libbase/accumulator.h

   1 // accumulator.h: accumulating value for boost program_options.
   2 //
   3 //   Copyright (C) 2010, 2011 Free Software Foundation, Inc
   4 //
   5 // This program is free software; you can redistribute it and/or modify
   6 // it under the terms of the GNU General Public License as published by
   7 // the Free Software Foundation; either version 3 of the License, or
   8 // (at your option) any later version.
   9 //
  10 // This program is distributed in the hope that it will be useful,
  11 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 // GNU General Public License for more details.
  14 //
  15 // You should have received a copy of the GNU General Public License
  16 // along with this program; if not, write to the Free Software
  17 // Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  18 //
  19
  20 #ifndef PROGRAM_OPTIONS_ACCUMULATOR_HPP
  21 #define PROGRAM_OPTIONS_ACCUMULATOR_HPP
  22
  23 #include <boost/program_options/value_semantic.hpp>
  24 #include <boost/any.hpp>
  25 #include <boost/function.hpp>
  26 #include <vector>
  27 #include <string>
  28
  29 /// An accumulating option value to handle multiple incrementing options.
  30 template<typename T>
  31 class accumulator_type : public boost::program_options::value_semantic
  32 {
  33 public:
  34
  35     accumulator_type() : _interval(1), _default(0) {}
  36
  37     /// Set the notifier function.
  38     accumulator_type* notifier(boost::function1<void, const T&> f) {
  39         _notifier = f;
  40         return this;
  41     }
  42
  43     /// Set the default value for this option.
  44     accumulator_type* default_value(const T& t) {
  45         _default = t;
  46         return this;
  47     }
  48
  49     /// Set the implicit value for this option.
  50     //
  51     /// Unlike for program_options::value, this specifies a value
  52     /// to be applied on each occurence of the option.
  53     accumulator_type* implicit_value(const T& t) {
  54         _interval = t;
  55         return this;
  56     }
  57
  58     virtual std::string name() const { return std::string(); }
  59
  60     /// There are no tokens for an accumulator_type
  61     virtual unsigned min_tokens() const { return 0; }
  62     virtual unsigned max_tokens() const { return 0; }
  63
  64     /// Accumulating from different sources is silly.
  65     virtual bool is_composing() const { return false; }
  66
  67     /// Requiring one or more appearances is unlikely.
  68     virtual bool is_required() const { return false; }
  69
  70     /// Every appearance of the option simply increments the value
  71     //
  72     /// There should never be any tokens.
  73     virtual void parse(boost::any& value_store,
  74                        const std::vector<std::string>& new_tokens,
  75                        bool /*utf8*/) const
  76     {
  77         assert(new_tokens.empty());
  78         if (value_store.empty()) value_store = T();
  79         boost::any_cast<T&>(value_store) += _interval;
  80     }
  81
  82     /// If the option doesn't appear, this is the default value.
  83     virtual bool apply_default(boost::any& value_store) const {
  84         value_store = _default;
  85         return true;
  86     }
  87
  88     /// Notify the user function with the value of the value store.
  89     virtual void notify(const boost::any& value_store) const {
  90         if (_notifier) _notifier(boost::any_cast<T>(value_store));
  91     }
  92
  93     virtual ~accumulator_type() {}
  94
  95 private:
  96     boost::function1<void, const T&> _notifier;
  97     T _interval;
  98     T _default;
  99 };
 100
 101 template<typename T>
 102 accumulator_type<T>* accumulator() {
 103     return new accumulator_type<T>();
 104 }
 105
 106 #endif