package edu.berkeley.sbp;
import edu.berkeley.sbp.*;
import edu.berkeley.sbp.util.*;
-import edu.berkeley.sbp.*;
import edu.berkeley.sbp.Sequence.Position;
-import edu.berkeley.sbp.*;
import java.io.*;
import java.util.*;
-import java.lang.reflect.*;
/** a parser which translates streams of Tokens of type T into a Forest<R> */
public abstract class Parser<T extends Token, R> {
protected Parser(Union u) { this.pt = new Table(u, top()); }
protected Parser(Table pt) { this.pt = pt; }
+ /** implement this method to create the output forest corresponding to a lone shifted input token */
public abstract Forest<R> shiftedToken(T t, Token.Location loc);
- public abstract Topology<T> top();
-
- /** parse <tt>input</tt> for a exactly one unique result, throwing <tt>Ambiguous</tt> if not unique or <tt>Failed</tt> if none */
- public Tree<R> parse1(Token.Stream<T> input) throws IOException, Failed, Ambiguous {
- Forest<R> ret = parse(input);
- try { return ret.expand1(); }
- catch (Ambiguous a) {
- System.out.println("while expanding:");
- System.out.println(ret);
- throw a;
- }
- }
+ /** this method must return an empty topology of the input token type */
+ public abstract Topology<T> top();
/** parse <tt>input</tt>, using the table <tt>pt</tt> to drive the parser */
- public Forest<R> parse(Token.Stream<T> input) throws IOException, Failed {
+ public Forest<R> parse(Token.Stream<T> input) throws IOException, ParseFailed {
GSS gss = new GSS();
Token.Location loc = input.getLocation();
- GSS.Phase current = gss.new Phase(null, input.next(), loc);
- current.newNode(null, null, pt.start, true);
+ GSS.Phase current = gss.new Phase(null, this, null, input.next(1, 0, 0), loc, null);
+ current.newNode(null, Forest.leaf(null, null), pt.start, true);
+ int count = 1;
for(;;) {
loc = input.getLocation();
- GSS.Phase next = gss.new Phase(current, input.next(), loc);
current.reduce();
Forest forest = current.token==null ? null : shiftedToken((T)current.token, loc);
- current.shift(next, forest);
+ GSS.Phase next = gss.new Phase(current, this, current, input.next(count, gss.resets, gss.waits), loc, forest);
+ count = next.hash.size();
if (current.isDone()) return (Forest<R>)current.finalResult;
- current.checkFailure();
current = next;
}
}
-
-
- // Exceptions //////////////////////////////////////////////////////////////////////////////
-
- public static class Failed extends Exception {
- private final Token.Location location;
- private final String message;
- public Failed() { this("", null); }
- public Failed(String message, Token.Location loc) { this.location = loc; this.message = message; }
- public Token.Location getLocation() { return location; }
- public String toString() { return message + (location==null ? "" : (" at " + location)); }
- }
-
- public static class Ambiguous extends RuntimeException {
- public final Forest ambiguity;
- public Ambiguous(Forest ambiguity) { this.ambiguity = ambiguity; }
- public String toString() {
- StringBuffer sb = new StringBuffer();
- sb.append("unresolved ambiguity "/*"at " + ambiguity.getLocation() + ":"*/);
- for(Object result : ambiguity.expand(false))
- sb.append("\n " + result);
- return sb.toString();
- }
- }
-
// Table //////////////////////////////////////////////////////////////////////////////
static class Table extends Walk.Cache {
public final Walk.Cache cache = this;
-
+
private void walk(Element e, HashSet<Element> hs) {
if (e==null) return;
if (hs.contains(e)) return;
HashSet<Element> all_elements = new HashSet<Element>();
walk(start0, all_elements);
for(Element e : all_elements)
- cache.ys.put(e, new Walk.YieldSet(e, cache).walk());
+ cache.ys.addAll(e, new Walk.YieldSet(e, cache).walk());
HashSet<Position> hp = new HashSet<Position>();
reachable(start0, hp);
this.start = new State(hp, all_states, all_elements);
if (start0.contains(p.owner()) && p.next()==null)
state.accept = true;
- // FIXME: how does right-nullability interact with follow restrictions?
- // all right-nullable rules get a reduction [Johnstone 2000]
- if (p.isRightNullable(cache)) {
+ if (isRightNullable(p)) {
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);
+
+ Topology follow = wf.walk(p.owner());
+ if (p.owner() instanceof Sequence.RewritingSequence &&
+ (((Sequence.RewritingSequence)p.owner()).tag+"").equals("emailaddr")) {
+ System.out.println("follow before: " + new edu.berkeley.sbp.misc.CharToken.CharRange(follow));
+ }
+ for(Position p2 = p; p2 != null && p2.element() != null; p2 = p2.next())
+ follow = follow.intersect(new Walk.Follow(top.empty(), p2.element(), all_elements, cache).walk(p2.element()));
+ if (p.owner() instanceof Sequence.RewritingSequence &&
+ (((Sequence.RewritingSequence)p.owner()).tag+"").equals("emailaddr")) {
+ System.out.println("follow after: " + new edu.berkeley.sbp.misc.CharToken.CharRange(follow));
+ }
+ state.reductions.put(follow, red);
if (wf.includesEof()) state.eofReductions.add(red);
}
}
}
+ private boolean isRightNullable(Position p) {
+ if (p.isLast()) return true;
+ if (!p.element().possiblyEpsilon(this)) return false;
+ return isRightNullable(p.next());
+ }
+
/** a single state in the LR table and the transitions possible from it */
- public class State implements Comparable<Table.State>, Iterable<Position> {
+
+ public class State implements Comparable<Table.State>, IntegerMappable, Iterable<Position> {
+ public int toInt() { return idx; }
+
+ public boolean lame() {
+ for(Position p : this)
+ for(Position p2 = p; p2!=null; p2=p2.next())
+ if (p2.isLast() && !p2.owner().lame)
+ return false;
+ return true;
+ }
/*
public boolean isResolvable(Token t) {
boolean found = false;
// "yields" [in one or more step] is used instead of "produces" [in exactly one step]
// to avoid having to iteratively construct our set of States as shown in most
// expositions of the algorithm (ie "keep doing XYZ until things stop changing").
- /*
- for(Element e : all_elements) {
- if (e instanceof Atom) continue;
- HashSet<Position> h = new Walk.Closure(null, g.cache).closure(e, hs);
- State s = all_states.get(h) == null ? new State(h, all_states, all_elements) : all_states.get(h);
- if (gotoSetNonTerminals.get(e) != null)
- throw new Error("this should not happen");
- gotoSetNonTerminals.put(e, s);
- }
- */
HashMapBag<Element,Position> move = new HashMapBag<Element,Position>();
for(Position p : hs) {
Element e = p.element();
if (e==null) continue;
- HashSet<Element> ys = cache.ys.get(e);
- if (ys != null) {
- for(Element y : ys) {
- HashSet<Position> hp = new HashSet<Position>();
- reachable(p.next(), hp);
- move.addAll(y, hp);
- }
+ for(Element y : cache.ys.getAll(e)) {
+ HashSet<Position> hp = new HashSet<Position>();
+ reachable(p.next(), hp);
+ move.addAll(y, hp);
}
}
for(Element y : move) {
}
}
- public String toString() { return "state["+idx+"]"; }
+ public String toString() {
+ //return "state["+idx+"]";
+ StringBuffer ret = new StringBuffer();
+ ret.append("state["+idx+"]: ");
+ for(Position p : this) ret.append("{"+p+"} ");
+ return ret.toString();
+ }
public int compareTo(Table.State s) { return idx==s.idx ? 0 : idx < s.idx ? -1 : 1; }
}
}
private void finish(GSS.Phase.Node parent, Forest result, GSS.Phase target) {
State state = parent.state.gotoSetNonTerminals.get(position.owner());
+ if (result==null) throw new Error();
if (state!=null)
- target.newNode(parent, result, state, numPop<=0);
+ target.newNode(parent, result, state, numPop<=0, this);
}
}
}
projects / sbp.git / blobdiff