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Struct template opt_parser

boost::parser::opt_parser

Synopsis

// In header: <boost/parser/parser.hpp>

template<typename Parser> 
struct opt_parser {

  // public member functions
  template<typename Iter, typename Sentinel, typename Context, 
           typename SkipParser> 
    auto call(Iter &, Sentinel, Context const &, SkipParser const &, 
              unspecified, bool &) const;
  template<typename Iter, typename Sentinel, typename Context, 
           typename SkipParser, typename Attribute> 
    void call(Iter &, Sentinel, Context const &, SkipParser const &, 
              unspecified, bool &, Attribute &) const;

  // public data members
  Parser parser_;
};

Description

Repeats the application of another parser of type Parser, [0, 1] times. The parse always succeeds. The attribute produced is a std::optional<T>, where T is the type of attribute produced by Parser.

`opt_parser` public member functions

template<typename Iter, typename Sentinel, typename Context, 
         typename SkipParser> 
  auto call(Iter & first, Sentinel last, Context const & context, 
            SkipParser const & skip, unspecified flags, bool & success) const;

template<typename Iter, typename Sentinel, typename Context, 
         typename SkipParser, typename Attribute> 
  void call(Iter & first, Sentinel last, Context const & context, 
            SkipParser const & skip, unspecified flags, bool & success, 
            Attribute & retval) const;