Inspect a nested hashtab as a list

as.list.hashtab.R

# Inspect a nested hash table as a list
as.list.hashtab <- function(h) {
  val <- vector("list", 0)
  maphash(h, function(k, v) {
    r <- if (is.hashtab(v)) {
      as.list.hashtab(v)
    }else {
      v
    }
    val[[k]] <<- r
  })
  val
}

h <- hashtab()
sethash(h, 1, FALSE)
sethash(h, 2, hashtab())
sethash(gethash(h, 2), "a", -1)
sethash(gethash(h, 2), "b", -2)

as.list(h)
# [[1]]
# [1] FALSE
#
# [[2]]
# [[2]]$bjkk
# [1] -2
#
# [[2]]$a
# [1] -1

# It fails when the key can't be used to name a list element.
h2 <- hashtab()
sethash(h2, new.env(), FALSE)
as.list(h2)