It was added after 9.6.0. It is not there on spack yet.
You don’t really need to recompile the library. You need one include file
(magic_enum.hpp from https://github.com/Neargye/magic_enum) in your include
path, and to copy this to one of your headers:
#include <magic_enum.hpp>
namespace dealii {
namespace Patterns {
namespace Tools {
template <class T>
struct Convert<T, typename std::enable_if<std::is_enum<T>::value>::type>
{
static std::unique_ptr<Patterns::PatternBase>
to_pattern()
{
const auto n = magic_enum::enum_names<T>();
std::vector<std::string> names = {n.begin(), n.end()};
const auto selection =
Patterns::Tools::Convert<decltype(names)>::to_string(
names,
Patterns::List(
Patterns::Anything(), names.size(), names.size(), "|"));
// Allow parsing a list of enums, and make bitwise or between them
return Patterns::List(Patterns::Selection(selection),
0,
names.size(),
"|")
.clone();
}
static std::string
to_string(const T &value,
const Patterns::PatternBase &p = *Convert<T>::to_pattern())
{
const auto values = magic_enum::enum_values<T>();
std::vector<std::string> names;
for (const auto &v : values)
if (magic_enum::bitwise_operators::operator&(value, v) == v)
names.push_back(std::string(magic_enum::enum_name(v)));
return Patterns::Tools::Convert<decltype(names)>::to_string(names, p);
}
static T
to_value(const std::string &s,
const dealii::Patterns::PatternBase &p = *to_pattern())
{
// Make sure we have a valid enum value, or empty value
AssertThrow(p.match(s), ExcNoMatch(s, p.description()));
T value = T();
std::vector<std::string> value_names;
value_names =
Patterns::Tools::Convert<decltype(value_names)>::to_value(s, p);
for (const auto &name : value_names)
{
auto v = magic_enum::enum_cast<T>(name);
if (v.has_value())
value =
magic_enum::bitwise_operators::operator|(value, v.value());
}
return value;
}
};
}
}
}
> On 9 May 2025, at 10:20, Paras Kumar <[email protected]> wrote:
>
> Hi Luca,
>
> Thank you for the quick response.
>
> One (may be off-topic) short follow-up. How can I turn on the
> DEAL_II_WITH_MAGIC_ENUM option on using spack. I could not find any relevant
> option in the
> spack/dealii-9.4.0/var/spack/repos/builtin/packages/dealii/package.py file.
>
> Best regards,
> Paras
>
> On Thursday, May 8, 2025 at 5:53:37 PM UTC+2 [email protected] wrote:
> This is supported by default on deal.II master if you compile with magic enum
> support.
>
> It will allow you to parse directly the enum.
>
> You can simply copy and paste the relevant code in patterns.h to your header
> if you have an older deal.II.
>
> Luca
>
>> Il giorno 8 mag 2025, alle ore 17:40, Paras Kumar <[email protected]> ha
>> scritto:
>>
>>
>> Dear All,
>>
>> Here is a kind of follow-up to the above question.
>>
>> I now to try to read a list of strings and each of the values in the list
>> must to be converted to an enum class type.
>>
>> But I get the following compile time error when I try to compile below code
>> snippet
>>
>> "
>> : error: use of deleted function ‘static T
>> dealii::Patterns::Tools::Convert<T, Enable>::to_value(const std::string&,
>> const dealii::Patterns::PatternBase&) [with T = NonlinearSolverType; Enable
>> = void; std::string = std::__cxx11::basic_string<char>]’
>> 1829 | Convert<typename T::value_type>::to_value(str,
>> *base_p));
>> "
>>
>> I also tried playing around with the second template option "A" of the
>> dealii::Patterns::Tools::Convert<T,A>() function but it did not help. I am
>> not sure if this function is not yet instantiated to work for T =
>> decltype(nonlinearSolverTypes_)? or am I make syntactical mistake in calling
>> the function?
>>
>> enum class NonlinearSolverType
>> {
>> NEWTON_STANDARD,
>> NEWTON_MODIFIED
>> };
>> using NonlinearSolverListType = std::vector<NonlinearSolverType>;
>> dealii::Patterns::List nonlinearSolverListPattern(
>> dealii::Patterns::MultipleSelection(
>> "NEWTON_STANDARD|NEWTON_MODIFIED"),
>> nMinListElems,
>> nMaxListElems,
>> "|");
>> const std::string nonlinearSolverTypesString =
>> parameterHandler.get("Nonlinear solver types");
>> blockNonlinearSolverParameters_.nonlinearSolverTypes_ =
>> dealii::Patterns::Tools::Convert<NonlinearSolverListType, typename
>> std::enable_if<dealii::Patterns::Tools::is_list_compatible<NonlinearSolverListType>::value>::type>::to_value(nonlinearSolverTypesString,
>> std::move(nonlinearSolverListPattern));
>>
>> Some suggestions on resolving this issue will be really helpful.
>>
>> Best regards,
>> Paras Kumar
>>
>> On Monday, April 19, 2021 at 5:38:31 PM UTC+2 Wolfgang Bangerth wrote:
>> On 4/19/21 4:19 AM, Paras Kumar wrote:
>> >
>> > std::unique_ptr<dealii::Patterns::PatternBase> nItersListPattern(new
>> > dealii::Patterns::List(dealii::Patterns::Integer(1), 2, 8, "|"));
>> > nIters =
>> > dealii::Patterns::Tools::Convert<decltype(nIters)>::to_value(nMaxItersString,
>> >
>> > nItersListPattern);
>>
>> I suspect you need to write this last line as
>> dealii::Patterns::Tools::Convert<decltype(nIters)>::to_value(nMaxItersString,
>>
>> std::move(nItersListPattern));
>>
>> but the idea seems right. I was using the latest development sources in
>> which
>> the argument has been changed from a unique-ptr to just a regular object.
>>
>> Best
>> W.
>>
>> --
>> ------------------------------------------------------------------------
>> Wolfgang Bangerth email: [email protected]
>> www: http://www.math.colostate.edu/~bangerth/
>>
>>
>> --
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>
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