field_traits.h

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//=================================================================================================
// Copyright (c) 2012, Johannes Meyer, TU Darmstadt
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//       TU Darmstadt, nor the names of its contributors may be used to
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#ifndef CPP_INTROSPECTION_FIELD_TRAITS_H
#define CPP_INTROSPECTION_FIELD_TRAITS_H

#include <boost/type_traits/integral_constant.hpp>
#include <vector>
#include <boost/array.hpp>
#include <ros/message_traits.h>

namespace cpp_introspection {
namespace field_traits {

  template <typename T> struct is_array : public boost::false_type {};
  template <typename T> struct is_vector : public boost::false_type {};
  template <typename T> struct is_container : public boost::false_type {};
  template <typename T> struct value {
    typedef T type;
    static type& reference(T& instance, std::size_t) { return instance; }
    static const type& reference(const T& instance, std::size_t) { return instance; }
    static const char *name() { return ros::message_traits::DataType<T>::value(); }
  };
  template <typename T> struct size {
    static std::size_t value() { return 1; }
    static std::size_t value(const T& x) { return 1; }
    static void resize(T& x, size_t new_size, const T& initial = T()) {}
    static bool empty() { return false; }
    static bool empty(const T& x) { return false; }
    static std::size_t capacity() { return 1; }
    static std::size_t capacity(const T& x) { return 1; }
  };

  // specializations for std::vector
  template <typename T> struct is_vector< std::vector<T> > : public boost::true_type {};
  template <typename T> struct is_container< std::vector<T> > : public boost::true_type {};
  template <typename T> struct value< std::vector<T> > {
    typedef T type;
    static type& reference(std::vector<T>& instance, std::size_t i) { return instance[i]; }
    static const type& reference(const std::vector<T>& instance, std::size_t i) { return instance[i]; }
    static const char *name() { return value<T>::name(); }
  };
  template <typename T> struct size< std::vector<T> > {
    static std::size_t value() { return 0; }
    static std::size_t value(const std::vector<T>& x) { return x.size(); }
    static void resize(std::vector<T>& x, size_t new_size, const T& initial = T()) { x.resize(new_size, initial); }
    static bool empty() { return true; }
    static bool empty(const std::vector<T>& x) { return x.empty(); }
    static std::size_t capacity() { return 0; }
    static std::size_t capacity(const std::vector<T>& x) { return x.capacity(); }
  };

  // specializations for boost::array
  template <typename T, std::size_t N> struct is_array< boost::array<T,N> > : public boost::true_type {};
  template <typename T, std::size_t N> struct is_container< boost::array<T,N> > : public boost::true_type {};
  template <typename T, std::size_t N> struct value< boost::array<T,N> > {
    typedef T type;
    static type& reference(boost::array<T,N>& instance, std::size_t i) { return instance[i]; }
    static const type& reference(const boost::array<T,N>& instance, std::size_t i) { return instance[i]; }
    static const char *name() { return value<T>::name(); }
  };
  template <typename T, std::size_t N> struct size< boost::array<T,N> > {
    static std::size_t value() { return boost::array<T,N>::size(); }
    static std::size_t value(const boost::array<T,N>& x) { return x.size(); }
    static void resize(boost::array<T,N>& x, size_t new_size, const T& initial = T()) {}
    static bool empty() { return boost::array<T,N>::empty(); }
    static bool empty(const boost::array<T,N>& x) { return x.empty(); }
    static std::size_t capacity() { return N; }
    static std::size_t capacity(const boost::array<T,N>& x) { return x.size(); }
  };

  // simple type traits
#define INTROSPECTION_DECLARE_SIMPLE_TRAITS(_type, _name) \
  template <> struct value< _type > { \
    typedef _type type; \
    static type& reference(_type& instance, std::size_t) { return instance; } \
    static const type& reference(const _type& instance, std::size_t) { return instance; } \
    static const char *name() { return _name; } \
  }

  INTROSPECTION_DECLARE_SIMPLE_TRAITS(bool, "bool");
  INTROSPECTION_DECLARE_SIMPLE_TRAITS(uint8_t, "uint8");
  INTROSPECTION_DECLARE_SIMPLE_TRAITS(int8_t, "int8");
  INTROSPECTION_DECLARE_SIMPLE_TRAITS(uint16_t, "uint8");
  INTROSPECTION_DECLARE_SIMPLE_TRAITS(int16_t, "int16");
  INTROSPECTION_DECLARE_SIMPLE_TRAITS(uint32_t, "uint32");
  INTROSPECTION_DECLARE_SIMPLE_TRAITS(int32_t, "int32");
  INTROSPECTION_DECLARE_SIMPLE_TRAITS(uint64_t, "uint64");
  INTROSPECTION_DECLARE_SIMPLE_TRAITS(int64_t, "int64");
  INTROSPECTION_DECLARE_SIMPLE_TRAITS(float, "float32");
  INTROSPECTION_DECLARE_SIMPLE_TRAITS(double, "float64");
  INTROSPECTION_DECLARE_SIMPLE_TRAITS(ros::Time, "time");
  INTROSPECTION_DECLARE_SIMPLE_TRAITS(ros::Duration, "duration");

}} // namespace

#endif // CPP_INTROSPECTION_FIELD_TRAITS_H