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[smlnj] View of /MLRISC/trunk/graphs/graph-topsort.sml
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View of /MLRISC/trunk/graphs/graph-topsort.sml

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Revision 2126 - (download) (annotate)
Thu Nov 2 16:11:29 2006 UTC (12 years, 7 months ago) by blume
File size: 701 byte(s)
moved MLRISC to toplevel
(*
 * This module computes a topological sort of a graph
 *
 * -- Allen
 *)

structure GraphTopsort : GRAPH_TOPOLOGICAL_SORT = 
struct

   structure G = Graph

   (*
    * Topological sort
    *)
   fun topsort (G.GRAPH G) roots = 
   let val visited = Word8Array.array(#capacity G (),0w0)
       val succ    = #succ G
       fun dfs (n, list) =
          if Word8Array.sub(visited,n) <> 0w0 then list
          else (Word8Array.update(visited,n,0w1); dfs'(n,succ n,list))
       and dfs'(x,[],list)    = x::list
         | dfs'(x,n::ns,list) = dfs'(x,ns,dfs(n,list))
       and dfs''([], list)    = list
         | dfs''(n::ns, list) = dfs''(ns,dfs(n,list))
   in
       dfs''(roots,[])
   end

end


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