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Posted to commits@lucenenet.apache.org by sy...@apache.org on 2014/09/06 21:36:17 UTC

[06/51] [abbrv] [partial] Cleaning up and getting ready to development towards v4.8

http://git-wip-us.apache.org/repos/asf/lucenenet/blob/1da1cb5b/src/Lucene.Net.Codecs/Memory/DirectPostingsFormat.cs
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diff --git a/src/Lucene.Net.Codecs/Memory/DirectPostingsFormat.cs b/src/Lucene.Net.Codecs/Memory/DirectPostingsFormat.cs
new file mode 100644
index 0000000..5d90e98
--- /dev/null
+++ b/src/Lucene.Net.Codecs/Memory/DirectPostingsFormat.cs
@@ -0,0 +1,2302 @@
+package org.apache.lucene.codecs.memory;
+
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import java.io.IOException;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.Iterator;
+import java.util.Map;
+import java.util.TreeMap;
+
+import org.apache.lucene.codecs.FieldsConsumer;
+import org.apache.lucene.codecs.FieldsProducer;
+import org.apache.lucene.codecs.PostingsFormat;
+import org.apache.lucene.codecs.lucene41.Lucene41PostingsFormat; // javadocs
+import org.apache.lucene.index.DocsAndPositionsEnum;
+import org.apache.lucene.index.DocsEnum;
+import org.apache.lucene.index.FieldInfo.IndexOptions;
+import org.apache.lucene.index.FieldInfo;
+import org.apache.lucene.index.Fields;
+import org.apache.lucene.index.OrdTermState;
+import org.apache.lucene.index.SegmentReadState;
+import org.apache.lucene.index.SegmentWriteState;
+import org.apache.lucene.index.TermState;
+import org.apache.lucene.index.Terms;
+import org.apache.lucene.index.TermsEnum;
+import org.apache.lucene.store.IOContext;
+import org.apache.lucene.store.RAMOutputStream;
+import org.apache.lucene.util.ArrayUtil;
+import org.apache.lucene.util.Bits;
+import org.apache.lucene.util.BytesRef;
+import org.apache.lucene.util.RamUsageEstimator;
+import org.apache.lucene.util.automaton.CompiledAutomaton;
+import org.apache.lucene.util.automaton.RunAutomaton;
+import org.apache.lucene.util.automaton.Transition;
+
+// TODO: 
+//   - build depth-N prefix hash?
+//   - or: longer dense skip lists than just next byte?
+
+/** Wraps {@link Lucene41PostingsFormat} format for on-disk
+ *  storage, but then at read time loads and stores all
+ *  terms & postings directly in RAM as byte[], int[].
+ *
+ *  <p><b><font color=red>WARNING</font></b>: This is
+ *  exceptionally RAM intensive: it makes no effort to
+ *  compress the postings data, storing terms as separate
+ *  byte[] and postings as separate int[], but as a result it 
+ *  gives substantial increase in search performance.
+ *
+ *  <p>This postings format supports {@link TermsEnum#ord}
+ *  and {@link TermsEnum#seekExact(long)}.
+
+ *  <p>Because this holds all term bytes as a single
+ *  byte[], you cannot have more than 2.1GB worth of term
+ *  bytes in a single segment.
+ *
+ * @lucene.experimental */
+
+public final class DirectPostingsFormat extends PostingsFormat {
+
+  private final int minSkipCount;
+  private final int lowFreqCutoff;
+
+  private final static int DEFAULT_MIN_SKIP_COUNT = 8;
+  private final static int DEFAULT_LOW_FREQ_CUTOFF = 32;
+
+  //private static final bool DEBUG = true;
+
+  // TODO: allow passing/wrapping arbitrary postings format?
+
+  public DirectPostingsFormat() {
+    this(DEFAULT_MIN_SKIP_COUNT, DEFAULT_LOW_FREQ_CUTOFF);
+  }
+  
+  /** minSkipCount is how many terms in a row must have the
+   *  same prefix before we put a skip pointer down.  Terms
+   *  with docFreq <= lowFreqCutoff will use a single int[]
+   *  to hold all docs, freqs, position and offsets; terms
+   *  with higher docFreq will use separate arrays. */
+  public DirectPostingsFormat(int minSkipCount, int lowFreqCutoff) {
+    super("Direct");
+    this.minSkipCount = minSkipCount;
+    this.lowFreqCutoff = lowFreqCutoff;
+  }
+  
+  @Override
+  public FieldsConsumer fieldsConsumer(SegmentWriteState state)  {
+    return PostingsFormat.forName("Lucene41").fieldsConsumer(state);
+  }
+
+  @Override
+  public FieldsProducer fieldsProducer(SegmentReadState state)  {
+    FieldsProducer postings = PostingsFormat.forName("Lucene41").fieldsProducer(state);
+    if (state.context.context != IOContext.Context.MERGE) {
+      FieldsProducer loadedPostings;
+      try {
+        postings.checkIntegrity();
+        loadedPostings = new DirectFields(state, postings, minSkipCount, lowFreqCutoff);
+      } finally {
+        postings.close();
+      }
+      return loadedPostings;
+    } else {
+      // Don't load postings for merge:
+      return postings;
+    }
+  }
+
+  private static final class DirectFields extends FieldsProducer {
+    private final Map<String,DirectField> fields = new TreeMap<>();
+
+    public DirectFields(SegmentReadState state, Fields fields, int minSkipCount, int lowFreqCutoff)  {
+      for (String field : fields) {
+        this.fields.put(field, new DirectField(state, field, fields.terms(field), minSkipCount, lowFreqCutoff));
+      }
+    }
+
+    @Override
+    public Iterator<String> iterator() {
+      return Collections.unmodifiableSet(fields.keySet()).iterator();
+    }
+
+    @Override
+    public Terms terms(String field) {
+      return fields.get(field);
+    }
+
+    @Override
+    public int size() {
+      return fields.size();
+    }
+
+    @Override
+    public long getUniqueTermCount() {
+      long numTerms = 0;      
+      for(DirectField field : fields.values()) {
+        numTerms += field.terms.length;
+      }
+      return numTerms;
+    }
+
+    @Override
+    public void close() {
+    }
+
+    @Override
+    public long ramBytesUsed() {
+      long sizeInBytes = 0;
+      for(Map.Entry<String,DirectField> entry: fields.entrySet()) {
+        sizeInBytes += entry.getKey().length() * RamUsageEstimator.NUM_BYTES_CHAR;
+        sizeInBytes += entry.getValue().ramBytesUsed();
+      }
+      return sizeInBytes;
+    }
+
+    @Override
+    public void checkIntegrity()  {
+      // if we read entirely into ram, we already validated.
+      // otherwise returned the raw postings reader
+    }
+  }
+
+  private final static class DirectField extends Terms {
+
+    private static abstract class TermAndSkip {
+      public int[] skips;
+
+      /** Returns the approximate number of RAM bytes used */
+      public abstract long ramBytesUsed();
+    }
+
+    private static final class LowFreqTerm extends TermAndSkip {
+      public final int[] postings;
+      public final byte[] payloads;
+      public final int docFreq;
+      public final int totalTermFreq;
+
+      public LowFreqTerm(int[] postings, byte[] payloads, int docFreq, int totalTermFreq) {
+        this.postings = postings;
+        this.payloads = payloads;
+        this.docFreq = docFreq;
+        this.totalTermFreq = totalTermFreq;
+      }
+
+      @Override
+      public long ramBytesUsed() {
+        return ((postings!=null) ? RamUsageEstimator.sizeOf(postings) : 0) + 
+            ((payloads!=null) ? RamUsageEstimator.sizeOf(payloads) : 0);
+      }
+    }
+
+    // TODO: maybe specialize into prx/no-prx/no-frq cases?
+    private static final class HighFreqTerm extends TermAndSkip {
+      public final long totalTermFreq;
+      public final int[] docIDs;
+      public final int[] freqs;
+      public final int[][] positions;
+      public final byte[][][] payloads;
+
+      public HighFreqTerm(int[] docIDs, int[] freqs, int[][] positions, byte[][][] payloads, long totalTermFreq) {
+        this.docIDs = docIDs;
+        this.freqs = freqs;
+        this.positions = positions;
+        this.payloads = payloads;
+        this.totalTermFreq = totalTermFreq;
+      }
+
+      @Override
+      public long ramBytesUsed() {
+         long sizeInBytes = 0;
+         sizeInBytes += (docIDs!=null)? RamUsageEstimator.sizeOf(docIDs) : 0;
+         sizeInBytes += (freqs!=null)? RamUsageEstimator.sizeOf(freqs) : 0;
+         
+         if(positions != null) {
+           for(int[] position : positions) {
+             sizeInBytes += (position!=null) ? RamUsageEstimator.sizeOf(position) : 0;
+           }
+         }
+         
+         if (payloads != null) {
+           for(byte[][] payload : payloads) {
+             if(payload != null) {
+               for(byte[] pload : payload) {
+                 sizeInBytes += (pload!=null) ? RamUsageEstimator.sizeOf(pload) : 0; 
+               }
+             }
+           }
+         }
+         
+         return sizeInBytes;
+      }
+    }
+
+    private final byte[] termBytes;
+    private final int[] termOffsets;
+
+    private final int[] skips;
+    private final int[] skipOffsets;
+
+    private final TermAndSkip[] terms;
+    private final bool hasFreq;
+    private final bool hasPos;
+    private final bool hasOffsets;
+    private final bool hasPayloads;
+    private final long sumTotalTermFreq;
+    private final int docCount;
+    private final long sumDocFreq;
+    private int skipCount;
+
+    // TODO: maybe make a separate builder?  These are only
+    // used during load:
+    private int count;
+    private int[] sameCounts = new int[10];
+    private final int minSkipCount;
+
+    private final static class IntArrayWriter {
+      private int[] ints = new int[10];
+      private int upto;
+
+      public void add(int value) {
+        if (ints.length == upto) {
+          ints = ArrayUtil.grow(ints);
+        }
+        ints[upto++] = value;
+      }
+
+      public int[] get() {
+        final int[] arr = new int[upto];
+        System.arraycopy(ints, 0, arr, 0, upto);
+        upto = 0;
+        return arr;
+      }
+    }
+
+    public DirectField(SegmentReadState state, String field, Terms termsIn, int minSkipCount, int lowFreqCutoff)  {
+      final FieldInfo fieldInfo = state.fieldInfos.fieldInfo(field);
+
+      sumTotalTermFreq = termsIn.getSumTotalTermFreq();
+      sumDocFreq = termsIn.getSumDocFreq();
+      docCount = termsIn.getDocCount();
+
+      final int numTerms = (int) termsIn.size();
+      if (numTerms == -1) {
+        throw new IllegalArgumentException("codec does not provide Terms.size()");
+      }
+      terms = new TermAndSkip[numTerms];
+      termOffsets = new int[1+numTerms];
+      
+      byte[] termBytes = new byte[1024];
+
+      this.minSkipCount = minSkipCount;
+
+      hasFreq = fieldInfo.getIndexOptions().compareTo(IndexOptions.DOCS_ONLY) > 0;
+      hasPos = fieldInfo.getIndexOptions().compareTo(IndexOptions.DOCS_AND_FREQS) > 0;
+      hasOffsets = fieldInfo.getIndexOptions().compareTo(IndexOptions.DOCS_AND_FREQS_AND_POSITIONS) > 0;
+      hasPayloads = fieldInfo.hasPayloads();
+
+      BytesRef term;
+      DocsEnum docsEnum = null;
+      DocsAndPositionsEnum docsAndPositionsEnum = null;
+      final TermsEnum termsEnum = termsIn.iterator(null);
+      int termOffset = 0;
+
+      final IntArrayWriter scratch = new IntArrayWriter();
+
+      // Used for payloads, if any:
+      final RAMOutputStream ros = new RAMOutputStream();
+
+      // if (DEBUG) {
+      //   System.out.println("\nLOAD terms seg=" + state.segmentInfo.name + " field=" + field + " hasOffsets=" + hasOffsets + " hasFreq=" + hasFreq + " hasPos=" + hasPos + " hasPayloads=" + hasPayloads);
+      // }
+
+      while ((term = termsEnum.next()) != null) {
+        final int docFreq = termsEnum.docFreq();
+        final long totalTermFreq = termsEnum.totalTermFreq();
+
+        // if (DEBUG) {
+        //   System.out.println("  term=" + term.utf8ToString());
+        // }
+
+        termOffsets[count] = termOffset;
+
+        if (termBytes.length < (termOffset + term.length)) {
+          termBytes = ArrayUtil.grow(termBytes, termOffset + term.length);
+        }
+        System.arraycopy(term.bytes, term.offset, termBytes, termOffset, term.length);
+        termOffset += term.length;
+        termOffsets[count+1] = termOffset;
+
+        if (hasPos) {
+          docsAndPositionsEnum = termsEnum.docsAndPositions(null, docsAndPositionsEnum);
+        } else {
+          docsEnum = termsEnum.docs(null, docsEnum);
+        }
+
+        final TermAndSkip ent;
+
+        final DocsEnum docsEnum2;
+        if (hasPos) {
+          docsEnum2 = docsAndPositionsEnum;
+        } else {
+          docsEnum2 = docsEnum;
+        }
+
+        int docID;
+
+        if (docFreq <= lowFreqCutoff) {
+
+          ros.reset();
+
+          // Pack postings for low-freq terms into a single int[]:
+          while ((docID = docsEnum2.nextDoc()) != DocsEnum.NO_MORE_DOCS) {
+            scratch.add(docID);
+            if (hasFreq) {
+              final int freq = docsEnum2.freq();
+              scratch.add(freq);
+              if (hasPos) {
+                for(int pos=0;pos<freq;pos++) {
+                  scratch.add(docsAndPositionsEnum.nextPosition());
+                  if (hasOffsets) {
+                    scratch.add(docsAndPositionsEnum.startOffset());
+                    scratch.add(docsAndPositionsEnum.endOffset());
+                  }
+                  if (hasPayloads) {
+                    final BytesRef payload = docsAndPositionsEnum.getPayload();
+                    if (payload != null) {
+                      scratch.add(payload.length);
+                      ros.writeBytes(payload.bytes, payload.offset, payload.length);
+                    } else {
+                      scratch.add(0);
+                    }
+                  }
+                }
+              }
+            }
+          }
+
+          final byte[] payloads;
+          if (hasPayloads) {
+            ros.flush();
+            payloads = new byte[(int) ros.length()];
+            ros.writeTo(payloads, 0);
+          } else {
+            payloads = null;
+          }
+
+          final int[] postings = scratch.get();
+        
+          ent = new LowFreqTerm(postings, payloads, docFreq, (int) totalTermFreq);
+        } else {
+          final int[] docs = new int[docFreq];
+          final int[] freqs;
+          final int[][] positions;
+          final byte[][][] payloads;
+          if (hasFreq) {
+            freqs = new int[docFreq];
+            if (hasPos) {
+              positions = new int[docFreq][];
+              if (hasPayloads) {
+                payloads = new byte[docFreq][][];
+              } else {
+                payloads = null;
+              }
+            } else {
+              positions = null;
+              payloads = null;
+            }
+          } else {
+            freqs = null;
+            positions = null;
+            payloads = null;
+          }
+
+          // Use separate int[] for the postings for high-freq
+          // terms:
+          int upto = 0;
+          while ((docID = docsEnum2.nextDoc()) != DocsEnum.NO_MORE_DOCS) {
+            docs[upto] = docID;
+            if (hasFreq) {
+              final int freq = docsEnum2.freq();
+              freqs[upto] = freq;
+              if (hasPos) {
+                final int mult;
+                if (hasOffsets) {
+                  mult = 3;
+                } else {
+                  mult = 1;
+                }
+                if (hasPayloads) {
+                  payloads[upto] = new byte[freq][];
+                }
+                positions[upto] = new int[mult*freq];
+                int posUpto = 0;
+                for(int pos=0;pos<freq;pos++) {
+                  positions[upto][posUpto] = docsAndPositionsEnum.nextPosition();
+                  if (hasPayloads) {
+                    BytesRef payload = docsAndPositionsEnum.getPayload();
+                    if (payload != null) {
+                      byte[] payloadBytes = new byte[payload.length];
+                      System.arraycopy(payload.bytes, payload.offset, payloadBytes, 0, payload.length);
+                      payloads[upto][pos] = payloadBytes;
+                    }
+                  }
+                  posUpto++;
+                  if (hasOffsets) {
+                    positions[upto][posUpto++] = docsAndPositionsEnum.startOffset();
+                    positions[upto][posUpto++] = docsAndPositionsEnum.endOffset();
+                  }
+                }
+              }
+            }
+
+            upto++;
+          }
+          Debug.Assert( upto == docFreq;
+          ent = new HighFreqTerm(docs, freqs, positions, payloads, totalTermFreq);
+        }
+
+        terms[count] = ent;
+        setSkips(count, termBytes);
+        count++;
+      }
+
+      // End sentinel:
+      termOffsets[count] = termOffset;
+
+      finishSkips();
+
+      //System.out.println(skipCount + " skips: " + field);
+
+      this.termBytes = new byte[termOffset];
+      System.arraycopy(termBytes, 0, this.termBytes, 0, termOffset);
+
+      // Pack skips:
+      this.skips = new int[skipCount];
+      this.skipOffsets = new int[1+numTerms];
+
+      int skipOffset = 0;
+      for(int i=0;i<numTerms;i++) {
+        final int[] termSkips = terms[i].skips;
+        skipOffsets[i] = skipOffset;
+        if (termSkips != null) {
+          System.arraycopy(termSkips, 0, skips, skipOffset, termSkips.length);
+          skipOffset += termSkips.length;
+          terms[i].skips = null;
+        }
+      }
+      this.skipOffsets[numTerms] = skipOffset;
+      Debug.Assert( skipOffset == skipCount;
+    }
+
+    /** Returns approximate RAM bytes used */
+    public long ramBytesUsed() {
+      long sizeInBytes = 0;
+      sizeInBytes += ((termBytes!=null) ? RamUsageEstimator.sizeOf(termBytes) : 0);
+      sizeInBytes += ((termOffsets!=null) ? RamUsageEstimator.sizeOf(termOffsets) : 0);
+      sizeInBytes += ((skips!=null) ? RamUsageEstimator.sizeOf(skips) : 0);
+      sizeInBytes += ((skipOffsets!=null) ? RamUsageEstimator.sizeOf(skipOffsets) : 0);
+      sizeInBytes += ((sameCounts!=null) ? RamUsageEstimator.sizeOf(sameCounts) : 0);
+      
+      if(terms!=null) {
+        for(TermAndSkip termAndSkip : terms) {
+          sizeInBytes += (termAndSkip!=null) ? termAndSkip.ramBytesUsed() : 0;
+        }
+      }
+      
+      return sizeInBytes;
+    }
+
+    // Compares in unicode (UTF8) order:
+    int compare(int ord, BytesRef other) {
+      final byte[] otherBytes = other.bytes;
+
+      int upto = termOffsets[ord];
+      final int termLen = termOffsets[1+ord] - upto;
+      int otherUpto = other.offset;
+      
+      final int stop = upto + Math.min(termLen, other.length);
+      while (upto < stop) {
+        int diff = (termBytes[upto++] & 0xFF) - (otherBytes[otherUpto++] & 0xFF);
+        if (diff != 0) {
+          return diff;
+        }
+      }
+    
+      // One is a prefix of the other, or, they are equal:
+      return termLen - other.length;
+    }
+
+    private void setSkips(int termOrd, byte[] termBytes) {
+
+      final int termLength = termOffsets[termOrd+1] - termOffsets[termOrd];
+
+      if (sameCounts.length < termLength) {
+        sameCounts = ArrayUtil.grow(sameCounts, termLength);
+      }
+
+      // Update skip pointers:
+      if (termOrd > 0) {
+        final int lastTermLength = termOffsets[termOrd] - termOffsets[termOrd-1];
+        final int limit = Math.min(termLength, lastTermLength);
+
+        int lastTermOffset = termOffsets[termOrd-1];
+        int termOffset = termOffsets[termOrd];
+
+        int i = 0;
+        for(;i<limit;i++) {
+          if (termBytes[lastTermOffset++] == termBytes[termOffset++]) {
+            sameCounts[i]++;
+          } else {
+            for(;i<limit;i++) {
+              if (sameCounts[i] >= minSkipCount) {
+                // Go back and add a skip pointer:
+                saveSkip(termOrd, sameCounts[i]);
+              }
+              sameCounts[i] = 1;
+            }
+            break;
+          }
+        }
+
+        for(;i<lastTermLength;i++) {
+          if (sameCounts[i] >= minSkipCount) {
+            // Go back and add a skip pointer:
+            saveSkip(termOrd, sameCounts[i]);
+          }
+          sameCounts[i] = 0;
+        }
+        for(int j=limit;j<termLength;j++) {
+          sameCounts[j] = 1;
+        }
+      } else {
+        for(int i=0;i<termLength;i++) {
+          sameCounts[i]++;
+        }
+      }
+    }
+
+    private void finishSkips() {
+      Debug.Assert( count == terms.length;
+      int lastTermOffset = termOffsets[count-1];
+      int lastTermLength = termOffsets[count] - lastTermOffset;
+
+      for(int i=0;i<lastTermLength;i++) {
+        if (sameCounts[i] >= minSkipCount) {
+          // Go back and add a skip pointer:
+          saveSkip(count, sameCounts[i]);
+        }
+      }
+
+      // Reverse the skip pointers so they are "nested":
+      for(int termID=0;termID<terms.length;termID++) {
+        TermAndSkip term = terms[termID];
+        if (term.skips != null && term.skips.length > 1) {
+          for(int pos=0;pos<term.skips.length/2;pos++) {
+            final int otherPos = term.skips.length-pos-1;
+
+            final int temp = term.skips[pos];
+            term.skips[pos] = term.skips[otherPos];
+            term.skips[otherPos] = temp;
+          }
+        }
+      }
+    }
+
+    private void saveSkip(int ord, int backCount) {
+      final TermAndSkip term = terms[ord - backCount];
+      skipCount++;
+      if (term.skips == null) {
+        term.skips = new int[] {ord};
+      } else {
+        // Normally we'd grow at a slight exponential... but
+        // given that the skips themselves are already log(N)
+        // we can grow by only 1 and still have amortized
+        // linear time:
+        final int[] newSkips = new int[term.skips.length+1];
+        System.arraycopy(term.skips, 0, newSkips, 0, term.skips.length);
+        term.skips = newSkips;
+        term.skips[term.skips.length-1] = ord;
+      }
+    }
+
+    @Override
+    public TermsEnum iterator(TermsEnum reuse) {
+      DirectTermsEnum termsEnum;
+      if (reuse != null && reuse instanceof DirectTermsEnum) {
+        termsEnum = (DirectTermsEnum) reuse;
+        if (!termsEnum.canReuse(terms)) {
+          termsEnum = new DirectTermsEnum();
+        }
+      } else {
+        termsEnum = new DirectTermsEnum();
+      }
+      termsEnum.reset();
+      return termsEnum;
+    }
+
+    @Override
+    public TermsEnum intersect(CompiledAutomaton compiled, final BytesRef startTerm) {
+      return new DirectIntersectTermsEnum(compiled, startTerm);
+    }
+
+    @Override
+    public long size() {
+      return terms.length;
+    }
+
+    @Override
+    public long getSumTotalTermFreq() {
+      return sumTotalTermFreq;
+    }
+
+    @Override
+    public long getSumDocFreq() {
+      return sumDocFreq;
+    }
+
+    @Override
+    public int getDocCount() {
+      return docCount;
+    }
+
+    @Override
+    public Comparator<BytesRef> getComparator() {
+      return BytesRef.getUTF8SortedAsUnicodeComparator();
+    }
+
+    @Override
+    public bool hasFreqs() {
+      return hasFreq;
+    }
+
+    @Override
+    public bool hasOffsets() {
+      return hasOffsets;
+    }
+
+    @Override
+    public bool hasPositions() {
+      return hasPos;
+    }
+    
+    @Override
+    public bool hasPayloads() {
+      return hasPayloads;
+    }
+
+    private final class DirectTermsEnum extends TermsEnum {
+
+      private final BytesRef scratch = new BytesRef();
+      private int termOrd;
+
+      bool canReuse(TermAndSkip[] other) {
+        return DirectField.this.terms == other;
+      }
+
+      private BytesRef setTerm() {
+        scratch.bytes = termBytes;
+        scratch.offset = termOffsets[termOrd];
+        scratch.length = termOffsets[termOrd+1] - termOffsets[termOrd];
+        return scratch;
+      }
+
+      public void reset() {
+        termOrd = -1;
+      }
+
+      @Override
+      public Comparator<BytesRef> getComparator() {
+        return BytesRef.getUTF8SortedAsUnicodeComparator();
+      }
+
+      @Override
+      public BytesRef next() {
+        termOrd++;
+        if (termOrd < terms.length) {
+          return setTerm();
+        } else {
+          return null;
+        }
+      }
+
+      @Override
+      public TermState termState() {
+        OrdTermState state = new OrdTermState();
+        state.ord = termOrd;
+        return state;
+      }
+
+      // If non-negative, exact match; else, -ord-1, where ord
+      // is where you would insert the term.
+      private int findTerm(BytesRef term) {
+
+        // Just do binary search: should be (constant factor)
+        // faster than using the skip list:
+        int low = 0;
+        int high = terms.length-1;
+
+        while (low <= high) {
+          int mid = (low + high) >>> 1;
+          int cmp = compare(mid, term);
+          if (cmp < 0) {
+            low = mid + 1;
+          } else if (cmp > 0) {
+            high = mid - 1;
+          } else {
+            return mid; // key found
+          }
+        }
+
+        return -(low + 1);  // key not found.
+      }
+
+      @Override
+      public SeekStatus seekCeil(BytesRef term) {
+        // TODO: we should use the skip pointers; should be
+        // faster than bin search; we should also hold
+        // & reuse current state so seeking forwards is
+        // faster
+        final int ord = findTerm(term);
+        // if (DEBUG) {
+        //   System.out.println("  find term=" + term.utf8ToString() + " ord=" + ord);
+        // }
+        if (ord >= 0) {
+          termOrd = ord;
+          setTerm();
+          return SeekStatus.FOUND;
+        } else if (ord == -terms.length-1) {
+          return SeekStatus.END;
+        } else {
+          termOrd = -ord - 1;
+          setTerm();
+          return SeekStatus.NOT_FOUND;
+        }
+      }
+
+      @Override
+      public bool seekExact(BytesRef term) {
+        // TODO: we should use the skip pointers; should be
+        // faster than bin search; we should also hold
+        // & reuse current state so seeking forwards is
+        // faster
+        final int ord = findTerm(term);
+        if (ord >= 0) {
+          termOrd = ord;
+          setTerm();
+          return true;
+        } else {
+          return false;
+        }
+      }
+
+      @Override
+      public void seekExact(long ord) {
+        termOrd = (int) ord;
+        setTerm();
+      }
+
+      @Override
+      public void seekExact(BytesRef term, TermState state)  {
+        termOrd = (int) ((OrdTermState) state).ord;
+        setTerm();
+        Debug.Assert( term.equals(scratch);
+      }
+
+      @Override
+      public BytesRef term() {
+        return scratch;
+      }
+
+      @Override
+      public long ord() {
+        return termOrd;
+      }
+
+      @Override
+      public int docFreq() {
+        if (terms[termOrd] instanceof LowFreqTerm) {
+          return ((LowFreqTerm) terms[termOrd]).docFreq;
+        } else {
+          return ((HighFreqTerm) terms[termOrd]).docIDs.length;
+        }
+      }
+
+      @Override
+      public long totalTermFreq() {
+        if (terms[termOrd] instanceof LowFreqTerm) {
+          return ((LowFreqTerm) terms[termOrd]).totalTermFreq;
+        } else {
+          return ((HighFreqTerm) terms[termOrd]).totalTermFreq;
+        }
+      }
+
+      @Override
+      public DocsEnum docs(Bits liveDocs, DocsEnum reuse, int flags) {
+        // TODO: implement reuse, something like Pulsing:
+        // it's hairy!
+
+        if (terms[termOrd] instanceof LowFreqTerm) {
+          final int[] postings = ((LowFreqTerm) terms[termOrd]).postings;
+          if (hasFreq) {
+            if (hasPos) {
+              int posLen;
+              if (hasOffsets) {
+                posLen = 3;
+              } else {
+                posLen = 1;
+              }
+              if (hasPayloads) {
+                posLen++;
+              }
+              LowFreqDocsEnum docsEnum;
+              if (reuse instanceof LowFreqDocsEnum) {
+                docsEnum = (LowFreqDocsEnum) reuse;
+                if (!docsEnum.canReuse(liveDocs, posLen)) {
+                  docsEnum = new LowFreqDocsEnum(liveDocs, posLen);
+                }
+              } else {
+                docsEnum = new LowFreqDocsEnum(liveDocs, posLen);
+              }
+
+              return docsEnum.reset(postings);
+            } else {
+              LowFreqDocsEnumNoPos docsEnum;
+              if (reuse instanceof LowFreqDocsEnumNoPos) {
+                docsEnum = (LowFreqDocsEnumNoPos) reuse;
+                if (!docsEnum.canReuse(liveDocs)) {
+                  docsEnum = new LowFreqDocsEnumNoPos(liveDocs);
+                }
+              } else {
+                docsEnum = new LowFreqDocsEnumNoPos(liveDocs);
+              }
+
+              return docsEnum.reset(postings);
+            }
+          } else {
+            LowFreqDocsEnumNoTF docsEnum;
+            if (reuse instanceof LowFreqDocsEnumNoTF) {
+              docsEnum = (LowFreqDocsEnumNoTF) reuse;
+              if (!docsEnum.canReuse(liveDocs)) {
+                docsEnum = new LowFreqDocsEnumNoTF(liveDocs);
+              }
+            } else {
+              docsEnum = new LowFreqDocsEnumNoTF(liveDocs);
+            }
+
+            return docsEnum.reset(postings);
+          }
+        } else {
+          final HighFreqTerm term = (HighFreqTerm) terms[termOrd];
+
+          HighFreqDocsEnum docsEnum;
+          if (reuse instanceof HighFreqDocsEnum) {
+            docsEnum = (HighFreqDocsEnum) reuse;
+            if (!docsEnum.canReuse(liveDocs)) {
+              docsEnum = new HighFreqDocsEnum(liveDocs);
+            }
+          } else {
+            docsEnum = new HighFreqDocsEnum(liveDocs);
+          }
+
+          //System.out.println("  DE for term=" + new BytesRef(terms[termOrd].term).utf8ToString() + ": " + term.docIDs.length + " docs");
+          return docsEnum.reset(term.docIDs, term.freqs);
+        }
+      }
+
+      @Override
+      public DocsAndPositionsEnum docsAndPositions(Bits liveDocs, DocsAndPositionsEnum reuse, int flags) {
+        if (!hasPos) {
+          return null;
+        }
+
+        // TODO: implement reuse, something like Pulsing:
+        // it's hairy!
+
+        if (terms[termOrd] instanceof LowFreqTerm) {
+          final LowFreqTerm term = ((LowFreqTerm) terms[termOrd]);
+          final int[] postings = term.postings;
+          final byte[] payloads = term.payloads;
+          return new LowFreqDocsAndPositionsEnum(liveDocs, hasOffsets, hasPayloads).reset(postings, payloads);
+        } else {
+          final HighFreqTerm term = (HighFreqTerm) terms[termOrd];
+          return new HighFreqDocsAndPositionsEnum(liveDocs, hasOffsets).reset(term.docIDs, term.freqs, term.positions, term.payloads);
+        }
+      }
+    }
+
+    private final class DirectIntersectTermsEnum extends TermsEnum {
+      private final RunAutomaton runAutomaton;
+      private final CompiledAutomaton compiledAutomaton;
+      private int termOrd;
+      private final BytesRef scratch = new BytesRef();
+
+      private final class State {
+        int changeOrd;
+        int state;
+        Transition[] transitions;
+        int transitionUpto;
+        int transitionMax;
+        int transitionMin;
+      }
+
+      private State[] states;
+      private int stateUpto;
+
+      public DirectIntersectTermsEnum(CompiledAutomaton compiled, BytesRef startTerm) {
+        runAutomaton = compiled.runAutomaton;
+        compiledAutomaton = compiled;
+        termOrd = -1;
+        states = new State[1];
+        states[0] = new State();
+        states[0].changeOrd = terms.length;
+        states[0].state = runAutomaton.getInitialState();
+        states[0].transitions = compiledAutomaton.sortedTransitions[states[0].state];
+        states[0].transitionUpto = -1;
+        states[0].transitionMax = -1;
+
+        //System.out.println("IE.init startTerm=" + startTerm);
+
+        if (startTerm != null) {
+          int skipUpto = 0;
+          if (startTerm.length == 0) {
+            if (terms.length > 0 && termOffsets[1] == 0) {
+              termOrd = 0;
+            }
+          } else {
+            termOrd++;
+
+            nextLabel:
+            for(int i=0;i<startTerm.length;i++) {
+              final int label = startTerm.bytes[startTerm.offset+i] & 0xFF;
+
+              while (label > states[i].transitionMax) {
+                states[i].transitionUpto++;
+                Debug.Assert( states[i].transitionUpto < states[i].transitions.length;
+                states[i].transitionMin = states[i].transitions[states[i].transitionUpto].getMin();
+                states[i].transitionMax = states[i].transitions[states[i].transitionUpto].getMax();
+                Debug.Assert( states[i].transitionMin >= 0;
+                Debug.Assert( states[i].transitionMin <= 255;
+                Debug.Assert( states[i].transitionMax >= 0;
+                Debug.Assert( states[i].transitionMax <= 255;
+              }
+
+              // Skip forwards until we find a term matching
+              // the label at this position:
+              while (termOrd < terms.length) {
+                final int skipOffset = skipOffsets[termOrd];
+                final int numSkips = skipOffsets[termOrd+1] - skipOffset;
+                final int termOffset = termOffsets[termOrd];
+                final int termLength = termOffsets[1+termOrd] - termOffset;
+
+                // if (DEBUG) {
+                //   System.out.println("  check termOrd=" + termOrd + " term=" + new BytesRef(termBytes, termOffset, termLength).utf8ToString() + " skips=" + Arrays.toString(skips) + " i=" + i);
+                // }
+
+                if (termOrd == states[stateUpto].changeOrd) {
+                  // if (DEBUG) {
+                  //   System.out.println("  end push return");
+                  // }
+                  stateUpto--;
+                  termOrd--;
+                  return;
+                }
+
+                if (termLength == i) {
+                  termOrd++;
+                  skipUpto = 0;
+                  // if (DEBUG) {
+                  //   System.out.println("    term too short; next term");
+                  // }
+                } else if (label < (termBytes[termOffset+i] & 0xFF)) {
+                  termOrd--;
+                  // if (DEBUG) {
+                  //   System.out.println("  no match; already beyond; return termOrd=" + termOrd);
+                  // }
+                  stateUpto -= skipUpto;
+                  Debug.Assert( stateUpto >= 0;
+                  return;
+                } else if (label == (termBytes[termOffset+i] & 0xFF)) {
+                  // if (DEBUG) {
+                  //   System.out.println("    label[" + i + "] matches");
+                  // }
+                  if (skipUpto < numSkips) {
+                    grow();
+
+                    final int nextState = runAutomaton.step(states[stateUpto].state, label);
+
+                    // Automaton is required to accept startTerm:
+                    Debug.Assert( nextState != -1;
+
+                    stateUpto++;
+                    states[stateUpto].changeOrd = skips[skipOffset + skipUpto++];
+                    states[stateUpto].state = nextState;
+                    states[stateUpto].transitions = compiledAutomaton.sortedTransitions[nextState];
+                    states[stateUpto].transitionUpto = -1;
+                    states[stateUpto].transitionMax = -1;
+                    //System.out.println("  push " + states[stateUpto].transitions.length + " trans");
+
+                    // if (DEBUG) {
+                    //   System.out.println("    push skip; changeOrd=" + states[stateUpto].changeOrd);
+                    // }
+
+                    // Match next label at this same term:
+                    continue nextLabel;
+                  } else {
+                    // if (DEBUG) {
+                    //   System.out.println("    linear scan");
+                    // }
+                    // Index exhausted: just scan now (the
+                    // number of scans required will be less
+                    // than the minSkipCount):
+                    final int startTermOrd = termOrd;
+                    while (termOrd < terms.length && compare(termOrd, startTerm) <= 0) {
+                      Debug.Assert( termOrd == startTermOrd || skipOffsets[termOrd] == skipOffsets[termOrd+1];
+                      termOrd++;
+                    }
+                    Debug.Assert( termOrd - startTermOrd < minSkipCount;
+                    termOrd--;
+                    stateUpto -= skipUpto;
+                    // if (DEBUG) {
+                    //   System.out.println("  end termOrd=" + termOrd);
+                    // }
+                    return;
+                  }
+                } else {
+                  if (skipUpto < numSkips) {
+                    termOrd = skips[skipOffset + skipUpto];
+                    // if (DEBUG) {
+                    //   System.out.println("  no match; skip to termOrd=" + termOrd);
+                    // }
+                  } else {
+                    // if (DEBUG) {
+                    //   System.out.println("  no match; next term");
+                    // }
+                    termOrd++;
+                  }
+                  skipUpto = 0;
+                }
+              }
+
+              // startTerm is >= last term so enum will not
+              // return any terms:
+              termOrd--;
+              // if (DEBUG) {
+              //   System.out.println("  beyond end; no terms will match");
+              // }
+              return;
+            }
+          }
+
+          final int termOffset = termOffsets[termOrd];
+          final int termLen = termOffsets[1+termOrd] - termOffset;
+
+          if (termOrd >= 0 && !startTerm.equals(new BytesRef(termBytes, termOffset, termLen))) {
+            stateUpto -= skipUpto;
+            termOrd--;
+          }
+          // if (DEBUG) {
+          //   System.out.println("  loop end; return termOrd=" + termOrd + " stateUpto=" + stateUpto);
+          // }
+        }
+      }
+
+      @Override
+      public Comparator<BytesRef> getComparator() {
+        return BytesRef.getUTF8SortedAsUnicodeComparator();
+      }
+
+      private void grow() {
+        if (states.length == 1+stateUpto) {
+          final State[] newStates = new State[states.length+1];
+          System.arraycopy(states, 0, newStates, 0, states.length);
+          newStates[states.length] = new State();
+          states = newStates;
+        }
+      }
+
+      @Override
+      public BytesRef next() {
+        // if (DEBUG) {
+        //   System.out.println("\nIE.next");
+        // }
+
+        termOrd++;
+        int skipUpto = 0;
+
+        if (termOrd == 0 && termOffsets[1] == 0) {
+          // Special-case empty string:
+          Debug.Assert( stateUpto == 0;
+          // if (DEBUG) {
+          //   System.out.println("  visit empty string");
+          // }
+          if (runAutomaton.isAccept(states[0].state)) {
+            scratch.bytes = termBytes;
+            scratch.offset = 0;
+            scratch.length = 0;
+            return scratch;
+          }
+          termOrd++;
+        }
+
+        nextTerm:
+
+        while (true) {
+          // if (DEBUG) {
+          //   System.out.println("  cycle termOrd=" + termOrd + " stateUpto=" + stateUpto + " skipUpto=" + skipUpto);
+          // }
+          if (termOrd == terms.length) {
+            // if (DEBUG) {
+            //   System.out.println("  return END");
+            // }
+            return null;
+          }
+
+          final State state = states[stateUpto];
+          if (termOrd == state.changeOrd) {
+            // Pop:
+            // if (DEBUG) {
+            //   System.out.println("  pop stateUpto=" + stateUpto);
+            // }
+            stateUpto--;
+            /*
+            if (DEBUG) {
+              try {
+                //System.out.println("    prefix pop " + new BytesRef(terms[termOrd].term, 0, Math.min(stateUpto, terms[termOrd].term.length)).utf8ToString());
+                System.out.println("    prefix pop " + new BytesRef(terms[termOrd].term, 0, Math.min(stateUpto, terms[termOrd].term.length)));
+              } catch (ArrayIndexOutOfBoundsException aioobe) {
+                System.out.println("    prefix pop " + new BytesRef(terms[termOrd].term, 0, Math.min(stateUpto, terms[termOrd].term.length)));
+              }
+            }
+            */
+
+            continue;
+          }
+
+          final int termOffset = termOffsets[termOrd];
+          final int termLength = termOffsets[termOrd+1] - termOffset;
+          final int skipOffset = skipOffsets[termOrd];
+          final int numSkips = skipOffsets[termOrd+1] - skipOffset;
+
+          // if (DEBUG) {
+          //   System.out.println("  term=" + new BytesRef(termBytes, termOffset, termLength).utf8ToString() + " skips=" + Arrays.toString(skips));
+          // }
+        
+          Debug.Assert( termOrd < state.changeOrd;
+
+          Debug.Assert( stateUpto <= termLength: "term.length=" + termLength + "; stateUpto=" + stateUpto;
+          final int label = termBytes[termOffset+stateUpto] & 0xFF;
+
+          while (label > state.transitionMax) {
+            //System.out.println("  label=" + label + " vs max=" + state.transitionMax + " transUpto=" + state.transitionUpto + " vs " + state.transitions.length);
+            state.transitionUpto++;
+            if (state.transitionUpto == state.transitions.length) {
+              // We've exhausted transitions leaving this
+              // state; force pop+next/skip now:
+              //System.out.println("forcepop: stateUpto=" + stateUpto);
+              if (stateUpto == 0) {
+                termOrd = terms.length;
+                return null;
+              } else {
+                Debug.Assert( state.changeOrd > termOrd;
+                // if (DEBUG) {
+                //   System.out.println("  jumpend " + (state.changeOrd - termOrd));
+                // }
+                //System.out.println("  jump to termOrd=" + states[stateUpto].changeOrd + " vs " + termOrd);
+                termOrd = states[stateUpto].changeOrd;
+                skipUpto = 0;
+                stateUpto--;
+              }
+              continue nextTerm;
+            }
+            Debug.Assert( state.transitionUpto < state.transitions.length: " state.transitionUpto=" + state.transitionUpto + " vs " + state.transitions.length;
+            state.transitionMin = state.transitions[state.transitionUpto].getMin();
+            state.transitionMax = state.transitions[state.transitionUpto].getMax();
+            Debug.Assert( state.transitionMin >= 0;
+            Debug.Assert( state.transitionMin <= 255;
+            Debug.Assert( state.transitionMax >= 0;
+            Debug.Assert( state.transitionMax <= 255;
+          }
+
+          /*
+          if (DEBUG) {
+            System.out.println("    check ord=" + termOrd + " term[" + stateUpto + "]=" + (char) label + "(" + label + ") term=" + new BytesRef(terms[termOrd].term).utf8ToString() + " trans " +
+                               (char) state.transitionMin + "(" + state.transitionMin + ")" + "-" + (char) state.transitionMax + "(" + state.transitionMax + ") nextChange=+" + (state.changeOrd - termOrd) + " skips=" + (skips == null ? "null" : Arrays.toString(skips)));
+            System.out.println("    check ord=" + termOrd + " term[" + stateUpto + "]=" + Integer.toHexString(label) + "(" + label + ") term=" + new BytesRef(termBytes, termOffset, termLength) + " trans " +
+                               Integer.toHexString(state.transitionMin) + "(" + state.transitionMin + ")" + "-" + Integer.toHexString(state.transitionMax) + "(" + state.transitionMax + ") nextChange=+" + (state.changeOrd - termOrd) + " skips=" + (skips == null ? "null" : Arrays.toString(skips)));
+          }
+          */
+
+          final int targetLabel = state.transitionMin;
+
+          if ((termBytes[termOffset+stateUpto] & 0xFF) < targetLabel) {
+            // if (DEBUG) {
+            //   System.out.println("    do bin search");
+            // }
+            //int startTermOrd = termOrd;
+            int low = termOrd+1;
+            int high = state.changeOrd-1;
+            while (true) {
+              if (low > high) {
+                // Label not found
+                termOrd = low;
+                // if (DEBUG) {
+                //   System.out.println("      advanced by " + (termOrd - startTermOrd));
+                // }
+                //System.out.println("  jump " + (termOrd - startTermOrd));
+                skipUpto = 0;
+                continue nextTerm;
+              }
+              int mid = (low + high) >>> 1;
+              int cmp = (termBytes[termOffsets[mid] + stateUpto] & 0xFF) - targetLabel;
+              // if (DEBUG) {
+              //   System.out.println("      bin: check label=" + (char) (termBytes[termOffsets[low] + stateUpto] & 0xFF) + " ord=" + mid);
+              // }
+              if (cmp < 0) {
+                low = mid+1;
+              } else if (cmp > 0) {
+                high = mid - 1;
+              } else {
+                // Label found; walk backwards to first
+                // occurrence:
+                while (mid > termOrd && (termBytes[termOffsets[mid-1] + stateUpto] & 0xFF) == targetLabel) {
+                  mid--;
+                }
+                termOrd = mid;
+                // if (DEBUG) {
+                //   System.out.println("      advanced by " + (termOrd - startTermOrd));
+                // }
+                //System.out.println("  jump " + (termOrd - startTermOrd));
+                skipUpto = 0;
+                continue nextTerm;
+              }
+            }
+          }
+
+          int nextState = runAutomaton.step(states[stateUpto].state, label);
+
+          if (nextState == -1) {
+            // Skip
+            // if (DEBUG) {
+            //   System.out.println("  automaton doesn't accept; skip");
+            // }
+            if (skipUpto < numSkips) {
+              // if (DEBUG) {
+              //   System.out.println("  jump " + (skips[skipOffset+skipUpto]-1 - termOrd));
+              // }
+              termOrd = skips[skipOffset+skipUpto];
+            } else {
+              termOrd++;
+            }
+            skipUpto = 0;
+          } else if (skipUpto < numSkips) {
+            // Push:
+            // if (DEBUG) {
+            //   System.out.println("  push");
+            // }
+            /*
+            if (DEBUG) {
+              try {
+                //System.out.println("    prefix push " + new BytesRef(term, 0, stateUpto+1).utf8ToString());
+                System.out.println("    prefix push " + new BytesRef(term, 0, stateUpto+1));
+              } catch (ArrayIndexOutOfBoundsException aioobe) {
+                System.out.println("    prefix push " + new BytesRef(term, 0, stateUpto+1));
+              }
+            }
+            */
+
+            grow();
+            stateUpto++;
+            states[stateUpto].state = nextState;
+            states[stateUpto].changeOrd = skips[skipOffset + skipUpto++];
+            states[stateUpto].transitions = compiledAutomaton.sortedTransitions[nextState];
+            states[stateUpto].transitionUpto = -1;
+            states[stateUpto].transitionMax = -1;
+            
+            if (stateUpto == termLength) {
+              // if (DEBUG) {
+              //   System.out.println("  term ends after push");
+              // }
+              if (runAutomaton.isAccept(nextState)) {
+                // if (DEBUG) {
+                //   System.out.println("  automaton accepts: return");
+                // }
+                scratch.bytes = termBytes;
+                scratch.offset = termOffsets[termOrd];
+                scratch.length = termOffsets[1+termOrd] - scratch.offset;
+                // if (DEBUG) {
+                //   System.out.println("  ret " + scratch.utf8ToString());
+                // }
+                return scratch;
+              } else {
+                // if (DEBUG) {
+                //   System.out.println("  automaton rejects: nextTerm");
+                // }
+                termOrd++;
+                skipUpto = 0;
+              }
+            }
+          } else {
+            // Run the non-indexed tail of this term:
+
+            // TODO: add Debug.Assert( that we don't inc too many times
+
+            if (compiledAutomaton.commonSuffixRef != null) {
+              //System.out.println("suffix " + compiledAutomaton.commonSuffixRef.utf8ToString());
+              Debug.Assert( compiledAutomaton.commonSuffixRef.offset == 0;
+              if (termLength < compiledAutomaton.commonSuffixRef.length) {
+                termOrd++;
+                skipUpto = 0;
+                continue nextTerm;
+              }
+              int offset = termOffset + termLength - compiledAutomaton.commonSuffixRef.length;
+              for(int suffix=0;suffix<compiledAutomaton.commonSuffixRef.length;suffix++) {
+                if (termBytes[offset + suffix] != compiledAutomaton.commonSuffixRef.bytes[suffix]) {
+                  termOrd++;
+                  skipUpto = 0;
+                  continue nextTerm;
+                }
+              }
+            }
+
+            int upto = stateUpto+1;
+            while (upto < termLength) {
+              nextState = runAutomaton.step(nextState, termBytes[termOffset+upto] & 0xFF);
+              if (nextState == -1) {
+                termOrd++;
+                skipUpto = 0;
+                // if (DEBUG) {
+                //   System.out.println("  nomatch tail; next term");
+                // }
+                continue nextTerm;
+              }
+              upto++;
+            }
+
+            if (runAutomaton.isAccept(nextState)) {
+              scratch.bytes = termBytes;
+              scratch.offset = termOffsets[termOrd];
+              scratch.length = termOffsets[1+termOrd] - scratch.offset;
+              // if (DEBUG) {
+              //   System.out.println("  match tail; return " + scratch.utf8ToString());
+              //   System.out.println("  ret2 " + scratch.utf8ToString());
+              // }
+              return scratch;
+            } else {
+              termOrd++;
+              skipUpto = 0;
+              // if (DEBUG) {
+              //   System.out.println("  nomatch tail; next term");
+              // }
+            }
+          }
+        }
+      }
+
+      @Override
+      public TermState termState() {
+        OrdTermState state = new OrdTermState();
+        state.ord = termOrd;
+        return state;
+      }
+
+      @Override
+      public BytesRef term() {
+        return scratch;
+      }
+
+      @Override
+      public long ord() {
+        return termOrd;
+      }
+
+      @Override
+      public int docFreq() {
+        if (terms[termOrd] instanceof LowFreqTerm) {
+          return ((LowFreqTerm) terms[termOrd]).docFreq;
+        } else {
+          return ((HighFreqTerm) terms[termOrd]).docIDs.length;
+        }
+      }
+
+      @Override
+      public long totalTermFreq() {
+        if (terms[termOrd] instanceof LowFreqTerm) {
+          return ((LowFreqTerm) terms[termOrd]).totalTermFreq;
+        } else {
+          return ((HighFreqTerm) terms[termOrd]).totalTermFreq;
+        }
+      }
+
+      @Override
+      public DocsEnum docs(Bits liveDocs, DocsEnum reuse, int flags) {
+        // TODO: implement reuse, something like Pulsing:
+        // it's hairy!
+
+        if (terms[termOrd] instanceof LowFreqTerm) {
+          final int[] postings = ((LowFreqTerm) terms[termOrd]).postings;
+          if (hasFreq) {
+            if (hasPos) {
+              int posLen;
+              if (hasOffsets) {
+                posLen = 3;
+              } else {
+                posLen = 1;
+              }
+              if (hasPayloads) {
+                posLen++;
+              }
+              return new LowFreqDocsEnum(liveDocs, posLen).reset(postings);
+            } else {
+              return new LowFreqDocsEnumNoPos(liveDocs).reset(postings);
+            }
+          } else {
+            return new LowFreqDocsEnumNoTF(liveDocs).reset(postings);
+          }
+        } else {
+          final HighFreqTerm term = (HighFreqTerm) terms[termOrd];
+          //  System.out.println("DE for term=" + new BytesRef(terms[termOrd].term).utf8ToString() + ": " + term.docIDs.length + " docs");
+          return new HighFreqDocsEnum(liveDocs).reset(term.docIDs, term.freqs);
+        }
+      }
+
+      @Override
+      public DocsAndPositionsEnum docsAndPositions(Bits liveDocs, DocsAndPositionsEnum reuse, int flags) {
+        if (!hasPos) {
+          return null;
+        }
+
+        // TODO: implement reuse, something like Pulsing:
+        // it's hairy!
+
+        if (terms[termOrd] instanceof LowFreqTerm) {
+          final LowFreqTerm term = ((LowFreqTerm) terms[termOrd]);
+          final int[] postings = term.postings;
+          final byte[] payloads = term.payloads;
+          return new LowFreqDocsAndPositionsEnum(liveDocs, hasOffsets, hasPayloads).reset(postings, payloads);
+        } else {
+          final HighFreqTerm term = (HighFreqTerm) terms[termOrd];
+          return new HighFreqDocsAndPositionsEnum(liveDocs, hasOffsets).reset(term.docIDs, term.freqs, term.positions, term.payloads);
+        }
+      }
+
+      @Override
+      public SeekStatus seekCeil(BytesRef term) {
+        throw new UnsupportedOperationException();
+      }
+
+      @Override
+      public void seekExact(long ord) {
+        throw new UnsupportedOperationException();
+      }
+    }
+  }
+
+  // Docs only:
+  private final static class LowFreqDocsEnumNoTF extends DocsEnum {
+    private int[] postings;
+    private final Bits liveDocs;
+    private int upto;
+
+    public LowFreqDocsEnumNoTF(Bits liveDocs) {
+      this.liveDocs = liveDocs;
+    }
+
+    public bool canReuse(Bits liveDocs) {
+      return liveDocs == this.liveDocs;
+    }
+
+    public DocsEnum reset(int[] postings) {
+      this.postings = postings;
+      upto = -1;
+      return this;
+    }
+
+    // TODO: can do this w/o setting members?
+
+    @Override
+    public int nextDoc() {
+      upto++;
+      if (liveDocs == null) {
+        if (upto < postings.length) {
+          return postings[upto];
+        }
+      } else {
+        while (upto < postings.length) {
+          if (liveDocs.get(postings[upto])) {
+            return postings[upto];
+          }
+          upto++;
+        }
+      }
+      return NO_MORE_DOCS;
+    }
+
+    @Override
+    public int docID() {
+      if (upto < 0) {
+        return -1;
+      } else if (upto < postings.length) {
+        return postings[upto];
+      } else {
+        return NO_MORE_DOCS;
+      }
+    }
+
+    @Override
+    public int freq() {
+      return 1;
+    }
+
+    @Override
+    public int advance(int target)  {
+      // Linear scan, but this is low-freq term so it won't
+      // be costly:
+      return slowAdvance(target);
+    }
+    
+    @Override
+    public long cost() {
+      return postings.length;
+    }
+  }
+
+  // Docs + freqs:
+  private final static class LowFreqDocsEnumNoPos extends DocsEnum {
+    private int[] postings;
+    private final Bits liveDocs;
+    private int upto;
+
+    public LowFreqDocsEnumNoPos(Bits liveDocs) {
+      this.liveDocs = liveDocs;
+    }
+
+    public bool canReuse(Bits liveDocs) {
+      return liveDocs == this.liveDocs;
+    }
+
+    public DocsEnum reset(int[] postings) {
+      this.postings = postings;
+      upto = -2;
+      return this;
+    }
+
+    // TODO: can do this w/o setting members?
+    @Override
+    public int nextDoc() {
+      upto += 2;
+      if (liveDocs == null) {
+        if (upto < postings.length) {
+          return postings[upto];
+        }
+      } else {
+        while (upto < postings.length) {
+          if (liveDocs.get(postings[upto])) {
+            return postings[upto];
+          }
+          upto += 2;
+        }
+      }
+      return NO_MORE_DOCS;
+    }
+
+    @Override
+    public int docID() {
+      if (upto < 0) {
+        return -1;
+      } else if (upto < postings.length) {
+        return postings[upto];
+      } else {
+        return NO_MORE_DOCS;
+      }
+    }
+
+    @Override
+    public int freq() {
+      return postings[upto+1];
+    }
+
+    @Override
+    public int advance(int target)  {
+      // Linear scan, but this is low-freq term so it won't
+      // be costly:
+      return slowAdvance(target);
+    }
+    
+    @Override
+    public long cost() {
+      return postings.length / 2;
+    }
+  }
+
+  // Docs + freqs + positions/offets:
+  private final static class LowFreqDocsEnum extends DocsEnum {
+    private int[] postings;
+    private final Bits liveDocs;
+    private final int posMult;
+    private int upto;
+    private int freq;
+
+    public LowFreqDocsEnum(Bits liveDocs, int posMult) {
+      this.liveDocs = liveDocs;
+      this.posMult = posMult;
+      // if (DEBUG) {
+      //   System.out.println("LowFreqDE: posMult=" + posMult);
+      // }
+    }
+
+    public bool canReuse(Bits liveDocs, int posMult) {
+      return liveDocs == this.liveDocs && posMult == this.posMult;
+    }
+
+    public DocsEnum reset(int[] postings) {
+      this.postings = postings;
+      upto = -2;
+      freq = 0;
+      return this;
+    }
+
+    // TODO: can do this w/o setting members?
+    @Override
+    public int nextDoc() {
+      upto += 2 + freq*posMult;
+      // if (DEBUG) {
+      //   System.out.println("  nextDoc freq=" + freq + " upto=" + upto + " vs " + postings.length);
+      // }
+      if (liveDocs == null) {
+        if (upto < postings.length) {   
+          freq = postings[upto+1];
+          Debug.Assert( freq > 0;
+          return postings[upto];
+        }
+      } else {
+        while (upto < postings.length) {
+          freq = postings[upto+1];
+          Debug.Assert( freq > 0;
+          if (liveDocs.get(postings[upto])) {
+            return postings[upto];
+          }
+          upto += 2 + freq*posMult;
+        }
+      }
+      return NO_MORE_DOCS;
+    }
+
+    @Override
+    public int docID() {
+      // TODO: store docID member?
+      if (upto < 0) {
+        return -1;
+      } else if (upto < postings.length) {
+        return postings[upto];
+      } else {
+        return NO_MORE_DOCS;
+      }
+    }
+
+    @Override
+    public int freq() {
+      // TODO: can I do postings[upto+1]?
+      return freq;
+    }
+
+    @Override
+    public int advance(int target)  {
+      // Linear scan, but this is low-freq term so it won't
+      // be costly:
+      return slowAdvance(target);
+    }
+    
+    @Override
+    public long cost() {
+      // TODO: could do a better estimate
+      return postings.length / 2;
+    }
+  }
+
+  private final static class LowFreqDocsAndPositionsEnum extends DocsAndPositionsEnum {
+    private int[] postings;
+    private final Bits liveDocs;
+    private final int posMult;
+    private final bool hasOffsets;
+    private final bool hasPayloads;
+    private final BytesRef payload = new BytesRef();
+    private int upto;
+    private int docID;
+    private int freq;
+    private int skipPositions;
+    private int startOffset;
+    private int endOffset;
+    private int lastPayloadOffset;
+    private int payloadOffset;
+    private int payloadLength;
+    private byte[] payloadBytes;
+
+    public LowFreqDocsAndPositionsEnum(Bits liveDocs, bool hasOffsets, bool hasPayloads) {
+      this.liveDocs = liveDocs;
+      this.hasOffsets = hasOffsets;
+      this.hasPayloads = hasPayloads;
+      if (hasOffsets) {
+        if (hasPayloads) {
+          posMult = 4;
+        } else {
+          posMult = 3;
+        }
+      } else if (hasPayloads) {
+        posMult = 2;
+      } else {
+        posMult = 1;
+      }
+    }
+
+    public DocsAndPositionsEnum reset(int[] postings, byte[] payloadBytes) {
+      this.postings = postings;
+      upto = 0;
+      skipPositions = 0;
+      startOffset = -1;
+      endOffset = -1;
+      docID = -1;
+      payloadLength = 0;
+      this.payloadBytes = payloadBytes;
+      return this;
+    }
+
+    @Override
+    public int nextDoc() {
+      if (hasPayloads) {
+        for(int i=0;i<skipPositions;i++) {
+          upto++;
+          if (hasOffsets) {
+            upto += 2;
+          }
+          payloadOffset += postings[upto++];
+        }
+      } else {
+        upto += posMult * skipPositions;
+      }
+
+      if (liveDocs == null) {
+        if (upto < postings.length) {
+          docID = postings[upto++];
+          freq = postings[upto++];
+          skipPositions = freq;
+          return docID;
+        }
+      } else {
+        while(upto < postings.length) {
+          docID = postings[upto++];
+          freq = postings[upto++];
+          if (liveDocs.get(docID)) {
+            skipPositions = freq;
+            return docID;
+          }
+          if (hasPayloads) {
+            for(int i=0;i<freq;i++) {
+              upto++;
+              if (hasOffsets) {
+                upto += 2;
+              }
+              payloadOffset += postings[upto++];
+            }
+          } else {
+            upto += posMult * freq;
+          }
+        }
+      }
+
+      return docID = NO_MORE_DOCS;
+    }
+
+    @Override
+    public int docID() {
+      return docID;
+    }
+
+    @Override
+    public int freq() {
+      return freq;
+    }
+
+    @Override
+    public int nextPosition() {
+      Debug.Assert( skipPositions > 0;
+      skipPositions--;
+      final int pos = postings[upto++];
+      if (hasOffsets) {
+        startOffset = postings[upto++];
+        endOffset = postings[upto++];
+      }
+      if (hasPayloads) {
+        payloadLength = postings[upto++];
+        lastPayloadOffset = payloadOffset;
+        payloadOffset += payloadLength;
+      }
+      return pos;
+    }
+
+    @Override
+    public int startOffset() {
+      return startOffset;
+    }
+
+    @Override
+    public int endOffset() {
+      return endOffset;
+    }
+
+    @Override
+    public int advance(int target)  {
+      return slowAdvance(target);
+    }
+
+    @Override
+    public BytesRef getPayload() {
+      if (payloadLength > 0) {
+        payload.bytes = payloadBytes;
+        payload.offset = lastPayloadOffset;
+        payload.length = payloadLength;
+        return payload;
+      } else {
+        return null;
+      }
+    }
+    
+    @Override
+    public long cost() {
+      // TODO: could do a better estimate
+      return postings.length / 2;
+    }
+  }
+
+  // Docs + freqs:
+  private final static class HighFreqDocsEnum extends DocsEnum {
+    private int[] docIDs;
+    private int[] freqs;
+    private final Bits liveDocs;
+    private int upto;
+    private int docID = -1;
+
+    public HighFreqDocsEnum(Bits liveDocs) {
+      this.liveDocs = liveDocs;
+    }
+
+    public bool canReuse(Bits liveDocs) {
+      return liveDocs == this.liveDocs;
+    }
+
+    public int[] getDocIDs() {
+      return docIDs;
+    }
+
+    public int[] getFreqs() {
+      return freqs;
+    }
+
+    public DocsEnum reset(int[] docIDs, int[] freqs) {
+      this.docIDs = docIDs;
+      this.freqs = freqs;
+      docID = upto = -1;
+      return this;
+    }
+
+    @Override
+    public int nextDoc() {
+      upto++;
+      if (liveDocs == null) {
+        try {
+          return docID = docIDs[upto];
+        } catch (ArrayIndexOutOfBoundsException e) {
+        }
+      } else {
+        while (upto < docIDs.length) {
+          if (liveDocs.get(docIDs[upto])) {
+            return docID = docIDs[upto];
+          }
+          upto++;
+        }
+      }
+      return docID = NO_MORE_DOCS;
+    }
+
+    @Override
+    public int docID() {
+      return docID;
+    }
+
+    @Override
+    public int freq() {
+      if (freqs == null) {
+        return 1;
+      } else {
+        return freqs[upto];
+      }
+    }
+
+    @Override
+    public int advance(int target) {
+      /*
+      upto++;
+      if (upto == docIDs.length) {
+        return docID = NO_MORE_DOCS;
+      }
+      final int index = Arrays.binarySearch(docIDs, upto, docIDs.length, target);
+      if (index < 0) {
+        upto = -index - 1;
+      } else {
+        upto = index;
+      }
+      if (liveDocs != null) {
+        while (upto < docIDs.length) {
+          if (liveDocs.get(docIDs[upto])) {
+            break;
+          }
+          upto++;
+        }
+      }
+      if (upto == docIDs.length) {
+        return NO_MORE_DOCS;
+      } else {
+        return docID = docIDs[upto];
+      }
+      */
+
+      //System.out.println("  advance target=" + target + " cur=" + docID() + " upto=" + upto + " of " + docIDs.length);
+      // if (DEBUG) {
+      //   System.out.println("advance target=" + target + " len=" + docIDs.length);
+      // }
+      upto++;
+      if (upto == docIDs.length) {
+        return docID = NO_MORE_DOCS;
+      }
+
+      // First "grow" outwards, since most advances are to
+      // nearby docs:
+      int inc = 10;
+      int nextUpto = upto+10;
+      int low;
+      int high;
+      while (true) {
+        //System.out.println("  grow nextUpto=" + nextUpto + " inc=" + inc);
+        if (nextUpto >= docIDs.length) {
+          low = nextUpto-inc;
+          high = docIDs.length-1;
+          break;
+        }
+        //System.out.println("    docID=" + docIDs[nextUpto]);
+
+        if (target <= docIDs[nextUpto]) {
+          low = nextUpto-inc;
+          high = nextUpto;
+          break;
+        }
+        inc *= 2;
+        nextUpto += inc;
+      }
+
+      // Now do normal binary search
+      //System.out.println("    after fwd: low=" + low + " high=" + high);
+
+      while (true) {
+
+        if (low > high) {
+          // Not exactly found
+          //System.out.println("    break: no match");
+          upto = low;
+          break;
+        }
+
+        int mid = (low + high) >>> 1;
+        int cmp = docIDs[mid] - target;
+        //System.out.println("    bsearch low=" + low + " high=" + high+ ": docIDs[" + mid + "]=" + docIDs[mid]);
+
+        if (cmp < 0) {
+          low = mid + 1;
+        } else if (cmp > 0) {
+          high = mid - 1;
+        } else {
+          // Found target
+          upto = mid;
+          //System.out.println("    break: match");
+          break;
+        }
+      }
+
+      //System.out.println("    end upto=" + upto + " docID=" + (upto >= docIDs.length ? NO_MORE_DOCS : docIDs[upto]));
+
+      if (liveDocs != null) {
+        while (upto < docIDs.length) {
+          if (liveDocs.get(docIDs[upto])) {
+            break;
+          }
+          upto++;
+        }
+      }
+      if (upto == docIDs.length) {
+        //System.out.println("    return END");
+        return docID = NO_MORE_DOCS;
+      } else {
+        //System.out.println("    return docID=" + docIDs[upto] + " upto=" + upto);
+        return docID = docIDs[upto];
+      }
+    }
+    
+    @Override
+    public long cost() {
+      return docIDs.length;
+    }
+  }
+
+  // TODO: specialize offsets and not
+  private final static class HighFreqDocsAndPositionsEnum extends DocsAndPositionsEnum {
+    private int[] docIDs;
+    private int[] freqs;
+    private int[][] positions;
+    private byte[][][] payloads;
+    private final Bits liveDocs;
+    private final bool hasOffsets;
+    private final int posJump;
+    private int upto;
+    private int docID = -1;
+    private int posUpto;
+    private int[] curPositions;
+
+    public HighFreqDocsAndPositionsEnum(Bits liveDocs, bool hasOffsets) {
+      this.liveDocs = liveDocs;
+      this.hasOffsets = hasOffsets;
+      posJump = hasOffsets ? 3 : 1;
+    }
+
+    public int[] getDocIDs() {
+      return docIDs;
+    }
+
+    public int[][] getPositions() {
+      return positions;
+    }
+
+    public int getPosJump() {
+      return posJump;
+    }
+
+    public Bits getLiveDocs() {
+      return liveDocs;
+    }
+
+    public DocsAndPositionsEnum reset(int[] docIDs, int[] freqs, int[][] positions, byte[][][] payloads) {
+      this.docIDs = docIDs;
+      this.freqs = freqs;
+      this.positions = positions;
+      this.payloads = payloads;
+      upto = -1;
+      return this;
+    }
+
+    @Override
+    public int nextDoc() {
+      upto++;
+      if (liveDocs == null) {
+        if (upto < docIDs.length) {
+          posUpto = -posJump;   
+          curPositions = positions[upto];
+          return docID = docIDs[upto];
+        }
+      } else {
+        while (upto < docIDs.length) {
+          if (liveDocs.get(docIDs[upto])) {
+            posUpto = -posJump;
+            curPositions = positions[upto];
+            return docID = docIDs[upto];
+          }
+          upto++;
+        }
+      }
+
+      return docID = NO_MORE_DOCS;
+    }
+
+    @Override
+    public int freq() {
+      return freqs[upto];
+    }
+
+    @Override
+    public int docID() {
+      return docID;
+    }
+
+    @Override
+    public int nextPosition() {
+      posUpto += posJump;
+      return curPositions[posUpto];
+    }
+
+    @Override
+    public int startOffset() {
+      if (hasOffsets) {
+        return curPositions[posUpto+1];
+      } else {
+        return -1;
+      }
+    }
+
+    @Override
+    public int endOffset() {
+      if (hasOffsets) {
+        return curPositions[posUpto+2];
+      } else {
+        return -1;
+      }
+    }
+
+    @Override
+    public int advance(int target) {
+
+      /*
+      upto++;
+      if (upto == docIDs.length) {
+        return NO_MORE_DOCS;
+      }
+      final int index = Arrays.binarySearch(docIDs, upto, docIDs.length, target);
+      if (index < 0) {
+        upto = -index - 1;
+      } else {
+        upto = index;
+      }
+      if (liveDocs != null) {
+        while (upto < docIDs.length) {
+          if (liveDocs.get(docIDs[upto])) {
+            break;
+          }
+          upto++;
+        }
+      }
+      posUpto = hasOffsets ? -3 : -1;
+      if (upto == docIDs.length) {
+        return NO_MORE_DOCS;
+      } else {
+        return docID();
+      }
+      */
+
+      //System.out.println("  advance target=" + target + " cur=" + docID() + " upto=" + upto + " of " + docIDs.length);
+      // if (DEBUG) {
+      //   System.out.println("advance target=" + target + " len=" + docIDs.length);
+      // }
+      upto++;
+      if (upto == docIDs.length) {
+        return docID = NO_MORE_DOCS;
+      }
+
+      // First "grow" outwards, since most advances are to
+      // nearby docs:
+      int inc = 10;
+      int nextUpto = upto+10;
+      int low;
+      int high;
+      while (true) {
+        //System.out.println("  grow nextUpto=" + nextUpto + " inc=" + inc);
+        if (nextUpto >= docIDs.length) {
+          low = nextUpto-inc;
+          high = docIDs.length-1;
+          break;
+        }
+        //System.out.println("    docID=" + docIDs[nextUpto]);
+
+        if (target <= docIDs[nextUpto]) {
+          low = nextUpto-inc;
+          high = nextUpto;
+          break;
+        }
+        inc *= 2;
+        nextUpto += inc;
+      }
+
+      // Now do normal binary search
+      //System.out.println("    after fwd: low=" + low + " high=" + high);
+
+      while (true) {
+
+        if (low > high) {
+          // Not exactly found
+          //System.out.println("    break: no match");
+          upto = low;
+          break;
+        }
+
+        int mid = (low + high) >>> 1;
+        int cmp = docIDs[mid] - target;
+        //System.out.println("    bsearch low=" + low + " high=" + high+ ": docIDs[" + mid + "]=" + docIDs[mid]);
+
+        if (cmp < 0) {
+          low = mid + 1;
+        } else if (cmp > 0) {
+          high = mid - 1;
+        } else {
+          // Found target
+          upto = mid;
+          //System.out.println("    break: match");
+          break;
+        }
+      }
+
+      //System.out.println("    end upto=" + upto + " docID=" + (upto >= docIDs.length ? NO_MORE_DOCS : docIDs[upto]));
+
+      if (liveDocs != null) {
+        while (upto < docIDs.length) {
+          if (liveDocs.get(docIDs[upto])) {
+            break;
+          }
+          upto++;
+        }
+      }
+      if (upto == docIDs.length) {
+        //System.out.println("    return END");
+        return docID = NO_MORE_DOCS;
+      } else {
+        //System.out.println("    return docID=" + docIDs[upto] + " upto=" + upto);
+        posUpto = -posJump;
+        curPositions = positions[upto];
+        return docID = docIDs[upto];
+      }
+    }
+
+    private final BytesRef payload = new BytesRef();
+
+    @Override
+    public BytesRef getPayload() {
+      if (payloads == null) {
+        return null;
+      } else {
+        final byte[] payloadBytes = payloads[upto][posUpto/(hasOffsets ? 3:1)];
+        if (payloadBytes == null) {
+          return null;
+        }
+        payload.bytes = payloadBytes;
+        payload.length = payloadBytes.length;
+        payload.offset = 0;
+        return payload;
+      }
+    }
+    
+    @Override
+    public long cost() {
+      return docIDs.length;
+    }
+  }
+}

http://git-wip-us.apache.org/repos/asf/lucenenet/blob/1da1cb5b/src/Lucene.Net.Codecs/Memory/FSTOrdPostingsFormat.cs
----------------------------------------------------------------------
diff --git a/src/Lucene.Net.Codecs/Memory/FSTOrdPostingsFormat.cs b/src/Lucene.Net.Codecs/Memory/FSTOrdPostingsFormat.cs
new file mode 100644
index 0000000..d8be831
--- /dev/null
+++ b/src/Lucene.Net.Codecs/Memory/FSTOrdPostingsFormat.cs
@@ -0,0 +1,83 @@
+package org.apache.lucene.codecs.memory;
+
+
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import java.io.IOException;
+
+import org.apache.lucene.codecs.FieldsConsumer;
+import org.apache.lucene.codecs.FieldsProducer;
+import org.apache.lucene.codecs.PostingsFormat;
+import org.apache.lucene.codecs.PostingsReaderBase;
+import org.apache.lucene.codecs.PostingsWriterBase;
+import org.apache.lucene.codecs.lucene41.Lucene41PostingsWriter;
+import org.apache.lucene.codecs.lucene41.Lucene41PostingsReader;
+import org.apache.lucene.index.FieldInfo.IndexOptions;
+import org.apache.lucene.index.SegmentReadState;
+import org.apache.lucene.index.SegmentWriteState;
+import org.apache.lucene.util.IOUtils;
+
+/** 
+ * FSTOrd term dict + Lucene41PBF
+ */
+
+public final class FSTOrdPostingsFormat extends PostingsFormat {
+  public FSTOrdPostingsFormat() {
+    super("FSTOrd41");
+  }
+
+  @Override
+  public String toString() {
+    return getName();
+  }
+
+  @Override
+  public FieldsConsumer fieldsConsumer(SegmentWriteState state)  {
+    PostingsWriterBase postingsWriter = new Lucene41PostingsWriter(state);
+
+    bool success = false;
+    try {
+      FieldsConsumer ret = new FSTOrdTermsWriter(state, postingsWriter);
+      success = true;
+      return ret;
+    } finally {
+      if (!success) {
+        IOUtils.closeWhileHandlingException(postingsWriter);
+      }
+    }
+  }
+
+  @Override
+  public FieldsProducer fieldsProducer(SegmentReadState state)  {
+    PostingsReaderBase postingsReader = new Lucene41PostingsReader(state.directory,
+                                                                state.fieldInfos,
+                                                                state.segmentInfo,
+                                                                state.context,
+                                                                state.segmentSuffix);
+    bool success = false;
+    try {
+      FieldsProducer ret = new FSTOrdTermsReader(state, postingsReader);
+      success = true;
+      return ret;
+    } finally {
+      if (!success) {
+        IOUtils.closeWhileHandlingException(postingsReader);
+      }
+    }
+  }
+}

http://git-wip-us.apache.org/repos/asf/lucenenet/blob/1da1cb5b/src/Lucene.Net.Codecs/Memory/FSTOrdPulsing41PostingsFormat.cs
----------------------------------------------------------------------
diff --git a/src/Lucene.Net.Codecs/Memory/FSTOrdPulsing41PostingsFormat.cs b/src/Lucene.Net.Codecs/Memory/FSTOrdPulsing41PostingsFormat.cs
new file mode 100644
index 0000000..257d2eb
--- /dev/null
+++ b/src/Lucene.Net.Codecs/Memory/FSTOrdPulsing41PostingsFormat.cs
@@ -0,0 +1,91 @@
+package org.apache.lucene.codecs.memory;
+
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import java.io.IOException;
+
+import org.apache.lucene.codecs.FieldsConsumer;
+import org.apache.lucene.codecs.FieldsProducer;
+import org.apache.lucene.codecs.PostingsBaseFormat;
+import org.apache.lucene.codecs.PostingsFormat;
+import org.apache.lucene.codecs.PostingsReaderBase;
+import org.apache.lucene.codecs.PostingsWriterBase;
+import org.apache.lucene.codecs.lucene41.Lucene41PostingsWriter;
+import org.apache.lucene.codecs.lucene41.Lucene41PostingsReader;
+import org.apache.lucene.codecs.lucene41.Lucene41PostingsBaseFormat;
+import org.apache.lucene.codecs.lucene41.Lucene41PostingsFormat;
+import org.apache.lucene.codecs.pulsing.PulsingPostingsWriter;
+import org.apache.lucene.codecs.pulsing.PulsingPostingsReader;
+import org.apache.lucene.index.SegmentReadState;
+import org.apache.lucene.index.SegmentWriteState;
+import org.apache.lucene.util.IOUtils;
+
+/** FSTOrd + Pulsing41
+ *  @lucene.experimental */
+
+public class FSTOrdPulsing41PostingsFormat extends PostingsFormat {
+  private final PostingsBaseFormat wrappedPostingsBaseFormat;
+  private final int freqCutoff;
+
+  public FSTOrdPulsing41PostingsFormat() {
+    this(1);
+  }
+  
+  public FSTOrdPulsing41PostingsFormat(int freqCutoff) {
+    super("FSTOrdPulsing41");
+    this.wrappedPostingsBaseFormat = new Lucene41PostingsBaseFormat();
+    this.freqCutoff = freqCutoff;
+  }
+
+  @Override
+  public FieldsConsumer fieldsConsumer(SegmentWriteState state)  {
+    PostingsWriterBase docsWriter = null;
+    PostingsWriterBase pulsingWriter = null;
+
+    bool success = false;
+    try {
+      docsWriter = wrappedPostingsBaseFormat.postingsWriterBase(state);
+      pulsingWriter = new PulsingPostingsWriter(state, freqCutoff, docsWriter);
+      FieldsConsumer ret = new FSTOrdTermsWriter(state, pulsingWriter);
+      success = true;
+      return ret;
+    } finally {
+      if (!success) {
+        IOUtils.closeWhileHandlingException(docsWriter, pulsingWriter);
+      }
+    }
+  }
+
+  @Override
+  public FieldsProducer fieldsProducer(SegmentReadState state)  {
+    PostingsReaderBase docsReader = null;
+    PostingsReaderBase pulsingReader = null;
+    bool success = false;
+    try {
+      docsReader = wrappedPostingsBaseFormat.postingsReaderBase(state);
+      pulsingReader = new PulsingPostingsReader(state, docsReader);
+      FieldsProducer ret = new FSTOrdTermsReader(state, pulsingReader);
+      success = true;
+      return ret;
+    } finally {
+      if (!success) {
+        IOUtils.closeWhileHandlingException(docsReader, pulsingReader);
+      }
+    }
+  }
+}