LR1Collection.java

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * This file is part of SableCC.                             *
 * See the file "LICENSE" for copyright information and the  *
 * terms and conditions for copying, distribution and        *
 * modification of SableCC.                                  *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

package org.sablecc.sablecc;

import java.util.Enumeration;
import java.util.TreeMap;
import java.util.Vector;

@SuppressWarnings({"rawtypes", "unchecked"})
final class LR1Collection {
    final LR0Collection collection;
    final TreeMap[] lookaheads;
    private final TreeMap[] propagation;

    LR1Collection(LR0ItemSet set
    ) {
        collection = new LR0Collection(set
        );

        // Initialize lookaheads to nothing, propagation to nothing
        LR0ItemSet[] sets = collection.sets();
        lookaheads = new TreeMap[sets.length];
        propagation = new TreeMap[sets.length];

        for (int i = 0; i < sets.length; i++) {
            System.out.print(".");
            lookaheads[i] = new TreeMap();
            propagation[i] = new TreeMap();

            LR0Item[] items = sets[i].items();
            for (int j = 0; j < items.length; j++) {
                lookaheads[i].put(items[j], new SymbolSet());
                propagation[i].put(items[j], new Vector(0));
            }
        }
        System.out.println();

        ((SymbolSet) lookaheads[0].get(set.items()[0])).setTerminal(Grammar.eof);

        for (int i = 0; i < sets.length; i++) {
            System.out.print(".");
            LR0Item[] items = sets[i].items();

            for (int j = 0; j < items.length; j++) {
                LR1ItemSet lr1Set = new LR1ItemSet();
                lr1Set.set(new LR1Item(items[j], Grammar.dummy));

                LR1Item[] closure = Grammar.CLOSURE(lr1Set).items();

                for (int k = 0; k < closure.length; k++) {
                    if (closure[k].terminal != Grammar.dummy) {
                        Symbol[] rightside = Production.
                                production(closure[k].lr0Item.production).
                                rightside();

                        if (closure[k].lr0Item.position < rightside.length) {
                            Integer destination = collection.GOTO(i,
                                    rightside[closure[k].lr0Item.position]);

                            if (destination != null) {

                                ((SymbolSet) lookaheads[destination.intValue()].
                                        get
                                                (new LR0Item(closure[k].lr0Item.production,
                                                        closure[k].lr0Item.position + 1))).
                                        setTerminal(closure[k].terminal);

                /*((SymbolSet) lookaheads[collection.GOTO(i,
                Production.production(closure[k].lr0Item.production).
                rightside(closure[k].lr0Item.position)).intValue()].
                get(new LR0Item(closure[k].lr0Item.production,
                closure[k].lr0Item.position + 1))).
                setTerminal(closure[k].terminal);*/
                            }
                        }
                    } else {
                        Symbol[] rightside = Production.
                                production(closure[k].lr0Item.production).
                                rightside();

                        if (closure[k].lr0Item.position < rightside.length) {
                            Integer destination = collection.GOTO(i,
                                    rightside[closure[k].lr0Item.position]);

                            if (destination != null) {
                                ((Vector) propagation[i].get(items[j])).
                                        addElement(new LR0ItemAndSetPair(
                                                new LR0Item(closure[k].lr0Item.production,
                                                        closure[k].lr0Item.position + 1),
                                                destination.intValue()));

                /*((Vector) propagation[i].get(items[j])).
                    addElement(new LR0ItemAndSetPair(
                    new LR0Item(closure[k].lr0Item.production,
                    closure[k].lr0Item.position + 1),
                    collection.GOTO(i,
                    Production.production(closure[k].lr0Item.production).
                    rightside(closure[k].lr0Item.position)).intValue()));*/
                            }
                        }
                    }
                }
            }
        }
        System.out.println();

        boolean changed;
        do {
            System.out.print(".");
            changed = false;
            for (int i = 0; i < sets.length; i++) {
                LR0Item[] items = sets[i].items();

                for (int j = 0; j < items.length; j++) {
                    for (Enumeration e = ((Vector) propagation[i].get(items[j])).
                            elements(); e.hasMoreElements(); ) {
                        LR0ItemAndSetPair pair = (LR0ItemAndSetPair) e.nextElement();

                        SymbolSet before = (SymbolSet)
                                ((SymbolSet) lookaheads[pair.set].get(pair.item)).clone();

                        ((SymbolSet) lookaheads[pair.set].get(pair.item)).
                                or((SymbolSet) lookaheads[i].get(items[j]));

                        if (!before.equals(lookaheads[pair.set].get(pair.item))) {
                            changed = true;
                        }
                    }
                }
            }
        }
        while (changed);
        System.out.println();
    }

    @Override
    public String toString() {
        StringBuffer result = new StringBuffer();

        result.append(collection);
        result.append(System.getProperty("line.separator"));

        result.append("Lookaheads" + System.getProperty("line.separator"));
        LR0ItemSet[] sets = collection.sets();

        for (int i = 0; i < sets.length; i++) {
            result.append(i + ":" + System.getProperty("line.separator"));
            LR0Item[] items = sets[i].items();

            for (int j = 0; j < items.length; j++) {
                result.append(items[j] + ":" + lookaheads[i].get(items[j]) +
                        System.getProperty("line.separator"));
            }
        }

        return result.toString();
    }
}