[#reject]
[section reject]

[h1 Synopsis]

  template <class Msg, class Pos>
  struct reject;

This is a [link metaprogramming_value template metaprogramming value].

[table Arguments
  [[Name]  [Type]]
  [[`Msg`] [[link metaprogramming_value template metaprogramming value]]]
  [[`Pos`] [[link source_position source position]]]
]

[h1 Description]

Values representing a failed parser application. It behaves as a
[link lazy_metafunction lazy template metafunction]: when it is evaluated as a
metafunction, it returns itself with its arguments evaluated. See expression
semantics for further details.

[note
Note that for backward compatibility when `Msg::type` is not defined,
`reject<....>::type` does not evaluate `Msg`. For example
`reject<int, start>::type` is `reject<int, start::type>`. Using types that are
not template metaprogramming values as `Msg` is deprecated and will not work
in future versions of the library.
]

[h1 Expressions semantics]

For any `m` template metaprogramming value and `p` source position the following
are equivalent:

  reject<m, p>::type
  
  reject<m, p::type>

[h1 Header]

  #include <boost/metaparse/reject.hpp>

[h1 Operations]

* [link get_position `get_position`]
* [link get_message `get_message`]

[endsect]