X-Git-Url: http://git.megacz.com/?p=sbp.git;a=blobdiff_plain;f=src%2Fedu%2Fberkeley%2Fsbp%2FSequence.java;h=1c76aefadda764a09bf478877d764ecb108c0675;hp=e18f5efc5ca56271fa6e225e75e0bf07d7062cbd;hb=584cef55d8811e3215858fde22e708d2a3d1cf70;hpb=242a8711e98cbd3ed6d05271bf910fde38e9be9a diff --git a/src/edu/berkeley/sbp/Sequence.java b/src/edu/berkeley/sbp/Sequence.java index e18f5ef..1c76aef 100644 --- a/src/edu/berkeley/sbp/Sequence.java +++ b/src/edu/berkeley/sbp/Sequence.java @@ -1,3 +1,5 @@ +// Copyright 2006 all rights reserved; see LICENSE file for BSD-style license + package edu.berkeley.sbp; import edu.berkeley.sbp.util.*; import edu.berkeley.sbp.*; @@ -7,95 +9,141 @@ import java.util.*; import java.lang.reflect.*; import java.lang.ref.*; -/** juxtaposition; zero or more adjacent Elements; can specify a rewriting */ -public abstract class Sequence extends Element implements Iterable { +/** juxtaposition; zero or more adjacent Elements; can specify a rewriting */ +public abstract class Sequence implements Iterable, SequenceOrElement { + + protected final Element[] elements; + + boolean needed_or_hated = false; + boolean in_a_union = false; + + final HashSet needs = new HashSet(); + final HashSet hates = new HashSet(); + + // FIXME: these are ugly -- migrate into Grammar + HashMap canNeed = new HashMap(); + HashMap canKill = new HashMap(); + + final Position firstp; + + Atom follow = null; // Static Constructors ////////////////////////////////////////////////////////////////////////////// - /** the empty sequence (matches the empty string) */ - public static final Sequence empty = new Sequence.Constant.Empty(); + /** create a sequence of one element */ + public static Sequence create(Element e) { return create(new Element[] { e }, 0); } - /** after matching the sequence, do not add anything to the output tree */ - public static Sequence drop(Element[] e, HashSet and, HashSet not, boolean lame) { return new Constant.Drop(e, and, not, lame); } + /** create a sequence which drops the result of all but one of its element */ + public static Sequence create(Element[] e, int which) { + return new Singleton(e, which); } - /** after matching the sequence, insert a constant into the output tree */ - public static Sequence constant(Element[] e, Object o, HashSet and, HashSet not) { return new Constant(e, o, and, not); } + /** create a sequence which always evaluates to a constant result */ + public static Sequence create(Object result, Element[] e) { + return new RewritingSequence(result, e, trues(e.length)); } - /** after matching the sequence, place the result of the idxth match in the output tree */ - public static Sequence singleton(Element[] e, int idx, HashSet and, HashSet not) { return new Singleton(e, idx, and, not); } + private static boolean[] trues(int length) { + boolean[] ret = new boolean[length]; + for(int i=0; ie whose corresponding boolean in drops is false will be included in the output tree + * create a sequence (general form) + * @param head the head of the output tree + * @param e the elements to match + * @param drop only elements of e whose corresponding boolean in drops + * is false will be included in the output tree + * @param lifts which (if any) child trees to lift **/ - public static Sequence rewritingSequence(Object tag, Element[] e, boolean[] drops, HashSet and, HashSet not) { - return new RewritingSequence(tag, e, drops, and, not); } - - //////////////////////////////////////////////////////////////////////////////// + public static Sequence create(Object head, Element[] e, boolean[] drop) { + return create(head, e, drop, new boolean[e.length]); } + public static Sequence create(Object head, Element[] e, boolean[] drop, boolean[] lifts) { + if (lifts==null) lifts = new boolean[e.length]; + return new RewritingSequence(head, e, drop, lifts); + } - public Element noFollow = null; - public final Topology noFollow() { return noFollow==null ? null : noFollow.toAtom(); } + /** return a new sequence identical to this one, but with a positive conjunct s */ + public Sequence and(Sequence s) { + if (s.in_a_union) + throw new RuntimeException("you may not use a sequence as a conjunct if it belongs to a Union"); + Sequence ret = dup(); + ret.needs.add(s); + s.needed_or_hated=true; + return ret; + } - Topology toAtom() { - if (elements.length!=1) throw new RuntimeException("cannot invoke toAtom() on a Sequence with " + elements.length + " elements: " + this); - return elements[0].toAtom(); + /** return a new sequence identical to this one, but with a negative conjunct s */ + public Sequence andnot(Sequence s) { + if (s.in_a_union) + throw new RuntimeException("you may not use a sequence as a conjunct if it belongs to a Union"); + Sequence ret = dup(); + ret.hates.add(s); + s.needed_or_hated=true; + return ret; } - protected final Element[] elements; + /** return a new sequence identical to this one, but with a follow-set restricted to a */ + public Sequence followedBy(Atom a) { Sequence ret = dup(); ret.follow = a; return ret; } - final HashSet needs; - final HashSet hates; - boolean lame = false; + //////////////////////////////////////////////////////////////////////////////// + + abstract Sequence _clone(); + private Sequence dup() { + Sequence ret = _clone(); + for(Sequence s : needs) { ret.needs.add(s); } + for(Sequence s : hates) { ret.hates.add(s); } + ret.follow = follow; + return ret; + } + + Iterable needs() { return needs; } + Iterable hates() { return hates; } - final Position firstp; Position firstp() { return firstp; } + Position lastp() { return firstp().last(); } public Iterator iterator() { return new ArrayIterator(elements); } - protected Sequence(Element[] elements, HashSet and, HashSet not) { - this.needs = and==null ? new HashSet() : and; - this.hates = not==null ? new HashSet() : not; - //for(Sequence s : needs) s.lame = true; - //for(Sequence s : hates) s.lame = true; + protected Sequence(Element[] elements) { this.elements = elements; - this.firstp = new Position(0); + for(int i=0; i h) { firstp().reachable(h); } + abstract Forest epsilonForm(Input.Region loc, Grammar cache); - Forest epsilonForm() { return firstp().rewrite(null); } - - protected abstract Forest postReduce(Token.Location loc, Forest[] args); + protected abstract Forest postReduce(Input.Region loc, Forest[] args, Position p); // Position ////////////////////////////////////////////////////////////////////////////// /** the imaginary position before or after an element of a sequence; corresponds to an "LR item" */ - public class Position { + class Position implements IntegerMappable { - void reachable(HashSet h) { - if (h.contains(this)) return; - h.add(this); - if (element() != null) element().reachable(h); - } + public int ord = -1; + private Forest zero = null; + /* + public Forest zero(Input.Region reg) { + if (zero != null) return zero; + if (pos > 0) throw new RuntimeException("Position.zero(): pos>0"); + return zero = rewrite(reg); + } + */ final int pos; private final Position next; + private final Position prev; final Forest[] holder; - private Position(int pos) { + private Position(int pos, Position prev) { this.pos = pos; - this.next = pos==elements.length ? null : new Position(pos+1); + this.next = pos==elements.length ? null : new Position(pos+1, this); this.holder = new Forest[elements.length]; + this.prev = prev; } boolean isFirst() { return pos==0; } - boolean isRightNullable(Walk.Cache cache) { - if (isLast()) return true; - if (!element().possiblyEpsilon(cache)) return false; - return next().isRightNullable(cache); - } /** the element immediately after this Position, or null if this is the last Position */ public Element element() { return pos>=elements.length ? null : elements[pos]; } @@ -108,14 +156,19 @@ public abstract class Sequence extends Element implements Iterable { /** true iff this Position is the last one in the sequence */ public boolean isLast() { return next()==null; } + public Position last() { return isLast() ? this : next().last(); } + public Position prev() { return prev; } - // Reduction ///////////////////////////////////////////////////////////////////////////////// + // Position ///////////////////////////////////////////////////////////////////////////////// - Forest rewrite(Token.Location loc) { - for(int i=pos; i ret = Sequence.this.postReduce(loc, holder); - for(int k=0; k Forest rewrite(Input.Region loc, Grammar cache) { + if (this==firstp()) epsilonForm(loc, cache); + for(int i=0; i { for(Position p = Sequence.this.firstp(); p != null; p = p.next()) { ret.append(' '); if (p==this) ret.append(" | "); - if (p.element()!=null) ret.append(p.element().possiblyEpsilon(null) ? "["+p.element()+"]" : p.element()); + if (p.element()!=null) ret.append(p.element()); else ret.append(' '); } ret.append("}>"); return ret.toString(); } + private final int idx = master_position_idx++; + public int toInt() { return idx; } } - + private static int master_position_idx = 0; // toString ////////////////////////////////////////////////////////////////////////////// @@ -139,9 +194,21 @@ public abstract class Sequence extends Element implements Iterable { StringBuffer toString(StringBuffer sb) { return toString(sb, true); } StringBuffer toString(StringBuffer sb, boolean spacing) { for(int i=0; i "); + sb.append(follow); + } + for(Sequence s : needs) { + sb.append("& "); + sb.append(s); + } + for(Sequence s : hates) { + sb.append("&~ "); + sb.append(s); + } return sb; } @@ -150,66 +217,68 @@ public abstract class Sequence extends Element implements Iterable { static class Constant extends Sequence { private final Object result; - public Constant(Element[] e, Object result, HashSet and, HashSet not) { super(e, and, not); this.result = result; } - public Forest postReduce(Token.Location loc, Forest[] args) { - return (Forest)Forest.leaf(loc, result, this); - } - static class Drop extends Constant { - public Drop(Element[] e, HashSet and, HashSet not, boolean lame) { - super(e, null, and, not); - this.lame = lame; - } + public Constant(Element[] e, Object result) { + super(e); + if (result==null) throw new Error("constant sequences may not have result==null"); + this.result = result; + } + Sequence _clone() { return new Constant(elements, result); } + public Forest postReduce(Input.Region loc, Forest[] args, Position p) { + return (Forest)Forest.create(loc, result, null, false); + } + Forest epsilonForm(Input.Region loc, Grammar cache) { + return Forest.create(loc, result, null, false); } - static class Empty extends Sequence.Constant.Drop { public Empty() { super(new Element[] { }, null, null, false); } } } static class Singleton extends Sequence { private final int idx; - public Singleton(Element e, HashSet and, HashSet not) { this(new Element[] { e }, 0, and, not); } - public Singleton(Element[] e, int idx, HashSet and, HashSet not) { super(e, and, not); this.idx = idx; } - public Forest postReduce(Token.Location loc, Forest[] args) { return (Forest)Forest.singleton(loc, args[idx], this); } - } - - static class Unwrap extends Sequence { - private boolean[] drops; - public Unwrap(Element[] e, HashSet and, HashSet not) { super(e, and, not); this.drops = null; } - public Unwrap(Element[] e, boolean[] drops, HashSet and, HashSet not) { super(e, and, not); this.drops = drops; } - public Forest postReduce(Token.Location loc, Forest[] args) { - if (drops==null) return Forest.create(loc, null, args, this, true, false); - int count = 0; - for(int i=0; i[] args2 = new Forest[count]; - int j = 0; - for(int i=0; i Forest postReduce(Input.Region loc, Forest[] args, Position p) { return args[idx]; } + Sequence _clone() { return new Singleton(elements,idx); } + Forest epsilonForm(Input.Region loc, Grammar cache) { + return ((Union)elements[idx]).epsilonForm(loc, cache); } } static class RewritingSequence extends Sequence { - private final Object tag; + private Object tag; private final boolean[] drops; - private int count = 0; - public RewritingSequence(Object tag, Element[] e, HashSet and, HashSet not) { this(tag, e, null, and, not); } - public RewritingSequence(Object tag, Element[] e, boolean[] drops, HashSet and, HashSet not) { - super(e, and, not); + private final boolean[] lifts; + Sequence _clone() { return new RewritingSequence(tag, elements, drops); } + public RewritingSequence(Object tag, Element[] e) { this(tag, e, null); } + public RewritingSequence(Object tag, Element[] e, boolean[] drops) { this(tag, e, drops, new boolean[e.length]); } + public RewritingSequence(Object tag, Element[] e, boolean[] drops, boolean[] lifts) { + super(e); + if (tag==null) throw new Error(); this.tag = tag; this.drops = drops == null ? new boolean[e.length] : drops; + int count = 0; for(int i=0; i Forest postReduce(Token.Location loc, Forest[] args) { - Forest[] args2 = new Forest[count]; + public Forest postReduce(Input.Region loc, Forest[] args, Position p) { + Forest[] args2 = new Forest[lifts.length]; int j = 0; for(int i=0; i "); - sb.append(tag); return sb; } + Forest epsilonForm(Input.Region loc, Grammar cache) { + return Forest.create(loc, tag, new Forest[0], lifts); + } } }