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Fernando Cacciola d2652525b8 Some additional functions added to optional (being new there won't be regressions) 
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<TITLE>Boost Numeric Conversion Library - Conversion Traits</TITLE>
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<H1 ALIGN="center">Boost Numeric Conversion Library</H1>
<H1><A HREF="http://www.boost.org">Header </A><A
HREF="../../../../boost/numeric/conversion/conversion_traits.hpp">boost/numeric/conversion/conversion_traits.hpp</A></H1>
</TH>
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</TABLE> <HR>
<H2>Contents</H2>
<DL CLASS="page-index">
<DT><A HREF="#types">Types</A></DT>
</DL>
<UL>
<LI><A HREF="#ncm"><CODE>enumeration boost::numeric::int_float_mixture_enum;</CODE></A></LI>
<LI><A HREF="#ncsm"><CODE>enumeration boost::numeric::sign_mixture_enum;</CODE></A></LI>
<LI><A HREF="#ncum"><CODE>enumeration boost::numeric::udt_builtin_mixture_enum;</CODE></A></LI>
<LI><A HREF="#ifm"><CODE>template class boost::numeric::int_float_mixture&lt;T,S&gt;</CODE></A></LI>
<LI><A HREF="#sm"><CODE>template class boost::numeric::sign_mixture&lt;T,S&gt;</CODE></A></LI>
<LI><A HREF="#ubm"><CODE>template class boost::numeric::udt_builtin_mixture&lt;T,S&gt;</CODE></A></LI>
<LI><A HREF="#isr"><CODE>template class boost::numeric::is_subranged&lt;T,S&gt;</CODE></A></LI>
<LI><A HREF="#nct"><CODE>template class boost::numeric::conversion_traits&lt;T,S&gt;</CODE></A></LI>
</UL>
<DL><DT><A HREF="#examples">Example(s)</A></DT></DL>
<HR>
<H2><A NAME="types"></A>Types</H2>
<H2><CODE><A NAME="ncm">enumeration int_float_mixture</A>_enum</CODE></H2>
<PRE>namespace boost { namespace numeric {
enum int_float_mixture_enum
{
integral_to_integral
,integral_to_float
,float_to_integral
,float_to_float
} ;
} } // namespace boost::numeric
</PRE>
<H2><CODE><A NAME="ncsm">enumeration sign_mixture</A>_enum</CODE></H2>
<PRE>namespace boost { namespace numeric {
enum sign_mixture_enum
{
unsigned_to_unsigned
,signed_to_signed
,signed_to_unsigned
,unsigned_to_signed
} ;
} } // namespace boost::numeric</PRE>
<H2><CODE><A NAME="ncum">enumeration udt_builtin_mixture</A>_enum</CODE></H2>
<PRE>namespace boost { namespace numeric {
enum udt_builtin_mixture_enum
{
builtin_to_builtin
,builtin_to_udt
,udt_to_builtin
,udt_to_udt
} ;
} } // namespace boost::numeric</PRE>
<hr>
<H2><A NAME="ifm"><CODE>template class int_float_mixture&lt;&gt;</CODE></A></H2>
<PRE>namespace boost { namespace numeric {
template &lt;class T, class S&gt;
struct int_float_mixture : mpl::integral_c&lt;int_float_mixture_enum, <i>impl-def-value</i>&gt; {} ;
} } // namespace boost::numeric
</PRE>
<p>Classifying <code>S</code> and <code>T</code> as either <code>integral</code>
or <code>float</code>, this <a href="../../../mpl/doc/refmanual/integral-constant.html">MPL's Integral Constant</a>
indicates the combination of these attributes. <br>
Its <code>::value</code> is of enumeration type <A HREF="#ncm"><CODE>boost::numeric::int_float_mixture_enum</CODE></A>
</p>
<hr>
<H2><A NAME="sm"><CODE>template class sign_mixture&lt;&gt;</CODE></A></H2>
<PRE>namespace boost { namespace numeric {
template &lt;class T, class S&gt;
struct sign_mixture : mpl::integral_c&lt;sign_mixture_enum, <i>impl-def-value</i>&gt; {} ;
} } // namespace boost::numeric
</PRE>
<p>Classifying <code>S</code> and <code>T</code> as either <code>signed</code>
or <code>unsigned</code>, this <a href="../../../mpl/doc/refmanual/integral-constant.html">MPL's Integral Constant</a>
indicates the combination of these attributes. <br>
Its <code>::value</code> is of enumeration type <A HREF="#ncm"><CODE>boost::numeric::sign_mixture_enum</CODE></A>
</p>
<hr>
<H2><A NAME="ubm"><CODE>template class udt_builtin_mixture&lt;&gt;</CODE></A></H2>
<PRE>namespace boost { namespace numeric {
template &lt;class T, class S&gt;
struct udt_builtin_mixture : mpl::integral_c&lt;udt_builtin__mixture_enum, <i>impl-def-value</i>&gt; {} ;
} } // namespace boost::numeric
</PRE>
<p>Classifying <code>S</code> and <code>T</code> as either <code>user-defined</code>
or <code>builtin</code>, this <a href="../../../mpl/doc/refmanual/integral-constant.html">MPL's Integral Constant</a>
indicates the combination of these attributes. <br>
Its <code>::value</code> is of enumeration type <A HREF="#ncm"><CODE>boost::numeric::udt_builtin_mixture_enum</CODE></A>
</p>
<hr>
<H2><A NAME="isr"><CODE>template class is_subranged&lt;&gt;</CODE></A></H2>
<PRE>namespace boost { namespace numeric {
template &lt;class T, class S&gt;
struct is_subranged : mpl::bool_&lt;<i>impl-def-value</i>&gt; {} ;
} } // namespace boost::numeric
</PRE>
<p>Indicates if the range of the target type T is a subset of the range of the source type S.
That is: if there are some source values which fall out of the Target type's range.<br>
It is a boolean <a href="../../../mpl/doc/refmanual/integral-constant.html">MPL's Integral Constant</a>..<br>
It does not indicate if
a <i>particular</i> conversion is effectively out of range; it indicates that
some conversion <i>might be</i> out of range because not all the source values
are representable as Target type.</p>
<hr>
<H2><A NAME="nct"><CODE>template class conversion_traits&lt;&gt;</CODE></A></H2>
<PRE>namespace boost { namespace numeric {
template &lt;class T, class S&gt;
struct conversion_traits
{
mpl::integral_c&lt;int_float_mixture_enum , ...&gt; int_float_mixture ;
mpl::integral_c&lt;sign_mixture_enum , ...&gt; sign_mixture;
mpl::integral_c&lt;udt_builtin_mixture_enum, ...&gt; udt_builtin_mixture ;
mpl::bool_&lt;...&gt; subranged ;
mpl::bool_&lt;...&gt; trivial ;
typedef T target_type ;
typedef S source_type ;
typedef ... argument_type ;
typedef ... result_type ;
typedef ... supertype ;
typedef ... subtype ;
} ;
} } // namespace numeric, namespace boost
</PRE>
<BLOCKQUOTE>
<P>This traits class indicates some properties of a <i>numeric conversion direction</i>:
from a source type <code>S</code> to a target type <code>T</code>. It does not indicate the properties of
a <i>specific</i> conversion, but of the conversion <i>direction</i>. See
<A href="definitions.html#subranged">Definitions</A> for details.<br>
</P>
<P>The traits class provides the following
<a href="../../../mpl/doc/refmanual/integral-constant.html">MPL's Integral Constants</a>
of enumeration type. They express the <i>combination</i> of certain attributes of the Source and
Target types (thus they are call <i>mixture</i>):</P>
<TABLE BORDER="1">
<TR>
<TD>&nbsp;<CODE><B>int_float_mixture</B></CODE>&nbsp;</TD>
<TD>
<P>Same as given by the traits class <A HREF="#ifm"><CODE>int_float_mixture</CODE></A></P>
</TD>
</TR>
<TR>
<TD>&nbsp;<CODE><B>sign_mixture</B></CODE>&nbsp;</TD>
<TD>
<P>Same as given by the traits class <A HREF="#sm"><CODE>sign_mixture</CODE></A></P>
</TD>
</TR>
<TR>
<TD>&nbsp;<CODE><B>udt_builtin_mixture</B></CODE>&nbsp;</TD>
<TD>
<P>Same as given by the traits class <A HREF="#ubm"><CODE>udt_builtin_mixture</CODE></A></P>
</TD>
</TR>
</TABLE>
<P>The traits class provides the following
<a href="../../../mpl/doc/refmanual/integral-constant.html">MPL's Integral Constants</a>
of boolean type which indicates indirectly the relation between the Source and Target
<i>ranges</i>
(see <A href="definitions.html#range">Definitions</A> for details).</P>
<TABLE BORDER="1">
<TR>
<TD>&nbsp;<CODE> <B>subranged</B></CODE>&nbsp;</TD>
<TD>
<P>Same as given by <A HREF="#isr"><CODE>is_subranged</CODE></A></P>
</TD>
</TR>
<TR>
<TD>&nbsp;<CODE> <B>trivial</B></CODE>&nbsp;</TD>
<TD>
<P>Indicates if both Source and Target, <u>without cv-qualifications</u>, are
the same type.<br>
Its <code>::value</code> is of boolean type.</P>
</TD>
</TR>
</TABLE>
<P>The traits class provides the following types. They are the Source and Target
types classified and qualified for different purposes.</P>
<TABLE BORDER="1" width="720">
<TR>
<TD>&nbsp;<CODE><B>target_type</B></CODE>&nbsp;</TD>
<TD>
<P>The template parameter <CODE>T</CODE><EM> without cv-qualifications</EM></P>
</TD>
</TR>
<TR>
<TD>&nbsp;<CODE><B>source_type</B></CODE>&nbsp;</TD>
<TD>
<P>The template parameter <CODE>S</CODE><EM> without cv-qualifications</EM></P>
</TD>
</TR>
<TR>
<TD>&nbsp;<CODE><B>argument_type</B></CODE>&nbsp;</TD>
<TD>
<P>This type is either <CODE>source_type</CODE> or <CODE>source_type
const&amp;</CODE>. <BR> It represents the <I>optimal</I> argument type for the
<A HREF="converter.html">converter</A> member functions.<BR>
If <CODE>S</CODE> is a built-in type, this is <CODE>source_type</CODE>,
otherwise, this is <CODE>source_type const&amp;</CODE>. </P>
</TD>
</TR>
<TR>
<TD>&nbsp;<CODE><B>result_type</B></CODE></TD>
<TD>
<P>This type is either <CODE>target_type</CODE> or <CODE>target_type
const&amp;</CODE> <BR> It represents the return type of the
<A HREF="converter.html">converter</A> member functions.<BR>
If <CODE>T==S</CODE>, it is <CODE>target_type const&amp;</CODE>, otherwise,
it is <CODE>target_type</CODE>.</P>
</TD>
</TR>
<TR>
<TD height="37">&nbsp;<CODE><B>supertype</B></CODE></TD>
<TD height="37">
<P>If the conversion is <CODE>subranged</CODE>, it is <CODE>source_type</CODE>,
otherwise, it is <CODE>target_type</CODE></P>
</TD>
</TR>
<TR>
<TD>&nbsp;<CODE><B>subtype</B></CODE></TD>
<TD height="37">
<P>If the conversion is <CODE>subranged</CODE>, it is <CODE>target_type</CODE>,
otherwise, it is <CODE>source_type</CODE></P>
</TD>
</TR>
</TABLE> </BLOCKQUOTE> <HR>
<H2><A NAME="examples">Examples</A></H2>
<BLOCKQUOTE>
<PRE>#include &lt;cassert&gt;
#include &lt;typeinfo&gt;
#include &lt;boost/numeric/conversion/conversion_traits.hpp&gt;
int main()
{
// A trivial conversion.
typedef boost::numeric::conversion_traits&lt;short,short&gt; Short2Short_Traits ;
assert ( Short2Short_Traits::trivial::value ) ;
// A subranged conversion.
typedef boost::numeric::conversion_traits&lt;double,unsigned int&gt; UInt2Double_Traits ;
assert ( UInt2Double_Traits::int_float_mixture::value == boost::numeric::integral_to_float ) ;
assert ( UInt2Double_Traits::sign_mixture::value == boost::numeric::unsigned_to_signed ) ;
assert ( !UInt2Double_Traits::subranged::value ) ;
assert ( typeid(UInt2Double_Traits::supertype) == typeid(double) ) ;
assert ( typeid(UInt2Double_Traits::subtype) == typeid(unsigned int) ) ;
// A doubly subranged conversion.
assert ( (boost::numeric::conversion_traits&lt;short, unsigned short&gt;::subranged::value) );
assert ( (boost::numeric::conversion_traits&lt;unsigned short, short&gt;::subranged::value) );
return 0;
}
</PRE>
</BLOCKQUOTE>
<HR>
<P>Back to <A HREF="index.html">Numeric Conversion library index</A></P>
<HR>
<P>Revised 16 May 2005</P>
<p>© Copyright Fernando Luis Cacciola Carballal, 2004</p>
<p> Use, modification, and distribution are subject to the Boost Software
License, Version 1.0. (See accompanying file <a href="../../../../LICENSE_1_0.txt">
LICENSE_1_0.txt</a> or copy at <a href="http://www.boost.org/LICENSE_1_0.txt">
www.boost.org/LICENSE_1_0.txt</a>)</p>
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