1 package edu.berkeley.sbp;
2 import edu.berkeley.sbp.util.*;
3 import edu.berkeley.sbp.*;
4 import edu.berkeley.sbp.*;
7 import java.lang.reflect.*;
8 import java.lang.ref.*;
10 /** juxtaposition; zero or more adjacent Elements; can specify a rewriting */
11 public abstract class Sequence extends Element implements Iterable<Element> {
13 // Static Constructors //////////////////////////////////////////////////////////////////////////////
15 public abstract Sequence and(Sequence s);
16 public abstract Sequence not(Sequence s);
18 private void needs(Sequence s) { s.needed.add(this); needs.add(s); }
19 private void hates(Sequence s) { s.hated.add(this); hates.add(s); }
21 /** the empty sequence (matches the empty string) */
22 public static final Sequence empty = new Sequence.Constant.Empty();
24 /** after matching the sequence, do not add anything to the output tree */
25 public static Sequence drop(Element[] e, boolean lame) { return new Constant.Drop(e, null, null, lame); }
27 /** after matching the sequence, insert a constant into the output tree */
28 public static Sequence constant(Element[] e, Object o) { return new Constant(e, o, null, null); }
30 /** after matching the sequence, place the result of the <tt>idx</tt>th match in the output tree */
31 public static Sequence singleton(Element[] e, int idx) { return new Singleton(e, idx, null, null); }
34 * after matching the sequence, create the specified output tree
35 * @param tag the tag for the output tree
36 * @param e the elements to match
37 * @param drops only elements of <tt>e</tt> whose corresponding <tt>boolean</tt> in <tt>drops</tt> is <i>false</i> will be included in the output tree
39 public static Sequence rewritingSequence(Object tag, Element[] e, boolean[] drops) { return new RewritingSequence(tag, e, drops, null, null); }
41 ////////////////////////////////////////////////////////////////////////////////
43 public Element noFollow = null;
44 public String name = null;
45 public void setName(String name) { this.name = name; }
46 public final Topology noFollow() { return noFollow==null ? null : noFollow.toAtom(); }
49 if (elements.length!=1) throw new RuntimeException("cannot invoke toAtom() on a Sequence with " + elements.length + " elements: " + this);
50 return elements[0].toAtom();
53 protected final Element[] elements;
55 final HashSet<Sequence> needed = new HashSet<Sequence>();
56 final HashSet<Sequence> hated = new HashSet<Sequence>();
57 final HashSet<Sequence> needs = new HashSet<Sequence>();
58 final HashSet<Sequence> hates = new HashSet<Sequence>();
59 public boolean lame = false;
61 final Position firstp;
62 Position firstp() { return firstp; }
64 public Iterator<Element> iterator() { return new ArrayIterator<Element>(elements); }
65 protected Sequence(Element[] elements, HashSet<Sequence> and, HashSet<Sequence> not) {
66 if (and!=null) for(Sequence s : and) { needs.add(s); s.needed.add(this); }
67 if (not!=null) for(Sequence s : not) { hates.add(s); s.hated.add(this); }
68 this.elements = elements;
69 this.firstp = new Position(0);
72 // DO NOT MESS WITH THE FOLLOWING LINE!!!
73 private Forest.Ref epsilonForm = null;
74 private boolean eps = false;
75 Forest epsilonForm() {
76 if (epsilonForm==null) {
77 epsilonForm = new Forest.Ref();
78 epsilonForm.merge(firstp().rewrite2(null));
83 protected abstract <T> Forest<T> postReduce(Input.Location loc, Forest<T>[] args);
86 // Position //////////////////////////////////////////////////////////////////////////////
88 /** the imaginary position before or after an element of a sequence; corresponds to an "LR item" */
89 public class Position implements IntegerMappable {
91 private Forest zero = null;
92 public Forest zero() {
93 if (zero != null) return zero;
94 if (pos > 0) throw new Error();
95 return zero = rewrite(null);
100 private final Position next;
101 final Forest[] holder;
103 private Position(int pos) {
105 this.next = pos==elements.length ? null : new Position(pos+1);
106 this.holder = new Forest[elements.length];
109 boolean isFirst() { return pos==0; }
111 /** the element immediately after this Position, or null if this is the last Position */
112 public Element element() { return pos>=elements.length ? null : elements[pos]; }
114 /** the element which produces the sequence to which this Position belongs */
115 public Sequence owner() { return Sequence.this; }
117 /** the next Position (the Position after <tt>this.element()</tt>) */
118 public Position next() { return next; }
120 /** true iff this Position is the last one in the sequence */
121 public boolean isLast() { return next()==null; }
123 // Position /////////////////////////////////////////////////////////////////////////////////
125 final <T> Forest<T> rewrite(Input.Location loc) {
126 if (this==firstp()) return epsilonForm();
127 return rewrite2(loc);
130 final <T> Forest<T> rewrite2(Input.Location loc) {
131 for(int i=0; i<pos; i++) if (holder[i]==null) throw new Error("realbad " + i);
132 for(int i=pos; i<elements.length; i++) {
133 if (holder[i]==null) holder[i] = elements[i].epsilonForm();
134 if (holder[i]==null) throw new Error("bad " + i);
136 Forest<T> ret = Sequence.this.postReduce(loc, holder);
137 for(int k=0; k<pos; k++) holder[k] = null; // to help GC
141 public String toString() {
142 StringBuffer ret = new StringBuffer();
144 for(Position p = Sequence.this.firstp(); p != null; p = p.next()) {
146 if (p==this) ret.append(" | ");
147 if (p.element()!=null) ret.append(p.element());
148 else ret.append(' ');
151 return ret.toString();
153 private final int idx = master_position_idx++;
154 public int toInt() { return idx; }
156 private static int master_position_idx = 0;
158 // toString //////////////////////////////////////////////////////////////////////////////
160 public String toString() { return toString(new StringBuffer(), false).toString(); }
161 StringBuffer toString(StringBuffer sb) { return toString(sb, true); }
162 StringBuffer toString(StringBuffer sb, boolean spacing) {
163 for(int i=0; i<elements.length; i++) {
164 sb.append(elements[i].toString());
171 // Specialized Subclasses //////////////////////////////////////////////////////////////////////////////
173 static class Constant extends Sequence {
174 private final Object result;
175 public Constant(Element[] e, Object result, HashSet<Sequence> and, HashSet<Sequence> not) { super(e, and, not); this.result = result; }
176 public Sequence and(Sequence s) { Sequence ret = new Constant(elements, result, needs, hates); ret.needs(s); return ret; }
177 public Sequence not(Sequence s) { Sequence ret = new Constant(elements, result, needs, hates); ret.hates(s); return ret; }
178 public <T> Forest<T> postReduce(Input.Location loc, Forest<T>[] args) {
179 return (Forest<T>)Forest.leaf(loc, result);
181 static class Drop extends Constant {
182 public Drop(Element[] e, HashSet<Sequence> and, HashSet<Sequence> not, boolean lame) {
183 super(e, null, and, not);
187 static class Empty extends Sequence.Constant.Drop { public Empty() { super(new Element[] { }, null, null, false); } }
190 static class Singleton extends Sequence {
191 private final int idx;
192 public Singleton(Element e, HashSet<Sequence> and, HashSet<Sequence> not) { this(new Element[] { e }, 0, and, not); }
193 public Singleton(Element[] e, int idx, HashSet<Sequence> and, HashSet<Sequence> not) { super(e, and, not); this.idx = idx; }
194 public <T> Forest<T> postReduce(Input.Location loc, Forest<T>[] args) { return (Forest<T>)Forest.singleton(loc, args[idx]); }
195 public Sequence and(Sequence s) { Sequence ret = new Singleton(elements, idx, needs, hates); ret.needs(s); return ret; }
196 public Sequence not(Sequence s) { Sequence ret = new Singleton(elements, idx, needs, hates); ret.hates(s); return ret; }
199 public static class Unwrap extends Sequence {
200 private boolean[] drops;
201 public Unwrap(Element[] e, HashSet<Sequence> and, HashSet<Sequence> not) { super(e, and, not); this.drops = null; }
202 public Unwrap(Element[] e, boolean[] drops, HashSet<Sequence> and, HashSet<Sequence> not) { super(e, and, not); this.drops = drops; }
203 public Sequence and(Sequence s) { Sequence ret = new Unwrap(elements, drops, needs, hates); ret.needs(s); return ret; }
204 public Sequence not(Sequence s) { Sequence ret = new Unwrap(elements, drops, needs, hates); ret.hates(s); return ret; }
205 public <T> Forest<T> postReduce(Input.Location loc, Forest<T>[] args) {
206 for(int i=0; i<args.length; i++) if (args[i]==null) throw new Error();
207 if (drops==null) return Forest.create(loc, null, args, true, false);
209 for(int i=0; i<drops.length; i++) if (!drops[i]) count++;
210 Forest<T>[] args2 = new Forest[count];
212 for(int i=0; i<args.length; i++) if (!drops[i]) args2[j++] = args[i];
213 return Forest.create(loc, null, args2, true, false);
217 static class RewritingSequence extends Sequence {
218 /*private*/public final Object tag;
219 private final boolean[] drops;
220 private int count = 0;
221 public Sequence and(Sequence s) { Sequence ret = new RewritingSequence(tag, elements, drops, needs, hates); ret.needs(s); return ret; }
222 public Sequence not(Sequence s) { Sequence ret = new RewritingSequence(tag, elements, drops, needs, hates); ret.hates(s); return ret; }
223 public RewritingSequence(Object tag, Element[] e, HashSet<Sequence> and, HashSet<Sequence> not) { this(tag, e, null, and, not); }
224 public RewritingSequence(Object tag, Element[] e, boolean[] drops, HashSet<Sequence> and, HashSet<Sequence> not) {
227 this.drops = drops == null ? new boolean[e.length] : drops;
228 for(int i=0; i<this.drops.length; i++) if (!this.drops[i]) count++;
230 public <T> Forest<T> postReduce(Input.Location loc, Forest<T>[] args) {
231 Forest<T>[] args2 = new Forest[count];
233 for(int i=0; i<args.length; i++) if (!drops[i]) args2[j++] = args[i];
234 //System.out.println("reduce \""+tag+"\"");
235 return Forest.create(loc, (T)tag, args2, false, false);
237 public StringBuffer toString(StringBuffer sb, boolean spacing) {
238 int len = sb.length();
239 super.toString(sb, spacing);
240 len = sb.length()-len;
241 if (spacing) for(int i=0; i<50-len; i++) sb.append(' ');