Revert "ProtoBuf update"

This reverts commit 9aaf507646c866ab131bf2bcd973882ff9f553cf.

4 files changed, 171 insertions, 653 deletions

diff --git a/src/com/google/common/io/protocol/IntMap.java b/src/com/google/common/io/protocol/IntMap.java
deleted file mode 100644
index 9f0b8fc..0000000
--- a/src/com/google/common/io/protocol/IntMap.java
+++ /dev/null
@@ -1,383 +0,0 @@
-// Copyright 2009 Google Inc. All Rights Reserved.
-
-package com.google.common.io.protocol;
-
-import java.util.Enumeration;
-import java.util.Hashtable;
-import java.util.NoSuchElementException;
-
-/**
- * A Map from primitive integers to Object values. This stores values
- * for smaller keys in an Object array, and uses {@link Hashtable}
- * only for larger keys. This is specifically designed to be used by
- * J2me protocol buffer runtime ({@link ProtoBuf}, {@link ProtoBufType})
- * to support large tags that are commonly used in Extensions/MessageSet.
- *
- * This class is not thread safe, so the client has to provide
- * appropriate locking mechanism if the map is to be used from
- * multiple threads.
- */
-public class IntMap {
-  private static final int MAX_LOWER_BUFFER_SIZE = 64;
-  private static final int INITIAL_LOWER_BUFFER_SIZE = 8;
-
-  /**
-   * An iterator that returns int keys of the IntMap. IntMap has its
-   * own Iterator instead of Enumeration to avoid autoboxing.  This
-   * uses the same buffer of the IntMap, so you should not update the
-   * IntMap while the iterator is in use. Once the IntMap is changed,
-   * the behavior of preiously obtained iterator is undefined, and a new
-   * KeyIterator has to be used instead.
-   */
-  public class KeyIterator {
-    private int oneAheadIndex = 0;
-    private int currentKey = Integer.MIN_VALUE;
-    private Enumeration  higherKeyEnumerator = null;
-
-    /**
-     * @returns true if there is more keys.
-     */
-    public boolean hasNext() {
-      if (currentKey != Integer.MIN_VALUE) {
-        return true;
-      }
-      if (oneAheadIndex <= maxLowerKey) {
-        for (; oneAheadIndex <= maxLowerKey; oneAheadIndex++) {
-          if (lower[oneAheadIndex] != null) {
-            // record the key, then increment the oneAheadIndex.
-            currentKey = oneAheadIndex++;
-            return true;
-          }
-        }
-      }
-      if (higher != null) {
-        if (higherKeyEnumerator == null) {
-          higherKeyEnumerator = higher.keys();
-        }
-        if (higherKeyEnumerator.hasMoreElements()) {
-          Integer key = (Integer) higherKeyEnumerator.nextElement();
-          currentKey = key.intValue();
-          return true;
-        }
-      }
-      return false;
-    }
-
-    /**
-     * @returns next key
-     * @throws NoSuchElementException if there is no more keys.
-     */
-    public int next() {
-      if (currentKey == Integer.MIN_VALUE && !hasNext()) {
-        throw new NoSuchElementException();
-      }
-      int key = currentKey;
-      currentKey = Integer.MIN_VALUE;
-      return key;
-    }
-  }
-
-  /** Stores values for lower keys */
-  private Object[] lower;
-
-  /** Hashtable for higher tags */
-  private Hashtable higher;
-
-  /** A maximum key that has been ever added to the lower buffer.*/
-  private int maxLowerKey;
-
-  /** A maximum key that has been ever added to the map.*/
-  private int maxKey;
-
-  /** the number of elements in lower buffer */
-  private int lowerCount;
-
-  /**
-   * Constructs an {@link IntMap} with default lower buffer size.
-   */
-  public IntMap() {
-    this(INITIAL_LOWER_BUFFER_SIZE); // can expand 3 times
-  }
-
-  /**
-   * Constructs an {@link IntMap} with the suggested initial lower buffer size.
-   * The argument is just a hint and may not be used. If its value is
-   * larger than {@link MAX_LOWER_BUFFER_SIZE} or negative, it will use the
-   * MAX_LOWER_BUFFER_SIZE instead.
-   */
-  IntMap(int initialLowerBufferSize) {
-    int lowerBufferSize = INITIAL_LOWER_BUFFER_SIZE;
-    if (initialLowerBufferSize > 0) {
-      lowerBufferSize = Math.min(initialLowerBufferSize, MAX_LOWER_BUFFER_SIZE);
-    }
-    lower = new Object[lowerBufferSize];
-    lowerCount = 0;
-    maxKey = Integer.MIN_VALUE;
-    maxLowerKey = Integer.MIN_VALUE;
-  }
-
-  /**
-   * A factory method to constructs an {@link IntMap} with the same
-   * lower buffer size.
-   *
-   * @return a new IntMap whose lower buffer size is same as
-   * this instance.
-   */
-  public IntMap newIntMapWithSameBufferSize() {
-    return new IntMap(maxLowerKey);
-  }
-
-  /**
-   * @return the {@link KeyIterator} of the map.
-   */
-  public KeyIterator keys() {
-    return new KeyIterator();
-  }
-
-  /**
-   * Returns max key that ever added to the map. Note that this is not
-   * max for current state. Removing the max key will not update the
-   * max key value. If nothing is added, it will return {@link
-   * Integer.MIN_VALUE}, which means you cannot tell if an value is
-   * added with MIN_VALUE key.
-   */
-  public int maxKey() {
-    return maxKey;
-  }
-
-  /**
-   * Returns the number of key-value pairs in the map.
-   */
-  public int size() {
-    return higher == null ? lowerCount : lowerCount + higher.size();
-  }
-
-  /**
-   * @return true if the map is empty.
-   */
-  public boolean isEmpty() {
-    return size() == 0;
-  }
-
-  /**
-   * Clears all key/value pairs. The map becomes empty after this
-   * operation, but does not release memory.
-   */
-  public void clear() {
-    for (int i = 0; i < lower.length; i++) {
-      lower[i] = null;
-    }
-    if (higher != null) higher.clear();
-    maxKey = Integer.MIN_VALUE;
-    maxLowerKey = Integer.MIN_VALUE;
-    lowerCount = 0;
-  }
-
-  /**
-   * Returns the value associated with the given key.
-   *
-   * @param key a key
-   * @return the value associated with the given key. null if the map has
-   * no value for the key.
-   */
-  public Object get(int key) {
-    if (key > maxKey) {
-      return null;
-    } else if (0 <= key && key <= maxLowerKey) {
-      return lower[key];
-    } else if (higher != null) {
-      return higher.get(key);
-    } else {
-      return null;
-    }
-  }
-
-  /**
-   * Maps the specified key to the given value in the {@link IntMap}.
-   * Caveat: Passing null value removes the value from the map. This is to
-   * keep the semantics used in {@link ProtoBuf}.
-   *
-   * @param key a key
-   * @param value the value to be added to the Map. If this is null,
-   * the key will be removed from the map. This method does nothing if
-   * the key does not exist and value is null.
-   */
-  public void put(int key, Object value) {
-    if (value == null) {
-      remove(key);
-      return;
-    }
-    expandLowerIfNecessary(key);
-    maxKey = Math.max(key, maxKey);
-    if (0 <= key && key < lower.length) {
-      maxLowerKey = Math.max(key, maxLowerKey);
-      if (lower[key] == null) {
-        lowerCount++;
-      }
-      lower[key] = value;
-    } else {
-      if (higher == null) {
-        higher = new Hashtable();
-      }
-      higher.put(key, value);
-    }
-  }
-
-  /**
-   * Removes the key and corresponding value from the {@link IntMap}.
-   *
-   * @param key the key to remove. This method does nothing if the map does not
-   * have the value corresponding for the key.
-   * @return the removed value. null if the map does not have the value for
-   * the key.
-   */
-  public Object remove(int key) {
-    Object deleted = null;
-    if (0 <= key && key < lower.length) {
-      deleted = lower[key];
-      if (deleted != null) {
-        lowerCount--;
-      }
-      lower[key] = null;
-    } else if (higher != null) {
-      return higher.remove(key);
-    }
-    return deleted;
-  }
-
-  /**
-   * Tests if given key has a corresponding value in this {@link IntMap}.
-   *
-   * @param key possible key.
-   * @return <code>true</code> if the given key has the correspoding
-   * value. <code>false</code> otherwise.
-   */
-  public boolean containsKey(int key) {
-    if (0 <= key && key < lower.length) {
-      return lower[key] != null;
-    } else if (higher != null) {
-      return higher.containsKey(key);
-    }
-    return false;
-  }
-
-  /**
-   * Returns hashcode for {@link IntMap}.
-   */
-  public int hashCode() {
-    int hashCode = 1;
-    for (int i = 0; i < lower.length ; i++) {
-      Object value = lower[i];
-      if (value != null) {
-        hashCode = 31 * hashCode + value.hashCode() + i;
-      }
-    }
-    // Hashtable in J2me does not implement hashCode(), so we simply
-    // use the size of hashtable.
-    return higher == null ? hashCode : hashCode + higher.size();
-  }
-
-  /**
-   * Compares the equality. Two IntMaps are considered equals iff
-   * both map have the same key-value pairs.
-   * Caveat: This assumes that the Class of each value object implements
-   * equals correctly. This may not be the case in J2me.
-   *
-   * @param object an object to be compared with
-   * @return true if the specified Object is equal to this IntMap
-   */
-  public boolean equals(Object object) {
-    if (this == object) {
-      return true;
-    }
-    if (object == null || !(object instanceof IntMap)) {
-      return false;
-    }
-    IntMap peer = (IntMap) object;
-    if (size() != peer.size()) {
-      return false;
-    }
-    return compareLowerBuffer(lower, peer.lower) &&
-        compareHashtable(higher, peer.higher);
-  }
-
-  private boolean compareLowerBuffer(Object[] lower1, Object[] lower2) {
-    int min = Math.min(lower1.length, lower2.length);
-
-    for (int i = 0; i < min; i++) {
-      if ((lower1[i] == null && lower2[i] != null) ||
-          (lower1[i] != null && !lower1[i].equals(lower2[i]))) {
-        return false;
-      }
-    }
-    // make sure there are no values in remaining fields.
-    if (lower1.length > lower2.length) {
-      for (int i = min; i < lower1.length; i++) {
-        if (lower1[i] != null) return false;
-      }
-    } else if (lower1.length < lower2.length) {
-      for (int i = min; i < lower2.length; i++) {
-        if (lower2[i] != null) return false;
-      }
-    }
-    return true;
-  }
-
-  /**
-   * J2me's Hashtable does not implement equal, Bummer!
-   */
-  private static boolean compareHashtable(Hashtable h1, Hashtable h2) {
-    if (h1 == h2) { // null == null is caught here
-      return true;
-    }
-    if (h1 == null || h2 == null) {
-      return false;
-    }
-    if (h1.size() != h2.size()) {
-      return false;
-    }
-    // Ensure the values are the same.
-    Enumeration h1Keys = h1.keys();
-    while (h1Keys.hasMoreElements()) {
-      Object key = h1Keys.nextElement();
-      Object h1Value = h1.get(key);
-      Object h2Value = h2.get(key);
-      if (!h1Value.equals(h2Value)) {
-        return false;
-      }
-    }
-    return true;
-  }
-
-  /**
-   * Expands lower buffer iff the key does not fit to current buffer size,
-   * but will fit in MAX buffer size.
-   */
-  private void expandLowerIfNecessary(int key) {
-    if (key <= MAX_LOWER_BUFFER_SIZE && key >= lower.length && key > 0) {
-      int size = lower.length;
-      do {
-        size <<= 1;
-      } while (size <= key);
-      size = Math.min(size, MAX_LOWER_BUFFER_SIZE);
-      Object[] newLower = new Object[size];
-      System.arraycopy(lower, 0, newLower, 0, lower.length);
-      lower = newLower;
-    }
-  }
-
-  /* {@inheritDoc} */
-  public String toString() {
-    StringBuffer buffer = new StringBuffer("IntMap{lower:");
-    for (int i = 0; i < lower.length; i++) {
-      if (lower[i] != null) {
-        buffer.append(i);
-        buffer.append("=>");
-        buffer.append(lower[i]);
-        buffer.append(", ");
-      }
-    }
-    buffer.append(", higher:" + higher + "}");
-    return buffer.toString();
-  }
-}
diff --git a/src/com/google/common/io/protocol/ProtoBuf.java b/src/com/google/common/io/protocol/ProtoBuf.java
index ae7e4a6..2a2f8b7 100644
--- a/src/com/google/common/io/protocol/ProtoBuf.java
+++ b/src/com/google/common/io/protocol/ProtoBuf.java
@@ -7,7 +7,9 @@ import java.io.*;
 import java.util.*;
 
 /**
- * Protocol buffer message object.
+ * Protocol buffer message object. Currently, it is assumed that tags ids are 
+ * not large. This could be improved by storing a start offset, reducing the 
+ * assumption to a dense number space.
  * <p>
  * ProtoBuf instances may or may not reference a ProtoBufType instance,
  * representing information from a corresponding .proto file, which defines tag 
@@ -31,6 +33,7 @@ import java.util.*;
  * this behavior is that default values cannot be removed -- they would reappear
  * after a serialization cycle. If a tag has repeated values, setXXX(tag, value)
  * will overwrite all of them and getXXX(tag) will throw an exception.
+ *
  */
 
 public class ProtoBuf {
@@ -42,9 +45,7 @@ public class ProtoBuf {
   private static final String MSG_MISMATCH = "Type mismatch";
   private static final String MSG_UNSUPPORTED = "Unsupp.Type";
 
-  // see
-  // http://code.google.com/apis/protocolbuffers/docs/overview.html
-  // for more details about wire format.
+  // names copied from //net/proto2/internal/wire_format.cc
   static final int WIRETYPE_END_GROUP = 4;
   static final int WIRETYPE_FIXED32 = 5;
   static final int WIRETYPE_FIXED64 = 1;
@@ -55,19 +56,20 @@ public class ProtoBuf {
   /** Maximum number of bytes for VARINT wire format (64 bit, 7 bit/byte) */
   private static final int VARINT_MAX_BYTES = 10;
   
+  private static Long[] SMALL_NUMBERS = {
+      new Long(0), new Long(1), new Long(2), new Long(3), new Long(4),
+      new Long(5), new Long(6), new Long(7), new Long(8), new Long(9),
+      new Long(10), new Long(11), new Long(12), new Long(13), new Long(14),
+      new Long(15)};
+
   private ProtoBufType msgType;
-  private final IntMap values;
+  private final Vector values = new Vector();
   
   /** 
    * Wire types picked up on the wire or implied by setters (if no other
    * type information is available.
    */
-  private final IntMap wireTypes;
-
-  /**
-   * Saved by a call to #getCachedDataSize(false) and returned in #getCachedSize()
-   */
-  private int cachedSize = Integer.MIN_VALUE;
+  private final StringBuffer wireTypes = new StringBuffer();
 
   /**
    * Creates a protocol message according to the given description. The
@@ -76,22 +78,14 @@ public class ProtoBuf {
    */
   public ProtoBuf(ProtoBufType type) {
     this.msgType = type;
-    if (type != null) {
-      // if the type is known, use the type to create IntMaps.
-      values = type.newIntMapForProtoBuf();
-      wireTypes = type.newIntMapForProtoBuf();
-    } else {
-      values = new IntMap();
-      wireTypes = new IntMap();
-    }
   }
 
-  /**
+  /** 
    * Clears all data stored in this ProtoBuf.
    */
   public void clear() {
-    values.clear();
-    wireTypes.clear();
+    values.setSize(0);
+    wireTypes.setLength(0);
   }
   
   /**
@@ -216,7 +210,7 @@ public class ProtoBuf {
     return (int) ((Long) getObject(tag, ProtoBufType.TYPE_INT32)).longValue();
   }
 
-  /**
+  /** 
    * Returns the integer value for the given repeated tag at the given index. 
    */
   public int getInt(int tag, int index) {
@@ -311,8 +305,7 @@ public class ProtoBuf {
    * @param type the new type
    */
   void setType(ProtoBufType type) {
-    // reject if the type is already set, or value is alreay set.
-    if (!values.isEmpty() ||
+    if (values.size() != 0 || 
         (msgType != null && type != null && type != msgType)) {
       throw new IllegalArgumentException();
     }
@@ -366,8 +359,7 @@ public class ProtoBuf {
    * @return          this
    * @throws          IOException raised if an IO exception occurs in the 
    *                  underlying stream or the end of the stream is reached at 
-   *                  an unexpected position, or if we encounter bad data
-   *                  while reading.
+   *                  an unexpected position
    */
   public int parse(InputStream is, int available) throws IOException {
 
@@ -384,7 +376,11 @@ public class ProtoBuf {
         break;
       }
       int tag = (int) (tagAndType >>> 3);
-      wireTypes.put(tag, wireType);
+      while (wireTypes.length() <= tag){
+        wireTypes.append((char) ProtoBufType.TYPE_UNDEFINED);
+      }
+      wireTypes.setCharAt(tag, (char) wireType);
+
       // first step: decode tag value
       Object value;
       switch (wireType) {
@@ -394,7 +390,8 @@ public class ProtoBuf {
           if (isZigZagEncodedType(tag)) {
             v = zigZagDecode(v);
           }
-          value = v;
+          value = (v >= 0 && v < SMALL_NUMBERS.length) ? 
+              SMALL_NUMBERS[(int) v] : new Long(v);
           break;
 
         // also used for fixed values
@@ -411,7 +408,9 @@ public class ProtoBuf {
             shift += 8;
           }
 
-          value = v;
+          value = (v >= 0 && v < SMALL_NUMBERS.length) 
+              ? SMALL_NUMBERS[(int) v]
+              : new Long(v);
           break;
 
         case WIRETYPE_LENGTH_DELIMITED:
@@ -446,8 +445,7 @@ public class ProtoBuf {
           break;
 
         default:
-          throw new IOException("Unknown wire type " + wireType +
-              ", reading garbage data?");
+          throw new RuntimeException(MSG_UNSUPPORTED + wireType);
       }
       insertObject(tag, getCount(tag), value);
     }
@@ -468,9 +466,9 @@ public class ProtoBuf {
       throw new ArrayIndexOutOfBoundsException();
     }
     if (count == 1){
-      values.remove(tag);
+      values.setElementAt(null, tag);
     } else {
-      Vector v = (Vector) values.get(tag);
+      Vector v = (Vector) values.elementAt(tag);
       v.removeElementAt(index);
     }
   }
@@ -479,15 +477,12 @@ public class ProtoBuf {
    * Returns the number of repeated and optional (0..1) values for a given tag.
    * Note: Default values are not counted (and in general not considered in 
    * access methods for repeated tags), but considered for has(tag). 
-   *
-   * @param tag the tag of the field
-   * @throws ArrayIndexOutOfBoundsException when tag is < 0
    */
   public int getCount(int tag) {
-    if (tag < 0) {
-      throw new ArrayIndexOutOfBoundsException(tag);
+    if (tag >= values.size()){
+      return 0;
     }
-    Object o = values.get(tag);
+    Object o = values.elementAt(tag);
     if (o == null){
       return 0;
     }
@@ -507,69 +502,38 @@ public class ProtoBuf {
       tagType = msgType.getType(tag);
     }
 
-    if (tagType == ProtoBufType.TYPE_UNDEFINED) {
-      Integer tagTypeObj = (Integer) wireTypes.get(tag);
-      if (tagTypeObj != null) {
-        tagType = tagTypeObj.intValue();
-      }
+    if (tagType == ProtoBufType.TYPE_UNDEFINED && tag < wireTypes.length()) {
+      tagType = wireTypes.charAt(tag);
     }
-
+    
     if (tagType == ProtoBufType.TYPE_UNDEFINED && getCount(tag) > 0) {
       Object o = getObject(tag, 0, ProtoBufType.TYPE_UNDEFINED);
-
-      tagType = (o instanceof Long) || (o instanceof Boolean)
+      
+      tagType = (o instanceof Long) || (o instanceof Boolean) 
         ? WIRETYPE_VARINT : WIRETYPE_LENGTH_DELIMITED;
     }
-
+    
     return tagType;
   }
-
+  
   /** 
    * Returns the number of bytes needed to store this protocol buffer 
    */
   public int getDataSize() {
-    return getCachedDataSize(false /* don't trust cache */);
-  }
-
-  /**
-   * Each Protobuf keeps track of a <code> cachedSize </code> that is
-   * used to short circuit evaluation of its children's sizes. This value
-   * should only be trusted if you are reasonably certain it cannot be
-   * corrupt. (A corrupt cache can happen if any child ProtoBuf of this
-   * ProtoBuf has had a value set. In general, it is best to only trust
-   * the cache if you have just finished cleansing it.)
-   *
-   * <P/>The cache can be cleansed by calling this method with
-   * trustCache = false.
-   *
-   * @param trustCache if the cached size should be trusted. Set false to
-   * recompuate the size.
-   */
-  private int getCachedDataSize(boolean trustCache) {
-    if (cachedSize != Integer.MIN_VALUE && trustCache) {
-      return cachedSize;
-    }
     int size = 0;
-    IntMap.KeyIterator itr = values.keys();
-    while(itr.hasNext()) {
-      int tag = itr.next();
+    for (int tag = 0; tag <= maxTag(); tag++) {
       for (int i = 0; i < getCount(tag); i++) {
-        size += getCachedDataSize(tag, i, trustCache);
+        size += getDataSize(tag, i);
       }
-    }
-    cachedSize = size;
-
-    return cachedSize;
+    }      
+    return size;
   }
-
-  /**
-   * Returns the size of the child.
-   *
-   * @param tag tag used to determine the type of this child
-   * @param i used to determine which count this child is
-   * @param trustSizeCache passed down to #getCachedDataSize()
+  
+ 
+  /** 
+   * Returns the size of the given value 
    */
-  private int getCachedDataSize(int tag, int i, boolean trustSizeCache) {
+  private int getDataSize(int tag, int i) {
     int tagSize = getVarIntSize(tag << 3);
     
     switch(getWireType(tag)){
@@ -587,20 +551,20 @@ public class ProtoBuf {
         // take end group into account....
         return tagSize + getProtoBuf(tag, i).getDataSize() + tagSize;
     }
-
+    
     // take the object as stored
     Object o = getObject(tag, i, ProtoBufType.TYPE_UNDEFINED);
-
+    
     int contentSize;
-
-    if (o instanceof byte[]) {
+    
+    if (o instanceof byte[]){
       contentSize = ((byte[]) o).length;
     } else if (o instanceof String) {
       contentSize = encodeUtf8((String) o, null, 0);
     } else {
-      contentSize = ((ProtoBuf) o).getCachedDataSize(trustSizeCache);
+      contentSize = ((ProtoBuf) o).getDataSize();
     }
-
+    
     return tagSize + getVarIntSize(contentSize) + contentSize;
   }
 
@@ -620,93 +584,67 @@ public class ProtoBuf {
     return size;
   }
 
-  /**
+  /** 
    * Writes this and nested protocol buffers to the given output stream.
    * 
    * @param os target output stream
-   * @throws IOException thrown if there is an IOException
+   * @throws   IOException thrown if there is an IOException
    */
   public void outputTo(OutputStream os) throws IOException {
-    // We can't know what changed since we last output, so refresh the children.
-    getDataSize();
-    outputToInternal(os);
-  }
-
-  /**
-   * Recursive output method wrapped by #outputTo()
-   * 
-   * @param os target output stream
-   * @throws IOException thrown if there is an IOException
-   */
-  private void outputToInternal(OutputStream os) throws IOException {
-    IntMap.KeyIterator itr = values.keys();
-    while (itr.hasNext()) {
-      int tag = itr.next();
-      outputField(tag, os);
-    }
-  }
-
-  /**
-   * Output a field indicated by the tag to given stream.
-   *
-   * @param tag the tag of the field to output.
-   * @param os target output stream
-   * @throws IOException thrown if there is an IOException
-   */
-  private void outputField(int tag, OutputStream os) throws IOException {
-    int size = getCount(tag);
-    int wireType = getWireType(tag);
-    int wireTypeTag = (tag << 3) | wireType;
-
-    // ignore default values
-    for (int i = 0; i < size; i++) {
-      writeVarInt(os, wireTypeTag);
-      switch (wireType) {
-        case WIRETYPE_FIXED32:
-        case WIRETYPE_FIXED64:
-          long v = ((Long) getObject(tag, i, ProtoBufType.TYPE_INT64))
-              .longValue();
-          int cnt = (wireType == WIRETYPE_FIXED32) ? 4 : 8;
-          for (int b = 0; b < cnt; b++) {
-            os.write((int) (v & 0x0ff));
-            v >>= 8;
-          }
-          break;
-
-        case WIRETYPE_VARINT:
-          v = ((Long) getObject(tag, i, ProtoBufType.TYPE_INT64)).longValue();
-          if (isZigZagEncodedType(tag)) {
-            v = zigZagEncode(v);
-          }
-          writeVarInt(os, v);
-          break;
-
-        case WIRETYPE_LENGTH_DELIMITED:
-          Object o = getObject(tag, i,
-                               getType(tag) == ProtoBufType.TYPE_MESSAGE
-                               ? ProtoBufType.TYPE_UNDEFINED
-                               : ProtoBufType.TYPE_DATA);
-
-          if (o instanceof byte[]) {
-            byte[] data = (byte[]) o;
-            writeVarInt(os, data.length);
-            os.write(data);
-          } else {
-
-            ProtoBuf msg = (ProtoBuf) o;
-            writeVarInt(os, msg.getCachedDataSize(true));
-            msg.outputToInternal(os);
-          }
-          break;
-
-        case WIRETYPE_START_GROUP:
-          ((ProtoBuf) getObject(tag, i, ProtoBufType.TYPE_GROUP))
-              .outputToInternal(os);
-          writeVarInt(os, (tag << 3) | WIRETYPE_END_GROUP);
-          break;
+    for (int tag = 0; tag <= maxTag(); tag++) {
+      int size = getCount(tag);
+      int wireType = getWireType(tag);
+      
+      // ignore default values
+      for (int i = 0; i < size; i++) {
+        writeVarInt(os, (tag << 3) | wireType);
+
+        switch (wireType) {
+          case WIRETYPE_FIXED32:
+          case WIRETYPE_FIXED64:
+            long v = ((Long) getObject(tag, i, ProtoBufType.TYPE_INT64))
+                .longValue();
+            int cnt = (wireType == WIRETYPE_FIXED32) ? 4 : 8;
+            for (int b = 0; b < cnt; b++) {
+              os.write((int) (v & 0x0ff));
+              v >>= 8;
+            }
+            break;
 
-        default:
-          throw new IllegalArgumentException();
+          case WIRETYPE_VARINT:
+            v = ((Long) getObject(tag, i, ProtoBufType.TYPE_INT64)).longValue();
+            if (isZigZagEncodedType(tag)) {
+              v = zigZagEncode(v);
+            }
+            writeVarInt(os, v);
+            break;
+
+          case WIRETYPE_LENGTH_DELIMITED:
+            Object o = getObject(tag, i, 
+                getType(tag) == ProtoBufType.TYPE_MESSAGE 
+                ? ProtoBufType.TYPE_UNDEFINED
+                : ProtoBufType.TYPE_DATA);
+            
+            if (o instanceof byte[]){
+              byte[] data = (byte[]) o;
+              writeVarInt(os, data.length);
+              os.write(data);
+            } else {
+              ProtoBuf msg = (ProtoBuf) o;
+              writeVarInt(os, msg.getDataSize());
+              msg.outputTo(os);
+            }
+            break;
+
+          case WIRETYPE_START_GROUP:
+            ((ProtoBuf) getObject(tag, i, ProtoBufType.TYPE_GROUP))
+                .outputTo(os);
+            writeVarInt(os, (tag << 3) | WIRETYPE_END_GROUP);
+            break;
+            
+          default:
+            throw new IllegalArgumentException();
+        }
       }
     }
   }
@@ -755,12 +693,12 @@ public class ProtoBuf {
     outputTo(baos);
     return baos.toByteArray();
   }
-
+  
   /**
    * Returns the largest tag id used in this message (to simplify testing). 
    */
   public int maxTag() {
-    return values.maxKey();
+    return values.size() - 1;
   }
 
   /** 
@@ -788,7 +726,8 @@ public class ProtoBuf {
    * Sets the given tag to the given long value.
    */
   public void setLong(int tag, long value) {
-    setObject(tag, value);
+    setObject(tag, value >= 0 && value < SMALL_NUMBERS.length
+        ? SMALL_NUMBERS[(int) value] : new Long(value));
   }
 
   /**
@@ -856,7 +795,8 @@ public class ProtoBuf {
    * Inserts the given long value for the given tag at the given index. 
    */
   public void insertLong(int tag, int index, long value) {
-    insertObject(tag, index, value);
+    insertObject(tag, index, value >= 0 && value < SMALL_NUMBERS.length
+        ? SMALL_NUMBERS[(int) value] : new Long(value));
   }
 
   /**
@@ -939,8 +879,8 @@ public class ProtoBuf {
         case ProtoBufType.TYPE_GROUP:
         case ProtoBufType.TYPE_MESSAGE:
           if (msgType == null || msgType.getData(tag) == null ||
-              ((ProtoBuf) object).msgType == null ||
-              ((ProtoBuf) object).msgType.equals(msgType.getData(tag))) {
+              ((ProtoBuf) object).msgType == null || 
+              ((ProtoBuf) object).msgType == msgType.getData(tag)) {
             return;
           }
       }
@@ -1004,7 +944,7 @@ public class ProtoBuf {
       throw new ArrayIndexOutOfBoundsException();
     }
 
-    Object o = values.get(tag);
+    Object o = values.elementAt(tag);
     
     Vector v = null;
     if (o instanceof Vector) {
@@ -1085,14 +1025,14 @@ public class ProtoBuf {
     if (count == 0) {
       setObject(tag, o);
     } else {
-      Object curr = values.get(tag);
+      Object curr = values.elementAt(tag);
       Vector v;
       if (curr instanceof Vector) {
         v = (Vector) curr;
       } else {
         v = new Vector();
         v.addElement(curr);
-        values.put(tag, v);
+        values.setElementAt(v, tag);
       }
       v.insertElementAt(o, index);
     }
@@ -1102,7 +1042,7 @@ public class ProtoBuf {
    * Converts the object if a better suited class exists for the given .proto 
    * type. If the formats are not compatible, an exception is thrown.
    */
-  private static Object convert(Object obj, int tagType) {
+  private Object convert(Object obj, int tagType) {
     switch (tagType) {
       case ProtoBufType.TYPE_UNDEFINED:
         return obj;
@@ -1128,7 +1068,7 @@ public class ProtoBuf {
       case ProtoBufType.TYPE_SINT32:
       case ProtoBufType.TYPE_SINT64:
         if (obj instanceof Boolean) {
-          return ((Boolean) obj).booleanValue() ? 1 : 0;
+          return SMALL_NUMBERS[((Boolean) obj).booleanValue() ? 1 : 0];
         }
         return obj;
       case ProtoBufType.TYPE_DATA:
@@ -1213,13 +1153,13 @@ public class ProtoBuf {
    * values.
    */
   private void setObject(int tag, Object o) {
-    if (tag < 0) {
-      throw new ArrayIndexOutOfBoundsException();
+    if (values.size() <= tag) {
+      values.setSize(tag + 1);
     }
     if (o != null) {
       assertTypeMatch(tag, o);
     }
-    values.put(tag, o);
+    values.setElementAt(o, tag);
   }
 
   /** 
diff --git a/src/com/google/common/io/protocol/ProtoBufType.java b/src/com/google/common/io/protocol/ProtoBufType.java
index 728346f..4b6408e 100644
--- a/src/com/google/common/io/protocol/ProtoBufType.java
+++ b/src/com/google/common/io/protocol/ProtoBufType.java
@@ -6,8 +6,9 @@ package com.google.common.io.protocol;
 import java.util.*;
 
 /**
- * This class can be used to create a memory model of a .proto file.
- * 
+ * This class can be used to create a memory model of a .proto file. Currently, 
+ * it is assumed that tags ids are not large. This could be improved by storing 
+ * a start offset, relaxing the assumption to a dense number space.
  */
 public class ProtoBufType {
   // Note: Values 0..15 are reserved for wire types!
@@ -41,46 +42,11 @@ public class ProtoBufType {
   public static final int REQUIRED = 0x100;
   public static final int OPTIONAL = 0x200;
   public static final int REPEATED = 0x400;
-
-  private final IntMap types = new IntMap();
-
-  /*
-   * A struct to store field type and default object.
-   * Two TypeInfo objects are equal iff both have the
-   * euqal type and object.
-   */
-  static class TypeInfo {
-    private int type;
-    private Object data;
-    TypeInfo(int t, Object d) {
-      type = t;
-      data = d;
-    }
-
-    public int hashCode() {
-      return type;
-    }
-
-    public boolean equals(Object obj) {
-      if (this == obj) {
-        return true;
-      }
-      if (obj == null || !(obj instanceof TypeInfo)) {
-        return false;
-      }
-      TypeInfo peerTypeInfo = (TypeInfo) obj;
-      return  type == peerTypeInfo.type &&
-          (data == peerTypeInfo.data ||
-           (data != null && data.equals(peerTypeInfo.data)));
-    }
-
-    public String toString() {
-      return "TypeInfo{type=" + type + ", data=" + data + "}";
-    }
-  };
-
+  
+  private final StringBuffer types = new StringBuffer();
+  private final Vector data = new Vector();
   private final String typeName;
-
+  
   /**
    * Empty constructor.
    */
@@ -108,36 +74,35 @@ public class ProtoBufType {
    * @return               this is returned to permit cascading
    */
   public ProtoBufType addElement(int optionsAndType, int tag, Object data) {
-    types.put(tag, new TypeInfo(optionsAndType, data));
-    return this;
-  }
+    while (types.length() <= tag) {
+      types.append((char) TYPE_UNDEFINED);
+      this.data.addElement(null);
+    }
+    types.setCharAt(tag, (char) optionsAndType);
+    this.data.setElementAt(data, tag);
 
-  /**
-   * Returns a IntMap that has the same lower buffer size as types.
-   * This is for ProtoBuf to create IntMap with pre-allocated
-   * internal buffer.
-   */
-  /* package protected */ IntMap newIntMapForProtoBuf() {
-    return types.newIntMapWithSameBufferSize();
+    return this;
   }
-
+  
   /** 
    * Returns the type for the given tag id (without modifiers such as OPTIONAL,
    * REPEATED). For undefined tags, TYPE_UNDEFINED is returned.
    */  
   public int getType(int tag) {
-    TypeInfo typeInfo = (TypeInfo) types.get(tag);
-    return typeInfo == null ? TYPE_UNDEFINED : typeInfo.type & MASK_TYPE;
+    return (tag < 0 || tag >= types.length()) 
+        ? TYPE_UNDEFINED
+        : (types.charAt(tag) & MASK_TYPE);
   }
   
-  /**
+  /** 
    * Returns a bit combination of the modifiers for the given tag id 
    * (OPTIONAL, REPEATED, REQUIRED). For undefined tags, OPTIONAL|REPEATED
    * is returned.
-   */
+   */  
   public int getModifiers(int tag) {
-    TypeInfo typeInfo = (TypeInfo) types.get(tag);
-    return typeInfo == null ? (OPTIONAL | REPEATED) : typeInfo.type & MASK_MODIFIER;
+    return (tag < 0 || tag >= types.length()) 
+        ? (OPTIONAL | REPEATED)
+        : (types.charAt(tag) & MASK_MODIFIER);
   }
   
   /**
@@ -146,15 +111,14 @@ public class ProtoBufType {
    * tags, null is returned.
    */
   public Object getData(int tag) {
-    TypeInfo typeInfo = (TypeInfo) types.get(tag);
-    return typeInfo == null ? typeInfo : typeInfo.data;
+    return (tag < 0 || tag >= data.size()) ? null : data.elementAt(tag);
   }
   
   /**
    * Returns the type name set in the constructor for debugging purposes.
    */
   public String toString() {
-    return "ProtoBufType Name: " + typeName;
+    return typeName;
   }
   
   /**
@@ -174,9 +138,9 @@ public class ProtoBufType {
     }
     ProtoBufType other = (ProtoBufType) object;
 
-    return types.equals(other.types);
+    return stringEquals(types, other.types);
   }
-
+   
   /**
    * {@inheritDoc}
    */
@@ -187,4 +151,20 @@ public class ProtoBufType {
       return super.hashCode();
     }
   }
+
+  public static boolean stringEquals(CharSequence a, CharSequence b) {
+    if (a == b) return true;
+    int length;
+    if (a != null && b != null && (length = a.length()) == b.length()) {
+      if (a instanceof String && b instanceof String) {
+        return a.equals(b);
+      } else {
+        for (int i = 0; i < length; i++) {
+          if (a.charAt(i) != b.charAt(i)) return false;
+        }
+        return true;
+      }
+    }
+    return false;
+  }
 }
diff --git a/src/com/google/common/io/protocol/ProtoBufUtil.java b/src/com/google/common/io/protocol/ProtoBufUtil.java
index b47e79c..72e1bca 100644
--- a/src/com/google/common/io/protocol/ProtoBufUtil.java
+++ b/src/com/google/common/io/protocol/ProtoBufUtil.java
@@ -22,25 +22,6 @@ public final class ProtoBufUtil {
     }
   }
 
-  /** Convenience method to return a string value from of a proto or null. */
-  public static String getProtoValueOrNull(ProtoBuf proto, int tag) {
-    try {
-      return (proto != null && proto.has(tag)) ? proto.getString(tag) : null;
-    } catch (ClassCastException e) {
-      return null;
-    }
-  }
-
-  /** Convenience method to return a string value from of a proto or null. */
-  public static String getProtoValueOrNull(ProtoBuf proto, int tag, int index) {
-    try {
-      return (proto != null && proto.has(tag) && proto.getCount(tag) > index) ?
-          proto.getString(tag, index) : null;
-    } catch (ClassCastException e) {
-      return null;
-    }
-  }
-
   /** Convenience method to return a string value from of a sub-proto or "". */
   public static String getSubProtoValueOrEmpty(
       ProtoBuf proto, int sub, int tag) {