// Copyright (C) 2003 Davis E. King (davis@dlib.net)

// License: Boost Software License See LICENSE.txt for the full license.

#undef DLIB_QUEUE_KERNEl_ABSTRACT_

#ifdef DLIB_QUEUE_KERNEl_ABSTRACT_

#include "../interfaces/enumerable.h"

#include "../interfaces/remover.h"

#include "../serialize.h"

#include "../algs.h"

namespace dlib

{

template <

typename T,

typename mem_manager = default_memory_manager

>

class queue : public enumerable<T>,

public remover<T>

{

/*!

REQUIREMENTS ON T

T must be swappable by a global swap()

T must have a default constructor

REQUIREMENTS ON mem_manager

must be an implementation of memory_manager/memory_manager_kernel_abstract.h or

must be an implementation of memory_manager_global/memory_manager_global_kernel_abstract.h or

must be an implementation of memory_manager_stateless/memory_manager_stateless_kernel_abstract.h

mem_manager::type can be set to anything.

POINTERS AND REFERENCES TO INTERNAL DATA

swap() and current() functions do not invalidate pointers or

references to internal data.

All other functions have no such guarantee.

INITIAL VALUE

size() == 0

ENUMERATION ORDER

The enumerator will iterate over the elements in the queue in the

same order they would be removed by repeated calls to dequeue().

(e.g. current() would be the first element enumerated)

WHAT THIS OBJECT REPRESENTS

This is a first in first out queue containing items of type T

e.g. if the queue is {b,c,d,e} and then 'a' is enqueued

the queue becomes {a,b,c,d,e} and then calling dequeue takes e out

making the queue {a,b,c,d}

Also note that unless specified otherwise, no member functions

of this object throw exceptions.

!*/

public:

typedef T type;

typedef mem_manager mem_manager_type;

queue (

);

/*!

ensures

- #*this is properly initialized

throws

- std::bad_alloc or any exception thrown by T's constructor

!*/

virtual ~queue (

);

/*!

ensures

- all memory associated with *this has been released

!*/

void clear(

);

/*!

ensures

- #*this has its initial value

throws

- std::bad_alloc or any exception thrown by T's constructor

if this exception is thrown then *this is unusable

until clear() is called and succeeds

!*/

void enqueue (

T& item

);

/*!

ensures

- item is now at the left end of #*this

- #item has an initial value for its type

- #size() == size() + 1

- #at_start() == true

throws

- std::bad_alloc or any exception thrown by T's constructor

if enqueue() throws then it has no effect

!*/

void dequeue (

T& item

);

/*!

requires

- size() != 0

ensures

- #size() == size() - 1

- the far right element of *this has been removed and swapped

into #item

- #at_start() == true

!*/

void cat (

queue& item

);

/*!

ensures

- item has been concatenated onto the left end of *this.

i.e. item.current() is attached onto the left end of *this and

the left most element in item will also be the left most item

in #*this

- #size() == size() + item.size()

- #item has its initial value

- #at_start() == true

throws

- std::bad_alloc or any exception thrown by T's constructor

if cat() throws then the state of #item and *this is undefined

until clear() is successfully called on them.

!*/

T& current (

);

/*!

requires

- size() != 0

ensures

- returns a const reference to the next element to be dequeued.

i.e. the right most element.

!*/

const T& current (

) const;

/*!

requires

- size() != 0

ensures

- returns a non-const reference to the next element to be dequeued.

i.e. the right most element.

!*/

void swap (

queue& item

);

/*!

ensures

- swaps *this and item

!*/

private:

// restricted functions

queue(queue&); // copy constructor

queue& operator=(queue&); // assignment operator

};

template <

typename T,

typename mem_manager

>

inline void swap (

queue<T,mem_manager>& a,

queue<T,mem_manager>& b

) { a.swap(b); }

/*!

provides a global swap function

!*/

template <

typename T,

typename mem_manager

>

void deserialize (

queue<T,mem_manager>& item,

std::istream& in

);

/*!

provides deserialization support

!*/

}

#endif // DLIB_QUEUE_KERNEl_ABSTRACT_