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 static int count = 0;
  14     public GSS() { }
  15
  16     private Phase.Node[] reducing_list = null;
  17     public int resets = 0;
  18     public int waits = 0;
  19
  20     HashMapBag<Sequence,Phase.Waiting> waiting         = new HashMapBag<Sequence,Phase.Waiting>();
  21     HashMapBag<Integer,Sequence>       performed       = new HashMapBag<Integer,Sequence>();
  22     HashMapBag<Integer,Sequence>       lastperformed   = new HashMapBag<Integer,Sequence>();
  23     HashMapBag<Integer,Sequence>       expected        = new HashMapBag<Integer,Sequence>();
  24
  25     /** FIXME */
  26     public  Forest.Ref finalResult;
  27
  28     /** corresponds to a positions <i>between tokens</i> the input stream; same as Tomita's U_i's */
  29     class Phase<Tok> implements Invokable<State, Forest, Phase<Tok>.Node>, IntegerMappable {
  30
  31         public void invoke(State st, Forest result, Node n) {
  32             good |= next.newNode(n, result, st, false);
  33         }
  34
  35         /** the token immediately after this phase */
  36         final Tok token;
  37
  38         private final int pos;
  39
  40         boolean reducing;
  41         private IntPairMap<Phase.Node> hash;  /* ALLOC */
  42         private IntPairMap<Forest> singularReductions;  /* ALLOC */
  43         private boolean closed;
  44         private boolean good;
  45         private Phase next = null;
  46         private Phase prev;
  47         private Input.Location location;
  48         public final Parser parser;
  49
  50         private Forest forest;
  51
  52         public Phase(Phase prev, Parser parser, Phase previous, Tok token, Input.Location location, Forest forest) throws ParseFailed {
  53             this.prev = prev;
  54             this.forest = forest;
  55             this.parser = parser;
  56             this.pos = previous==null ? 0 : previous.pos+1;
  57             this.token = token;
  58             this.location = location;
  59             performed.clear();
  60             reset();
  61         }
  62
  63         public void reset() throws ParseFailed {
  64             waiting.clear();
  65             expected.clear();
  66             lastperformed.clear();
  67             lastperformed.addAll(performed);
  68             performed.clear();
  69             hash = new IntPairMap<Phase.Node>();
  70             singularReductions = new IntPairMap<Forest>();
  71             reset = false;
  72             good = false;
  73             closed = false;
  74             reducing = false;
  75             finalResult = null;
  76             if (prev != null) prev.shift(this, forest);
  77         }
  78
  79
  80         public boolean isDone() throws ParseFailed {
  81             if (token != null) return false;
  82             if (token==null && finalResult==null)
  83                 throw new ParseFailed(ParseFailed.error(ANSI.red("unexpected end of file\n"), token, hash.values()), getLocation());
  84             return true;
  85         }
  86
  87         public Input.Location getLocation() { return location; }
  88
  89         /** add a new node (merging with existing nodes if possible)
  90          *  @param parent             the parent of the new node
  91          *  @param result             the SPPF result corresponding to the new node
  92          *  @param state              the state that the new node is in
  93          *  @param fromEmptyReduction true iff this node is being created as a result of a reduction of length zero (see GRMLR paper)
  94          *  @param start              the earliest part of the input contributing to this node (used to make merging decisions)
  95          */
  96         public boolean newNode(Node parent, Forest pending, State state, boolean fromEmptyReduction) {
  97             Node p = hash.get(state, parent==null?null:parent.phase());
  98             if (p != null)  return newNode2(p, parent, pending, state, fromEmptyReduction);
  99             else            return newNode3(parent, pending, state, fromEmptyReduction);
 100         }
 101         public void newNode(Node parent, Forest pending, State state, boolean fromEmptyReduction, Position reduction) {
 102             int pos = parent==null?0:parent.phase()==null?0:parent.phase().pos;
 103             Sequence owner = reduction==null ? null : reduction.owner();
 104             if (reduction!=null) {
 105                 if (owner.hates!=null) {
 106                     for (Sequence s : performed.getAll(pos))
 107                         if (owner.hates.contains(s))
 108                             return;
 109                     for (Sequence s : lastperformed.getAll(pos))
 110                         if (owner.hates.contains(s)) {
 111                             //System.out.println("now expecting ["+pos+"] => " + s);
 112                             expected.add(pos, s);
 113                             return;
 114                         }
 115                 }
 116                 if (owner.needs != null)
 117                     for(Sequence s : owner.needs)
 118                         if (!performed.contains(pos, s)) {
 119                             waiting.add(s, new Waiting(parent, pending, state, fromEmptyReduction, reduction));
 120                             return;
 121                         }
 122                 if (!performed.contains(pos, owner)) {
 123                     performed.add(pos, owner);
 124                     if (owner.hated != null)
 125                         for(Sequence seq : owner.hated)
 126                             if (performed.contains(pos, seq)) {
 127                                 performed.remove(pos, seq);
 128                                 reset = true;
 129                             }
 130                 }
 131             }
 132             if (!owner.lame)
 133                 newNode(parent, pending, state, fromEmptyReduction);
 134             if (reduction != null) {
 135                 boolean redo = true;
 136                 while(redo) {
 137                     redo = false;
 138                     for(Waiting w : waiting.getAll(owner)) {
 139                         if (w.parent==parent || (parent!=null&&w.parent!=null&&w.parent.phase()==parent.phase())) {
 140                             waiting.remove(owner, w);
 141                             w.perform();
 142                             redo = true;
 143                             break;
 144                         }
 145                     }
 146                 }
 147             }
 148         }
 149         private boolean newNode2(Node p, Node parent, Forest pending, State state, boolean fromEmptyReduction) {
 150             p.holder.merge(pending);
 151             if (p.parents().contains(parent)) return true;
 152             p.parents().add(parent, true);
 153             if (p!=parent && !fromEmptyReduction && reducing) p.performReductions(parent);
 154             return true;
 155         }
 156         private boolean newNode3(Node parent, Forest pending, State state, boolean fromEmptyReduction) {
 157             do {
 158                 if (token != null && state.canShift(token)) break;
 159                 if (state.isAccepting()) break;
 160                 if (token==null) break;
 161                 if (!state.canReduce(token)) return false;
 162                 //if (count > 1) break;
 163                 //if (r.numPop == 0) break;
 164                 //r.reduce(pending, parent, null, Phase.this, null);
 165                 //return;
 166             } while(false);
 167
 168             Node n = new Node(parent, pending, state);  // ALLOC
 169             if (reducing) {
 170                 n.performEmptyReductions();
 171                 if (!fromEmptyReduction) n.performReductions(parent);
 172             }
 173             return true;
 174         }
 175
 176         /** perform all reduction operations */
 177         public void reduce() throws ParseFailed {
 178             try {
 179                 reducing = true;
 180                 if (reducing_list==null || reducing_list.length < hash.size())
 181                     reducing_list = new Phase.Node[hash.size() * 4];
 182                 hash.toArray(reducing_list);
 183                 int num = hash.size();
 184                 for(int i=0; i<num; i++) {
 185                     Node n = reducing_list[i];
 186                     n.performEmptyReductions();
 187                     // INVARIANT: we never "see" a node until its parent-set is complete, modulo merges
 188                 }
 189                 for(int i=0; i<num; i++) {
 190                     Node n = reducing_list[i];
 191                     reducing_list[i] = null;
 192                     n.performReductions();
 193                 }
 194                 if (reset) {
 195                     reset = false;
 196                     resets++;
 197                     throw new Reset();
 198                 }
 199                 for(int i : expected)
 200                     for(Sequence s : expected.getAll(i))
 201                         if (!performed.contains(i, s)) {
 202                             //System.out.println("resetting due to pos="+i+": " + s + " " + System.identityHashCode(s));
 203                             resets++;
 204                             throw new Reset();
 205                         }
 206             } catch (Reset r) {
 207                 reset();
 208                 reduce();
 209             }
 210             count = 0;
 211         }
 212
 213         private boolean reset = false;
 214         class Reset extends RuntimeException { }
 215
 216         /** perform all shift operations, adding promoted nodes to <tt>next</tt> */
 217         public void shift(Phase next, Forest result) throws ParseFailed {
 218             // this massively improves GC performance
 219             if (prev!=null) {
 220                 prev.hash = null;
 221                 prev.singularReductions = null;
 222             }
 223             this.next = next;
 224             closed = true;
 225             Forest res = null;
 226             boolean ok = false;
 227             for(Phase.Node n : hash.values()) {
 228                 if (token == null && n.state.isAccepting()) {
 229                     if (finalResult==null) finalResult = new Forest.Ref();
 230                     finalResult.merge(n.holder);
 231                 }
 232                 if (token == null) continue;
 233                 n.state.invokeShifts(token, this, result, n);
 234             }
 235
 236             if (!good && token!=null)
 237                 throw new ParseFailed(ParseFailed.error(ANSI.red("unexpected character ")+" \'"+
 238                                                         ANSI.purple(StringUtil.escapify(token+"", "\\\'\r\n"))+
 239                                                         "\' encountered at "+
 240                                                         ANSI.green(getLocation())+"\n", token, hash.values()),
 241                                         getLocation());
 242             if (token==null && finalResult==null)
 243                 throw new ParseFailed(ParseFailed.error(ANSI.red("unexpected end of file\n"), token, hash.values()),
 244                                         getLocation());
 245         }
 246
 247
 248         class Waiting {
 249             Node parent;
 250             Forest pending;
 251             State state;
 252             boolean fromEmptyReduction;
 253             Position reduction;
 254             public Waiting(Node parent, Forest pending, State state, boolean fromEmptyReduction, Position reduction) {
 255                 waits++;
 256                 this.parent = parent;
 257                 this.pending = pending;
 258                 this.state = state;
 259                 this.fromEmptyReduction = fromEmptyReduction;
 260                 this.reduction = reduction;
 261             }
 262             public void perform() {
 263                 //System.out.println("performing: " + reduction.position);
 264                 newNode(parent, pending, state, fromEmptyReduction, reduction);
 265             }
 266         }
 267
 268         // Node /////////////////////////////////////////////////////////////////////////////////
 269
 270         /** a node in the GSS */
 271         final class Node extends FastSet<Node> implements Invokable<Position, Node, Node>, IntegerMappable {
 272
 273             private Forest.Ref holder = null;
 274             private boolean allqueued = false;
 275
 276             /** what state this node is in */
 277             public final Parser.Table<Tok>.State<Tok> state;
 278
 279             /** which Phase this Node belongs to (node that Node is also a non-static inner class of Phase) */
 280             public  Phase phase() { return Phase.this; }
 281             public  Forest.Ref holder() { return holder==null ? (holder = new Forest.Ref()) : holder; }
 282             public  Forest pending() { return Phase.this.closed ? holder().resolve() : holder; }
 283             public  FastSet<Node> parents() { return this; }
 284
 285             public void performReductions() {
 286                 if (allqueued) return;
 287                 allqueued = true;
 288                 state.invokeReductions(token, this, this, null);
 289             }
 290
 291             public void performReductions(Node n2) {
 292                 if (!allqueued) performReductions();
 293                 else            state.invokeReductions(token, this, this, n2);
 294             }
 295
 296             public void performEmptyReductions() { state.invokeReductions(token, this, null, null); }
 297             public final void invoke(Position r, Node n, Node n2) {
 298                 if (n==null || n2==null || r.pos==0) {
 299                     if (r.pos==0) {
 300                         if (n==null) n = this;
 301                         else return;
 302                     }
 303                     if (n==null) return;
 304                     Forest[] holder = new Forest[r.pos];
 305                     if (r.pos==0) n.finish(r, r.zero(), n.phase(), holder);
 306                     else                   n.reduce(r, r.pos-1, n.phase(), holder);
 307                 } else {
 308                     Forest[] holder = new Forest[r.pos];
 309                     if (r.pos<=0) throw new Error("called wrong form of reduce()");
 310                     int pos = r.pos-1;
 311                     n.reduce(r, pos, n.phase(), holder, n2);
 312                 }
 313             }
 314
 315             public void reduce(Position r, int pos, Phase target, Forest[] holder) { reduce(r, pos, target, holder, null); }
 316             public void reduce(Position r, int pos, Phase target, Forest[] holder, Node only) {
 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
 324                     // FIXME: I'm unsure about this -- basically we want to deal with the case where
 325                     //        there are two nodes, each of whose Ref points to the same Forest instance.
 326                     //        Some node in the next phase has both of these as parents.  This might happen
 327                     //        since the same reduction can appear in more than one state.
 328                     if (r.pos==1)  rex = singularReductions.get(this.pending(), r);
 329                     if (rex==null) {
 330                         rex = r.rewrite(phase().getLocation());
 331                         if (r.pos==1) singularReductions.put(this.pending(), r, rex);
 332                     }
 333                     if (only != null)  only.finish(r, rex, target, holder);
 334                     else               for(Node child : this.parents()) child.finish(r, rex, target, holder);
 335                 } else {
 336                     if (only != null)  only.reduce(r, pos-1, target, holder);
 337                     else               for(Node child : this.parents()) child.reduce(r, pos-1, target, holder);
 338                 }
 339                 holder[pos] = old;
 340             }
 341
 342             public void finish(Position r, Forest result, Phase<Tok> target, Forest[] holder) {
 343                 Parser.Table<Tok>.State<Tok> state0 = state.gotoSetNonTerminals.get(r.owner());
 344                 if (result==null) throw new Error();
 345                 if (state0!=null)
 346                     target.newNode(this, result, state0, r.pos<=0, r);
 347             }
 348
 349             private Node(Node parent, Forest pending, State state) {
 350                 this.state = state;
 351                 this.holder().merge(pending);
 352                 Phase start = parent==null ? null : parent.phase();
 353                 if (parent != null) parents().add(parent, true);
 354                 if (Phase.this.hash.get(state, start) != null) throw new Error("severe problem!");
 355                 Phase.this.hash.put(state, start, this);
 356             }
 357             public int toInt() { return idx; }
 358             private final int idx = node_idx++;
 359         }
 360         private int node_idx = 0;
 361
 362         public int toInt() { return pos+1; }
 363         public int size() { return hash==null ? 0 : hash.size(); }
 364     }
 365
 366 }