[#spaces]
[section spaces]

[h1 Synopsis]

  struct spaces;

This is a [link parser parser].

[h1 Description]

`spaces` accepts any number of whitespace characters. It requires at least one
to be present.

[h1 Header]

  #include <boost/metaparse/spaces.hpp>

[h1 Expression semantics]

  spaces

is equivalent to

  repeated1<space>

[h1 Example]

  #include <boost/metaparse/spaces.hpp>
  #include <boost/metaparse/start.hpp>
  #include <boost/metaparse/string.hpp>
  #include <boost/metaparse/is_error.hpp>
  #include <boost/metaparse/get_remaining.hpp>
  
  #include <type_traits>
  
  using namespace boost::metaparse;
  
  static_assert(
    std::is_same<
      BOOST_METAPARSE_STRING("foo"),
      get_remaining<spaces::apply<BOOST_METAPARSE_STRING("  foo"), start>>::type
    >::type::value,
    "it should consume all whitespaces at the beginning of the input"
  );
  
  static_assert(
    is_error<spaces::apply<BOOST_METAPARSE_STRING("x"), start>>::type::value,
    "it should return an error when the input does not begin with a whitespace"
  );

[endsect]