[Oorexx-rfes] [ oorexx-Feature Requests-1749740 ] Please supply an "Iterator" for any collection

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Feature Requests item #1749740, was opened at 2007-07-07 23:45
Message generated for change (Comment added) made by orexx
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Category: Classes
Group: Next Release
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Rony G. Flatscher (orexx)
Assigned to: Nobody/Anonymous (nobody)
Summary: Please supply an "Iterator" for any collection

Initial Comment:
As pointed out in the "Cursor" RFE I have come up with an implemenation of a class "Iterator" that can be used with any collection. Its methods and logic duplicates as much of Supplier as possible (it adds positioning).

An iterator object should work on a snapshot of the colletction and supply the following methods:

- init(collection): constructor expecting a collection
- available: returns .true if an index/item pair is available
- next: positions on the next index/item pair
- previous: positions on the previous index/item pair
- first: positions on the first index/item pair
- last: positions on the last index/item pair
- position: attribute which stores the number of the index/item pair the iterator is currently addressing
- index: returns the index value
- item: returns the item value

The class is uploaded with this RFE.

A possible program using that class, followed by its output:


------------- cut here -------------
arr=.array~of("a", "b", "c")

say "Iterating using 'next':"
it=.Iterator~new(arr)      -- create an ierator
do while it~available
   say it~position"/"it~items":" "index="it~index"," "item="it~item
   it~next
end
say "---"

say "Positioning using 'last', ierating using 'previous':"
it~last     -- position on last index/item pair
do while it~available
   say it~position"/"it~items":" "index="it~index"," "item="it~item
   it~previous
end
say "---"

say "Positioning on second index/item pair:"
it~position=2
say it~position"/"it~items":" "index="it~index"," "item="it~item
say "---"


::requires "Iterator.cls" -- get the "Iterator" class
------------- cut here -------------

Output of previous program, if run with the uploaded "Iterator.cls" definition:

------------- cut here -------------
Iterating using 'next':
1/3: index=1, item=a
2/3: index=2, item=b
3/3: index=3, item=c
---
Positioning using 'last', ierating using 'previous':
3/3: index=3, item=c
2/3: index=2, item=b
1/3: index=1, item=a
---
Positioning on second index/item pair:
2/3: index=2, item=b
---
------------- cut here -------------


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>Comment By: Rony G. Flatscher (orexx)
Date: 2007-07-07 23:51

Message:
Logged In: YES 
user_id=662126
Originator: YES

Sorry, forgot the "items" method which returns the number of index/item
pairs in the iterator (this method is available in the Iterator class
implementation).

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You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=684733&aid=1749740&group_id=119701