# File lib/ruote/svc/dollar_sub.rb, line 191 def extract_prefix(key) i = key.index(':') return [ 'f', key ] if not i # 'f' is the default prefix (field, not variable) pr = key[0..i-1] # until ':' pr = pr[0, 2] # the first two chars pr = pr[0, 1] unless (pr == 'vf') or (pr == 'fv') [ pr, key[i+1..-1] ] end