;
; floating point number
;
float    = [sign] decimal [exponent]
sign     = "+" / "-"
decimal  = integer [dot [fraction]]
           / dot fraction
integer  = 1*%d48-57
dot      = "."
fraction = 1*%d48-57
exponent = "e" [esign] exp
esign    = "+" / "-"
exp      = 1*%d48-57