mirrors/eiffel-org
1
0
Fork 0
mirror of https://github.com/EiffelSoftware/eiffel-org.git synced 2025-12-07 23:32:42 +01:00
Code Issues Packages Projects Releases Wiki Activity

Corrections in the paragraph about Stacks based on user's comments.

Browse Source 
Updated wikipage EiffelBase, Dispensers.
	(Signed-off-by:WilliamsLima).

git-svn-id: https://svn.eiffel.com/eiffel-org/trunk@2080 abb3cda0-5349-4a8f-a601-0c33ac3a8c38
This commit is contained in:
eiffel-org
2018-09-14 22:39:40 +00:00
parent 33c3a941f5
commit c4694a0ea0
1 changed files with 4 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
documentation/18.07/solutions/basic-computing/eiffelbase/eiffelbase-tutorial/eiffelbase-data-structures-overview/eiffelbase-dispensers.wiki
View File

@@ -1,16 +1,18 @@
[[Property:modification_date|Fri, 14 Sep 2018 22:39:40 GMT]]
[[Property:publication_date|Fri, 14 Sep 2018 22:39:40 GMT]]
[[Property:title|EiffelBase, Dispensers]] [[Property:title|EiffelBase, Dispensers]]
[[Property:weight|2]] [[Property:weight|2]]
[[Property:uuid|4f65d62b-940b-c3c2-557e-d709a2a1bcaf]] [[Property:uuid|4f65d62b-940b-c3c2-557e-d709a2a1bcaf]]
A dispenser is called that way because of the image of a vending machine (a dispenser) of a rather primitive nature, in which there is only one button. If you press the button and the dispenser is not empty, you get one of its items in the exit tray at the bottom, but you do not choose that item: the machine does. There is also an input slot at the top, into which you may deposit new items; but you have no control over the order in which successive button press operations will retrieve these items. A dispenser is called that way because of the image of a vending machine (a dispenser) of a rather primitive nature, in which there is only one button. If you press the button and the dispenser is not empty, you get one of its items in the exit tray at the bottom, but you do not choose that item: the machine does. There is also an input slot at the top, into which you may deposit new items; but you have no control over the order in which successive button press operations will retrieve these items.
The deferred class [[ref:libraries/base/reference/dispenser_chart|DISPENSER]] provides the facilities which will be shared by all specialized classes. In fact, the interface of all dispenser classes is nearly identical, with the exception of a few extra possibilities offered by priority queues. Many kinds of dispenser are possible, each defined by the relation that the machine defines between the order in which items are inserted and the order in which they arereturned. The Base libraries support three important categories - stacks, queues, and priority queues: The deferred class [[ref:libraries/base/reference/dispenser_chart|DISPENSER]] provides the facilities which will be shared by all specialized classes. In fact, the interface of all dispenser classes is nearly identical, with the exception of a few extra possibilities offered by priority queues. Many kinds of dispenser are possible, each defined by the relation that the machine defines between the order in which items are inserted and the order in which they are returned. The Base libraries support three important categories - stacks, queues, and priority queues:
* A stack is a dispenser with a last-in, first-out (LIFO) internal policy: items come out in the reverse order of their insertion. Each button press returns the last deposited item. * A stack is a dispenser with a last-in, first-out (LIFO) internal policy: items come out in the reverse order of their insertion. Each button press returns the last deposited item.
* A queue is a dispenser with a first-in, first-out (FIFO) internal policy: items come out in the order of their insertion. Each button press returns the oldest item deposited and not yet removed. * A queue is a dispenser with a first-in, first-out (FIFO) internal policy: items come out in the order of their insertion. Each button press returns the oldest item deposited and not yet removed.
* In a priority queue, items have an associated notion of order; the element that comes out at any given time is the largest of those which are in the dispenser. * In a priority queue, items have an associated notion of order; the element that comes out at any given time is the largest of those which are in the dispenser.
==Stacks== ==Stacks==
Stacks - dispensers with a LIFO retrieval policy - are a ubiquitous structure in software development. Their most famous application is to parsing (syntactic analysis), but many other types of systems use one or more stacks. Class STACK describes general stacks, without commitment to a representation. This is a deferred class which may not be directly instantiated. The fundamental operations are put (add an element at end of queue), item (retrieve the oldest element, non-destructively), remove (remove the oldest element), is_empty (test for empty queue). <br/> Stacks - dispensers with a LIFO retrieval policy - are a ubiquitous structure in software development. Their most famous application is to parsing (syntactic analysis), but many other types of systems use one or more stacks. Class STACK describes general stacks, without commitment to a representation. This is a deferred class which may not be directly instantiated. The fundamental operations are put (add an element to the top of the stack), item (retrieve the element from the top, non-destructively), remove (remove the element from the top), is_empty (test for an empty stack). <br/>
Three effective heirs are provided: Three effective heirs are provided:
* [[ref:libraries/base/reference/linked_stack_chart|LINKED_STACK]] : stacks implemented as linked lists, with no limit on the number of items (<eiffel>count</eiffel>). * [[ref:libraries/base/reference/linked_stack_chart|LINKED_STACK]] : stacks implemented as linked lists, with no limit on the number of items (<eiffel>count</eiffel>).
* [[ref:libraries/base/reference/bounded_stack_chart|BOUNDED_STACK]] : stacks implemented as arrays. For such stacks, the maximum number of items (<eiffel>capacity</eiffel>) is set at creation time. * [[ref:libraries/base/reference/bounded_stack_chart|BOUNDED_STACK]] : stacks implemented as arrays. For such stacks, the maximum number of items (<eiffel>capacity</eiffel>) is set at creation time.