[#is_whitespace_c]
[section is_whitespace_c]

[h1 Synopsis]

  namespace util
  {
    template <char C>
    struct is_whitespace_c;
  }

This is a template class similar to a [link metafunction template metafunction]
but taking a `char` value as argument.

[table Arguments
  [[Name] [Type]]
  [[`D`]  [`char` value]]
]

[h1 Description]

Checks if `C` is a whitespace character. Returns a boxed boolean value.

[h1 Header]

  #include <boost/metaparse/util/is_whitespace_c.hpp>

[h1 Expression semantics]

The following expressions are equivalent:

  is_whitespace_c<' '>::type
  boost::mpl::true_

  is_whitespace_c<'\t'>::type
  boost::mpl::true_

  is_whitespace_c<'\r'>::type
  boost::mpl::true_

  is_whitespace_c<'\n'>::type
  boost::mpl::true_

For any `c` character other than the above listed ones the following are
equivalent:

  is_whitespace_c<c>::type
  boost::mpl::false_

[h1 Example]

  #include <boost/metaparse/util/is_whitespace_c.hpp>
  
  #include <type_traits>
  
  using namespace boost::metaparse;
  
  static_assert(
    util::is_whitespace_c<' '>::type::value,
    "a space should be a whitespace character"
  );
  
  static_assert(
    !util::is_whitespace_c<'0'>::type::value,
    "a number should not be a whitespace character"
  );
  

[endsect]