Class: SelectingReadStream

• Inheritance
• Description
• Class protocol
  • instance creation
• Instance protocol
  • instance creation
  • queries
  • reading
• Examples

Inheritance:

   Object
   |
   +--Stream
      |
      +--SelectingReadStream

Package:

stx:libbasic2

Category:

Streams-Misc

Version:

rev: 1.5 date: 2014/04/30 18:20:55

user: cg

file: SelectingReadStream.st directory: libbasic2

module: stx stc-classLibrary: libbasic2

Description:

A stream which only delivers elements for which a select block returns true
from an underlying stream. 

Needs readAhead for proper atEnd handling.


[instance variables:]
    hasReadAhead        - because nil is a valid read-element,
                        this is used to know if readAhead is valid.

copyright
COPYRIGHT (c) 2009 by eXept Software AG
             All Rights Reserved

This software is furnished under a license and may be used
only in accordance with the terms of that license and with the
inclusion of the above copyright notice.   This software may not
be provided or otherwise made available to, or used by, any
other person.  No title to or ownership of the software is
hereby transferred.

Class protocol:

 on: aStream selecting: aBlock

Instance protocol:

 on: aStream selecting: aBlock

 atEnd

(comment from inherited method)
return true if the end of the stream has been reached;
- we do not know here how to do it, it must be redefined in subclass

 contentsSpecies

return a class of which instances will be returned, when
parts of the collection are asked for.
(see upTo-kind of methods in Stream)

 next

(comment from inherited method)
return the next element of the stream
- we do not know here how to do it, it must be redefined in subclass

Examples:

|s|

s := SelectingReadStream 
        on:#(1 2 3 4 5 6 7 8) readStream
        selecting:[:each | each even].
s upToEnd