mapnik/include/mapnik/params_impl.hpp
2024-05-18 10:22:29 +02:00

233 lines
6.8 KiB
C++

/*****************************************************************************
*
* This file is part of Mapnik (c++ mapping toolkit)
*
* Copyright (C) 2021 Artem Pavlenko
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
*****************************************************************************/
// NOTE: This is an implementation header file and is only meant to be included
// from implementation files. It therefore doesn't have an include guard.
// mapnik
#include <mapnik/params.hpp>
#include <mapnik/value/types.hpp>
#include <mapnik/boolean.hpp>
#include <mapnik/util/conversions.hpp>
#include <mapnik/warning.hpp>
MAPNIK_DISABLE_WARNING_PUSH
#include <mapnik/warning_ignore.hpp>
#include <boost/lexical_cast.hpp>
MAPNIK_DISABLE_WARNING_POP
// stl
#include <string>
#include <sstream>
#include <stdexcept>
#include <optional>
namespace mapnik {
namespace detail {
template<typename T>
struct extract_value
{
static inline std::optional<T> do_extract_from_string(std::string const& /*source*/)
{
std::ostringstream s;
s << "No conversion from std::string to " << typeid(T).name();
throw std::runtime_error(s.str());
}
static inline std::optional<T> do_extract_from_bool(value_bool const& /*source*/)
{
std::ostringstream s;
s << "No conversion from boolean to " << typeid(T).name();
throw std::runtime_error(s.str());
}
};
template<>
struct extract_value<value_bool>
{
static inline std::optional<value_bool> do_extract_from_string(std::string const& source)
{
bool result;
if (mapnik::util::string2bool(source, result))
return std::optional<value_bool>(result);
return std::nullopt;
}
static inline std::optional<value_bool> do_extract_from_bool(value_bool const& source) { return source; }
};
template<>
struct extract_value<mapnik::boolean_type>
{
static inline std::optional<mapnik::boolean_type> do_extract_from_string(std::string const& source)
{
bool result;
if (mapnik::util::string2bool(source, result))
return std::optional<mapnik::boolean_type>(result);
return std::nullopt;
}
static inline std::optional<mapnik::boolean_type> do_extract_from_bool(value_bool const& source)
{
return std::optional<mapnik::boolean_type>(source);
}
};
template<>
struct extract_value<mapnik::value_integer>
{
static inline std::optional<mapnik::value_integer> do_extract_from_string(std::string const& source)
{
mapnik::value_integer result;
if (mapnik::util::string2int(source, result))
return std::optional<mapnik::value_integer>(result);
return std::nullopt;
}
static inline std::optional<mapnik::value_integer> do_extract_from_bool(value_bool const& source)
{
return std::optional<mapnik::value_integer>(boost::lexical_cast<mapnik::value_integer>(source));
}
};
template<>
struct extract_value<mapnik::value_double>
{
static inline std::optional<mapnik::value_double> do_extract_from_string(std::string const& source)
{
mapnik::value_double result;
if (mapnik::util::string2double(source, result))
return std::optional<double>(result);
return std::nullopt;
}
static inline std::optional<mapnik::value_double> do_extract_from_bool(value_bool const& source)
{
return std::optional<double>(boost::lexical_cast<double>(source));
}
};
template<>
struct extract_value<mapnik::value_null>
{
static inline std::optional<mapnik::value_null> do_extract_from_string(std::string const&)
{
return std::nullopt; // FIXME
}
static inline std::optional<mapnik::value_null> do_extract_from_bool(value_bool const&)
{
return std::nullopt; // FIXME
}
};
template<>
struct extract_value<std::string>
{
static inline std::optional<std::string> do_extract_from_string(std::string const& source)
{
return std::optional<std::string>(source);
}
static inline std::optional<std::string> do_extract_from_bool(value_bool const& source)
{
return source ? "true" : "false";
}
};
template<typename T>
std::optional<T> param_cast(std::string const& source)
{
return extract_value<T>::do_extract_from_string(source);
}
template<typename T>
std::optional<T> param_cast(value_bool const& source)
{
return extract_value<T>::do_extract_from_bool(source);
}
} // end namespace detail
template<typename T>
struct value_extractor_visitor
{
value_extractor_visitor(std::optional<T>& var)
: var_(var)
{}
void operator()(std::string const& val) const { var_ = detail::param_cast<T>(val); }
void operator()(value_bool const& val) const { var_ = detail::param_cast<T>(val); }
template<typename T1>
void operator()(T1 const& val) const
{
try
{
var_ = boost::lexical_cast<T>(val);
}
catch (boost::bad_lexical_cast const&)
{
std::ostringstream s;
s << "Failed converting from " << typeid(T1).name() << " to " << typeid(T).name();
throw std::runtime_error(s.str());
}
}
std::optional<T>& var_;
};
namespace params_detail {
template<typename T>
struct converter
{
using value_type = T;
using return_type = std::optional<value_type>;
static return_type
extract(parameters const& params, std::string const& name, std::optional<T> const& default_opt_value)
{
std::optional<T> result(default_opt_value);
parameters::const_iterator itr = params.find(name);
if (itr != params.end())
{
util::apply_visitor(value_extractor_visitor<T>(result), itr->second);
}
return result;
}
};
} // end namespace params_detail
template<typename T>
std::optional<T> parameters::get(std::string const& key) const
{
return params_detail::converter<T>::extract(*this, key, std::nullopt);
}
template<typename T>
std::optional<T> parameters::get(std::string const& key, T const& default_opt_value) const
{
return params_detail::converter<T>::extract(*this, key, std::optional<T>(default_opt_value));
}
} // namespace mapnik