src/edu/berkeley/sbp/GSS.java

   1 package edu.berkeley.sbp;
   2 import edu.berkeley.sbp.*;
   3 import edu.berkeley.sbp.util.*;
   4 import edu.berkeley.sbp.Parser.Table.*;
   5 import edu.berkeley.sbp.Sequence.Position;
   6 import java.io.*;
   7 import java.util.*;
   8 import java.lang.reflect.*;
   9
  10 /** implements Tomita's Graph Structured Stack */
  11 class GSS {
  12
  13     public GSS() { }
  14
  15     private Phase.Node[] reducing_list = null;
  16     public int resets = 0;
  17     public int waits = 0;
  18
  19     HashMapBag<Integer,Sequence>       inhibited = new HashMapBag<Integer,Sequence>();
  20     HashMapBag<Sequence,Phase.Waiting> waiting   = new HashMapBag<Sequence,Phase.Waiting>();
  21     HashMapBag<Integer,Sequence>       performed = new HashMapBag<Integer,Sequence>();
  22
  23     /** FIXME */
  24     public  Forest.Ref finalResult;
  25
  26     /** corresponds to a positions <i>between tokens</i> the input stream; same as Tomita's U_i's */
  27     public class Phase<Tok> implements Invokable<State, Forest, Phase<Tok>.Node>, IntegerMappable {
  28
  29         public void invoke(State st, Forest result, Node n) {
  30             good |= next.newNode(n, result, st, false);
  31         }
  32
  33         /** the token immediately after this phase */
  34         final Tok token;
  35
  36         private final int pos;
  37
  38         boolean reducing;
  39         private IntPairMap<Phase.Node> hash;  /* ALLOC */
  40         private IntPairMap<Forest> singularReductions;  /* ALLOC */
  41         private boolean closed;
  42         private boolean good;
  43         private Phase next = null;
  44         private Phase prev;
  45         private Token.Location location;
  46         public final Parser parser;
  47
  48         private Forest forest;
  49
  50         public Phase(Phase prev, Parser parser, Phase previous, Tok token, Token.Location location, Forest forest) {
  51             this.prev = prev;
  52             this.forest = forest;
  53             this.parser = parser;
  54             this.pos = previous==null ? 0 : previous.pos+1;
  55             this.token = token;
  56             this.location = location;
  57             inhibited.clear();
  58             reset();
  59         }
  60
  61         public void reset() {
  62             waiting.clear();
  63             performed.clear();
  64             hash = new IntPairMap<Phase.Node>();
  65             singularReductions = new IntPairMap<Forest>();
  66             good = false;
  67             closed = false;
  68             reducing = false;
  69             finalResult = null;
  70             if (prev != null) prev.shift(this, forest);
  71         }
  72
  73
  74         public boolean isDone() throws ParseFailed {
  75             if (token != null) return false;
  76             if (token==null && finalResult==null)
  77                 throw new ParseFailed(ParseFailed.error(ANSI.red("unexpected end of file\n"), token, hash.values()), getLocation());
  78             return true;
  79         }
  80
  81         public Token.Location getLocation() { return location; }
  82
  83         /** add a new node (merging with existing nodes if possible)
  84          *  @param parent             the parent of the new node
  85          *  @param result             the SPPF result corresponding to the new node
  86          *  @param state              the state that the new node is in
  87          *  @param fromEmptyReduction true iff this node is being created as a result of a reduction of length zero (see GRMLR paper)
  88          *  @param start              the earliest part of the input contributing to this node (used to make merging decisions)
  89          */
  90         public boolean newNode(Node parent, Forest pending, State state, boolean fromEmptyReduction) {
  91             Node p = hash.get(state, parent==null?null:parent.phase());
  92             if (p != null)  return newNode2(p, parent, pending, state, fromEmptyReduction);
  93             else            return newNode3(parent, pending, state, fromEmptyReduction);
  94         }
  95         public void newNode(Node parent, Forest pending, State state, boolean fromEmptyReduction, Position reduction) {
  96             int pos = parent==null?0:parent.phase()==null?0:parent.phase().pos;
  97             Sequence owner = reduction==null ? null : reduction.owner();
  98             if (reduction!=null) {
  99                 if (inhibited.contains(pos, owner)) return;
 100                 if (owner.needs != null)
 101                     for(Sequence s : owner.needs)
 102                         if (!performed.contains(pos, s)) {
 103                             waiting.add(s, new Waiting(parent, pending, state, fromEmptyReduction, reduction));
 104                             return;
 105                         }
 106                 if ((owner.needed != null && owner.needed.size()>0) ||
 107                     (owner.hated != null && owner.hated.size()>0) ||
 108                     (owner.hates != null && owner.hates.size()>0))
 109                     performed.add(pos, owner);
 110             }
 111             if (!owner.lame)
 112                 newNode(parent, pending, state, fromEmptyReduction);
 113             if (reduction!=null) inhibit(reduction, parent==null?0:parent.phase().pos);
 114             if (reduction != null) {
 115                 boolean redo = true;
 116                 while(redo) {
 117                     redo = false;
 118                     for(Waiting w : waiting.getAll(owner)) {
 119                         if (w.parent==parent || (parent!=null&&w.parent!=null&&w.parent.phase()==parent.phase())) {
 120                             waiting.remove(owner, w);
 121                             w.perform();
 122                             redo = true;
 123                             break;
 124                         }
 125                     }
 126                 }
 127             }
 128         }
 129         private boolean newNode2(Node p, Node parent, Forest pending, State state, boolean fromEmptyReduction) {
 130             p.holder.merge(pending);
 131             if (p.parents().contains(parent)) return true;
 132             p.parents().add(parent, true);
 133             if (p!=parent && !fromEmptyReduction && reducing) p.performReductions(parent);
 134             return true;
 135         }
 136         private boolean newNode3(Node parent, Forest pending, State state, boolean fromEmptyReduction) {
 137             do {
 138                 if (token != null && state.canShift(token)) break;
 139                 if (state.isAccepting()) break;
 140                 if (token==null) break;
 141                 if (!state.canReduce(token)) return false;
 142                 //if (count > 1) break;
 143                 //if (r.numPop == 0) break;
 144                 //r.reduce(pending, parent, null, Phase.this, null);
 145                 //return;
 146             } while(false);
 147
 148             Node n = new Node(parent, pending, state);  // ALLOC
 149             if (reducing) {
 150                 n.performEmptyReductions();
 151                 if (!fromEmptyReduction) n.performReductions(parent);
 152             }
 153             return true;
 154         }
 155
 156         public void uninhibit(int p, Sequence s) {
 157             if (s.hated!=null)
 158                 for(Sequence s2 : s.hated)
 159                     inhibited.remove(p, s2);
 160         }
 161
 162         public void inhibit(Position r, int p) {
 163             if (r.owner().hated == null) return;
 164             // remember that dead states are still allowed to shift -- just not allowed to reduce
 165             boolean reset = false;
 166             for(Sequence seq : r.owner().hated) {
 167                 if (performed.contains(p,seq)) {
 168                     uninhibit(p, seq);
 169                     //System.out.println("\nresetting due to " + r.owner() + " killing " + seq);
 170                     //inhibited.clear();
 171                     inhibited.add(p, seq);
 172                     //inhibited = new HashMapBag<Integer,Sequence>();
 173                     reset = true;
 174                     resets++;
 175                     throw new Reset();
 176                 }
 177                 inhibited.add(p, seq);
 178             }
 179         }
 180
 181         /** perform all reduction operations */
 182         public void reduce() {
 183             try {
 184                 reducing = true;
 185                 if (reducing_list==null || reducing_list.length < hash.size())
 186                     reducing_list = new Phase.Node[hash.size() * 4];
 187                 hash.toArray(reducing_list);
 188                 int num = hash.size();
 189                 for(int i=0; i<num; i++) {
 190                     Node n = reducing_list[i];
 191                     n.performEmptyReductions();
 192                     // INVARIANT: we never "see" a node until its parent-set is complete, modulo merges
 193                 }
 194                 for(int i=0; i<num; i++) {
 195                     Node n = reducing_list[i];
 196                     reducing_list[i] = null;
 197                     n.performReductions();
 198                 }
 199             } catch (Reset r) {
 200                 reset();
 201                 reduce();
 202             }
 203         }
 204
 205         class Reset extends RuntimeException { }
 206
 207         /** perform all shift operations, adding promoted nodes to <tt>next</tt> */
 208         public void shift(Phase next, Forest result) throws ParseFailed {
 209             // this massively improves GC performance
 210             if (prev!=null) {
 211                 prev.hash = null;
 212                 prev.singularReductions = null;
 213             }
 214             this.next = next;
 215             closed = true;
 216             Forest res = null;
 217             boolean ok = false;
 218             for(Phase.Node n : hash.values()) {
 219                 if (token == null && n.state.isAccepting()) {
 220                     if (finalResult==null) finalResult = new Forest.Ref();
 221                     finalResult.merge(n.holder);
 222                 }
 223                 if (token == null) continue;
 224                 n.state.invokeShifts(token, this, result, n);
 225             }
 226
 227             if (!good && token!=null)
 228                 throw new ParseFailed(ParseFailed.error(ANSI.red("unexpected character")+" "+ANSI.purple(token)+" encountered at "+ANSI.green(getLocation())+"\n", token, hash.values()),
 229                                         getLocation());
 230             if (token==null && finalResult==null)
 231                 throw new ParseFailed(ParseFailed.error(ANSI.red("unexpected end of file\n"), token, hash.values()),
 232                                         getLocation());
 233         }
 234
 235
 236         public class Waiting {
 237             Node parent;
 238             Forest pending;
 239             State state;
 240             boolean fromEmptyReduction;
 241             Position reduction;
 242             public Waiting(Node parent, Forest pending, State state, boolean fromEmptyReduction, Position reduction) {
 243                 waits++;
 244                 this.parent = parent;
 245                 this.pending = pending;
 246                 this.state = state;
 247                 this.fromEmptyReduction = fromEmptyReduction;
 248                 this.reduction = reduction;
 249             }
 250             public void perform() {
 251                 //System.out.println("performing: " + reduction.position);
 252                 newNode(parent, pending, state, fromEmptyReduction, reduction);
 253             }
 254         }
 255
 256         // Node /////////////////////////////////////////////////////////////////////////////////
 257
 258         /** a node in the GSS */
 259         public final class Node extends FastSet<Node> implements Invokable<Position, Node, Node>, IntegerMappable {
 260
 261             private Forest.Ref holder = null;
 262             private boolean allqueued = false;
 263
 264             /** what state this node is in */
 265             public final Parser.Table<Tok>.State<Tok> state;
 266
 267             /** which Phase this Node belongs to (node that Node is also a non-static inner class of Phase) */
 268             public  Phase phase() { return Phase.this; }
 269             public  Forest.Ref holder() { return holder==null ? (holder = new Forest.Ref()) : holder; }
 270             public  Forest pending() { return Phase.this.closed ? holder().resolve() : holder; }
 271             public  FastSet<Node> parents() { return this; }
 272
 273             public void performReductions() {
 274                 if (allqueued) return;
 275                 allqueued = true;
 276                 state.invokeReductions(token, this, this, null);
 277             }
 278
 279             public void performReductions(Node n2) {
 280                 if (!allqueued) performReductions();
 281                 else            state.invokeReductions(token, this, this, n2);
 282             }
 283
 284             public final void invoke(Position r, Node n, Node n2) {
 285                 if (n==null || n2==null || r.pos==0) {
 286                     if (r.pos==0) {
 287                         if (n==null) n = this;
 288                         else return;
 289                     }
 290                     if (n==null) return;
 291                     Forest[] holder = new Forest[r.pos];
 292                     if (r.pos==0) n.finish(r, r.zero(), n.phase(), holder);
 293                     else                   n.reduce(r, r.pos-1, n.phase(), holder);
 294                 } else {
 295                     Forest[] holder = new Forest[r.pos];
 296                     if (r.pos<=0) throw new Error("called wrong form of reduce()");
 297                     int pos = r.pos-1;
 298                     Forest old = holder[pos];
 299                     holder[pos] = n.pending();
 300                     if (pos==0) {
 301                         System.arraycopy(holder, 0, r.holder, 0, holder.length);
 302                         Forest rex = null;
 303                         if (r.pos==1)  rex = singularReductions.get(this, r);
 304                         if (rex==null) {
 305                             rex = r.rewrite(n.phase().getLocation());
 306                             if (r.pos==1) singularReductions.put(this, r, rex);
 307                         }
 308                         n2.finish(r, rex, n.phase(), holder);
 309                     } else {
 310                         n2.reduce(r, pos-1, n.phase(), holder);
 311                     }
 312                     holder[pos] = old;
 313                 }
 314             }
 315
 316             public void reduce(Position r, int pos, Phase target, Forest[] holder) {
 317                 Forest old = holder[pos];
 318                 holder[pos] = this.pending();
 319                 if (pos==0) {
 320                     System.arraycopy(holder, 0, r.holder, 0, holder.length);
 321                     for(int i=0; i<r.pos; i++) if (r.holder[i]==null) throw new Error("realbad");
 322                     Forest rex = null;
 323                     if (r.pos==1)  rex = singularReductions.get(this, r);
 324                     if (rex==null) {
 325                         rex = r.rewrite(phase().getLocation());
 326                         if (r.pos==1) singularReductions.put(this, r, rex);
 327                     }
 328                     for(Node child : this.parents()) child.finish(r, rex, target, holder);
 329                 } else {
 330                     for(Node child : this.parents()) child.reduce(r, pos-1, target, holder);
 331                 }
 332                 holder[pos] = old;
 333             }
 334
 335             public void finish(Position r, Forest result, Phase<Tok> target, Forest[] holder) {
 336                 Parser.Table<Tok>.State<Tok> state0 = state.gotoSetNonTerminals.get(r.owner());
 337                 if (result==null) throw new Error();
 338                 if (state0!=null)
 339                     target.newNode(this, result, state0, r.pos<=0, r);
 340             }
 341
 342             public void performEmptyReductions() { state.invokeReductions(token, this, null, null); }
 343
 344             private Node(Node parent, Forest pending, State state) {
 345                 this.state = state;
 346                 this.holder().merge(pending);
 347                 Phase start = parent==null ? null : parent.phase();
 348                 if (parent != null) parents().add(parent, true);
 349                 if (Phase.this.hash.get(state, start) != null) throw new Error("severe problem!");
 350                 Phase.this.hash.put(state, start, this);
 351             }
 352             public int toInt() { return idx; }
 353             private final int idx = node_idx++;
 354         }
 355         private int node_idx = 0;
 356
 357         public int toInt() { return pos+1; }
 358         public int size() { return hash==null ? 0 : hash.size(); }
 359     }
 360
 361 }