1 // Copyright 2006-2007 all rights reserved; see LICENSE file for BSD-style license
3 package edu.berkeley.sbp;
4 import edu.berkeley.sbp.util.*;
5 import edu.berkeley.sbp.*;
6 import edu.berkeley.sbp.*;
9 import java.lang.reflect.*;
10 import java.lang.ref.*;
12 /** <font color=green>juxtaposition; zero or more adjacent Elements; can specify a rewriting</font> */
13 public abstract class Sequence implements Iterable<Element>, SequenceOrElement {
15 protected final Element[] elements;
17 boolean needed_or_hated = false;
18 boolean in_a_union = false;
20 final HashSet<Sequence> needs = new HashSet<Sequence>();
21 final HashSet<Sequence> hates = new HashSet<Sequence>();
23 // FIXME: these are ugly -- migrate into Grammar
24 HashMap<Sequence,Boolean> canNeed = new HashMap<Sequence,Boolean>();
25 HashMap<Sequence,Boolean> canKill = new HashMap<Sequence,Boolean>();
27 final Position firstp;
31 private static int global_sernum = 0;
32 private int sernum = global_sernum++;
34 int[] ret = new int[needs.size()];
36 for(Sequence s : needs) ret[i++] = s.sernum;
40 int[] ret = new int[hates.size()];
42 for(Sequence s : hates) ret[i++] = s.sernum;
47 // Static Constructors //////////////////////////////////////////////////////////////////////////////
49 /** create a sequence of one element */
50 public static Sequence create(Element e) { return create(new Element[] { e }, 0); }
52 /** create a sequence which drops the result of all but one of its element */
53 public static Sequence create(Element[] e, int which) {
54 return new Singleton(e, which); }
56 /** create a sequence which always evaluates to a constant result */
57 public static Sequence create(Object result, Element[] e) {
58 return new RewritingSequence(result, e, trues(e.length)); }
60 private static boolean[] trues(int length) {
61 boolean[] ret = new boolean[length];
62 for(int i=0; i<ret.length; i++) ret[i] = true;
67 * create a sequence (general form)
68 * @param head the head of the output tree
69 * @param e the elements to match
70 * @param drop only elements of <tt>e</tt> whose corresponding <tt>boolean</tt> in <tt>drops</tt>
71 * is <i>false</i> will be included in the output tree
72 * @param lifts which (if any) child trees to lift
74 public static Sequence create(Object head, Element[] e, boolean[] drop) {
75 return create(head, e, drop, new boolean[e.length]); }
76 public static Sequence create(Object head, Element[] e, boolean[] drop, boolean[] lifts) {
77 if (lifts==null) lifts = new boolean[e.length];
78 return new RewritingSequence(head, e, drop, lifts);
81 /** return a new sequence identical to this one, but with a positive conjunct <tt>s</tt> */
82 public Sequence and(Sequence s) {
84 throw new RuntimeException("you may not use a sequence as a conjunct if it belongs to a Union");
87 s.needed_or_hated=true;
91 /** return a new sequence identical to this one, but with a negative conjunct <tt>s</tt> */
92 public Sequence andnot(Sequence s) {
94 throw new RuntimeException("you may not use a sequence as a conjunct if it belongs to a Union");
97 s.needed_or_hated=true;
101 /** return a new sequence identical to this one, but with a follow-set restricted to <tt>a</tt> */
102 public Sequence followedBy(Atom a) { Sequence ret = dup(); ret.follow = a; return ret; }
104 ////////////////////////////////////////////////////////////////////////////////
106 abstract Sequence _clone();
107 private Sequence dup() {
108 Sequence ret = _clone();
109 for(Sequence s : needs) { ret.needs.add(s); }
110 for(Sequence s : hates) { ret.hates.add(s); }
115 Iterable<Sequence> needs() { return needs; }
116 Iterable<Sequence> hates() { return hates; }
118 Position firstp() { return firstp; }
119 Position lastp() { return firstp().last(); }
121 public Iterator<Element> iterator() { return new ArrayIterator<Element>(elements); }
122 protected Sequence(Element[] elements) {
123 this.elements = elements;
124 for(int i=0; i<elements.length; i++)
125 if (elements[i]==null)
126 throw new RuntimeException("cannot have nulls in a sequence: " + this);
127 this.firstp = new Position(0, null);
130 abstract Forest epsilonForm(Input.Region loc, Grammar cache);
132 protected abstract <T> Forest<T> postReduce(Input.Region loc, Forest<T>[] args, Position p);
135 // Position //////////////////////////////////////////////////////////////////////////////
137 static abstract class Pos implements IntegerMappable, Comparable<Pos>, Serializable {
138 final Forest[] holder;
139 Pos(int len) { this.holder = new Forest[len]; }
141 public abstract int provides();
142 public abstract int[] needs();
143 public abstract int[] hates();
144 public abstract boolean owner_needed_or_hated();
146 public abstract int numPops();
147 public abstract <T> Forest<T> rewrite(Input.Region loc, Grammar cache);
150 /** the imaginary position before or after an element of a sequence; corresponds to an "LR item" */
151 class Position extends Pos implements IntegerMappable {
153 public Pos getPos() {
154 return new DumbPos(elements.length, provides(), needs(), hates(), owner_needed_or_hated(), numPops(),
155 public int provides();
156 public int[] needs();
157 public int[] hates();
158 public boolean owner_needed_or_hated();
159 public int numPops();
160 public <T> Forest<T> rewrite(Input.Region loc, Grammar cache)
165 public int ord() { return ord; }
166 public int numPops() { return pos; }
169 private final Position next;
170 private final Position prev;
172 public int provides() { return owner().sernum; }
173 public int[] needs() { return owner().needs_int(); }
174 public int[] hates() { return owner().hates_int(); }
175 public boolean owner_needed_or_hated() { return owner().needed_or_hated; }
177 private Position(int pos, Position prev) {
178 super(elements.length);
180 this.next = pos==elements.length ? null : new Position(pos+1, this);
184 public int compareTo(Pos p) {
185 return ord - ((Position)p).ord;
188 boolean isFirst() { return pos==0; }
189 public int pos() { return pos; }
191 /** the element immediately after this Position, or null if this is the last Position */
192 public Element element() { return pos>=elements.length ? null : elements[pos]; }
194 /** the element which produces the sequence to which this Position belongs */
195 public Sequence owner() { return Sequence.this; }
197 /** the next Position (the Position after <tt>this.element()</tt>) */
198 public Position next() { return next; }
200 /** true iff this Position is the last one in the sequence */
201 public boolean isLast() { return next()==null; }
202 public Position last() { return isLast() ? this : next().last(); }
203 public Position prev() { return prev; }
205 // Position /////////////////////////////////////////////////////////////////////////////////
207 public final <T> Forest<T> rewrite(Input.Region loc, Grammar cache) {
208 if (this==firstp()) epsilonForm(loc, cache);
209 for(int i=0; i<pos; i++) if (holder[i]==null) throw new Error("realbad " + i);
210 for(int i=pos; i<elements.length; i++) {
211 if (holder[i]==null) holder[i] = ((Union)elements[i]).epsilonForm(loc, cache);
212 if (holder[i]==null) throw new Error("bad");
214 return Sequence.this.postReduce(loc, holder, this);
217 public String toString() {
218 StringBuffer ret = new StringBuffer();
220 for(Position p = Sequence.this.firstp(); p != null; p = p.next()) {
222 if (p==this) ret.append(" | ");
223 if (p.element()!=null) ret.append(p.element());
224 else ret.append(' ');
227 return ret.toString();
229 private final int idx = master_position_idx++;
230 public int toInt() { return idx; }
232 private static int master_position_idx = 0;
235 // toString //////////////////////////////////////////////////////////////////////////////
237 public String toString() { return toString(new StringBuffer(), false).toString(); }
238 StringBuffer toString(StringBuffer sb) { return toString(sb, true); }
239 StringBuffer toString(StringBuffer sb, boolean spacing) {
240 for(int i=0; i<elements.length; i++) {
241 sb.append(elements[i]+"");
244 if (follow != null) {
248 for(Sequence s : needs) {
252 for(Sequence s : hates) {
260 // Specialized Subclasses //////////////////////////////////////////////////////////////////////////////
262 static class Singleton extends Sequence {
263 private final int idx;
264 public Singleton(Element e) { this(new Element[] { e }, 0); }
265 public Singleton(Element[] e, int idx) { super(e); this.idx = idx; }
266 public <T> Forest<T> postReduce(Input.Region loc, Forest<T>[] args, Position p) { return args[idx]; }
267 Sequence _clone() { return new Singleton(elements,idx); }
268 Forest epsilonForm(Input.Region loc, Grammar cache) {
269 return ((Union)elements[idx]).epsilonForm(loc, cache);
273 static class RewritingSequence extends Sequence {
274 private final Object tag;
275 private final boolean[] drops;
276 private final boolean[] lifts;
277 Sequence _clone() { return new RewritingSequence(tag, elements, drops); }
278 public RewritingSequence(Object tag, Element[] e) { this(tag, e, null); }
279 public RewritingSequence(Object tag, Element[] e, boolean[] drops) { this(tag, e, drops, new boolean[e.length]); }
280 public RewritingSequence(Object tag, Element[] e, boolean[] drops, boolean[] lifts) {
282 if (tag==null) throw new Error();
284 this.drops = drops == null ? new boolean[e.length] : drops;
286 for(int i=0; i<this.drops.length; i++) if (!this.drops[i]) count++;
287 this.lifts = new boolean[count];
289 for(int i=0; i<this.drops.length; i++)
291 this.lifts[j++] = lifts[i];
293 public <T> Forest<T> postReduce(Input.Region loc, Forest<T>[] args, Position p) {
294 Forest<T>[] args2 = new Forest[lifts.length];
296 for(int i=0; i<args.length; i++) if (!drops[i]) args2[j++] = args[i];
297 return Forest.create(loc, (T)tag, args2, lifts);
299 public StringBuffer toString(StringBuffer sb, boolean spacing) {
300 int len = sb.length();
302 sb.append("\""+StringUtil.escapify(tag.toString(),"\"\r\n")+"\":: ");
303 super.toString(sb, spacing);
304 len = sb.length()-len;
305 if (spacing) for(int i=0; i<50-len; i++) sb.append(' ');
308 Forest epsilonForm(Input.Region loc, Grammar cache) {
309 return Forest.create(loc, tag, new Forest[0], lifts);