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java.lang.Object
   |
   +----edu.utah.janos.antsr.core.TypeID

Summary

public final class  TypeID
     extends java.lang.Object
{
          // Fields 2
     private final byte[] bits;
     private static final Hashtable interned;

          // Constructors 3
     private TypeID();
     private TypeID(boolean, byte[], int);
     public TypeID(byte[], int);

          // Methods 9
     public static TypeID computeFromIDs(TypeID[]);
     public static void sortArray(TypeID[]);
     public static TypeID wrap(byte[]);

     public int compare(TypeID);
     public boolean equals(Object);
     public int hashCode();
     public TypeID intern();
     public String toString();
     public byte[] unwrap();
}

Capsule, CapsuleClass, CodeGroup and Protocol identifiers. This class wraps 128 bit MD5 hashes stored in byte arrays.

See the text file On_IDs.txt for a description of how these IDs are used.

Author:

David Wetherall

Cross Reference

Returned By:

CapsuleClass.computeMethodID(), CapsuleClass.protocolID(), Node.findMID(), Node.findPID(), TypeID.computeFromIDs(), TypeID.intern(), TypeID.wrap(), Xdr.TYPEID()

   private final byte[] bits

We only use the first 16 bytes (128 bits)

   private static final Hashtable interned

Table of known TypeIDs. Used to keep/find canonical versions of TypeIDs.

XXX A global table. Not clear if this really should be global.

Constructors

· TypeID

Summary  |  Top

   private TypeID() 

No-arg constructor is private to prevent construction of invalid TypeIDs.

   public TypeID(byte[] buf, 
                 int offset) 

Construct a new TypeID and initialize by deep copy.

Parameter	Description
buf	the byte[] to copy into this new TypeID.
offset	offset in buf to copy from

Throws: IndexOutOfBoundsException

if buf is too short

   private TypeID(boolean copybuf, 
                  byte[] buf, 
                  int offset) 

Construct a new type id. Use the given buffer. The copybuf argument indicates if the buffer is copied or simply pointed to.

   public int hashCode() 

Overrides:

hashCode in class Object

   public boolean equals(Object obj) 

Compare this TypeID with the given one. The given TypeID must match all 16 bytes.

Overrides:

equals in class Object

   public TypeID intern() 

Intern a TypeID and return its canonical value.

Returns:

the canonical version of this TypeID.

   public int compare(TypeID t) 

Compare two TypeIDs

Returns:

-1 (this < t), 0 (this.equals(t), 1 (this > t)

   public static void sortArray(TypeID[] ids) 

Sort an array of TypeIDs. Good for short vectors only -- uses insertion sort. Sorts the array inline.

   public static TypeID computeFromIDs(TypeID[] ids) 

Compute an ID from a vector of codeIDs.

This is done by computing a multiple-element md5 hash over a sorted list of code ids.

XXX Combine the insertion sort and the id.update() step from this function. Should only have to iterate over the list once.

Returns:

a TypeID representing this vector's ID.

   public String toString() 

Overrides:

toString in class Object

   public byte[] unwrap() 

Unwrap this TypeID, returning the inner byte array. Does not return a copy, returns the actual array.

Returns:

the byte[] representing this TypeID.

   public static TypeID wrap(byte[] buf) 

Construct and initialize by shallow copy. The different notation is meant to emphasize that a complete object is not being created but rather an existing object is being packaged for convenience.

The length of the buf is not checked.

Parameter	Description
buf	Byte[] containing an MD5 checksum.

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