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[smlnj] View of /sml/trunk/src/smlnj-lib/Util/int-list-map.sml
 [smlnj] / sml / trunk / src / smlnj-lib / Util / int-list-map.sml

# View of /sml/trunk/src/smlnj-lib/Util/int-list-map.sml

Sat Oct 4 23:33:09 1997 UTC (22 years ago) by monnier
File size: 5302 byte(s)
Initial revision
(* int-list-map.sml
*
* COPYRIGHT (c) 1996 by AT&T Research.  See COPYRIGHT file for details.
*
* An implementation of finite maps on integer keys, which uses a sorted list
* representation.
*)

structure IntListMap :> ORD_MAP where type Key.ord_key = Int.int =
struct

structure Key =
struct
type ord_key = int
val compare = Int.compare
end

type 'a map = (int * 'a) list

val empty = []

fun insert (l, key, item) = let
fun f [] = [(key, item)]
| f ((elem as (key', _))::r) = (case Key.compare(key, key')
of LESS => (key, item) :: elem :: r
| EQUAL => (key, item) :: r
| GREATER => elem :: (f r)
(* end case *))
in
f l
end

(* Look for an item, return NONE if the item doesn't exist *)
fun find (l, key) = let
fun f [] = NONE
| f ((key', x) :: r) = (case Key.compare(key, key')
of LESS => NONE
| EQUAL => SOME x
| GREATER => f r
(* end case *))
in
f l
end

(* Remove an item, returning new map and value removed.
*)
fun remove (l, key) = let
fun f (_, []) = raise LibBase.NotFound
| f (prefix, (elem as (key', x)) :: r) = (case Key.compare(key, key')
of LESS => raise LibBase.NotFound
| EQUAL => (List.revAppend(prefix, r), x)
| GREATER => f(elem :: prefix, r)
(* end case *))
in
f ([], l)
end

(* Return the number of items in the map *)
fun numItems l = List.length l

(* Return a list of the items (and their keys) in the map *)
fun listItems (l : 'a map) = List.map #2 l
fun listItemsi l = l

fun collate cmpRng = let
fun cmp ([], []) = EQUAL
| cmp ([], _) = LESS
| cmp (_, []) = GREATER
| cmp ((x1, y1)::r1, (x2, y2)::r2) = (case Key.compare(x1, x2)
of EQUAL => (case cmpRng(y1, y2)
of EQUAL => cmp (r1, r2)
| order => order
(* end case *))
| order => order
(* end case *))
in
cmp
end

(* return a map whose domain is the union of the domains of the two input
* maps, using the supplied function to define the map on elements that
* are in both domains.
*)
fun unionWith f (m1 : 'a map, m2 : 'a map) = let
fun merge ([], [], l) = List.rev l
| merge ([], m2, l) = List.revAppend(l, m2)
| merge (m1, [], l) = List.revAppend(l, m1)
| merge (m1 as ((k1, x1)::r1), m2 as ((k2, x2)::r2), l) = (
case Key.compare (k1, k2)
of LESS => merge (r1, m2, (k1, x1)::l)
| EQUAL => merge (r1, r2, (k1, f(x1, x2)) :: l)
| GREATER => merge (m1, r2, (k2, x2)::l)
(* end case *))
in
merge (m1, m2, [])
end
fun unionWithi f (m1 : 'a map, m2 : 'a map) = let
fun merge ([], [], l) = List.rev l
| merge ([], m2, l) = List.revAppend(l, m2)
| merge (m1, [], l) = List.revAppend(l, m1)
| merge (m1 as ((k1, x1)::r1), m2 as ((k2, x2)::r2), l) = (
case Key.compare (k1, k2)
of LESS => merge (r1, m2, (k1, x1)::l)
| EQUAL => merge (r1, r2, (k1, f(k1, x1, x2)) :: l)
| GREATER => merge (m1, r2, (k2, x2)::l)
(* end case *))
in
merge (m1, m2, [])
end

(* return a map whose domain is the intersection of the domains of the
* two input maps, using the supplied function to define the range.
*)
fun intersectWith f (m1 : 'a map, m2 : 'b map) = let
fun merge (m1 as ((k1, x1)::r1), m2 as ((k2, x2)::r2), l) = (
case Key.compare (k1, k2)
of LESS => merge (r1, m2, l)
| EQUAL => merge (r1, r2, (k1, f(x1, x2)) :: l)
| GREATER => merge (m1, r2, l)
(* end case *))
| merge (_, _, l) = List.rev l
in
merge (m1, m2, [])
end
fun intersectWithi f (m1 : 'a map, m2 : 'b map) = let
fun merge (m1 as ((k1, x1)::r1), m2 as ((k2, x2)::r2), l) = (
case Key.compare (k1, k2)
of LESS => merge (r1, m2, l)
| EQUAL => merge (r1, r2, (k1, f(k1, x1, x2)) :: l)
| GREATER => merge (m1, r2, l)
(* end case *))
| merge (_, _, l) = List.rev l
in
merge (m1, m2, [])
end

(* Apply a function to the entries of the map in map order. *)
val appi = List.app
fun app f l = appi (fn (_, item) => f item) l

(* Create a new table by applying a map function to the
* name/value pairs in the table.
*)
fun mapi f l = List.map (fn (key, item) => (key, f(key, item))) l
fun map f l = List.map (fn (key, item) => (key, f item)) l

(* Apply a folding function to the entries of the map
* in increasing map order.
*)
fun foldli f init l =
List.foldl (fn ((key, item), accum) => f(key, item, accum)) init l
fun foldl f init l = List.foldl (fn ((_, item), accum) => f(item, accum)) init l

(* Apply a folding function to the entries of the map
* in decreasing map order.
*)
fun foldri f init l =
List.foldr (fn ((key, item), accum) => f(key, item, accum)) init l
fun foldr f init l = List.foldr (fn ((_, item), accum) => f(item, accum)) init l

fun filter pred l = List.filter (fn (_, item) => pred item) l
fun filteri pred l = List.filter pred l

fun mapPartiali f l = let
fun f' (key, item) = (case f (key, item)
of NONE => NONE
| SOME y => SOME(key, y)
(* end case *))
in
List.mapPartial f' l
end
fun mapPartial f l = mapPartiali (fn (_, item) => f item) l

end (* IntListMap *)