--- a/src/Pure/net.ML Mon Jan 29 13:50:10 1996 +0100
+++ b/src/Pure/net.ML Mon Jan 29 13:56:41 1996 +0100
@@ -1,6 +1,6 @@
-(* Title: net
+(* Title: net
ID: $Id$
- Author: Lawrence C Paulson, Cambridge University Computer Laboratory
+ Author: Lawrence C Paulson, Cambridge University Computer Laboratory
Copyright 1993 University of Cambridge
Discrimination nets: a data structure for indexing items
@@ -46,9 +46,9 @@
*)
fun add_key_of_terms (t, cs) =
let fun rands (f$t, cs) = CombK :: rands (f, add_key_of_terms(t, cs))
- | rands (Const(c,_), cs) = AtomK c :: cs
- | rands (Free(c,_), cs) = AtomK c :: cs
- | rands (Bound i, cs) = AtomK (string_of_bound i) :: cs
+ | rands (Const(c,_), cs) = AtomK c :: cs
+ | rands (Free(c,_), cs) = AtomK c :: cs
+ | rands (Bound i, cs) = AtomK (string_of_bound i) :: cs
in case (head_of t) of
Var _ => VarK :: cs
| Abs _ => VarK :: cs
@@ -66,9 +66,9 @@
Lookup functions preserve order in items stored at same level.
*)
datatype 'a net = Leaf of 'a list
- | Net of {comb: 'a net,
- var: 'a net,
- alist: (string * 'a net) list};
+ | Net of {comb: 'a net,
+ var: 'a net,
+ alist: (string * 'a net) list};
val empty = Leaf[];
val emptynet = Net{comb=empty, var=empty, alist=[]};
@@ -76,7 +76,7 @@
(*** Insertion into a discrimination net ***)
-exception INSERT; (*duplicate item in the net*)
+exception INSERT; (*duplicate item in the net*)
(*Adds item x to the list at the node addressed by the keys.
@@ -89,25 +89,25 @@
if gen_mem eq (x,xs) then raise INSERT else Leaf(x::xs)
| ins1 (keys, Leaf[]) = ins1 (keys, emptynet) (*expand empty...*)
| ins1 (CombK :: keys, Net{comb,var,alist}) =
- Net{comb=ins1(keys,comb), var=var, alist=alist}
- | ins1 (VarK :: keys, Net{comb,var,alist}) =
- Net{comb=comb, var=ins1(keys,var), alist=alist}
- | ins1 (AtomK a :: keys, Net{comb,var,alist}) =
- let fun newpair net = (a, ins1(keys,net))
- fun inslist [] = [newpair empty]
- | inslist((b: string, netb) :: alist) =
- if a=b then newpair netb :: alist
- else if a<b then (*absent, ins1ert in alist*)
- newpair empty :: (b,netb) :: alist
- else (*a>b*) (b,netb) :: inslist alist
- in Net{comb=comb, var=var, alist= inslist alist} end
+ Net{comb=ins1(keys,comb), var=var, alist=alist}
+ | ins1 (VarK :: keys, Net{comb,var,alist}) =
+ Net{comb=comb, var=ins1(keys,var), alist=alist}
+ | ins1 (AtomK a :: keys, Net{comb,var,alist}) =
+ let fun newpair net = (a, ins1(keys,net))
+ fun inslist [] = [newpair empty]
+ | inslist((b: string, netb) :: alist) =
+ if a=b then newpair netb :: alist
+ else if a<b then (*absent, ins1ert in alist*)
+ newpair empty :: (b,netb) :: alist
+ else (*a>b*) (b,netb) :: inslist alist
+ in Net{comb=comb, var=var, alist= inslist alist} end
in ins1 (keys,net) end;
fun insert_term ((t,x), net, eq) = insert((key_of_term t, x), net, eq);
(*** Deletion from a discrimination net ***)
-exception DELETE; (*missing item in the net*)
+exception DELETE; (*missing item in the net*)
(*Create a new Net node if it would be nonempty*)
fun newnet {comb=Leaf[], var=Leaf[], alist=[]} = empty
@@ -124,19 +124,19 @@
let fun del1 ([], Leaf xs) =
if gen_mem eq (x,xs) then Leaf (gen_rem eq (xs,x))
else raise DELETE
- | del1 (keys, Leaf[]) = raise DELETE
- | del1 (CombK :: keys, Net{comb,var,alist}) =
- newnet{comb=del1(keys,comb), var=var, alist=alist}
- | del1 (VarK :: keys, Net{comb,var,alist}) =
- newnet{comb=comb, var=del1(keys,var), alist=alist}
- | del1 (AtomK a :: keys, Net{comb,var,alist}) =
- let fun newpair net = (a, del1(keys,net))
- fun dellist [] = raise DELETE
- | dellist((b: string, netb) :: alist) =
- if a=b then conspair(newpair netb, alist)
- else if a<b then (*absent*) raise DELETE
- else (*a>b*) (b,netb) :: dellist alist
- in newnet{comb=comb, var=var, alist= dellist alist} end
+ | del1 (keys, Leaf[]) = raise DELETE
+ | del1 (CombK :: keys, Net{comb,var,alist}) =
+ newnet{comb=del1(keys,comb), var=var, alist=alist}
+ | del1 (VarK :: keys, Net{comb,var,alist}) =
+ newnet{comb=comb, var=del1(keys,var), alist=alist}
+ | del1 (AtomK a :: keys, Net{comb,var,alist}) =
+ let fun newpair net = (a, del1(keys,net))
+ fun dellist [] = raise DELETE
+ | dellist((b: string, netb) :: alist) =
+ if a=b then conspair(newpair netb, alist)
+ else if a<b then (*absent*) raise DELETE
+ else (*a>b*) (b,netb) :: dellist alist
+ in newnet{comb=comb, var=var, alist= dellist alist} end
in del1 (keys,net) end;
fun delete_term ((t,x), net, eq) = delete((key_of_term t, x), net, eq);
@@ -154,7 +154,7 @@
(*Return the list of items at the given node, [] if no such node*)
fun lookup (Leaf(xs), []) = xs
- | lookup (Leaf _, _::_) = [] (*non-empty keys and empty net*)
+ | lookup (Leaf _, _::_) = [] (*non-empty keys and empty net*)
| lookup (Net{comb,var,alist}, CombK :: keys) = lookup(comb,keys)
| lookup (Net{comb,var,alist}, VarK :: keys) = lookup(var,keys)
| lookup (Net{comb,var,alist}, AtomK a :: keys) =
@@ -166,7 +166,7 @@
| net_skip (Net{comb,var,alist}, nets) =
foldr net_skip
(net_skip (comb,[]),
- foldr (fn ((_,net), nets) => net::nets) (alist, var::nets));
+ foldr (fn ((_,net), nets) => net::nets) (alist, var::nets));
(** Matching and Unification**)
@@ -182,25 +182,25 @@
*)
fun matching unif t (net,nets) =
let fun rands _ (Leaf _, nets) = nets
- | rands t (Net{comb,alist,...}, nets) =
- case t of
- f$t => foldr (matching unif t) (rands f (comb,[]), nets)
- | Const(c,_) => look1 (alist, c) nets
- | Free(c,_) => look1 (alist, c) nets
- | Bound i => look1 (alist, string_of_bound i) nets
- | _ => nets
+ | rands t (Net{comb,alist,...}, nets) =
+ case t of
+ f$t => foldr (matching unif t) (rands f (comb,[]), nets)
+ | Const(c,_) => look1 (alist, c) nets
+ | Free(c,_) => look1 (alist, c) nets
+ | Bound i => look1 (alist, string_of_bound i) nets
+ | _ => nets
in
case net of
- Leaf _ => nets
+ Leaf _ => nets
| Net{var,...} =>
- case (head_of t) of
- Var _ => if unif then net_skip (net,nets)
- else var::nets (*only matches Var in net*)
+ case (head_of t) of
+ Var _ => if unif then net_skip (net,nets)
+ else var::nets (*only matches Var in net*)
(*If "unif" then a var instantiation in the abstraction could allow
an eta-reduction, so regard the abstraction as a wildcard.*)
- | Abs _ => if unif then net_skip (net,nets)
- else var::nets (*only a Var can match*)
- | _ => rands t (net, var::nets) (*var could match also*)
+ | Abs _ => if unif then net_skip (net,nets)
+ else var::nets (*only a Var can match*)
+ | _ => rands t (net, var::nets) (*var could match also*)
end;
val extract_leaves = flat o map (fn Leaf(xs) => xs);