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value traits to control to value conversions + fix is_null

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This commit is contained in:
artemp 2014-08-08 16:41:03 +01:00
parent 784d24828f
commit 7b255f2b95
1 changed files with 90 additions and 37 deletions
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127
include/mapnik/value.hpp
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@ -31,12 +31,10 @@
// boost
#include <boost/concept_check.hpp>
#include <boost/functional/hash.hpp>
// stl
#include <string>
#include <cmath>
#include <memory>
#include <iostream>
// icu
#include <unicode/unistr.h>
#include <unicode/ustring.h>
@ -66,7 +64,7 @@ inline void to_utf8(mapnik::value_unicode_string const& input, std::string & tar
}
}
using value_base = util::variant<value_null,value_bool,value_integer,value_double,value_unicode_string>;
using value_base = util::variant<value_null, value_bool, value_integer,value_double, value_unicode_string>;
namespace impl {
@ -814,6 +812,88 @@ struct to_expression_string : public util::static_visitor<std::string>
namespace value_adl_barrier {
namespace detail {
template <typename T>
struct is_value_bool
{
bool value = std::is_same<T, bool>::value;
};
template <typename T>
struct is_value_integer
{
bool value = std::is_integral<T>::value && !std::is_same<T, bool>::value;
};
template <typename T>
struct is_value_double
{
bool value = std::is_floating_point<T>::value;
};
template <typename T>
struct is_value_unicode_string
{
bool value = std::is_same<T,mapnik::value_unicode_string>::value;
};
template <typename T>
struct is_value_string
{
bool value = std::is_same<T,std::string>::value;
};
template <typename T>
struct is_value_null
{
bool value = std::is_same<T, value_null>::value;
};
} // namespace detail
template <typename T, class Enable = void>
struct mapnik_value_type
{
using type = T;
};
// value_null
template <typename T>
struct mapnik_value_type<T, typename std::enable_if<detail::is_value_null<T>::value>::type>
{
using type = mapnik::value_null;
};
// value_bool
template <typename T>
struct mapnik_value_type<T, typename std::enable_if<detail::is_value_bool<T>::value>::type>
{
using type = mapnik::value_bool;
};
// value_integer
template <typename T>
struct mapnik_value_type<T, typename std::enable_if<detail::is_value_integer<T>::value>::type>
{
using type = mapnik::value_integer;
};
// value_double
template <typename T>
struct mapnik_value_type<T, typename std::enable_if<detail::is_value_double<T>::value>::type>
{
using type = mapnik::value_double;
};
// value_unicode_string
template <typename T>
struct mapnik_value_type<T, typename std::enable_if<detail::is_value_unicode_string<T>::value>::type>
{
using type = mapnik::value_unicode_string;
};
class value
{
value_base base_;
@ -827,20 +907,9 @@ public:
value () noexcept //-- comment out for VC++11
: base_(value_null()) {}
value(value_integer val)
: base_(val) {}
value(value_double val)
: base_(val) {}
value(value_bool val)
: base_(val) {}
value(value_null val)
: base_(val) {}
value(value_unicode_string const& val)
: base_(val) {}
template <typename T>
value ( T const& val)
: base_(typename mapnik_value_type<T>::type(val)) {}
value (value const& other)
: base_(other.base_) {}
@ -974,20 +1043,14 @@ operator << (std::basic_ostream<charT,traits>& out,
return out;
}
inline std::size_t hash_value(value const& val)
{
std::cerr << "hash_value" << std::endl;
return 123; // FIXME hash_value(val.base());
}
} // namespace value_adl_barrier
using value_adl_barrier::value;
using value_adl_barrier::operator<<;
namespace impl {
namespace detail {
struct is_null : public util::static_visitor<bool>
struct is_null_visitor : public util::static_visitor<bool>
{
bool operator() (value const& val) const
{
@ -1004,25 +1067,15 @@ struct is_null : public util::static_visitor<bool>
bool operator() (T const& val) const
{
boost::ignore_unused_variable_warning(val);
std::cerr << "is_null" << std::endl;
return false;
}
//template <BOOST_VARIANT_ENUM_PARAMS(typename T)>
//bool operator() (boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)> const& val) const
//{
// return util::apply_visitor(*this, val);
//}
};
} // namespace impl
// constant visitor instance substitutes overloaded function
impl::is_null const is_null = impl::is_null();
} // namespace detail
inline bool value::is_null() const
{
return util::apply_visitor(impl::is_null(), base_);
return util::apply_visitor(mapnik::detail::is_null_visitor(), base_);
}
} // namespace mapnik