Class: ReadStream

• Inheritance
• Description
• Class protocol
  • blocked instance creation
• Instance protocol
  • Compatibility-Squeak
  • converting
  • emphasis
  • queries
  • reading
  • reading-numbers
  • writing

Inheritance:

   Object
   |
   +--Stream
      |
      +--PeekableStream
         |
         +--PositionableStream
            |
            +--ReadStream
               |
               +--FCGI::FCGIReadStream

Package:

stx:libbasic

Category:

Streams

Version:

rev: 1.98 date: 2019/03/27 14:41:37

user: cg

file: ReadStream.st directory: libbasic

module: stx stc-classLibrary: libbasic

Author:

Claus Gittinger

Description:

ReadStream defines protocol for reading streamwise over collections.

Class protocol:

 with: aCollection

with on readStream makes no sense
- what do you want to read from the end of a collection?

** This is an obsolete interface - do not use it (it may vanish in future versions) **

Instance protocol:

 next: n into: aCollection startingAt: startIndex

Read n objects into the given collection.
Return aCollection or a partial copy if less than
n elements have been read.

 nextInto: aCollection
( an extension from the stx:libcompat package )

Read the next elements of the receiver into aCollection.
Return aCollection or a partial copy if less than aCollection
size elements have been read.

 readStream

return a readStream from the receiver. Since this is already
a readStream, return self.

 readStreamOrNil

return a readStream from the receiver. Since this is already
a readStream, return self.

This method has been defined for protocol copmatibility with Filename

 emphasis

return the emphasis of the current (i.e. next returned by #next)
element. Streams on a string will return nil for all elements.
Streams on collections which nothing at all about emphasises,
will report an error.

 collectionSize

return the overall number of elements in the streamed collection
(both already read and to be read).

 copyFrom: beginning to: end

 isReadable

return true, if reading is supported by the receiver.
Here, true is always returned.

 isWritable

return true, if writing is supported by the receiver.
This has to be redefined in concrete subclasses.

 remainingSize

return the number of remaining elements in the streamed collection.

 size

return the number of remaining elements in the streamed collection.

Notice: VW and Squeak seem to return the overall size here,
which is an incompatibility that should be fixed.
However, fixing seems to break some existing applications,
so this will be delayed for some time...

ST/X provides two methods which are more explicit: collectionSize and remainingSize.
Change the sender to use either one, but no longer #size

 next

return the next element; advance read pointer.
return nil, if there is no next element.
- tuned for a bit more speed on String/ByteArray/Array-Streams

 next: count

return the next count elements of the stream as aCollection,
which depends on the streams type - (see #contentsSpecies).

usage example(s):

#[1 2 3 4 5 6 7 8 9] readStream next; next:5; next.

 nextAlphaNumericWord

read the next word (i.e. up to non letter-or-digit).
return a string containing those characters.
Skips any non-alphanumeric chars first.
- tuned for speed on String-Streams for faster scanning

 nextByte

return the next element as an integer between 0 and 255; advance read pointer.
- tuned for a bit more speed on String/ByteArray/Array-Streams

 nextOrNil

return the next element; advance read pointer.
return nil, if there is no next element.
- tuned for a bit more speed on String/ByteArray/Array-Streams

 nextPeek

advance read pointer return the peek element.
this is equivalent to (self next; peek).
- tuned for speed on String-Streams for faster scanning

 nextPeekOrNil

advance read pointer return the peek element.
this is equivalent to (self next; peekOrNil).
- tuned for speed on String-Streams for faster scanning

 nextUnicode16CharacterMSB: msb

#[16r00 16r51] readStream nextUnicode16CharacterMSB:true
#[16r00 16r51] readStream nextUnicode16CharacterMSB:false

 nextUnicode16Characters: count MSB: msb

easily tuned, if heavily used

usage example(s):

#[16r00 16r51] readStream nextUnicode16Characters:1 MSB:true #[16r00 16r51] readStream nextUnicode16Characters:1 MSB:false

 peek

return the next element; do NOT advance read pointer.
return nil, if there is no next element.
- tuned for a bit more speed on String/ByteArray/Array-Streams

 peekOrNil

return the next element; do NOT advance read pointer.
return nil, if there is no next element.
This is much like #peek -
However, unlike #peek, this does not raise an atEnd-query signal - even
if handled. Instead, nil is returned immediately.

 skipSeparators

skip all whitespace; next will return next non-white-space element.
Return the peeked character or nil, if the end-of-stream was reached.
- reimplemented for speed on String-Streams for faster scanning

 skipSeparatorsExceptCR

skip all whitespace except newlines;
next will return next non-white-space element.
- reimplemented for speed on String-Streams for faster scanning

 skipThrough: anObject

skip all objects up-to and including anObject.
Return the receiver if skip was successful,
otherwise (i.e. if not found) return nil and leave the stream positioned at the end.
On success, the next read operation will return the element after anObject.
- reimplemented for speed on String-Streams for faster scanning

 upTo: anObject

(comment from inherited method)
read a collection of all objects up-to anObject and return these
elements, but excluding anObject.
The next read operation will return the element after anObject.
(i.e. anObject is considered a separator, which is skipped)
Similar to #through:, but the matching object is not included in the
returned collection.
If anObject is not encountered, all elements up to the end are read
and returned.
Compare this with #through: which also reads up to some object
and also positions behind it, but DOES include it in the returned
value.

 nextDecimalInteger

read the next integer in radix 10.
Does NOT skip initial whitespace.
Does NOT care for an initial sign.
The stream's elements should be characters.

Be careful - this method returns 0 if not positioned on a digit initially
or if the end of the stream is encountered.

Tuned for speed on String-Streams for faster scanning

usage example(s):

fall-back for non-string streams - we have to continue where above primitive left off, in case of a large integer ... (instead of doing a super nextDecimalInteger)

 nextPut: anElement

catch write access to readstreams - report an error