pos=0 len=0
Match
pos=0 len=0   # Same pos & len as last pass -> No match.
pos=1 len=0
Match
pos=1 len=0   # Same pos & len as last pass -> No match.
pos=2 len=0
Match
pos=2 len=0   # Same pos & len as last pass -> No match.

pos=1 len=1
Match
pos=2 len=1
Match
pos=3 len=1
Match