 create mode 100644 doc/ostream_string.qbk
 create mode 100644 include/boost/utility/ostream_string.hpp
 create mode 100644 test/ostream_string_test.cpp

diff --git a/doc/Jamfile.v2 b/doc/Jamfile.v2
index dda8f39..b2d5229 100644
--- a/doc/Jamfile.v2
+++ b/doc/Jamfile.v2
@@ -99,6 +99,19 @@ boostbook standalone_declval
         <xsl:param>generate.section.toc.level=1
      ;
 
+xml ostream_string : ostream_string.qbk ;
+boostbook standalone_ostream_string
+    :
+        ostream_string
+    :
+        <xsl:param>root.filename=ostream_string
+        <xsl:param>chunk.section.depth=0
+        <xsl:param>chunk.first.sections=0
+        <xsl:param>toc.section.depth=1
+        <xsl:param>toc.max.depth=1
+        <xsl:param>generate.section.toc.level=1
+     ;
+
 xml string_ref : string_ref.qbk ;
 boostbook standalone_string_ref
     :
@@ -123,5 +136,5 @@ alias boostdoc ;
 explicit boostdoc ;
 alias boostrelease :
     standalone_base_from_member standalone_compressed_pair
-    standalone_declval standalone_string_ref ;
+    standalone_declval standalone_ostream_string standalone_string_ref ;
 explicit boostrelease ;
diff --git a/doc/ostream_string.qbk b/doc/ostream_string.qbk
new file mode 100644
index 0000000..a99ad0c
--- /dev/null
+++ b/doc/ostream_string.qbk
@@ -0,0 +1,62 @@
+[/
+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)
+]
+
+[article ostream_string
+[quickbook 1.5]
+[authors [Fernandes, Glen]]
+[copyright 2019 Glen Joseph Fernandes]
+[license Distributed under the Boost Software License, Version 1.0.]]
+
+[section Overview]
+
+The header <boost/utility/ostream_string.hpp> provides the function template
+boost::ostream_string for formatted output that satisfies the requirements of
+\[ostream.formatted.reqmts\].
+
+[endsect]
+
+[section Examples]
+
+The inserter for class template `basic_string_view` could be implemented as
+follows:
+
+```
+template<class charT, class traits>
+std::basic_ostream<charT, traits>&
+operator<<(std::basic_ostream<charT, traits>& os,
+    const basic_string_view<charT, traits>& str)
+{
+    return boost::ostream_string(os, str.data(), str.size());
+}
+```
+
+[endsect]
+
+[section Reference]
+
+```
+namespace boost {
+
+template<class charT, class traits>
+std::basic_ostream<charT, traits>&
+ostream_string(std::basic_ostream<charT, traits>& os,
+    const charT* data, std::size_t size);
+
+} /* boost */
+```
+
+[variablelist
+[[Effects]
+[Behaves like a formatted inserter (as described in
+\[ostream.formatted.reqmts\]) of `os`. Creates a character sequence `seq` of
+`size` characters starting at `data`, each widened using `os.widen()`
+(\[basic.ios.members\]). Determines padding for `seq` as described in
+\[ostream.formatted.reqmts\]. Inserts `seq` into `os`. Calls `width(0)`.]]
+[[Returns] [`os`.]]]
+
+[endsect]
diff --git a/include/boost/utility/ostream_string.hpp b/include/boost/utility/ostream_string.hpp
new file mode 100644
index 0000000..8722e58
--- /dev/null
+++ b/include/boost/utility/ostream_string.hpp
@@ -0,0 +1,95 @@
+/*
+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_UTILITY_OSTREAM_STRING_HPP
+#define BOOST_UTILITY_OSTREAM_STRING_HPP
+
+#include <boost/config.hpp>
+#include <iosfwd>
+#include <cstddef>
+
+namespace boost {
+namespace detail {
+
+template<class charT, class traits>
+inline std::size_t
+oss_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
+oss_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::detail::oss_put(os, fill, chunk) != chunk) {
+            return false;
+        }
+    }
+    return boost::detail::oss_put(os, fill, size) == size;
+}
+
+template<class charT, class traits>
+class oss_guard {
+public:
+    explicit oss_guard(std::basic_ostream<charT, traits>& os) BOOST_NOEXCEPT
+        : os_(&os) { }
+    ~oss_guard() BOOST_NOEXCEPT_IF(false) {
+        if (os_) {
+            os_->setstate(std::basic_ostream<charT, traits>::badbit);
+        }
+    }
+    void release() BOOST_NOEXCEPT {
+        os_ = 0;
+    }
+private:
+    oss_guard(const oss_guard&);
+    oss_guard& operator=(const oss_guard&);
+    std::basic_ostream<charT, traits>* os_;
+};
+
+} /* detail */
+
+template<class charT, class traits>
+inline std::basic_ostream<charT, traits>&
+ostream_string(std::basic_ostream<charT, traits>& os, const charT* data,
+    std::size_t size)
+{
+    typedef std::basic_ostream<charT, traits> stream;
+    detail::oss_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::oss_put(os, data, size) != size) {
+                return os;
+            }
+        } else if ((os.flags() & stream::adjustfield) == stream::left) {
+            if (detail::oss_put(os, data, size) != size ||
+                !detail::oss_fill(os, width - size)) {
+                return os;
+            }
+        } else if (!detail::oss_fill(os, width - size) ||
+            detail::oss_put(os, data, size) != size) {
+            return os;
+        }
+        os.width(0);
+    }
+    guard.release();
+    return os;
+}
+
+} /* boost */
+
+#endif
diff --git a/include/boost/utility/string_ref.hpp b/include/boost/utility/string_ref.hpp
index 36f4fc8..999f1c3 100644
--- a/include/boost/utility/string_ref.hpp
+++ b/include/boost/utility/string_ref.hpp
@@ -18,6 +18,7 @@
 
 #include <boost/config.hpp>
 #include <boost/detail/workaround.hpp>
+#include <boost/utility/ostream_string.hpp>
 #include <boost/utility/string_ref_fwd.hpp>
 #include <boost/throw_exception.hpp>
 
@@ -422,76 +423,11 @@ namespace boost {
         return basic_string_ref<charT, traits>(x) >= y;
         }
 
-    namespace detail {
-
-        template<class charT, class traits>
-        inline std::size_t sr_os_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 sr_os_fill(std::basic_ostream<charT, traits>& os,
-            std::size_t size) {
-            enum { chunk = 8 };
-            charT fill[chunk];
-            std::fill_n(fill, static_cast<std::size_t>(chunk), os.fill());
-            for (; size > chunk; size -= chunk) {
-                if (detail::sr_os_put(os, fill, chunk) != chunk) {
-                    return false;
-                }
-            }
-            return detail::sr_os_put(os, fill, size) == size;
-        }
-
-        template<class charT, class traits>
-        class sr_os_holder {
-        public:
-            explicit sr_os_holder(std::basic_ostream<charT, traits>& os)
-                : os_(&os) { }
-            ~sr_os_holder() BOOST_NOEXCEPT_IF(false) {
-                if (os_) {
-                    os_->setstate(std::basic_ostream<charT, traits>::badbit);
-                }
-            }
-            void release() {
-                os_ = 0;
-            }
-        private:
-            sr_os_holder(const sr_os_holder&);
-            sr_os_holder& operator=(const sr_os_holder&);
-            std::basic_ostream<charT, traits>* os_;
-        };
-
-        } // namespace detail
-
     // Inserter
     template<class charT, class traits>
     inline std::basic_ostream<charT, traits>&
     operator<<(std::basic_ostream<charT, traits>& os, const basic_string_ref<charT,traits>& str) {
-        typedef std::basic_ostream<charT, traits> stream;
-        detail::sr_os_holder<charT, traits> hold(os);
-        typename stream::sentry entry(os);
-        if (entry) {
-            std::size_t width = static_cast<std::size_t>(os.width());
-            std::size_t size = str.size();
-            if (width <= size) {
-                if (detail::sr_os_put(os, str.data(), size) != size) {
-                    return os;
-                }
-            } else if ((os.flags() & stream::adjustfield) == stream::left) {
-                if (detail::sr_os_put(os, str.data(), size) != size ||
-                    !detail::sr_os_fill(os, width - size)) {
-                    return os;
-                }
-            } else if (!detail::sr_os_fill(os, width - size) ||
-                detail::sr_os_put(os, str.data(), size) != size) {
-                return os;
-            }
-            os.width(0);
-        }
-        hold.release();
-        return os;
+        return boost::ostream_string(os, str.data(), str.size());
         }
 
 #if 0
diff --git a/include/boost/utility/string_view.hpp b/include/boost/utility/string_view.hpp
index 5cab012..1677e9f 100644
--- a/include/boost/utility/string_view.hpp
+++ b/include/boost/utility/string_view.hpp
@@ -20,6 +20,7 @@
 
 #include <boost/config.hpp>
 #include <boost/detail/workaround.hpp>
+#include <boost/utility/ostream_string.hpp>
 #include <boost/utility/string_view_fwd.hpp>
 #include <boost/throw_exception.hpp>
 #include <boost/container_hash/hash_fwd.hpp>
@@ -572,77 +573,12 @@ namespace boost {
         return basic_string_view<charT, traits>(x) >= y;
         }
 
-    namespace detail {
-
-        template<class charT, class traits>
-        inline std::size_t sv_os_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 sv_os_fill(std::basic_ostream<charT, traits>& os,
-            std::size_t size) {
-            enum { chunk = 8 };
-            charT fill[chunk];
-            std::fill_n(fill, static_cast<std::size_t>(chunk), os.fill());
-            for (; size > chunk; size -= chunk) {
-                if (detail::sv_os_put(os, fill, chunk) != chunk) {
-                    return false;
-                }
-            }
-            return detail::sv_os_put(os, fill, size) == size;
-        }
-
-        template<class charT, class traits>
-        class sv_os_holder {
-        public:
-            explicit sv_os_holder(std::basic_ostream<charT, traits>& os)
-                : os_(&os) { }
-            ~sv_os_holder() BOOST_NOEXCEPT_IF(false) {
-                if (os_) {
-                    os_->setstate(std::basic_ostream<charT, traits>::badbit);
-                }
-            }
-            void release() {
-                os_ = 0;
-            }
-        private:
-            sv_os_holder(const sv_os_holder&);
-            sv_os_holder& operator=(const sv_os_holder&);
-            std::basic_ostream<charT, traits>* os_;
-        };
-
-        } // namespace detail
-
     // Inserter
     template<class charT, class traits>
     inline std::basic_ostream<charT, traits>&
     operator<<(std::basic_ostream<charT, traits>& os,
       const basic_string_view<charT,traits>& str) {
-        typedef std::basic_ostream<charT, traits> stream;
-        detail::sv_os_holder<charT, traits> hold(os);
-        typename stream::sentry entry(os);
-        if (entry) {
-            std::size_t width = static_cast<std::size_t>(os.width());
-            std::size_t size = str.size();
-            if (width <= size) {
-                if (detail::sv_os_put(os, str.data(), size) != size) {
-                    return os;
-                }
-            } else if ((os.flags() & stream::adjustfield) == stream::left) {
-                if (detail::sv_os_put(os, str.data(), size) != size ||
-                    !detail::sv_os_fill(os, width - size)) {
-                    return os;
-                }
-            } else if (!detail::sv_os_fill(os, width - size) ||
-                detail::sv_os_put(os, str.data(), size) != size) {
-                return os;
-            }
-            os.width(0);
-        }
-        hold.release();
-        return os;
+        return boost::ostream_string(os, str.data(), str.size());
         }
 
 #if 0
diff --git a/index.html b/index.html
index 57fa56f..7dcdd64 100644
--- a/index.html
+++ b/index.html
@@ -31,6 +31,7 @@
 				<a href="utility.htm#result_of">result_of</a><br>
 				<a href="throw_exception.html">throw_exception</a><br>
 				<a href="utility.htm">utility</a><br>
+            <a href="doc/html/ostream_string.html">ostream_string</a><br>
             <a href="doc/html/string_ref.html">string_ref</a><br>
             <a href="value_init.htm">value_init</a><br>
          </p>
diff --git a/test/Jamfile.v2 b/test/Jamfile.v2
index 739edc0..d0277ef 100644
--- a/test/Jamfile.v2
+++ b/test/Jamfile.v2
@@ -42,3 +42,5 @@ compile-fail value_init_test_fail2.cpp ;
 compile-fail value_init_test_fail3.cpp ;
 compile-fail initialized_test_fail1.cpp ;
 compile-fail initialized_test_fail2.cpp ;
+
+run ostream_string_test.cpp ;
diff --git a/test/ostream_string_test.cpp b/test/ostream_string_test.cpp
new file mode 100644
index 0000000..e6145b3
--- /dev/null
+++ b/test/ostream_string_test.cpp
@@ -0,0 +1,136 @@
+/*
+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)
+*/
+#include <boost/core/lightweight_test.hpp>
+#include <boost/utility/ostream_string.hpp>
+#include <sstream>
+#include <string>
+
+int main()
+{
+    {
+        std::ostringstream os;
+        os.width(1);
+        os.fill('.');
+        os.setf(std::ios_base::left, std::ios_base::adjustfield);
+        boost::ostream_string(os, "xy", 2);
+        BOOST_TEST(os.good());
+        BOOST_TEST(os.width() == 0);
+        BOOST_TEST(os.str() == "xy");
+    }
+    {
+        std::wostringstream os;
+        os.width(1);
+        os.fill('.');
+        os.setf(std::ios_base::left, std::ios_base::adjustfield);
+        boost::ostream_string(os, L"xy", 2);
+        BOOST_TEST(os.good());
+        BOOST_TEST(os.width() == 0);
+        BOOST_TEST(os.str() == L"xy");
+    }
+    {
+        std::ostringstream os;
+        os.width(1);
+        os.fill('.');
+        os.setf(std::ios_base::right, std::ios_base::adjustfield);
+        boost::ostream_string(os, "xy", 2);
+        BOOST_TEST(os.good());
+        BOOST_TEST(os.width() == 0);
+        BOOST_TEST(os.str() == "xy");
+    }
+    {
+        std::wostringstream os;
+        os.width(1);
+        os.fill('.');
+        os.setf(std::ios_base::right, std::ios_base::adjustfield);
+        boost::ostream_string(os, L"xy", 2);
+        BOOST_TEST(os.good());
+        BOOST_TEST(os.width() == 0);
+        BOOST_TEST(os.str() == L"xy");
+    }
+    {
+        std::ostringstream os;
+        os.width(4);
+        os.fill('.');
+        os.setf(std::ios_base::left, std::ios_base::adjustfield);
+        boost::ostream_string(os, "xy", 2);
+        BOOST_TEST(os.good());
+        BOOST_TEST(os.width() == 0);
+        BOOST_TEST(os.str() == "xy..");
+    }
+    {
+        std::wostringstream os;
+        os.width(4);
+        os.fill(L'.');
+        os.setf(std::ios_base::left, std::ios_base::adjustfield);
+        boost::ostream_string(os, L"xy", 2);
+        BOOST_TEST(os.good());
+        BOOST_TEST(os.width() == 0);
+        BOOST_TEST(os.str() == L"xy..");
+    }
+    {
+        std::ostringstream os;
+        os.width(4);
+        os.fill('.');
+        os.setf(std::ios_base::right, std::ios_base::adjustfield);
+        boost::ostream_string(os, "xy", 2);
+        BOOST_TEST(os.good());
+        BOOST_TEST(os.width() == 0);
+        BOOST_TEST(os.str() == "..xy");
+    }
+    {
+        std::wostringstream os;
+        os.width(4);
+        os.fill(L'.');
+        os.setf(std::ios_base::right, std::ios_base::adjustfield);
+        boost::ostream_string(os, L"xy", 2);
+        BOOST_TEST(os.good());
+        BOOST_TEST(os.width() == 0);
+        BOOST_TEST(os.str() == L"..xy");
+    }
+    {
+        std::ostringstream os;
+        os.width(12);
+        os.fill('.');
+        os.setf(std::ios_base::left, std::ios_base::adjustfield);
+        boost::ostream_string(os, "xy", 2);
+        BOOST_TEST(os.good());
+        BOOST_TEST(os.width() == 0);
+        BOOST_TEST(os.str() == "xy..........");
+    }
+    {
+        std::wostringstream os;
+        os.width(12);
+        os.fill(L'.');
+        os.setf(std::ios_base::left, std::ios_base::adjustfield);
+        boost::ostream_string(os, L"xy", 2);
+        BOOST_TEST(os.good());
+        BOOST_TEST(os.width() == 0);
+        BOOST_TEST(os.str() == L"xy..........");
+    }
+    {
+        std::ostringstream os;
+        os.width(12);
+        os.fill('.');
+        os.setf(std::ios_base::right, std::ios_base::adjustfield);
+        boost::ostream_string(os, "xy", 2);
+        BOOST_TEST(os.good());
+        BOOST_TEST(os.width() == 0);
+        BOOST_TEST(os.str() == "..........xy");
+    }
+    {
+        std::wostringstream os;
+        os.width(12);
+        os.fill(L'.');
+        os.setf(std::ios_base::right, std::ios_base::adjustfield);
+        boost::ostream_string(os, L"xy", 2);
+        BOOST_TEST(os.good());
+        BOOST_TEST(os.width() == 0);
+        BOOST_TEST(os.str() == L"..........xy");
+    }
+    return boost::report_errors();
+}