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Task/Arrays/Brainf---/arrays.bf

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+===========[
+ARRAY DATA STRUCTURE
+
+AUTHOR: Keith Stellyes
+WRITTEN: June 2016
+
+This is a zero-based indexing array data structure, it assumes the following
+precondition:
+
+>INDEX<|NULL|VALUE|NULL|VALUE|NULL|VALUE|NULL
+
+(Where >< mark pointer position, and | separates addresses)
+
+It relies heavily on [>] and [<] both of which are idioms for
+finding the next left/right null
+
+HOW INDEXING WORKS:
+It runs a loop _index_ number of times, setting that many nulls
+to a positive, so it can be skipped by the mentioned idioms.
+Basically, it places that many "milestones".
+
+EXAMPLE:
+If we seek index 2, and our array is {1 , 2 , 3 , 4 , 5}
+
+FINDING INDEX 2:
+   (loop to find next null, set to positive, as a milestone
+   decrement index)
+
+index
+  2  |0|1|0|2|0|3|0|4|0|5|0
+  1  |0|1|1|2|0|3|0|4|0|5|0
+  0  |0|1|1|2|1|3|0|4|0|5|0
+
+===========]
+
+=======UNIT TEST=======
+ SET ARRAY {48 49 50}
+>>++++++++++++++++++++++++++++++++++++++++++++++++>>
++++++++++++++++++++++++++++++++++++++++++++++++++>>
+++++++++++++++++++++++++++++++++++++++++++++++++++
+<<<<<<++ Move back to index and set it to 2
+=======================
+
+===RETRIEVE ELEMENT AT INDEX===
+
+=ACCESS INDEX=
+[>>[>]+[<]<-] loop that sets a null to a positive for each iteration
+              First it moves the pointer from index to first value
+               Then it uses a simple loop that finds the next null
+              it sets the null to a positive (1 in this case)
+               Then it uses that same loop reversed to find the first
+                 null which will always be one right of our index
+                 so we decrement our index
+               Finally we decrement pointer from the null byte to our
+              index and decrement it
+
+>>            Move pointer to the first value otherwise we can't loop
+
+[>]<          This will find the next right null which will always be right
+              of the desired value; then go one left
+
+
+.             Output the value (In the unit test this print "2"
+
+[<[-]<]       Reset array
+
+===ASSIGN VALUE AT INDEX===
+
+STILL NEED TO ADJUST UNIT TESTS
+
+NEWVALUE|>INDEX<|NULL|VALUE etc
+
+[>>[>]+[<]<-] Like above logic except it empties the value and doesn't reset
+>>[>]<[-]
+
+[<]<          Move pointer to desired value note that where the index was stored
+              is null because of the above loop
+			
+[->>[>]+[<]<] If NEWVALUE is GREATER than 0 then decrement it & then find the
+              newly emptied cell and increment it
+
+[>>[>]<+[<]<<-] Move pointer to first value find right null move pointer left
+                then increment where we want our NEWVALUE to be stored then
+                return back by finding leftmost null then decrementing pointer
+                twice then decrement our NEWVALUE cell