X-Git-Url: http://git.megacz.com/?p=sbp.git;a=blobdiff_plain;f=src%2Fedu%2Fberkeley%2Fsbp%2FParser.java;h=65f3dc3e9e3f17b80be3d03950ffc9d22ddc0901;hp=5b31b3103459251c690eaa34f5000717b2217ba5;hb=b0ec1efcb13eceb539f9cd033a0d2908fc2be27a;hpb=888e9ccbab5f458a727c16da9d9291fd8951d909 diff --git a/src/edu/berkeley/sbp/Parser.java b/src/edu/berkeley/sbp/Parser.java index 5b31b31..65f3dc3 100644 --- a/src/edu/berkeley/sbp/Parser.java +++ b/src/edu/berkeley/sbp/Parser.java @@ -13,9 +13,7 @@ public abstract class Parser { private final Table pt; - /** - * create a parser to parse the grammar with start symbol u - */ + /** create a parser to parse the grammar with start symbol u */ protected Parser(Union u) { this.pt = new Table(u, top()); } protected Parser(Table pt) { this.pt = pt; } @@ -24,7 +22,15 @@ public abstract class Parser { /** parse input for a exactly one unique result, throwing Ambiguous if not unique or Failed if none */ - public Tree parse1(Token.Stream input) throws IOException, Failed, Ambiguous { return parse(input).expand1(); } + public Tree parse1(Token.Stream input) throws IOException, Failed, Ambiguous { + Forest ret = parse(input); + try { return ret.expand1(); } + catch (Ambiguous a) { + System.out.println("while expanding:"); + System.out.println(ret); + throw a; + } + } /** parse input, using the table pt to drive the parser */ public Forest parse(Token.Stream input) throws IOException, Failed { @@ -72,18 +78,9 @@ public abstract class Parser { // Table ////////////////////////////////////////////////////////////////////////////// /** an SLR(1) parse table which may contain conflicts */ - static class Table { + static class Table extends Walk.Cache { - private final Union start0 = new Union("0"); - private final Sequence start0seq; - - public final Walk.Cache cache = new Walk.Cache(); - - public HashSet closure() { - HashSet hp = new HashSet(); - reachable(start0, hp); - return hp; - } + public final Walk.Cache cache = this; private void walk(Element e, HashSet hs) { if (e==null) return; @@ -96,21 +93,6 @@ public abstract class Parser { walk(p.element(), hs); } } - public HashSet walk() { - HashSet ret = new HashSet(); - walk(start0, ret); - return ret; - } - - /* - public String toString() { - StringBuffer sb = new StringBuffer(); - for(Element e : walk()) - if (e instanceof Union) - ((Union)e).toString(sb); - return sb.toString(); - } - */ /** the start state */ public final State start; @@ -121,27 +103,29 @@ public abstract class Parser { /** construct a parse table for the given grammar */ public Table(Topology top) { this("s", top); } public Table(String startSymbol, Topology top) { this(new Union(startSymbol), top); } - public Table(Union u, Topology top) { + public Table(Union ux, Topology top) { + Union start0 = new Union("0"); + start0.add(new Sequence.Singleton(ux, null, null)); + + for(Sequence s : start0) cache.eof.put(s, true); cache.eof.put(start0, true); - start0seq = new Sequence.Singleton(u, null, null); - cache.eof.put(start0seq, true); - start0.add(start0seq); // construct the set of states HashMap,State> all_states = new HashMap,State>(); - HashSet all_elements = walk(); - all_elements.add(start0); - all_elements.add(start0seq); + HashSet all_elements = new HashSet(); + walk(start0, all_elements); for(Element e : all_elements) cache.ys.put(e, new Walk.YieldSet(e, cache).walk()); - this.start = new State(closure(), all_states, all_elements); + HashSet hp = new HashSet(); + reachable(start0, hp); + this.start = new State(hp, all_states, all_elements); // for each state, fill in the corresponding "row" of the parse table for(State state : all_states.values()) for(Position p : state.hs) { // the Grammar's designated "last position" is the only accepting state - if (p==start0seq.firstp().next()) + if (start0.contains(p.owner()) && p.next()==null) state.accept = true; // FIXME: how does right-nullability interact with follow restrictions? @@ -150,7 +134,7 @@ public abstract class Parser { Walk.Follow wf = new Walk.Follow(top.empty(), p.owner(), all_elements, cache); Reduction red = new Reduction(p); state.reductions.put(wf.walk(p.owner()), red); - if (wf.includesEof()) state.eofReductions.add(red, true); + if (wf.includesEof()) state.eofReductions.add(red); } // if the element following this position is an atom, copy the corresponding @@ -163,14 +147,35 @@ public abstract class Parser { /** a single state in the LR table and the transitions possible from it */ public class State implements Comparable, Iterable { - public final int idx = master_state_idx++; + /* + public boolean isResolvable(Token t) { + boolean found = false; + for(Reduction r : getReductions(t)) { + Position p = r.position; + if (!p.isRightNullable(cache)) continue; + if (p.owner().firstp()==p) continue; + if (found) { + // found two items meeting criteria #1 + return false; + } else { + found = true; + continue; + } + if (p.element()==null) continue; + Topology first = new Walk.First(top(), cache).walk(p.element()); + if (first.contains(t)) + } + } + */ + + public final int idx = master_state_idx++; private final HashSet hs; private transient HashMap gotoSetNonTerminals = new HashMap(); private transient TopologicalBag gotoSetTerminals = new TopologicalBag(); private TopologicalBag reductions = new TopologicalBag(); - private FastSet eofReductions = new FastSet(); + private HashSet eofReductions = new HashSet(); private TopologicalBag shifts = new TopologicalBag(); private boolean accept = false; @@ -179,7 +184,7 @@ public abstract class Parser { public boolean canShift(Token t) { return shifts.contains(t); } public Iterable getShifts(Token t) { return shifts.get(t); } public boolean isAccepting() { return accept; } - public Iterable getReductions(Token t) { return reductions.get(t); } + public Iterable getReductions(Token t) { return t==null ? eofReductions : reductions.get(t); } public Iterable getEofReductions() { return eofReductions; } public Iterator iterator() { return hs.iterator(); } @@ -289,7 +294,7 @@ public abstract class Parser { public class Reduction { // FIXME: cleanup; almost everything in here could go in either Sequence.Position.getRewrite() or else in GSS.Reduct public final int numPop; - private final Position position; + /*private*/ final Position position; private final Forest[] holder; // to avoid constant reallocation public int hashCode() { return position.hashCode(); } public boolean equals(Object o) { @@ -305,34 +310,51 @@ public abstract class Parser { this.holder = new Forest[numPop]; } public String toString() { return "[reduce " + position + "]"; } - public Forest reduce(Forest f, GSS.Phase.Node parent, GSS.Phase.Node onlychild, GSS.Phase target, Forest rex) { - holder[numPop-1] = f; - return reduce(parent, numPop-2, rex, onlychild, target); + + public Forest reduce(GSS.Phase.Node parent) { + if (numPop==0) return finish(parent, zero(), parent.phase()); + return reduce(parent, numPop-1, null, parent.phase()); } - public Forest reduce(GSS.Phase.Node parent, GSS.Phase.Node onlychild, GSS.Phase target, Forest rex) { - return reduce(parent, numPop-1, rex, onlychild, target); + + public Forest reduce(GSS.Phase.Node parent, GSS.Phase.Node onlychild) { + if (numPop<=0) throw new Error("called wrong form of reduce()"); + int pos = numPop-1; + holder[pos] = parent.pending(); + Forest rex = null; + if (pos==0) { + if (rex==null) { + System.arraycopy(holder, 0, position.holder, 0, holder.length); + rex = position.rewrite(parent.phase().getLocation()); + } + } + return reduce(onlychild, pos-1, rex, parent.phase()); + } + + private Forest zero = null; + public Forest zero() { + if (zero != null) return zero; + if (numPop > 0) throw new Error(); + return zero = position.rewrite(null); } // FIXME: this could be more elegant and/or cleaner and/or somewhere else - private Forest reduce(GSS.Phase.Node parent, int pos, Forest rex, GSS.Phase.Node onlychild, GSS.Phase target) { - if (pos>=0) holder[pos] = parent.pending(); - if (pos<=0 && rex==null) { + private Forest reduce(GSS.Phase.Node parent, int pos, Forest rex, GSS.Phase target) { + if (pos<0) return finish(parent, rex, target); + holder[pos] = parent.pending(); + if (pos==0 && rex==null) { System.arraycopy(holder, 0, position.holder, 0, holder.length); rex = position.rewrite(target.getLocation()); } - if (pos >=0) { - if (onlychild != null) - reduce(onlychild, pos-1, rex, null, target); - else - for(GSS.Phase.Node child : parent.parents()) - reduce(child, pos-1, rex, null, target); - } else { - State state = parent.state.gotoSetNonTerminals.get(position.owner()); - if (state!=null) - target.newNode(parent, rex, state, numPop<=0, parent.phase); - } + for(GSS.Phase.Node child : parent.parents()) + reduce(child, pos-1, rex, target); return rex; } + private Forest finish(GSS.Phase.Node parent, Forest result, GSS.Phase target) { + State state = parent.state.gotoSetNonTerminals.get(position.owner()); + if (state!=null) + target.newNode(parent, result, state, numPop<=0, parent.phase()); + return result; + } } }