X-Git-Url: https://git.dogcows.com/gitweb?p=chaz%2Fyoink;a=blobdiff_plain;f=src%2Fcml%2Fcore%2Fmeta%2Fswitch.h;fp=src%2Fcml%2Fcore%2Fmeta%2Fswitch.h;h=736e21a5b97763789c0535709062aee7d942383f;hp=0000000000000000000000000000000000000000;hb=6b0a0d0efafe34d48ab344fca3b479553bd4e62c;hpb=85783316365181491a3e3c0c63659972477cebba diff --git a/src/cml/core/meta/switch.h b/src/cml/core/meta/switch.h new file mode 100644 index 0000000..736e21a --- /dev/null +++ b/src/cml/core/meta/switch.h @@ -0,0 +1,116 @@ +/* -*- C++ -*- ------------------------------------------------------------ + +Copyright (c) 2007 Jesse Anders and Demian Nave http://cmldev.net/ + +The Configurable Math Library (CML) is distributed under the terms of the +Boost Software License, v1.0 (see cml/LICENSE for details). + + *-----------------------------------------------------------------------*/ +/** @file + * @brief + */ + +#ifndef meta_switch_h +#define meta_switch_h + +#include +#include + +namespace cml { + +struct NilCase {}; /* For terminating the case list. */ +struct Default {}; /* For indicating the default result. */ + +/* The working parts of the meta-switch go into namespace meta: */ +namespace meta { + +/* "Interior" case statements: */ +template +struct select_case +{ + template struct match { + typedef typename select_if< + same_type::is_true, + Result, + typename NextCase::template match::result + >::result result; + }; +}; + +/* Default case, returned when no match is found in a previous case: */ +template +struct select_case +{ + template struct match { + typedef Result result; + }; +}; + +/* The last case statement (if no match until now, the result is 'void'): */ +template +struct select_case +{ + template struct match { + typedef typename select_if< + same_type::is_true, + Result, + void + >::result result; + }; +}; + +} // namespace meta + +/** Return the matched type (like a switch/case statement). + * + * This is a convenience wrapper to avoid having to explicitly type out + * select_case for each case in the list of types to match against. + */ +template struct select_switch +{ + typedef typename + meta::select_case< T1,R1 + , meta::select_case< T2,R2 + , meta::select_case< T3,R3 + , meta::select_case< T4,R4 + , meta::select_case< T5,R5 + , meta::select_case< T6,R6 + , meta::select_case< T7,R7 + , meta::select_case< T8,R8 + , meta::select_case< T9,R9 + , meta::select_case< T10,R10 + , meta::select_case< T11,R11 + , meta::select_case< T12,R12 + , meta::select_case< T13,R13 + , meta::select_case< T14,R14 + , meta::select_case< T15,R15 + , meta::select_case< T16,R16 + , NilCase + > > > > > > /* 6 */ + > > > > > > > > > > /* 10 */ + ::template match::result result; +}; + +} // namespace cml + +#endif + +// ------------------------------------------------------------------------- +// vim:ft=cpp