--- /dev/null
+// Copyright 2006 all rights reserved; see LICENSE file for BSD-style license
+
+package edu.berkeley.sbp;
+import edu.berkeley.sbp.*;
+import edu.berkeley.sbp.util.*;
+import edu.berkeley.sbp.Sequence.Position;
+import java.io.*;
+import java.util.*;
+import java.lang.reflect.*;
+import java.lang.ref.*;
+
+class Cache {
+ private Union root;
+ private Topology top;
+
+ public HashMap<Sequence, Topology> follow = new HashMap<Sequence, Topology>();
+ public HashSet<Sequence> followEof = new HashSet<Sequence>();
+ public final HashMap<SequenceOrElement,Boolean> possiblyEpsilon = new HashMap<SequenceOrElement,Boolean>();
+ public HashSet<SequenceOrElement> all = new HashSet<SequenceOrElement>();
+
+ public Cache(Union root, Topology top) {
+ this.root = root;
+ this.top = top;
+ }
+
+ // Follow //////////////////////////////////////////////////////////////////////////////
+
+ public Topology follow(Sequence s) { return follow.get(s); }
+
+ public void buildFollowSet(Sequence seq, Topology followTopology, boolean eof) {
+ all.add(seq);
+ Topology old = follow.get(seq);
+ if (old==null) old = followTopology;
+ else old = old.union(followTopology);
+ if (seq.follow != null) old = old.intersect(seq.follow.getTokenTopology());
+ if (follow.get(seq) != null && follow.get(seq).containsAll(old) && (!eof || followEof.contains(seq)))
+ return;
+ follow.put(seq, old);
+ if (eof) followEof.add(seq);
+
+ for(Position p = seq.firstp().last().prev(); p!=null; p = p.prev()) {
+ all.add(p.element());
+ if (p.element() instanceof Union)
+ for(Sequence s2 : ((Union)p.element())) {
+ buildFollowSet(s2, followTopology, eof);
+ for(Sequence ss : s2.needs()) buildFollowSet(ss, followTopology, eof);
+ for(Sequence ss : s2.hates()) buildFollowSet(ss, followTopology, eof);
+ }
+ if (!possiblyEpsilon(p.element())) {
+ followTopology = followTopology.empty();
+ eof = false;
+ }
+ followTopology = followTopology.union(first(p.element(), new HashSet<Sequence>()));
+ }
+ }
+
+ public Topology epsilonFollowSet(Union u) {
+ Topology ret = top.empty();
+ for(Sequence s : u)
+ ret = ret.union(epsilonFollowSet(s, new HashSet<Sequence>()));
+ return ret;
+ }
+ public Topology epsilonFollowSet(Sequence seq, HashSet<Sequence> seen) {
+ Topology ret = seq.follow==null ? top.empty().complement() : seq.follow.getTokenTopology();
+ if (seen.contains(seq)) return ret;
+ seen.add(seq);
+ for(Position p = seq.firstp(); p!=null && !p.isLast(); p = p.next()) {
+ if (!(p.element() instanceof Union)) continue;
+ Topology t = top.empty();
+ for(Sequence s : ((Union)p.element()))
+ if (possiblyEpsilon(s))
+ t = t.union(epsilonFollowSet(s, seen));
+ ret = ret.intersect(t);
+ }
+ return ret;
+ }
+
+ public Topology first(SequenceOrElement e, HashSet<Sequence> seen) {
+ if (e instanceof Atom) return ((Atom)e).getTokenTopology();
+ Topology ret = top.empty();
+ if (e instanceof Union) {
+ for(Sequence s : ((Union)e)) ret = ret.union(first(s, seen));
+ } else {
+ Sequence seq = (Sequence)e;
+ if (seen.contains(seq)) return top.empty();
+ seen.add(seq);
+ for(Position p = seq.firstp(); p!=null && !p.isLast(); p = p.next()) {
+ ret = ret.union(first(p.element(), seen));
+ if (!possiblyEpsilon(p.element())) break;
+ }
+ }
+ return ret;
+ }
+
+ // Epsilon-Ness //////////////////////////////////////////////////////////////////////////////
+
+ final boolean possiblyEpsilon(SequenceOrElement e) {
+ Boolean ret = possiblyEpsilon.get(e);
+ if (ret != null) return ret.booleanValue();
+ ret = possiblyEpsilon(e, new HashMap<SequenceOrElement,Boolean>());
+ possiblyEpsilon.put(e, ret);
+ return ret;
+ }
+
+ private boolean possiblyEpsilon(SequenceOrElement e, HashMap<SequenceOrElement,Boolean> hm) {
+ if (hm.get(e) != null) return hm.get(e);
+ hm.put(e, false);
+ boolean ret = false;
+ if (e instanceof Atom) ret = false;
+ else if (e instanceof Union) { for(Sequence s : (Union)e) ret |= possiblyEpsilon(s, hm); }
+ else if (e instanceof Sequence) {
+ ret = true;
+ Sequence s = (Sequence)e;
+ for(Position p = s.firstp(); p!=null && !p.isLast(); p = p.next())
+ ret &= possiblyEpsilon(p.element(), hm);
+ }
+ hm.put(e, ret);
+ return ret;
+ }
+
+ public boolean isRightNullable(Position p) {
+ if (p.isLast()) return true;
+ if (!possiblyEpsilon(p.element())) return false;
+ return isRightNullable(p.next());
+ }
+
+ public boolean isNulledSubsequence(Sequence parent, Sequence potentialSubSequence) {
+ HashSet<Sequence> eq = new HashSet<Sequence>();
+ gatherNulledSubsequences(parent, eq);
+ return eq.contains(potentialSubSequence);
+ }
+ private void gatherNulledSubsequences(Sequence seq, HashSet<Sequence> eq) {
+ if (eq.contains(seq)) return;
+ eq.add(seq);
+ Position p = seq.firstp();
+ for(; !p.isLast(); p = p.next()) {
+ if (!p.isLast() && isRightNullable(p.next()) && p.element() instanceof Union)
+ for(Sequence s : ((Union)p.element()))
+ gatherNulledSubsequences(s, eq);
+ if (!possiblyEpsilon(p.element())) break;
+ }
+ }
+
+ // Position Ordinality Comparisons //////////////////////////////////////////////////////////////////////////////
+
+ public boolean canKill(Position mep, Position himp) {
+ if (!isRightNullable(mep)) return false;
+ if (!isRightNullable(himp)) return false;
+ Sequence me = mep.owner();
+ Sequence him = himp.owner();
+ Boolean b = me.canKill.get(him);
+ if (b!=null) return b;
+ for(Sequence killer : him.hates())
+ if (isNulledSubsequence(killer, me))
+ { me.canKill.put(him, true); return true; }
+ me.canKill.put(him, false);
+ return false;
+ }
+
+ public boolean canNeed(Position mep, Position himp) {
+ if (!isRightNullable(mep)) return false;
+ if (!isRightNullable(himp)) return false;
+ Sequence me = mep.owner();
+ Sequence him = himp.owner();
+ Boolean b = me.canNeed.get(him);
+ if (b!=null) return b;
+ for(Sequence needer : him.needs())
+ if (isNulledSubsequence(needer, me))
+ { me.canNeed.put(him, true); return true; }
+ me.canNeed.put(him, false);
+ return false;
+ }
+
+ public int comparePositions(Position position, Position rposition) {
+ int ret = 0;
+ if (canKill(position, rposition) && canKill(rposition, position)) throw new Error();
+ if (canKill(position, rposition)) ret = -1;
+ else if (canKill(rposition, position)) ret = 1;
+ else if (canNeed(position, rposition)) ret = -1;
+ else if (canNeed(rposition, position)) ret = 1;
+ /*
+ else if (isNulledSubsequence(position.owner(), rposition.owner()) && isNulledSubsequence(rposition.owner(), position.owner())) ret = 0;
+ else if (isNulledSubsequence(position.owner(), rposition.owner())) ret = 1;
+ else if (isNulledSubsequence(rposition.owner(), position.owner())) ret = -1;
+ */
+ return ret;
+ }
+
+}
+
projects / sbp.git / blobdiff