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|
// ####################################################################
/// Various utility functions
///
/// author: Aleksandar Milicevic (t-alekm@microsoft.com)
// ####################################################################
module Utils
// -------------------------------------------
// ----------- collection util funcs ---------
// -------------------------------------------
// =====================================
/// ensures: ret = b ? Some(b) : None
// =====================================
let BoolToOption b =
if b then
Some(b)
else
None
// =====================================
/// ensures: ret = (opt == Some(_))
// =====================================
let IsSomeOption opt =
match opt with
| Some(_) -> true
| None -> false
// =====================================
/// ensures: ret = (opt == None)
// =====================================
let IsNoneOption opt = IsSomeOption opt |> not
// =====================================
/// requres: x = Some(a) or failswith msg
/// ensures: ret = a
// =====================================
let ExtractOptionMsg msg x =
match x with
| Some(a) -> a
| None -> failwith msg
// ====================
/// requres: x = Some(a)
/// ensures: ret = a
// ====================
let ExtractOption x =
ExtractOptionMsg "can't extract anything from a None" x
// ==========================================================
/// requres: List.length lst <= 1, otherwise fails with errMsg
/// ensures: if |lst| = 0 then
/// ret = None
/// else
/// ret = Some(lst[0])
// ==========================================================
let ListToOptionMsg lst errMsg =
if List.length lst > 1 then
failwith errMsg
if List.isEmpty lst then
None
else
Some(lst.[0])
let ListToOption lst = ListToOptionMsg lst "given list contains more than one element"
// =============================================================
/// ensures: forall i :: 0 <= i < |lst| ==> ret[i] = Some(lst[i])
// =============================================================
let rec ConvertToOptionList lst =
match lst with
| fs :: rest -> Some(fs) :: ConvertToOptionList rest
| [] -> []
// =========================================================
/// requres: Seq.length seq <= 1, otherwise fails with errMsg
/// ensures: if |seq| = 0 then
/// ret = None
/// else
/// ret = Some(seq[0])
// =========================================================
let SeqToOptionMsg seq errMsg =
if Seq.length seq > 1 then
failwith errMsg
if Seq.isEmpty seq then
None
else
Some(Seq.nth 0 seq)
let SeqToOption seq = SeqToOptionMsg seq "given seq contains more than one element"
// =========================================================
/// requires: Set.count set <= 1, otherwise fails with errMsg
/// ensures: if |set| = 0 then
/// ret = None
/// else
/// ret = Some(set[0])
// =========================================================
let SetToOptionMsg set errMsg =
if Set.count set > 1 then
failwith errMsg
if (Set.isEmpty set) then
None
else
Some(set |> Set.toList |> List.head)
let SetToOption set = SetToOptionMsg set "give set contains more than one value"
// ============================================================
/// requires: n >= 0
/// ensures: |ret| = n && forall i :: 0 <= i < n ==> ret[i] = e
// ============================================================
let rec GenList n e =
if n < 0 then
failwith "n must be positive"
if n = 0 then
[]
else
e :: (GenList (n-1) e)
// ==========================
/// ensures: ret = elem in lst
// ==========================
let ListContains elem lst =
lst |> List.exists (fun e -> e = elem)
// ===============================================================
/// ensures: |ret| = max(|lst| - cnt, 0)
/// ensures: forall i :: cnt <= i < |lst| ==> ret[i] = lst[i-cnt]
// ===============================================================
let rec ListSkip cnt lst =
if cnt = 0 then
lst
else
match lst with
| fs :: rest -> ListSkip (cnt-1) rest
| [] -> []
// ===============================================================
/// ensures: forall i :: 0 <= i < max(|srcList|, |dstList|) ==>
/// if i = idx then
/// ret[i] = v
/// elif i < |srcList| then
/// ret[i] = srcList[i]
/// else
/// ret[i] = dstList[i]
// ===============================================================
let rec ListBuild srcList idx v dstList =
match srcList, dstList with
| fs1 :: rest1, fs2 :: rest2 -> if idx = 0 then
v :: List.concat [rest1 ; ListSkip (List.length rest1) rest2]
else
fs1 :: ListBuild rest1 (idx-1) v rest2
| [], fs2 :: rest2 -> if idx = 0 then
v :: rest2
else
fs2 :: ListBuild [] (idx-1) v rest2
| _, [] -> failwith "index out of range"
// =======================================
/// ensures: forall i :: 0 <= i < |lst| ==>
/// if i = idx then
/// ret[i] = v
/// else
/// ret[i] = lst[i]
// =======================================
let rec ListSet idx v lst =
match lst with
| fs :: rest -> if idx = 0 then
v :: rest
else
fs :: ListSet (idx-1) v rest
| [] -> failwith "index out of range"
// =======================================
/// ensures: forall k,v ::
/// if k,v in map2 then
// k,v in ret
/// elif k,v in map1 then
/// k,v in ret
/// else
/// k,v !in ret
// =======================================
let rec MapAddAll map1 map2 =
map2 |> Map.fold (fun acc k v -> acc |> Map.add k v) map1
// -------------------------------------------
// ------ string active patterns -------------
// -------------------------------------------
let (|Prefix|_|) (p:string) (s:string) =
if s.StartsWith(p) then
Some(s.Substring(p.Length))
else
None
// -------------------------------------------
// --------------- workflow ------------------
// -------------------------------------------
let IfDo1 cond func1 a =
if cond then
func1 a
else
a
let IfDo2 cond func2 (a1,a2) =
if cond then
func2 a1 a2
else
a1,a2
type CascadingBuilder<'a>(failVal: 'a) =
member this.Bind(v, f) =
match v with
| Some(x) -> f x
| None -> failVal
member this.Return(v) = v
// -------------------------------------------
// --------------- random --------------------
// -------------------------------------------
let Iden x = x
|
