You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
131 lines
3.8 KiB
C++
131 lines
3.8 KiB
C++
// Copyright (C) 2003 Davis E. King (davis@dlib.net)
|
|
// License: Boost Software License See LICENSE.txt for the full license.
|
|
#ifndef DLIB_ENUMERABLe_INTERFACE_
|
|
#define DLIB_ENUMERABLe_INTERFACE_
|
|
|
|
namespace dlib
|
|
{
|
|
|
|
// ----------------------------------------------------------------------------------------
|
|
|
|
template <
|
|
typename T
|
|
>
|
|
class enumerable
|
|
{
|
|
/*!
|
|
POINTERS AND REFERENCES TO INTERNAL DATA
|
|
- if (at_start()) then
|
|
- all pointers and references to data returned via element() are
|
|
invalid.
|
|
- calling move_next() or reset() invalidates pointers and references to
|
|
data returned via element() and only data returned via element().
|
|
- calling at_start(), current_element_valid(), size(), or element()
|
|
does NOT invalidate pointers or references to any internal data.
|
|
|
|
INITIAL VALUE
|
|
current_element_valid() == false
|
|
at_start() == true
|
|
|
|
WHAT THIS OBJECT REPRESENTS
|
|
This object represent an interface for iterating through the
|
|
elements in a container. It starts out one before the first element
|
|
in the container.
|
|
|
|
|
|
EXAMPLE: The following loops though all elements in the container
|
|
and prints them to cout.
|
|
|
|
container.reset();
|
|
while(container.move_next()) {
|
|
cout << container.element();
|
|
}
|
|
!*/
|
|
|
|
public:
|
|
typedef T type;
|
|
|
|
inline virtual ~enumerable(
|
|
) = 0;
|
|
|
|
virtual bool at_start (
|
|
) const = 0;
|
|
/*!
|
|
ensures
|
|
- returns true if *this represents one position before the first element
|
|
in the container (this would also make the current element invalid)
|
|
else returns false
|
|
!*/
|
|
|
|
virtual void reset (
|
|
) const = 0;
|
|
/*!
|
|
ensures
|
|
- #current_element_valid() == false
|
|
- #at_start() == true
|
|
!*/
|
|
|
|
virtual bool current_element_valid (
|
|
) const = 0;
|
|
/*!
|
|
ensures
|
|
- returns true if we are currently at a valid element else
|
|
returns false
|
|
!*/
|
|
|
|
virtual const T& element (
|
|
) const = 0;
|
|
/*!
|
|
requires
|
|
- current_element_valid() == true
|
|
ensures
|
|
- returns a const reference to the current element
|
|
!*/
|
|
|
|
virtual T& element (
|
|
) = 0;
|
|
/*!
|
|
requires
|
|
- current_element_valid() == true
|
|
ensures
|
|
- returns a non-const reference to the current element
|
|
!*/
|
|
|
|
virtual bool move_next (
|
|
) const = 0;
|
|
/*!
|
|
ensures
|
|
- moves to the next element. i.e. #element() will now
|
|
return the next element in the container
|
|
- the return value will be equal to #current_element_valid()
|
|
- #at_start() == false
|
|
|
|
- returns true if there is another element
|
|
- returns false if there are no more elements in the container
|
|
!*/
|
|
|
|
virtual size_t size (
|
|
) const = 0;
|
|
/*!
|
|
ensures
|
|
- returns the number of elements in *this
|
|
!*/
|
|
|
|
protected:
|
|
|
|
// restricted functions
|
|
enumerable& operator=(const enumerable&) {return *this;} // no assignment operator
|
|
|
|
};
|
|
|
|
// destructor does nothing
|
|
template <typename T>
|
|
enumerable<T>::~enumerable() {}
|
|
|
|
// ----------------------------------------------------------------------------------------
|
|
|
|
}
|
|
|
|
#endif // DLIB_ENUMERABLe_INTERFACE_
|
|
|