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introspection: add enum code generation macros

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This commit is contained in:
Danny Robson 2016-03-11 19:16:35 +11:00
parent 1c9d446d87
commit 6a6335163e
1 changed files with 164 additions and 2 deletions
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166
introspection.hpp
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@ -17,7 +17,8 @@
#ifndef __UTIL_INTROSPECTION_HPP
#define __UTIL_INTROSPECTION_HPP
#include "variadic.hpp"
#include "./preprocessor.hpp"
#include "./variadic.hpp"
#include <cstddef>
#include <string>
@ -60,7 +61,7 @@ namespace util {
template <
typename E
>
struct enum_values {
struct enum_traits {
/// Specialisations must provide the following constexpr:
///
/// value_type: typename
@ -68,6 +69,167 @@ namespace util {
/// values: static const std::array<value_type,value_count>
};
///////////////////////////////////////////////////////////////////////////
/// Defines specialisations for introspection data structures for an
/// enum E, in namespace NS, with variadic values __VA_ARGS__.
///
/// Expects to be caleld from outside all namespaces.
#define INTROSPECTION_ENUM_DECL(NS,E, ...) \
namespace util { \
template <> \
struct enum_traits<NS::E> { \
using value_type = NS::E; \
\
static constexpr \
size_t value_count = param_count (__VA_ARGS__); \
\
static constexpr \
std::array<value_type,value_count> \
values = { __VA_ARGS__ }; \
\
static constexpr \
std::array<const char*,value_count> \
names = { MAP(STRINGIZE_LIST, __VA_ARGS__) }; \
}; \
\
template <> \
struct type_string<E> { \
static constexpr const char value[] = #E; \
}; \
} \
///------------------------------------------------------------------------
/// Declares specialisations for introspection data structures for an
/// enum E, in namespace NS, with variadic values __VA_ARGS__.
///
/// Expects to be caleld from outside all namespaces.
#define INTROSPECTION_ENUM_IMPL(NS,E, ...) \
constexpr \
std::array< \
util::enum_traits<NS::E>::value_type, \
util::enum_traits<NS::E>::value_count \
> util::enum_traits<NS::E>::values; \
\
constexpr \
std::array< \
const char*, \
util::enum_traits<NS::E>::value_count \
> util::enum_traits<NS::E>::names; \
\
constexpr \
const char util::type_string<NS::E>::value[]; \
///------------------------------------------------------------------------
/// Defines an istream extraction operator for an enumeration E, within
/// namespace NS
///
/// Expects to be called from outside all namespaces.
///
/// The user is responsible for specialising the ::util::enum_traits<NS::E>
/// parameters which are used to drive the implementation (eg, through
/// INTROSPECTION_ENUM_DECL, and INTROSPECTION_ENUM_IMPL).
///
/// For trivial enumerations INTROSPECTION_ENUM may be easier to use.
#define INTROSPECTION_ENUM_ISTREAM(NS,E) \
std::istream& \
NS::operator>> (std::istream &is, NS::E &e) \
{ \
using traits = util::enum_traits<E>; \
\
std::string name; \
is >> name; \
\
std::transform (std::begin (name), \
std::end (name), \
std::begin (name), \
::toupper); \
\
auto name_pos = std::find ( \
std::cbegin (traits::names), \
std::cend (traits::names), \
name \
); \
\
if (name_pos == std::cend (traits::names)) { \
is.setstate (std::istream::failbit); \
} else { \
auto d = std::distance ( \
std::begin (traits::names), \
name_pos \
); \
\
e = traits::values[d]; \
} \
\
return is; \
}
/// Defines an ostream insertion operator for an enumeration E, within
/// namespace NS.
///
/// Expects to be called from outside all namespaces.
///
/// The user is responsible for specialising the ::util::enum_traits<NS::E>
/// parameters which are used to drive the implementation (eg, through
/// INTROSPECTION_ENUM_DECL, and INTROSPECTION_ENUM_IMPL).
///
/// For trivial enumerations INTROSPECTION_ENUM may be easier to use.
#define INTROSPECTION_ENUM_OSTREAM(NS,E) \
std::ostream& \
NS::operator<< (std::ostream &os, NS::E e) \
{ \
using traits = ::util::enum_traits<NS::E>; \
\
auto val_pos = std::find ( \
std::cbegin (traits::values), \
std::cend (traits::values), \
e \
); \
\
if (val_pos == std::cend (traits::values)) { \
os.setstate (std::ostream::failbit); \
} else { \
auto d = std::distance ( \
std::cbegin (traits::values), \
val_pos \
); \
\
os << traits::names[d]; \
} \
\
return os; \
}
/// Defines an enum, its values, associated introspection structures, and
/// istream and ostream operators.
///
/// This must be called from outside all namespaces as
/// INTROSPECTION_ENUM_DECL and INTROSPECTION_ENUM_IMPL need to declare
/// and define structures outside the user's namespace.
///
/// The enum will be defined inside an inline namespace to simplify the
/// passing of parameters to functions which require some namespace
/// prefixing. This shouldn't have a practical effect on user code.
#define INTROSPECTION_ENUM(E, ...) \
inline namespace detail_intr_enum { \
enum E { __VA_ARGS__ }; \
std::ostream& operator<< (std::ostream&, E); \
std::istream& operator>> (std::istream&, E&); \
} \
INTROSPECTION_ENUM_DECL(detail_intr_enum,E,__VA_ARGS__) \
INTROSPECTION_ENUM_IMPL(detail_intr_enum,E,__VA_ARGS__) \
INTROSPECTION_ENUM_ISTREAM(detail_intr_enum,E) \
INTROSPECTION_ENUM_OSTREAM(detail_intr_enum,E)
///////////////////////////////////////////////////////////////////////////
/// Describes a single member variable in a type availabe for introspection
///