honeylisp/lib/util.fnl

(local lume (require :lib.lume))
(local json (require :lib.dkjson))
(local core (require :core))

(fn string.fromhex [str]
  (str:gsub ".." (fn [cc] (string.char (tonumber cc 16)))))
(fn string.tohex [str]
  (str:gsub "." (fn [c] (string.format "%02X" (string.byte c)))))

(fn lo [v] (bit.band v 0xff))
(fn hi [v] (bit.band (bit.rshift v 8) 0xff))
(fn loword [v] (bit.band v 0xffff))
(fn hiword [v] (bit.band (bit.rshift v 16) 0xffff))

(fn int8-to-bytes [i]
  (string.char (lo i)))
(fn int16-to-bytes [i]
  (string.char (lo i) (hi i)))
(fn int24-to-bytes [i]
  (string.char (lo i) (hi i) (lo (bit.rshift i 16))))
(fn int32-to-bytes [i]
  (string.char (lo i) (hi i) (lo (bit.rshift i 16)) (hi (bit.rshift i 16))))
(fn bytes-to-uint8 [b ?offset]
  (string.byte b (+ 1 (or ?offset 0)) (+ 1 (or ?offset 0))))
(fn bytes-to-uint16 [b ?offset]
  (local (lo hi) (string.byte b (+ 1 (or ?offset 0))   (+ 2 (or ?offset 0))))
  (bit.bor lo (bit.lshift hi 8)))
(fn bytes-to-uint24 [b ?offset]
  (local (lo mid hi) (string.byte b (+ 1 (or ?offset 0)) (+ 3 (or ?offset 0))))
  (bit.bor lo (bit.lshift mid 8) (bit.lshift hi 16)))

(fn splice [bytes offset str]
  (.. (bytes:sub 1 offset)
      str
      (bytes:sub (+ (length str) offset 1))))

(fn reload [modname]
  (tset package.loaded modname nil)
  (require modname))

; lume.hotswap really assumes your module is a table
(fn hotswap [modname]
  (if (= (type (. package.loaded modname)) :table)
    (lume.hotswap modname)
    (reload modname)))

(fn mk-swappable-fn [table k]
  (fn [...] ((. table k) ...)))

(fn swappable [table]
  (local s {})
  (each [k v (pairs table)]
    (if (= (type v) :function)
      (tset s k (mk-swappable-fn table k))
      (tset s k v)))
  s)

(fn swappable-require [modname]
  (swappable (require modname)))

(fn hot-table [modname]
  (local tbl {})
  (fn find-table []
    (let [loaded-pkg (. package.loaded modname)]
      (if (= (type loaded-pkg) :table) loaded-pkg tbl)))
  (setmetatable {:hot tbl} {
    :__index (fn [_ key] (. (find-table) key))
    :__newindex (fn [_ key val] (tset (find-table) key val))
  }))

(fn readjson [filename]
  (local f (io.open filename :r))
  (local text (f:read "*a"))
  (f:close)
  (json.decode text))

(fn writejson [filename value]
  (local f (io.open filename :w))
  (f:write (json.encode value))
  (f:close))

(fn waitfor [pred]
  (local coro (coroutine.running))
  (core.add_thread
    (fn []
      (while (not (pred))
        (coroutine.yield))
      (coroutine.resume coro))
    coro)
  (coroutine.yield))

(fn in-coro [f ...] (-> (coroutine.create f) (coroutine.resume ...)))

(fn multival-next [multival i]
  (when (< i multival.n)
    (values (+ i 1) (. multival (+ i 1)))))

(fn multival-ipairs [multival]
  (values multival-next multival 0))

(fn multival [...]
  (local multival {:n (select :# ...) :ipairs multival-ipairs})
  (for [i 1 multival.n]
    (tset multival i (select i ...)))
  multival)

(fn nested-tset [t keys value]
  (let [next-key (. keys 1)]
    (if (= (length keys) 1) (tset t next-key value)
      (do (when (= (. t next-key) nil)
            (tset t next-key {}))
          (nested-tset (. t next-key) (lume.slice keys 2) value)))))

(fn file-exists [name]
  (let [f (io.open name :r)]
    (when (not= f nil) (io.close f))
    (not= f nil)))

(fn pairoff [l]
  (fn [_ iprev] (let [i (if iprev (+ iprev 2) 1)]
                          (when (< i (length l)) (values i (. l i) (. l (+ i 1)))))))

{: int8-to-bytes : int16-to-bytes : int24-to-bytes : int32-to-bytes : bytes-to-uint8 : bytes-to-uint16 : bytes-to-uint24
 : splice : lo : hi : loword : hiword
 : reload : hotswap : swappable :require swappable-require : hot-table : nested-tset : pairoff
 : readjson : writejson : file-exists : waitfor : in-coro : multival}