Challenge307_Easy.txt

[2017-03-20] Challenge #307 [Easy] base 255 part1
submitted 17 days ago by Godspiral3 3
encoding a variable length binary data array can be done with a length encoding, or by one of the 4 methods in this challenge. Generally, a seperator value (usually ascii char 0) is used as separator of elements, but there needs to be some way of embedding/escaping possible seperator values that are included in the data. ie. binary data may include the byte value 0.
For ease of posting to reddit, instead of char code 0 as "magic" separator + will be used in these examples. Your function should accept the 256th char in the base as a separator code.
1. escape followed by code

with separator code +, the 2 character code ++ indicates an embedded + in data while +, (, is ascii(+) + 1) indicates a field/element separator.
encode input:
abc+def
ghij
klmno++p+
decode of 3 input strings:
 abc++def+,ghij+,klmno++++p++
code that reverses decode output into input is also needed.
2. encode seperator byte count

based on section 2 (extendable byte base) of this challenge: https://www.reddit.com/r/dailyprogrammer/comments/54lu54/20160926_challenge_285_easy_cross/
an embedded "magic char" can be followed by the count of the consecutive number of that "magic char". In a real world scenario, extendible byte base 256 can be used. For ease of using printable characters in this challenge, base 10 and still + magic char code will be used.
so +0 is a separator. +8 is 8 consecutive embedded +s. +90 is 9 embedded +s. +991 is 19 embedded +s.
encoded part 1 input:
abc+1def+0ghij+0klmno+2p+1
3. When no leading (xor trailing) nulls (magic chars) allowed

In a binary encoding of numeric array data, leading nulls (0s) in a field can't happen. So an encoding where data nulls are doubled up, but single separator nulls are used to delimit fields/array values, then an odd number of consecutive "magic chars" always means trailing data nulls followed by end-of-field.
encoded part 1 input:
abc++def+ghij+klmno++++p+++
4. possible but rare trailing or starting embedded nulls

variation on 3, when an odd number of "magic chars" > 2 are encountered, a trailing code removes the ambiguity of whether there are trailing "magic chars" in the field just ended (code 0), or leading "magic chars" in the field following the separator (code 1)
encoded part 1 input:
abc++def+ghij+klmno++++p+++0
The advantage of parts 3 and 4 approach is the assumption that embedded "magic chars" are rare, but a separator is common in the output string, and so these encodings hope to be shorter.