Class: BaseNCoder

• Inheritance
• Description
• Related information
• Class protocol
  • decoding
  • initialization
  • instance creation
  • queries
• Instance protocol
  • accessing
  • decoding
  • encoding
  • initialization
  • misc
  • private
  • queries
  • stream compatibility
  • subclass responsibility

Inheritance:

   Object
   |
   +--Visitor
      |
      +--AspectVisitor
         |
         +--ObjectCoder
            |
            +--BaseNCoder
               |
               +--Base32Coder
               |
               +--Base64Coder

Package:

stx:libbasic2

Category:

System-Storage

Version:

rev: 1.11 date: 2017/02/10 10:15:52

user: cg

file: BaseNCoder.st directory: libbasic2

module: stx stc-classLibrary: libbasic2

Author:

Stefan Vogel (stefan@zwerg)

Description:

Abstract superclass of Base64Coder and Base32Coder
Their main entry point API is 
    <BaseNCoder> encode:aStringOrBytes
and
    <BaseNCoder> decode:aString

If the decoder should return a string, use
    <BaseNCoder> decodeAsString:aString.

[examples:]
    Base64Coder encode:'helloWorld'
    
    Base64Coder decode:'aGVsbG9Xb3JsZA=='
    
    Base64Coder decodeAsString:'aGVsbG9Xb3JsZA=='
    

[instance variables:]
    buffer          SmallInteger   buffered data
    bits            SmallInteger   Number of valid bits in buffer
    charCount       SmallInteger   Number of characters since last cr
    atEnd           Boolean        true if end of Base64 string reached

[class variables:]

Related information:

Class protocol:

 decodeAsString: encodedString

decode a base-n encoded string.
We already expect a string instead of a ByteArray

 initializeMappings

 new

 isAbstract

Return if this class is an abstract class.
True is returned here for myself only; false for subclasses.
Abstract subclasses must redefine this again.

Instance protocol:

 lineLimit: something

set the line length of the encoded output.
Default is a line length of 76 characters.

If nil, no line breaks will be done.

 next

answer the next decoded byte

 next: count

return the next count bytes of the stream as ByteArray

 peek

answer the next decoded byte. Do not consume this byte

 visitByteArray: aByteArray with: aParameter

Base64Coder encodingOf:#[1 2 3 4 5 6 255]

 visitObject: anObject with: aParameter

not defined. Use nextPut or nextPutAll:.
Could encode the printString here

 visitStream: aStream with: aParameter

Base64Coder encodingOf:#[1 2 3 4 5 6 255]
Base64Coder encodingOf:#[1 2 3 4 5 6 255] readStream

 visitString: aString with: aParameter

|encoded decoded decoder|

encoded := Base64Coder encode:'hello world'.
decoded := #[] writeStream.
decoder := Base64Coder on:encoded readStream.
[decoder atEnd] whileFalse:[
decoded nextPut:(decoder next).
].
decoded := decoded contents.
decoded asString.

 emptyWriteStream

answer an empty stream. We encode as string

 initialize

must be called if redefined

 reset

reset to initial state

 basicNext

answer the next decoded byte.
No peekByte handling is done here.

 atEnd

answer true, if no more bytes can be read

 binary

switch to binary mode - nothing is done here.
Defined for compatibility with ExternalStream.

 isStream

we simulate a stream

 nextBytesInto: anObject startingAt: offset

copy bytes into anObject starting at offset

 nextPut: aByte

encode aByte on the output stream

 nextPutAll: aCollection startingAt: first to: last

append the elements with index from first to last
of the argument, aCollection onto the receiver.

 nextPutBytes: aCollectionOfBytes

encode all objects from the argument

 stringUpToEnd

return a collection of the elements up-to the end

 upToEnd

return a collection of the elements up-to the end

 fillBuffer

fill buffer with next n characters each representing m bits

** This method raises an error - it must be redefined in concrete classes **

 flush

flush the remaining bits of buffer.
The number of bits in buffer is not a multiple of m, so we pad
the buffer and signal that padding has been done via $= characters.

** This method raises an error - it must be redefined in concrete classes **

 nextPutByte: aByte

encode aByte on the output stream

** This method raises an error - it must be redefined in concrete classes **