/home/palakars/workspace-inprogress/code-in-progress/aitools3/aitools3-aq-invertedindex2-java/src/de/aitools/aq/invertedindex/core/Postlist.java

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// Copyright (C) 2011 webis.de. All rights reserved.
package de.aitools.aq.invertedindex.core;

import java.io.PrintStream;
import java.util.Iterator;
import java.util.NoSuchElementException;

import com.sun.jna.Native;
import com.sun.jna.Pointer;
import com.sun.jna.Structure;

import de.aitools.aq.check.A;
import de.aitools.aq.invertedindex.usage.UsingSearcher;
import de.aitools.aq.value.Value;
import de.aitools.aq.value.single.SingleInt;
import de.aitools.aq.value.single.SingleString;

public class Postlist<V extends Value> implements Iterable<V> {
        
        static {
                Native.register(Configuration.NATIVE_LIB);
        }
        
        public static class Head extends Structure {
                
                public int getValueCount() {
                        return valueCount;
                }

                public short getValueSize() {
                        return valueSize;
                }

                public int getTotalSize() {
                        return totalSize;
                }
                
                public PrintStream print(PrintStream stream) {
                        stream.format("valueCount : %1$d\n", getValueCount());
                        stream.format("valueSize : %1$d\n", getValueSize());
                        stream.format("totalSize : %1$d", getTotalSize());
                        return stream;
                }

                // This is public for JNA
                public int   valueCount;
                public short valueSize;
                public int   totalSize;
        }
        
        private class PostlistIterator implements Iterator<V> {
                
                @Override
                public boolean hasNext() {
                        return index < head.valueCount;
                }

                @Override
                public V next() {
                        if (index >= head.valueCount) {
                                throw new NoSuchElementException();
                        }
                        V value = null;
                        try {
                                value = clazz.newInstance();
                                value.copyFrom(raw_postlist_next(nativePostlist));
                                ++index;
                        } catch (InstantiationException e) {
                                e.printStackTrace();
                        } catch (IllegalAccessException e) {
                                e.printStackTrace();
                        }
                        return value;
                }

                @Override
                public void remove() {
                        throw new UnsupportedOperationException();
                }
                
                public void rewind() {
                        raw_postlist_rewind(nativePostlist);
                        index = 0;
                }
                
                private int index;
        }
        
        protected Postlist(Class<V> clazz, Pointer nativePtr, Head head) {
                A.CHECK_NOT_NULL(clazz, nativePtr, head);
                this.iterator = new PostlistIterator();
                this.nativePostlist = nativePtr;
                this.clazz = clazz;
                this.head = head;
        }
        
        @Override
        public Iterator<V> iterator() {
                return iterator;
        }
        
        public void deleteNative() {
                if (nativePostlist == null) return;
                raw_postlist_delete(nativePostlist);
                nativePostlist = null;
                head.valueCount = 0;
                head.valueSize = 0;
                head.totalSize = 0;
        }
        
        @Override
        protected void finalize() throws Throwable {
                this.deleteNative();
                super.finalize();
        }
        
        public Head getHead() {
                return head;
        }

        public boolean isEmpty() {
                return head.valueCount == 0;
        }
        
        public int size() {
                return head.valueCount;
        }
        
        public void rewind() {
                iterator.rewind();
    }

        private PostlistIterator iterator;
        private Pointer nativePostlist;
        private Class<V> clazz;
        private Head head;
        
        // -------------------------------------------------------------------------
        // JNA functions - TOUCH AND DIE
        // -------------------------------------------------------------------------
        
        private native Pointer raw_postlist_next(Pointer raw_postlist);
        private native void    raw_postlist_rewind(Pointer raw_postlist);
        private native void    raw_postlist_delete(Pointer raw_postlist);
}

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