Class: Base64Coder

• Inheritance
• Description
• Related information
• Class protocol
  • initialization
• Instance protocol
  • encoding
  • misc
  • private
• Examples

Inheritance:

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

Package:

stx:libbasic2

Category:

System-Storage

Version:

rev: 1.30 date: 2017/09/28 08:23:16

user: mawalch

file: Base64Coder.st directory: libbasic2

module: stx stc-classLibrary: libbasic2

Author:

Stefan Vogel

Description:

Instances of this class perform Base64 en- and decoding as defined in RFC 2045
3 bytes are mapped to 4 characters, representing 6 bits each.
The encoded string consists only of characters from the set:
    'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/='

The main entry point API is
    Base64Coder encode:aStringOrBytes
and
    Base64Coder decode:aString

If the decoder should return a string, use
    Base64Coder decodeAsString:aString.



[instance variables:]

[class variables:]
    Base64Mapping         String   Mapping from bytes (with 6 valid bits)
                                   to Base64 characters
    Base64ReverseMapping  Array    Mapping from Base64 characters to 6-bit-Bytes

Related information:

Class protocol:

 initializeMappings

initialize class variables

usage example(s):

self initializeMappings

Instance protocol:

 nextPutByte: aByte

encode aByte on the output stream

 flush

flush the remaining bits of buffer.
The number of bits in buffer is not a multiple of 6, so we pad
the buffer and signal that padding has been done via $= characters.

 fillBuffer

fill buffer with next 4 characters each representing 6 bits

Examples:

   (Base64Coder encode:'queen%27s%20gambit') asString = 'cXVlZW4lMjdzJTIwZ2FtYml0'

   (Base64Coder decode:'cXVlZW4lMjdzJTIwZ2FtYml0') asString = 'queen%27s%20gambit'

   |data1 text data2|

   data1 := #[0 1 16r7F 16r80 16r81 16rFE 16rFF].
   text := Base64Coder encode:data1.
   data2 := Base64Coder decode:text.
   data2

   |coder|

   coder := Base64Coder on:'' writeStream.
   coder nextPutAll:#[0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19].
   coder flush.
   coder contents inspect.
   coder reset.
   coder nextPut:254.
   coder contents inspect.

   |coder decoder|

   coder := Base64Coder on:'' writeStream.
   coder nextPutAll:#[0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20].
   coder flush.

   decoder := Base64Coder on:(coder contents readStream).
   [decoder atEnd] whileFalse:[
      Transcript show:decoder next
   ].
   Transcript cr.

   |coder|

   coder := Base64Coder on:'' writeStream.
   coder nextPutAll:(0 to:200) asByteArray.
   coder flush.

   Transcript showCR:(coder contents).