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implementation module history
// $Id$
import spine
import rule
import graph
import basic
import StdEnv
:: History sym var
:== [(var,[Rgraph sym var])]
/*
> history * ** == [(**,[rgraph * **])]
> showhistory :: (*->[char]) -> (**->[char]) -> history * ** -> [char]
> showhistory showa showb = showlist (showpair showb (showlist (showrgraph showa showb)))
> printhistory :: (*->[char]) -> (**->[char]) -> history * ** -> [[char]]
> printhistory showa showb
> = concat.map print
> where print (node,rgraphs)
> = showb node:map2 (++) ("<= ":repeat " ") (map (printrgraph showa showb) rgraphs)
*/
extendhistory
:: (Graph sym var)
(var -> var)
(Spine sym var pvar)
(History sym var)
-> History sym var
extendhistory sgraph redirection spine history
= snd (foldspine (extendpair sgraph redirection) d d id d (const d) (extendpartial sgraph) (const d) (extendredex sgraph history) d spine)
where d = (emptygraph,history)
/*
> extendpair :: graph * ** -> (**->**) -> ** -> (graph * **,history * **) -> (graph * **,history * **)
> extendpair sgraph redirect snode (hgraph,history)
> = (hgraph',remap (redirect snode) (mkrgraph snode hgraph':foldmap id [] history snode) (forget snode history))
> where hgraph' = cond sdef (updategraph snode scont hgraph) hgraph
> (sdef,scont) = dnc (const "in extendpair") sgraph snode
*/
extendpair
:: (Graph sym var)
(var->var)
var
(Graph sym var,History sym var)
-> (Graph sym var,History sym var)
extendpair _ _ _ _ = undef
/*
> extendpartial :: graph * ** -> rule * *** -> pfun *** ** -> (graph * **,history * **) -> (graph * **,history * **)
> extendpartial sgraph rule matching (hgraph,history)
> = (extgraph' sgraph rule matching hgraph,history)
*/
extendpartial
:: (Graph sym var)
(Rule sym pvar)
(Pfun pvar var)
(Graph sym var,History sym var)
-> (Graph sym var,History sym var)
extendpartial _ _ _ _ = undef
/*
> extendredex :: graph * ** -> history * ** -> rule * *** -> pfun *** ** -> (graph * **,history * **)
> extendredex sgraph history rule matching
> = (extgraph' sgraph rule matching emptygraph,history)
*/
extendredex
:: (Graph sym var)
(History sym var)
(Rule sym pvar)
(Pfun pvar var)
-> (Graph sym var,History sym var)
extendredex _ _ _ _ = undef
/*
> extgraph' sgraph rule
> = extgraph sgraph rgraph (nodelist rgraph (lhs rule))
> where rgraph = rulegraph rule
*/
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