src/edu/berkeley/sbp/GSS.java

   1 // Copyright 2006 all rights reserved; see LICENSE file for BSD-style license
   2
   3 package edu.berkeley.sbp;
   4 import edu.berkeley.sbp.*;
   5 import edu.berkeley.sbp.util.*;
   6 import edu.berkeley.sbp.Parser.Table.*;
   7 import edu.berkeley.sbp.Sequence.Position;
   8 import java.io.*;
   9 import java.util.*;
  10 import java.lang.reflect.*;
  11
  12 /** implements Tomita's Graph Structured Stack */
  13 class GSS {
  14
  15     static int count = 0;
  16     static int shifts = 0;
  17     static int reductions = 0;
  18     int resets = 0;
  19     int waits = 0;
  20
  21     Input input;
  22
  23     public GSS(Input input) { this.input = input; }
  24
  25     private Phase.Node[] reducing_list = null;
  26
  27     // FIXME: right now, these are the performance bottleneck
  28     HashMapBag<Sequence,Phase.Waiting> waiting         = new HashMapBag<Sequence,Phase.Waiting>();
  29     HashMapBag<Integer,Sequence>       performed       = new HashMapBag<Integer,Sequence>();
  30     HashMapBag<Integer,Sequence>       lastperformed   = new HashMapBag<Integer,Sequence>();
  31     HashMapBag<Integer,Sequence>       expected        = new HashMapBag<Integer,Sequence>();
  32
  33     /** FIXME */
  34     Forest.Many finalResult;
  35
  36     /** corresponds to a positions <i>between tokens</i> the input stream; same as Tomita's U_i's */
  37     class Phase<Tok> implements Invokable<State, Forest, Phase<Tok>.Node>, IntegerMappable, GraphViz.ToGraphViz, Iterable<Phase.Node> {
  38
  39         public Iterator<Phase.Node> iterator() { return hash.iterator(); }
  40         public void invoke(State st, Forest result, Node n) {
  41             shifts++;
  42             good |= next.newNode(n, result, st, false);
  43         }
  44
  45         /** the token immediately after this phase */
  46         final Tok token;
  47
  48         private final int pos;
  49
  50         boolean reducing;
  51         private IntPairMap<Phase.Node> hash;  /* ALLOC */
  52         private boolean closed;
  53         private boolean good;
  54         private Phase next = null;
  55         private Phase prev;
  56         private Input.Location location;
  57         private Input.Location nextLocation;
  58         private Input.Location prevLocation;
  59
  60         public final Parser parser;
  61
  62         private Forest forest;
  63
  64         public Phase(Phase prev, Parser parser, Phase previous, Tok token, Input.Location location,
  65                      Input.Location nextLocation, Forest forest) throws ParseFailed {
  66             this.prevLocation = prev==null ? location : prev.getLocation();
  67             this.prev = prev;
  68             this.forest = forest;
  69             this.parser = parser;
  70             this.pos = previous==null ? 0 : previous.pos+1;
  71             this.token = token;
  72             this.location = location;
  73             this.nextLocation = nextLocation;
  74             performed.clear();
  75             reset();
  76         }
  77
  78         public void reset() throws ParseFailed {
  79             waiting.clear();
  80             expected.clear();
  81             lastperformed.clear();
  82             lastperformed.addAll(performed);
  83             performed.clear();
  84             hash = new IntPairMap<Phase.Node>();
  85             reset = false;
  86             good = false;
  87             closed = false;
  88             reducing = false;
  89             finalResult = null;
  90             if (prev != null) prev.shift(this, forest);
  91         }
  92
  93
  94         public boolean isDone() throws ParseFailed {
  95             if (token != null) return false;
  96             if (token==null && finalResult==null)
  97                 ParseFailed.error("unexpected end of file",
  98                                   getLocation(),
  99                                   token,
 100                                   hash.values(),
 101                                   getLocation().createRegion(getLocation()),
 102                                   input,
 103                                   GSS.this);
 104             return true;
 105         }
 106
 107         public Input.Location getPrevLocation() { return prevLocation; }
 108         public Input.Location getLocation() { return location; }
 109         public Input.Region   getRegion() { return getPrevLocation().createRegion(getLocation()); }
 110         public Input.Location getNextLocation() { return nextLocation; }
 111
 112         /** add a new node (merging with existing nodes if possible)
 113          *  @param parent             the parent of the new node
 114          *  @param result             the SPPF result corresponding to the new node
 115          *  @param state              the state that the new node is in
 116          *  @param fromEmptyReduction true iff this node is being created as a result of a reduction of length zero (see GRMLR paper)
 117          *  @param start              the earliest part of the input contributing to this node (used to make merging decisions)
 118          */
 119         public boolean newNode(Node parent, Forest pending, State state, boolean fromEmptyReduction) {
 120             Node p = hash.get(state, parent==null?null:parent.phase());
 121             if (p != null)  return newNode2(p, parent, pending, state, fromEmptyReduction);
 122             else            return newNode3(parent, pending, state, fromEmptyReduction);
 123         }
 124         public void newNode(Node parent, Forest pending, State state, boolean fromEmptyReduction, Position reduction) {
 125             int pos = parent==null?0:parent.phase()==null?0:parent.phase().pos;
 126             Sequence owner = reduction==null ? null : reduction.owner();
 127             if (reduction!=null) {
 128                 if (owner.hates!=null) {
 129                     for (Sequence s : performed.getAll(pos))
 130                         if (owner.hates.contains(s))
 131                             return;
 132                     for (Sequence s : lastperformed.getAll(pos))
 133                         if (owner.hates.contains(s)) {
 134                             //System.out.println("now expecting ["+pos+"] => " + s);
 135                             expected.add(pos, s);
 136                             return;
 137                         }
 138                 }
 139                 if (owner.needs != null)
 140                     for(Sequence s : owner.needs)
 141                         if (!performed.contains(pos, s)) {
 142                             waiting.add(s, new Waiting(parent, pending, state, fromEmptyReduction, reduction));
 143                             return;
 144                         }
 145                 if (!performed.contains(pos, owner)) {
 146                     performed.add(pos, owner);
 147                     if (owner.hated != null)
 148                         for(Sequence seq : owner.hated)
 149                             if (performed.contains(pos, seq)) {
 150                                 performed.remove(pos, seq);
 151                                 reset = true;
 152                             }
 153                 }
 154             }
 155             newNode(parent, pending, state, fromEmptyReduction);
 156             if (reduction != null) {
 157                 boolean redo = true;
 158                 while(redo) {
 159                     redo = false;
 160                     for(Waiting w : waiting.getAll(owner)) {
 161                         if (w.parent==parent || (parent!=null&&w.parent!=null&&w.parent.phase()==parent.phase())) {
 162                             waiting.remove(owner, w);
 163                             w.perform();
 164                             redo = true;
 165                             break;
 166                         }
 167                     }
 168                 }
 169             }
 170         }
 171
 172         private boolean newNode2(Node p, Node parent, Forest pending, State state, boolean fromEmptyReduction) {
 173             if (p.merge(parent, pending)) return true;
 174             p.parents().add(parent, true);
 175             if (p!=parent && !fromEmptyReduction && reducing) p.performReductions(parent);
 176             return true;
 177         }
 178
 179         private boolean newNode3(Node parent, Forest pending, State state, boolean fromEmptyReduction) {
 180             do {
 181                 if (token != null && state.canShift(token)) break;
 182                 if (state.isAccepting()) break;
 183                 if (token==null) break;
 184                 if (!state.canReduce(token)) return false;
 185                 //if (count > 1) break;
 186                 //if (r.numPop == 0) break;
 187                 //r.reduce(pending, parent, null, Phase.this, null);
 188                 //return;
 189             } while(false);
 190
 191             Node n = new Node(parent, pending, state);  // ALLOC
 192             if (reducing) {
 193                 n.performEmptyReductions();
 194                 if (!fromEmptyReduction) n.performReductions(parent);
 195             }
 196             return true;
 197         }
 198
 199         LinkedList<Node> reductionQueue = new LinkedList<Node>();
 200
 201         /** perform all reduction operations */
 202         public void reduce() throws ParseFailed {
 203             try {
 204                 reducing = true;
 205                 if (reducing_list==null || reducing_list.length < hash.size())
 206                     reducing_list = new Phase.Node[hash.size() * 4];
 207                 hash.toArray(reducing_list);
 208                 int num = hash.size();
 209                 for(int i=0; i<num; i++) {
 210                     Node n = reducing_list[i];
 211                     n.performEmptyReductions();
 212                     // INVARIANT: we never "see" a node until its parent-set is complete, modulo merges
 213                 }
 214                 for(int i=0; i<num; i++) {
 215                     reductionQueue.add(reducing_list[i]);
 216                     reducing_list[i] = null;
 217                 }
 218                 while(!reductionQueue.isEmpty()) {
 219                     reductionQueue.remove().performReductions();
 220                 }
 221                 if (reset) {
 222                     reset = false;
 223                     resets++;
 224                     throw new Reset();
 225                 }
 226                 for(int i : expected)
 227                     for(Sequence s : expected.getAll(i))
 228                         if (!performed.contains(i, s)) {
 229                             //System.out.println("resetting due to pos="+i+": " + s + " " + System.identityHashCode(s));
 230                             resets++;
 231                             throw new Reset();
 232                         }
 233             } catch (Reset r) {
 234                 reset();
 235                 reduce();
 236             }
 237             count = 0;
 238         }
 239
 240         private boolean reset = false;
 241         class Reset extends RuntimeException { }
 242
 243         /** perform all shift operations, adding promoted nodes to <tt>next</tt> */
 244         public void shift(Phase next, Forest result) throws ParseFailed {
 245             // this massively improves GC performance
 246             if (prev!=null && parser.helpgc) {
 247                 prev.hash = null;
 248             }
 249             this.next = next;
 250             closed = true;
 251             Forest res = null;
 252             boolean ok = false;
 253             for(Phase.Node n : hash.values()) {
 254                 if (token == null && n.state.isAccepting()) {
 255                     if (finalResult==null) finalResult = new Forest.Many();
 256                     for(Object f : n.results())
 257                         finalResult.merge((Forest)f);
 258                 }
 259                 if (token == null) continue;
 260                 n.state.invokeShifts(token, this, result, n);
 261             }
 262
 263             if (!good && token!=null)
 264                 ParseFailed.error("unexpected character",
 265                                   getLocation(),
 266                                   token,
 267                                   hash.values(),
 268                                   getRegion(),
 269                                   input,
 270                                   GSS.this);
 271
 272             if (token==null && finalResult==null)
 273                 ParseFailed.error("unexpected end of file",
 274                                   getLocation(),
 275                                   token,
 276                                   hash.values(),
 277                                   getLocation().createRegion(getLocation()),
 278                                   input,
 279                                   GSS.this);
 280         }
 281
 282
 283         class Waiting {
 284             Node parent;
 285             Forest pending;
 286             State state;
 287             boolean fromEmptyReduction;
 288             Position reduction;
 289             public Waiting(Node parent, Forest pending, State state, boolean fromEmptyReduction, Position reduction) {
 290                 waits++;
 291                 this.parent = parent;
 292                 this.pending = pending;
 293                 this.state = state;
 294                 this.fromEmptyReduction = fromEmptyReduction;
 295                 this.reduction = reduction;
 296             }
 297             public void perform() {
 298                 //System.out.println("performing: " + reduction.position);
 299                 newNode(parent, pending, state, fromEmptyReduction, reduction);
 300             }
 301         }
 302
 303         // Node /////////////////////////////////////////////////////////////////////////////////
 304
 305         /** a node in the GSS */
 306         final class Node implements Invokable<Position, Node, Node>, IntegerMappable, GraphViz.ToGraphViz {
 307             public FastSet<Node> set = new FastSet<Node>();
 308             private boolean allqueued = false;
 309
 310             /** what state this node is in */
 311             public final Parser.Table<Tok>.State<Tok> state;
 312
 313             /** which Phase this Node belongs to (node that Node is also a non-static inner class of Phase) */
 314             public  Phase phase() { return Phase.this; }
 315
 316             private HashSet<Forest.Many> resultMap = new HashSet<Forest.Many>();
 317             public Iterable<Forest.Many> results() { return resultMap; }
 318             public FastSet<Node> parents() { return set; }
 319             public boolean merge(Node parent, Forest result) {
 320                 // FIXME: inefficient!
 321                 for(Forest.Many f : results()) {
 322                     if (f.parents.contains(parent) /* UGLY: */ && f.parents.size()==1) {
 323                         f.merge(result);
 324                         return true;
 325                     }
 326                 }
 327                 Forest.Many f = new Forest.Many();
 328                 f.parents.add(parent);
 329                 f.merge(result);
 330                 resultMap.add(f);
 331                 set.add(parent, true);
 332                 return false;
 333             }
 334
 335             public void performReductions() {
 336                 if (allqueued) return;
 337                 allqueued = true;
 338                 state.invokeReductions(token, this, this, null);
 339             }
 340
 341             public void performReductions(Node n2) {
 342                 if (!allqueued) reductionQueue.add(this);//performReductions();
 343                 else            state.invokeReductions(token, this, this, n2);
 344             }
 345
 346             public void performEmptyReductions() { state.invokeReductions(token, this, null, null); }
 347             public final void invoke(Position r, Node n, Node n2) {
 348                 reductions++;
 349                 if (n==null || n2==null || r.pos==0) {
 350                     if (r.pos==0) {
 351                         if (n==null) n = this;
 352                         else return;
 353                     }
 354                     if (n==null) return;
 355                     Forest[] holder = new Forest[r.pos];
 356                     if (r.pos==0) n.finish(r, r.zero(n.phase().getLocation().createRegion(n.phase().getLocation())), n.phase());
 357                     else          n.reduce(r, r.pos-1,  n.phase(), null);
 358                 } else {
 359                     if (r.pos<=0) throw new Error("called wrong form of reduce()");
 360                     int pos = r.pos-1;
 361                     n.reduce(r, pos, n.phase(), n2);
 362                 }
 363             }
 364
 365             public void reduce(Position r, int pos, Phase target, Node only) {
 366                 Forest[] holder = r.holder;
 367                 Forest old = holder[pos];
 368
 369                 HashSet<Forest> rr = new HashSet<Forest>();
 370                 for(Forest result : results()) rr.add(result);
 371                 for(Forest result : rr)
 372                     for(Node child : ((Forest.Many<?>)result).parents) {
 373                         if (only != null && child!=only) continue;
 374                         holder[pos] = result;
 375                         if (pos==0) child.finish(r, r.rewrite(child.phase().getLocation().createRegion(target.getLocation())), target);
 376                         else        child.reduce(r, pos-1, target, null);
 377                     }
 378
 379                 holder[pos] = old;
 380             }
 381
 382             public void finish(Position r, Forest result, Phase<Tok> target) {
 383                 Parser.Table<Tok>.State<Tok> state0 = state.gotoSetNonTerminals.get(r.owner());
 384                 if (result==null) throw new Error();
 385                 if (state0!=null)
 386                     target.newNode(this, result, state0, r.pos<=0, r);
 387             }
 388
 389             private Node(Node parent, Forest pending, State state) {
 390                 this.state = state;
 391                 this.merge(parent, pending);
 392                 Phase start = parent==null ? null : parent.phase();
 393                 if (parent != null) parents().add(parent, true);
 394                 if (Phase.this.hash.get(state, start) != null) throw new Error("severe problem!");
 395                 Phase.this.hash.put(state, start, this);
 396             }
 397             public int toInt() { return idx; }
 398             private final int idx = node_idx++;
 399
 400             // GraphViz //////////////////////////////////////////////////////////////////////////////
 401
 402             public GraphViz.Node toGraphViz(GraphViz gv) {
 403                 if (gv.hasNode(this)) return gv.createNode(this);
 404                 GraphViz.Node n = gv.createNode(this);
 405                 n.label = ""+state.toStringx();
 406                 n.shape = "rectangle";
 407                 n.fill = "green";
 408                 for(Forest result : results()) n.edge(result, "");
 409                 for(Node parent : parents()) n.edge(parent, "");
 410                 ((GraphViz.Group)phase().toGraphViz(gv)).add(n);
 411                 return n;
 412             }
 413             public boolean isTransparent() { return false; }
 414             public boolean isHidden() { return false; }
 415
 416         }
 417         private int node_idx = 0;
 418
 419         public int toInt() { return pos+1; }
 420         public int size() { return hash==null ? 0 : hash.size(); }
 421
 422         // GraphViz //////////////////////////////////////////////////////////////////////////////
 423
 424         public GraphViz.Node toGraphViz(GraphViz gv) {
 425             if (gv.hasNode(this)) return gv.createNode(this);
 426             GraphViz.Group g = gv.createGroup(this);
 427             g.label = "Phase " + pos;
 428             g.color = "gray";
 429             g.cluster = true;
 430             return g;
 431         }
 432         public boolean isTransparent() { return false; }
 433         public boolean isHidden() { return false; }
 434
 435     }
 436 }