comparison DEPENDENCIES/generic/include/boost/units/io.hpp @ 16:2665513ce2d3

Add boost headers

+// Boost.Units - A C++ library for zero-overhead dimensional analysis and 
+// unit/quantity manipulation and conversion
+//
+// Copyright (C) 2003-2008 Matthias Christian Schabel
+// Copyright (C) 2007-2010 Steven Watanabe
+//
+// Distributed under the Boost Software License, Version 1.0. (See
+// accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_UNITS_IO_HPP
+#define BOOST_UNITS_IO_HPP
+
+/// \file
+/// \brief Stream input and output for rationals, units and quantities.
+/// \details Functions and manipulators for output and input of units and quantities.
+///   symbol and name format, and engineering and binary autoprefix.
+///   Serialization output is also supported.
+
+#include <cassert>
+#include <cmath>
+#include <string>
+#include <iosfwd>
+#include <ios>
+#include <sstream>
+
+#include <boost/serialization/nvp.hpp>
+
+#include <boost/units/units_fwd.hpp>
+#include <boost/units/heterogeneous_system.hpp>
+#include <boost/units/make_scaled_unit.hpp>
+#include <boost/units/quantity.hpp>
+#include <boost/units/scale.hpp>
+#include <boost/units/static_rational.hpp>
+#include <boost/units/unit.hpp>
+#include <boost/units/detail/utility.hpp>
+
+namespace boost {
+
+namespace serialization {
+
+/// Boost Serialization library support for units.
+template<class Archive,class System,class Dim>
+inline void serialize(Archive& ar,boost::units::unit<Dim,System>&,const unsigned int /*version*/)
+{ }
+
+/// Boost Serialization library support for quantities.
+template<class Archive,class Unit,class Y>
+inline void serialize(Archive& ar,boost::units::quantity<Unit,Y>& q,const unsigned int /*version*/)
+{
+    ar & boost::serialization::make_nvp("value", units::quantity_cast<Y&>(q));
+}
+        
+} // namespace serialization
+
+namespace units {
+
+// get string representation of arbitrary type.
+template<class T> std::string to_string(const T& t)
+{
+    std::stringstream sstr;
+    
+    sstr << t;
+    
+    return sstr.str();
+}
+
+/// get string representation of integral-valued @c static_rational.
+template<integer_type N> std::string to_string(const static_rational<N>&)
+{
+    return to_string(N);
+}
+
+/// get string representation of @c static_rational.
+template<integer_type N, integer_type D> std::string to_string(const static_rational<N,D>&)
+{
+    return '(' + to_string(N) + '/' + to_string(D) + ')';
+}
+
+/// Write @c static_rational to @c std::basic_ostream.
+template<class Char, class Traits, integer_type N, integer_type D>
+inline std::basic_ostream<Char, Traits>& operator<<(std::basic_ostream<Char, Traits>& os,const static_rational<N,D>& r)
+{
+    os << to_string(r);
+    return os;
+}
+
+/// traits template for unit names.
+template<class BaseUnit>
+struct base_unit_info
+{
+    /// INTERNAL ONLY
+    typedef void base_unit_info_primary_template;
+    /// The full name of the unit (returns BaseUnit::name() by default)
+    static std::string name()
+    {
+        return(BaseUnit::name());
+    }
+    /// The symbol for the base unit (Returns BaseUnit::symbol() by default)
+    static std::string symbol()
+    {
+        return(BaseUnit::symbol());  ///  \returns BaseUnit::symbol(), for example "m"
+    }
+};
+
+/// \enum format_mode format of output of units, for example "m" or "meter".
+enum format_mode
+{
+    symbol_fmt = 0,     /// default - reduces unit names to known symbols for both base and derived units.
+    name_fmt = 1,           /// output full unit names for base and derived units, for example "meter".
+    raw_fmt = 2,            /// output only symbols for base units (but not derived units), for example "m".
+    typename_fmt = 3,       /// output demangled typenames (useful only for diagnosis).
+    fmt_mask = 3 /// Bits used for format.
+};
+
+/// \enum autoprefix_mode automatic scaling and prefix (controlled by value of quantity) a, if any,
+enum autoprefix_mode
+{
+    autoprefix_none = 0, /// No automatic prefix.
+    autoprefix_engineering = 4, /// Scale and prefix with 10^3 multiples, 1234.5 m output as 1.2345 km.
+    autoprefix_binary = 8, /// Scale and prefix with 2^10 (1024) multiples, 1024 as 1 kb.
+    autoprefix_mask = 12 ///  Bits used for autoprefix.
+};
+
+namespace detail {
+
+template<bool>
+struct xalloc_key_holder 
+{
+    static int value;
+    static bool initialized;
+};
+
+template<bool b>
+int xalloc_key_holder<b>::value = 0;
+
+template<bool b>
+bool xalloc_key_holder<b>::initialized = 0;
+
+struct xalloc_key_initializer_t 
+{
+    xalloc_key_initializer_t() 
+    {
+        if (!xalloc_key_holder<true>::initialized) 
+        {
+            xalloc_key_holder<true>::value = std::ios_base::xalloc();
+            xalloc_key_holder<true>::initialized = true;
+        }
+    }
+};
+
+namespace /**/ {
+    
+xalloc_key_initializer_t xalloc_key_initializer;
+
+} // namespace
+
+} // namespace detail
+
+/// returns flags controlling output.
+inline long get_flags(std::ios_base& ios, long mask) 
+{
+    return(ios.iword(detail::xalloc_key_holder<true>::value) & mask);
+}
+
+/// Set new flags controlling output format.
+inline void set_flags(std::ios_base& ios, long new_flags, long mask) 
+{
+    assert((~mask & new_flags) == 0);
+    long& flags = ios.iword(detail::xalloc_key_holder<true>::value);
+    flags = (flags & ~mask) | new_flags;
+}
+
+/// returns flags controlling output format.
+inline format_mode get_format(std::ios_base& ios) 
+{
+    return(static_cast<format_mode>((get_flags)(ios, fmt_mask)));
+}
+
+/// Set new flags controlling output format.
+inline void set_format(std::ios_base& ios, format_mode new_mode) 
+{
+    (set_flags)(ios, new_mode, fmt_mask);
+}
+
+/// Set new flags for type_name output format.
+inline std::ios_base& typename_format(std::ios_base& ios) 
+{
+    (set_format)(ios, typename_fmt);
+    return(ios);
+}
+
+/// set new flag for raw format output, for example "m".
+inline std::ios_base& raw_format(std::ios_base& ios) 
+{
+    (set_format)(ios, raw_fmt);
+    return(ios);
+}
+
+/// set new format flag for symbol output, for example "m".
+inline std::ios_base& symbol_format(std::ios_base& ios) 
+{
+    (set_format)(ios, symbol_fmt);
+    return(ios);
+}
+
+/// set new format for name output, for example "meter".
+inline std::ios_base& name_format(std::ios_base& ios) 
+{
+    (set_format)(ios, name_fmt);
+    return(ios);
+}
+
+/// get autoprefix flags for output.
+inline autoprefix_mode get_autoprefix(std::ios_base& ios)
+{
+    return static_cast<autoprefix_mode>((get_flags)(ios, autoprefix_mask));
+}
+
+/// Get format for output.
+inline void set_autoprefix(std::ios_base& ios, autoprefix_mode new_mode)
+{
+    (set_flags)(ios, new_mode, autoprefix_mask);
+}
+
+/// Clear autoprefix flags.
+inline std::ios_base& no_prefix(std::ios_base& ios)
+{
+    (set_autoprefix)(ios, autoprefix_none);
+    return ios;
+}
+
+/// Set flag for engineering prefix, so 1234.5 m displays as "1.2345 km".
+inline std::ios_base& engineering_prefix(std::ios_base& ios)
+{
+    (set_autoprefix)(ios, autoprefix_engineering);
+    return ios;
+}
+
+/// Set flag for binary prefix, so 1024 byte displays as "1 Kib".
+inline std::ios_base& binary_prefix(std::ios_base& ios)
+{
+    (set_autoprefix)(ios, autoprefix_binary);
+    return ios;
+}
+
+namespace detail {
+
+/// \return exponent string like "^1/2".
+template<integer_type N, integer_type D>
+inline std::string exponent_string(const static_rational<N,D>& r)
+{
+    return '^' + to_string(r);
+}
+
+/// \return empty exponent string for integer rational like 2.
+template<>
+inline std::string exponent_string(const static_rational<1>&)
+{
+    return "";
+}
+
+template<class T>
+inline std::string base_unit_symbol_string(const T&)
+{
+    return base_unit_info<typename T::tag_type>::symbol() + exponent_string(typename T::value_type());
+}
+
+template<class T>    
+inline std::string base_unit_name_string(const T&)
+{
+    return base_unit_info<typename T::tag_type>::name() + exponent_string(typename T::value_type());
+}
+
+// stringify with symbols.
+template<int N>
+struct symbol_string_impl
+{
+    template<class Begin>
+    struct apply
+    {
+        typedef typename symbol_string_impl<N-1>::template apply<typename Begin::next> next;
+        static void value(std::string& str)
+        {
+            str += base_unit_symbol_string(typename Begin::item()) + ' ';
+            next::value(str);
+        }
+    };
+};
+
+template<>
+struct symbol_string_impl<1>
+{
+    template<class Begin>
+    struct apply
+    {
+        static void value(std::string& str)
+        {
+            str += base_unit_symbol_string(typename Begin::item());
+        };
+    };
+};
+
+template<>
+struct symbol_string_impl<0>
+{
+    template<class Begin>
+    struct apply
+    {
+        static void value(std::string& str)
+        {
+            // better shorthand for dimensionless?
+            str += "dimensionless";
+        }
+    };
+};
+
+template<int N>
+struct scale_symbol_string_impl 
+{
+    template<class Begin>
+    struct apply 
+    {
+        static void value(std::string& str) 
+        {
+            str += Begin::item::symbol();
+            scale_symbol_string_impl<N - 1>::template apply<typename Begin::next>::value(str);
+        }
+    };
+};
+
+template<>
+struct scale_symbol_string_impl<0>
+{
+    template<class Begin>
+    struct apply 
+    {
+        static void value(std::string&) { }
+    };
+};
+
+// stringify with names.
+template<int N>
+struct name_string_impl
+{
+    template<class Begin>
+    struct apply
+    {
+        typedef typename name_string_impl<N-1>::template apply<typename Begin::next> next;
+        static void value(std::string& str)
+        {
+            str += base_unit_name_string(typename Begin::item()) + ' ';
+            next::value(str);
+        }
+    };
+};
+
+template<>
+struct name_string_impl<1>
+{
+    template<class Begin>
+    struct apply
+    {
+        static void value(std::string& str)
+        {
+            str += base_unit_name_string(typename Begin::item());
+        };
+    };
+};
+
+template<>
+struct name_string_impl<0>
+{
+    template<class Begin>
+    struct apply
+    {
+        static void value(std::string& str)
+        {
+            str += "dimensionless";
+        }
+    };
+};
+
+template<int N>
+struct scale_name_string_impl 
+{
+    template<class Begin>
+    struct apply 
+    {
+        static void value(std::string& str) 
+        {
+            str += Begin::item::name();
+            scale_name_string_impl<N - 1>::template apply<typename Begin::next>::value(str);
+        }
+    };
+};
+
+template<>
+struct scale_name_string_impl<0>
+{
+    template<class Begin>
+    struct apply 
+    {
+        static void value(std::string&) { }
+    };
+};
+
+} // namespace detail
+
+namespace detail {
+
+// These two overloads of symbol_string and name_string will
+// will pick up homogeneous_systems.  They simply call the
+// appropriate function with a heterogeneous_system.
+template<class Dimension,class System, class SubFormatter>
+inline std::string
+to_string_impl(const unit<Dimension,System>&, SubFormatter f)
+{
+    return f(typename reduce_unit<unit<Dimension, System> >::type());
+}
+
+/// INTERNAL ONLY
+// this overload picks up heterogeneous units that are not scaled.
+template<class Dimension,class Units, class Subformatter>
+inline std::string
+to_string_impl(const unit<Dimension, heterogeneous_system<heterogeneous_system_impl<Units, Dimension, dimensionless_type> > >&, Subformatter f)
+{
+    std::string str;
+    f.template append_units_to<Units>(str);
+    return(str);
+}
+
+// This overload is a special case for heterogeneous_system which
+// is really unitless
+/// INTERNAL ONLY
+template<class Subformatter>
+inline std::string
+to_string_impl(const unit<dimensionless_type, heterogeneous_system<heterogeneous_system_impl<dimensionless_type, dimensionless_type, dimensionless_type> > >&, Subformatter)
+{
+    return("dimensionless");
+}
+
+// this overload deals with heterogeneous_systems which are unitless
+// but scaled.
+/// INTERNAL ONLY
+template<class Scale, class Subformatter>
+inline std::string
+to_string_impl(const unit<dimensionless_type, heterogeneous_system<heterogeneous_system_impl<dimensionless_type, dimensionless_type, Scale> > >&, Subformatter f)
+{
+    std::string str;
+    f.template append_scale_to<Scale>(str);
+    return(str);
+}
+
+// this overload deals with scaled units.
+/// INTERNAL ONLY
+template<class Dimension,class Units,class Scale, class Subformatter>
+inline std::string
+to_string_impl(const unit<Dimension, heterogeneous_system<heterogeneous_system_impl<Units, Dimension, Scale> > >&, Subformatter f)
+{
+    std::string str;
+
+    f.template append_scale_to<Scale>(str);
+
+    std::string without_scale = f(unit<Dimension, heterogeneous_system<heterogeneous_system_impl<Units, Dimension, dimensionless_type> > >());
+    
+    if (f.is_default_string(without_scale, unit<Dimension, heterogeneous_system<heterogeneous_system_impl<Units, Dimension, dimensionless_type> > >()))
+    {
+        str += "(";
+        str += without_scale;
+        str += ")";
+    } 
+    else 
+    {
+        str += without_scale;
+    }
+
+    return(str);
+}
+
+// This overload catches scaled units that have a single base unit
+// raised to the first power.  It causes si::nano * si::meters to not
+// put parentheses around the meters.  i.e. nm rather than n(m)
+/// INTERNAL ONLY
+template<class Dimension,class Unit,class Scale, class Subformatter>
+inline std::string
+to_string_impl(const unit<Dimension, heterogeneous_system<heterogeneous_system_impl<list<heterogeneous_system_dim<Unit, static_rational<1> >,dimensionless_type>, Dimension, Scale> > >&, Subformatter f)
+{
+    std::string str;
+
+    f.template append_scale_to<Scale>(str);
+    str += f(unit<Dimension, heterogeneous_system<heterogeneous_system_impl<list<heterogeneous_system_dim<Unit, static_rational<1> >, dimensionless_type>, Dimension, dimensionless_type> > >());
+
+    return(str);
+}
+
+// This overload is necessary to disambiguate.
+// it catches units that are unscaled and have a single
+// base unit raised to the first power.  It is treated the
+// same as any other unscaled unit.
+/// INTERNAL ONLY
+template<class Dimension,class Unit,class Subformatter>
+inline std::string
+to_string_impl(const unit<Dimension, heterogeneous_system<heterogeneous_system_impl<list<heterogeneous_system_dim<Unit, static_rational<1> >,dimensionless_type>, Dimension, dimensionless_type> > >&, Subformatter f)
+{
+    std::string str;
+    f.template append_units_to<list<heterogeneous_system_dim<Unit, static_rational<1> >,dimensionless_type> >(str);
+    return(str);
+}
+
+// This overload catches scaled units that have a single scaled base unit
+// raised to the first power.  It moves that scaling on the base unit
+// to the unit level scaling and recurses.  By doing this we make sure that
+// si::milli * si::kilograms will print g rather than mkg.
+//
+// This transformation will not be applied if base_unit_info is specialized
+// for the scaled base unit.
+//
+/// INTERNAL ONLY
+template<class Dimension,class Unit,class UnitScale, class Scale, class Subformatter>
+inline std::string
+to_string_impl(
+    const unit<
+        Dimension,
+        heterogeneous_system<
+            heterogeneous_system_impl<
+                list<heterogeneous_system_dim<scaled_base_unit<Unit, UnitScale>, static_rational<1> >, dimensionless_type>,
+                Dimension,
+                Scale
+            >
+        >
+    >&,
+    Subformatter f,
+    typename base_unit_info<scaled_base_unit<Unit, UnitScale> >::base_unit_info_primary_template* = 0)
+{
+    return(f(
+        unit<
+            Dimension,
+            heterogeneous_system<
+                heterogeneous_system_impl<
+                    list<heterogeneous_system_dim<Unit, static_rational<1> >, dimensionless_type>,
+                    Dimension,
+                    typename mpl::times<Scale, list<scale_list_dim<UnitScale>, dimensionless_type> >::type
+                >
+            >
+        >()));
+}
+
+// this overload disambuguates between the overload for an unscaled unit
+// and the overload for a scaled base unit raised to the first power.
+/// INTERNAL ONLY
+template<class Dimension,class Unit,class UnitScale,class Subformatter>
+inline std::string
+to_string_impl(
+    const unit<
+        Dimension,
+        heterogeneous_system<
+            heterogeneous_system_impl<
+                list<heterogeneous_system_dim<scaled_base_unit<Unit, UnitScale>, static_rational<1> >, dimensionless_type>,
+                Dimension,
+                dimensionless_type
+            >
+        >
+    >&,
+    Subformatter f,
+    typename base_unit_info<scaled_base_unit<Unit, UnitScale> >::base_unit_info_primary_template* = 0)
+{
+    std::string str;
+    f.template append_units_to<list<heterogeneous_system_dim<scaled_base_unit<Unit, UnitScale>, static_rational<1> >, dimensionless_type> >(str);
+    return(str);
+}
+
+struct format_raw_symbol_impl {
+    template<class Units>
+    void append_units_to(std::string& str) {
+        detail::symbol_string_impl<Units::size::value>::template apply<Units>::value(str);
+    }
+    template<class Scale>
+    void append_scale_to(std::string& str) {
+        detail::scale_symbol_string_impl<Scale::size::value>::template apply<Scale>::value(str);
+    }
+    template<class Unit>
+    std::string operator()(const Unit& u) {
+        return(to_string_impl(u, *this));
+    }
+    template<class Unit>
+    bool is_default_string(const std::string&, const Unit&) {
+        return(true);
+    }
+};
+
+struct format_symbol_impl : format_raw_symbol_impl {
+    template<class Unit>
+    std::string operator()(const Unit& u) {
+        return(symbol_string(u));
+    }
+    template<class Unit>
+    bool is_default_string(const std::string& str, const Unit& u) {
+        return(str == to_string_impl(u, format_raw_symbol_impl()));
+    }
+};
+
+struct format_raw_name_impl {
+    template<class Units>
+    void append_units_to(std::string& str) {
+        detail::name_string_impl<(Units::size::value)>::template apply<Units>::value(str);
+    }
+    template<class Scale>
+    void append_scale_to(std::string& str) {
+        detail::scale_name_string_impl<Scale::size::value>::template apply<Scale>::value(str);
+    }
+    template<class Unit>
+    std::string operator()(const Unit& u) {
+        return(to_string_impl(u, *this));
+    }
+    template<class Unit>
+    bool is_default_string(const std::string&, const Unit&) {
+        return(true);
+    }
+};
+
+struct format_name_impl : format_raw_name_impl {
+    template<class Unit>
+    std::string operator()(const Unit& u) {
+        return(name_string(u));
+    }
+    template<class Unit>
+    bool is_default_string(const std::string& str, const Unit& u) {
+        return(str == to_string_impl(u, format_raw_name_impl()));
+    }
+};
+
+template<class Char, class Traits>
+inline void do_print(std::basic_ostream<Char, Traits>& os, const std::string& s)
+{
+    os << s.c_str();
+}
+
+inline void do_print(std::ostream& os, const std::string& s)
+{
+    os << s;
+}
+
+template<class Char, class Traits>
+inline void do_print(std::basic_ostream<Char, Traits>& os, const char* s)
+{
+    os << s;
+}
+
+// For automatically applying the appropriate prefixes.
+
+}
+
+#ifdef BOOST_UNITS_DOXYGEN
+
+/// ADL customization point for automatic prefixing.
+/// Returns a non-negative value.  Implemented as std::abs
+/// for built-in types.
+template<class T>
+double autoprefix_norm(const T& arg);
+
+#else
+
+template<class T, bool C = boost::is_arithmetic<T>::value>
+struct autoprefix_norm_impl;
+
+template<class T>
+struct autoprefix_norm_impl<T, true>
+{
+    typedef double type;
+    static double call(const T& arg) { return std::abs(arg); }
+};
+
+template<class T>
+struct autoprefix_norm_impl<T, false>
+{
+    typedef one type;
+    static one call(const T&) { return one(); }
+};
+
+template<class T>
+typename autoprefix_norm_impl<T>::type autoprefix_norm(const T& arg)
+{
+    return autoprefix_norm_impl<T>::call(arg);
+}
+
+#endif
+
+namespace detail {
+
+template<class End, class Prev, class T, class F>
+bool find_matching_scale_impl(End, End, Prev, T, double, F)
+{
+    return false;
+}
+
+template<class Begin, class End, class Prev, class T, class F>
+bool find_matching_scale_impl(Begin, End end, Prev prev, T t, double x, F f)
+{
+    if(Begin::item::value() > x) {
+        f(prev, t);
+        return true;
+    } else {
+        return detail::find_matching_scale_impl(
+            typename Begin::next(),
+            end,
+            typename Begin::item(),
+            t,
+            x,
+            f
+        );
+    }
+}
+
+template<class End, class T, class F>
+bool find_matching_scale_i(End, End, T, double, F)
+{
+    return false;
+}
+
+template<class Begin, class End, class T, class F>
+bool find_matching_scale_i(Begin, End end, T t, double x, F f)
+{
+    if(Begin::item::value() > x) {
+        return false;
+    } else {
+        return detail::find_matching_scale_impl(typename Begin::next(), end, typename Begin::item(), t, x, f);
+    }
+}
+
+template<class Scales, class T, class F>
+bool find_matching_scale(T t, double x, F f)
+{
+    return detail::find_matching_scale_i(Scales(), dimensionless_type(), t, x, f);
+}
+
+typedef list<scale<10, static_rational<-24> >,
+        list<scale<10, static_rational<-21> >,
+        list<scale<10, static_rational<-18> >,
+        list<scale<10, static_rational<-15> >,
+        list<scale<10, static_rational<-12> >,
+        list<scale<10, static_rational<-9> >,
+        list<scale<10, static_rational<-6> >,
+        list<scale<10, static_rational<-3> >,
+        list<scale<10, static_rational<0> >,
+        list<scale<10, static_rational<3> >,
+        list<scale<10, static_rational<6> >,
+        list<scale<10, static_rational<9> >,
+        list<scale<10, static_rational<12> >,
+        list<scale<10, static_rational<15> >,
+        list<scale<10, static_rational<18> >,
+        list<scale<10, static_rational<21> >,
+        list<scale<10, static_rational<24> >,
+        list<scale<10, static_rational<27> >,
+        dimensionless_type> > > > > > > > > > > > > > > > > > engineering_prefixes;
+
+typedef list<scale<2, static_rational<10> >,
+        list<scale<2, static_rational<20> >,
+        list<scale<2, static_rational<30> >,
+        list<scale<2, static_rational<40> >,
+        list<scale<2, static_rational<50> >,
+        list<scale<2, static_rational<60> >,
+        list<scale<2, static_rational<70> >,
+        dimensionless_type> > > > > > > binary_prefixes;
+
+template<class Os, class Quantity>
+struct print_default_t {
+    typedef void result_type;
+    void operator()() const
+    {
+        *os << q->value() << ' ' << typename Quantity::unit_type();
+    }
+    Os* os;
+    const Quantity* q;
+};
+
+template<class Os, class Quantity>
+print_default_t<Os, Quantity> print_default(Os& os, const Quantity& q)
+{
+    print_default_t<Os, Quantity> result = { &os, &q };
+    return result;
+}
+
+template<class Os>
+struct print_scale_t {
+    typedef void result_type;
+    template<class Prefix, class T>
+    void operator()(Prefix, const T& t) const
+    {
+        *prefixed = true;
+        *os << t / Prefix::value() << ' ';
+        switch(units::get_format(*os)) {
+            case name_fmt: do_print(*os, Prefix::name()); break;
+            case raw_fmt:
+            case symbol_fmt: do_print(*os, Prefix::symbol()); break;
+            case typename_fmt: do_print(*os, units::simplify_typename(Prefix())); *os << ' '; break;
+        }
+    }
+    template<long N, class T>
+    void operator()(scale<N, static_rational<0> >, const T& t) const
+    {
+        *prefixed = false;
+        *os << t << ' ';
+    }
+    Os* os;
+    bool* prefixed;
+};
+
+template<class Os>
+print_scale_t<Os> print_scale(Os& os, bool& prefixed)
+{
+    print_scale_t<Os> result = { &os, &prefixed };
+    return result;
+}
+
+// puts parentheses around a unit
+/// INTERNAL ONLY
+template<class Dimension,class Units,class Scale, class Subformatter>
+inline std::string
+maybe_parenthesize(const unit<Dimension, heterogeneous_system<heterogeneous_system_impl<Units, Dimension, Scale> > >&, Subformatter f)
+{
+    std::string str;
+
+    std::string without_scale = f(unit<Dimension, heterogeneous_system<heterogeneous_system_impl<Units, Dimension, dimensionless_type> > >());
+
+    if (f.is_default_string(without_scale, unit<Dimension, heterogeneous_system<heterogeneous_system_impl<Units, Dimension, dimensionless_type> > >()))
+    {
+        str += "(";
+        str += without_scale;
+        str += ")";
+    }
+    else
+    {
+        str += without_scale;
+    }
+
+    return(str);
+}
+
+// This overload catches scaled units that have a single base unit
+// raised to the first power.  It causes si::nano * si::meters to not
+// put parentheses around the meters.  i.e. nm rather than n(m)
+/// INTERNAL ONLY
+template<class Dimension,class Unit,class Scale, class Subformatter>
+inline std::string
+maybe_parenthesize(const unit<Dimension, heterogeneous_system<heterogeneous_system_impl<list<heterogeneous_system_dim<Unit, static_rational<1> >,dimensionless_type>, Dimension, Scale> > >&, Subformatter f)
+{
+    return f(unit<Dimension, heterogeneous_system<heterogeneous_system_impl<list<heterogeneous_system_dim<Unit, static_rational<1> >, dimensionless_type>, Dimension, dimensionless_type> > >());
+}
+
+template<class Prefixes, class CharT, class Traits, class Unit, class T, class F>
+void do_print_prefixed_impl(std::basic_ostream<CharT, Traits>& os, const quantity<Unit, T>& q, F default_)
+{
+    bool prefixed;
+    if(detail::find_matching_scale<Prefixes>(q.value(), autoprefix_norm(q.value()), detail::print_scale(os, prefixed))) {
+        if(prefixed) {
+            switch(units::get_format(os)) {
+                case symbol_fmt: do_print(os, maybe_parenthesize(Unit(), format_symbol_impl())); break;
+                case raw_fmt: do_print(os, maybe_parenthesize(Unit(), format_raw_symbol_impl())); break;
+                case name_fmt: do_print(os, maybe_parenthesize(Unit(), format_name_impl())); break;
+                case typename_fmt: do_print(os, simplify_typename(Unit())); break;
+            }
+        } else {
+            os << Unit();
+        }
+    } else {
+        default_();
+    }
+}
+
+// Handle units like si::kilograms that have a scale embedded in the
+// base unit.  This overload is disabled if the scaled base unit has
+// a user-defined string representation.
+template<class Prefixes, class CharT, class Traits, class Dimension, class BaseUnit, class BaseScale, class Scale, class T>
+typename base_unit_info<
+    scaled_base_unit<BaseUnit, Scale>
+>::base_unit_info_primary_template
+do_print_prefixed(
+    std::basic_ostream<CharT, Traits>& os,
+    const quantity<
+        unit<
+            Dimension,
+            heterogeneous_system<
+                heterogeneous_system_impl<
+                    list<
+                        heterogeneous_system_dim<
+                            scaled_base_unit<BaseUnit, BaseScale>,
+                            static_rational<1>
+                        >,
+                        dimensionless_type
+                    >,
+                    Dimension,
+                    Scale
+                >
+            >
+        >,
+        T
+    >& q)
+{
+    quantity<
+        unit<
+            Dimension,
+            heterogeneous_system<
+                heterogeneous_system_impl<
+                    list<
+                        heterogeneous_system_dim<BaseUnit, static_rational<1> >,
+                        dimensionless_type
+                    >,
+                    Dimension,
+                    dimensionless_type
+                >
+            >
+        >,
+        T
+    > unscaled(q);
+    detail::do_print_prefixed_impl<Prefixes>(os, unscaled, detail::print_default(os, q));
+}
+
+template<class Prefixes, class CharT, class Traits, class Dimension, class L, class Scale, class T>
+void do_print_prefixed(
+    std::basic_ostream<CharT, Traits>& os,
+    const quantity<
+        unit<
+            Dimension,
+            heterogeneous_system<
+                heterogeneous_system_impl<
+                    L,
+                    Dimension,
+                    Scale
+                >
+            >
+        >,
+        T
+    >& q)
+{
+    quantity<
+        unit<
+            Dimension,
+            heterogeneous_system<
+                heterogeneous_system_impl<
+                    L,
+                    Dimension,
+                    dimensionless_type
+                >
+            >
+        >,
+        T
+    > unscaled(q);
+    detail::do_print_prefixed_impl<Prefixes>(os, unscaled, detail::print_default(os, q));
+}
+
+template<class Prefixes, class CharT, class Traits, class Dimension, class System, class T>
+void do_print_prefixed(std::basic_ostream<CharT, Traits>& os, const quantity<unit<Dimension, System>, T>& q)
+{
+    detail::do_print_prefixed<Prefixes>(os, quantity<unit<Dimension, typename make_heterogeneous_system<Dimension, System>::type>, T>(q));
+}
+
+template<class Prefixes, class CharT, class Traits, class Unit, class T>
+void do_print_prefixed(std::basic_ostream<CharT, Traits>& os, const quantity<Unit, T>& q)
+{
+    detail::print_default(os, q)();
+}
+
+template<class Prefixes, class CharT, class Traits, class Unit, class T>
+void maybe_print_prefixed(std::basic_ostream<CharT, Traits>& os, const quantity<Unit, T>& q, mpl::true_)
+{
+    detail::do_print_prefixed<Prefixes>(os, q);
+}
+
+template<class Prefixes, class CharT, class Traits, class Unit, class T>
+void maybe_print_prefixed(std::basic_ostream<CharT, Traits>& os, const quantity<Unit, T>& q, mpl::false_)
+{
+    detail::print_default(os, q)();
+}
+
+inline mpl::true_ test_norm(double) { return mpl::true_(); }
+inline mpl::false_ test_norm(one) { return mpl::false_(); }
+
+} // namespace detail
+
+template<class Dimension,class System>
+inline std::string
+typename_string(const unit<Dimension, System>&)
+{
+    return simplify_typename(typename reduce_unit< unit<Dimension,System> >::type());
+}
+
+template<class Dimension,class System>
+inline std::string
+symbol_string(const unit<Dimension, System>&)
+{
+    return detail::to_string_impl(unit<Dimension,System>(), detail::format_symbol_impl());
+}
+
+template<class Dimension,class System>
+inline std::string
+name_string(const unit<Dimension, System>&)
+{
+    return detail::to_string_impl(unit<Dimension,System>(), detail::format_name_impl());
+}
+
+/// Print a @c unit as a list of base units and their exponents.
+///
+///     for @c symbol_format outputs e.g. "m s^-1" or "J".
+///     for @c name_format  outputs e.g. "meter second^-1" or "joule".
+///     for @c raw_format  outputs e.g. "m s^-1" or "meter kilogram^2 second^-2".
+///     for @c typename_format  outputs the typename itself (currently demangled only on GCC).
+template<class Char, class Traits, class Dimension, class System>
+inline std::basic_ostream<Char, Traits>& operator<<(std::basic_ostream<Char, Traits>& os, const unit<Dimension, System>& u)
+{
+    if (units::get_format(os) == typename_fmt) 
+    {
+        detail::do_print(os, typename_string(u));
+    }
+    else if (units::get_format(os) == raw_fmt) 
+    {
+        detail::do_print(os, detail::to_string_impl(u, detail::format_raw_symbol_impl()));
+    }
+    else if (units::get_format(os) == symbol_fmt) 
+    {
+        detail::do_print(os, symbol_string(u));
+    }
+    else if (units::get_format(os) == name_fmt) 
+    {
+        detail::do_print(os, name_string(u));
+    }
+    else 
+    {
+        assert(!"The format mode must be one of: typename_format, raw_format, name_format, symbol_format");
+    }
+    
+    return(os);
+}
+
+/// \brief Print a @c quantity.
+/// \details Prints the value followed by the unit.
+/// If the engineering_prefix, or binary_prefix is set,
+/// tries to scale the value appropriately.
+/// For example, it might print 12.345 km instead of 12345 m.
+/// (Note does @b not attempt to automatically scale scalars like double, float...)
+template<class Char, class Traits, class Unit, class T>
+inline std::basic_ostream<Char, Traits>& operator<<(std::basic_ostream<Char, Traits>& os, const quantity<Unit, T>& q)
+{
+    if (units::get_autoprefix(os) == autoprefix_none)
+    {
+        os << q.value() << ' ' << Unit();
+    }
+    else if (units::get_autoprefix(os) == autoprefix_engineering)
+    {
+        detail::maybe_print_prefixed<detail::engineering_prefixes>(os, q, detail::test_norm(autoprefix_norm(q.value())));
+    }
+    else if (units::get_autoprefix(os) == autoprefix_binary)
+    {
+        detail::maybe_print_prefixed<detail::binary_prefixes>(os, q, detail::test_norm(autoprefix_norm(q.value())));
+    }
+    else
+    {
+        assert(!"Autoprefixing must be one of: no_prefix, engineering_prefix, binary_prefix");
+    }
+    return(os);
+}
+
+} // namespace units
+
+} // namespace boost
+
+#endif