How to convert a Java Enum using Sharpen

Question

I am trying to convert the unbound id ldap java sdk source code to c# using the sharpen converter from versant. However, I am getting an exception related to a java enum class that has several constructors and seems different than a normal .NET enum.

The error message is the following:

ERROR: /sharpened/src/com/unboundid/asn1/ASN1Messages.java:240: Enum can contain
only fields and a private constructor.

The java class looks like the following:

enum ASN1Messages
{
  /**
   * ASN.1 Boolean elements must have a value whose length is exactly one byte.
   */
  ERR_BOOLEAN_INVALID_LENGTH("ASN.1 Boolean elements must have a value whose length is exactly one byte."),



  /**
   * Unable to decode the provided byte array as an ASN.1 BER element:  {0}
   */
  ERR_ELEMENT_DECODE_EXCEPTION("Unable to decode the provided byte array as an ASN.1 BER element:  {0}"),

And the problematic method from this class is:

/**
   * Retrieves a localized version of the message.
   * This method should only be used for messages which do not take any arguments.
   *
   * @return  A localized version of the message.
   */
  public String get()
  {
    String s = MESSAGE_STRINGS.get(this);
    if (s == null)
    {

What is the best way to overcome this problem using the sharpen tool?

The full class file source code is below:

/* * Copyright 2012 UnboundID Corp. * All Rights Reserved. / / * Copyright (C) 2012 UnboundID Corp. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License (GPLv2 only) * or the terms of the GNU Lesser General Public License (LGPLv2.1 only) * as published by the Free Software Foundation. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, see http://www.gnu.org/licenses. */ package com.unboundid.asn1;

import java.text.MessageFormat;
import java.util.ResourceBundle;
import java.util.concurrent.ConcurrentHashMap;



/**
 * This enum defines a set of message keys for messages in the
 * com.unboundid.asn1 package, which correspond to messages in the
 * unboundid-ldapsdk-asn1.properties properties file.
 * <BR><BR>
 * This source file was generated from the properties file.
 * Do not edit it directly.
 */
enum ASN1Messages
{
  /**
   * ASN.1 Boolean elements must have a value whose length is exactly one byte.
   */
  ERR_BOOLEAN_INVALID_LENGTH("ASN.1 Boolean elements must have a value whose length is exactly one byte."),



  /**
   * Unable to decode the provided byte array as an ASN.1 BER element:  {0}
   */
  ERR_ELEMENT_DECODE_EXCEPTION("Unable to decode the provided byte array as an ASN.1 BER element:  {0}"),



  /**
   * The decoded length of {0,number,0} does not match the number of bytes remaining in the provided array ({1,number,0}).
   */
  ERR_ELEMENT_LENGTH_MISMATCH("The decoded length of {0,number,0} does not match the number of bytes remaining in the provided array ({1,number,0})."),



  /**
   * Invalid value length of {0,number,0} for an ASN.1 enumerated element.  Enumerated element values must have a length between 1 and 4 bytes.
   */
  ERR_ENUMERATED_INVALID_LENGTH("Invalid value length of {0,number,0} for an ASN.1 enumerated element.  Enumerated element values must have a length between 1 and 4 bytes."),



  /**
   * Invalid value length of {0,number,0} for an ASN.1 integer element.  Integer element values must have a length between 1 and 4 bytes.
   */
  ERR_INTEGER_INVALID_LENGTH("Invalid value length of {0,number,0} for an ASN.1 integer element.  Integer element values must have a length between 1 and 4 bytes."),



  /**
   * Invalid value length of {0,number,0} for an ASN.1 long element.  Long element values must have a length between 1 and 8 bytes.
   */
  ERR_LONG_INVALID_LENGTH("Invalid value length of {0,number,0} for an ASN.1 long element.  Long element values must have a length between 1 and 8 bytes."),



  /**
   * ASN.1 null elements must not have a value.
   */
  ERR_NULL_HAS_VALUE("ASN.1 null elements must not have a value."),



  /**
   * The end of the input stream was reached before the first length byte could be read.
   */
  ERR_READ_END_BEFORE_FIRST_LENGTH("The end of the input stream was reached before the first length byte could be read."),



  /**
   * The end of the input stream was reached before the full length could be read.
   */
  ERR_READ_END_BEFORE_LENGTH_END("The end of the input stream was reached before the full length could be read."),



  /**
   * The end of the input stream was reached before the full value could be read.
   */
  ERR_READ_END_BEFORE_VALUE_END("The end of the input stream was reached before the full value could be read."),



  /**
   * The element indicated that it required {0,number,0} bytes to hold the value, but this is larger than the maximum of {1,number,0} bytes that the client has been configured to accept.
   */
  ERR_READ_LENGTH_EXCEEDS_MAX("The element indicated that it required {0,number,0} bytes to hold the value, but this is larger than the maximum of {1,number,0} bytes that the client has been configured to accept."),



  /**
   * The element indicated that it required {0,number,0} bytes to encode the multi-byte length, but multi-byte lengths must be encoded in 1 to 4 bytes.
   */
  ERR_READ_LENGTH_TOO_LONG("The element indicated that it required {0,number,0} bytes to encode the multi-byte length, but multi-byte lengths must be encoded in 1 to 4 bytes."),



  /**
   * Unable to decode the provided byte array as a sequence:  {0}
   */
  ERR_SEQUENCE_BYTES_DECODE_EXCEPTION("Unable to decode the provided byte array as a sequence:  {0}"),



  /**
   * Unable to decode the provided byte array as a sequence because the decoded length of an embedded element exceeds the number of bytes remaining.
   */
  ERR_SEQUENCE_BYTES_DECODE_LENGTH_EXCEEDS_AVAILABLE("Unable to decode the provided byte array as a sequence because the decoded length of an embedded element exceeds the number of bytes remaining."),



  /**
   * Unable to decode the provided ASN.1 element {0} as a sequence:  {1}
   */
  ERR_SEQUENCE_DECODE_EXCEPTION("Unable to decode the provided ASN.1 element {0} as a sequence:  {1}"),



  /**
   * Unable to decode the provided ASN.1 element {0} as a sequence because the decoded length of an embedded element exceeds the number of bytes remaining.
   */
  ERR_SEQUENCE_DECODE_LENGTH_EXCEEDS_AVAILABLE("Unable to decode the provided ASN.1 element {0} as a sequence because the decoded length of an embedded element exceeds the number of bytes remaining."),



  /**
   * Unable to decode the provided byte array as a set:  {0}
   */
  ERR_SET_BYTES_DECODE_EXCEPTION("Unable to decode the provided byte array as a set:  {0}"),



  /**
   * Unable to decode the provided byte array as a set because the decoded length of an embedded element exceeds the number of bytes remaining.
   */
  ERR_SET_BYTES_DECODE_LENGTH_EXCEEDS_AVAILABLE("Unable to decode the provided byte array as a set because the decoded length of an embedded element exceeds the number of bytes remaining."),



  /**
   * Unable to decode the provided ASN.1 element {0} as a set:  {1}
   */
  ERR_SET_DECODE_EXCEPTION("Unable to decode the provided ASN.1 element {0} as a set:  {1}"),



  /**
   * Unable to decode the provided ASN.1 element {0} as a set because the decoded length of an embedded element exceeds the number of bytes remaining.
   */
  ERR_SET_DECODE_LENGTH_EXCEEDS_AVAILABLE("Unable to decode the provided ASN.1 element {0} as a set because the decoded length of an embedded element exceeds the number of bytes remaining."),



  /**
   * The ASN.1 stream reader has already read beyond the end of this sequence (expected sequence of length {0} to end at {1} bytes into the stream, but {2} bytes have already been read from the stream).
   */
  ERR_STREAM_READER_SEQUENCE_READ_PAST_END("The ASN.1 stream reader has already read beyond the end of this sequence (expected sequence of length {0} to end at {1} bytes into the stream, but {2} bytes have already been read from the stream)."),



  /**
   * The ASN.1 stream reader has already read beyond the end of this set (expected set of length {0} to end at {1} bytes into the stream, but {2} bytes have already been read from the stream).
   */
  ERR_STREAM_READER_SET_READ_PAST_END("The ASN.1 stream reader has already read beyond the end of this set (expected set of length {0} to end at {1} bytes into the stream, but {2} bytes have already been read from the stream).");



  /**
   * The resource bundle that will be used to load the properties file.
   */
  private static final ResourceBundle RESOURCE_BUNDLE;
  static
  {
    ResourceBundle rb = null;
    try
    {
      rb = ResourceBundle.getBundle("unboundid-ldapsdk-asn1");
    } catch (Exception e) {}
    RESOURCE_BUNDLE = rb;
  }



  /**
   * The map that will be used to hold the unformatted message strings, indexed by property name.
   */
  private static final ConcurrentHashMap<ASN1Messages,String> MESSAGE_STRINGS = new ConcurrentHashMap<ASN1Messages,String>();



  /**
   * The map that will be used to hold the message format objects, indexed by property name.
   */
  private static final ConcurrentHashMap<ASN1Messages,MessageFormat> MESSAGES = new ConcurrentHashMap<ASN1Messages,MessageFormat>();



  // The default text for this message
  private final String defaultText;



  /**
   * Creates a new message key.
   */
  private ASN1Messages(final String defaultText)
  {
    this.defaultText = defaultText;
  }



  /**
   * Retrieves a localized version of the message.
   * This method should only be used for messages which do not take any arguments.
   *
   * @return  A localized version of the message.
   */
  public String get()
  {
    String s = MESSAGE_STRINGS.get(this);
    if (s == null)
    {
      if (RESOURCE_BUNDLE == null)
      {
        return defaultText;
      }
      else
      {
        try
        {
          s = RESOURCE_BUNDLE.getString(name());
        }
        catch (final Exception e)
        {
          s = defaultText;
        }
        MESSAGE_STRINGS.putIfAbsent(this, s);
      }
    }
    return s;
  }



  /**
   * Retrieves a localized version of the message.
   *
   * @param  args  The arguments to use to format the message.
   *
   * @return  A localized version of the message.
   */
  public String get(final Object... args)
  {
    MessageFormat f = MESSAGES.get(this);
    if (f == null)
    {
      if (RESOURCE_BUNDLE == null)
      {
        f = new MessageFormat(defaultText);
      }
      else
      {
        try
        {
          f = new MessageFormat(RESOURCE_BUNDLE.getString(name()));
        }
        catch (final Exception e)
        {
          f = new MessageFormat(defaultText);
        }
      }
      MESSAGES.putIfAbsent(this, f);
    }
    synchronized (f)
    {
      return f.format(args);
    }
  }



  /**
   * Retrieves a string representation of this message key.
   *
   * @return  A string representation of this message key.
   */
  @Override()
  public String toString()
  {
    return get();
  }
}

Answer 1

The get() methods seem to be included to output the String corresponding with each enumerated value.

I ran Sharpen on the above code but with the get() and toString() methods commented out. This conversion succeeds, but the strings associated with the enum values are not transferred to the C# file.

So, if it is doable with a reasonable amount of effort, I would recommend to split the Java code into a pure enum file without the associated strings, and a static helper class holding a map for enum-to-String conversion and implementing the get functionality.

If the enum is included in the refactored get method signatures,

ASN1MessagesHelper.get(ASN1Messages mess)

the Java functionality to invoke get() on the enum could still be mimicked by afterwards modifying the obtained C# code:

ASN1MessagesHelper.Get(ASN1Messages mess) 
=> ASN1MessagesHelper.Get(this ASN1Messages mess)

Answer 2

According to your enum declaration, you have the modifier private on your enum constructor. I think this is not valid. Try this constructor instead:

ASN1Messages(final String defaultText) {
  this.defaultText = defaultText;
}

Answer 3

I am wondering if Sharpen supports such an enum implementation. Here is the source code, from what I understand, it seems to throw an exception as soon as a public methods is found in an enum :

private boolean processEnumType(TypeDeclaration node) {
    if (!isEnum(node)) {
        return false;
    }
    final CSEnum theEnum = new CSEnum(typeName(node));
    mapVisibility(node, theEnum);
    mapJavadoc(node, theEnum);
    addType(theEnum);

    node.accept(new ASTVisitor() {
        public boolean visit(VariableDeclarationFragment node) {
            theEnum.addValue(identifier(node.getName()));
            return false;
        }

        @Override
        public boolean visit(MethodDeclaration node) {
            if (node.isConstructor() && isPrivate(node)) {
                return false;
            }
            unsupportedConstruct(node, "Enum can contain only fields and a private constructor.");
            return false;
        }
    });
    return true;
}

But, this link http://tracker.db4o.com/browse/COR-496 seems to confirm that this works for public getters. That is, if you respect this construction :

enum ASN1Messages {
    /**
     * ASN.1 Boolean elements must have a value whose length is exactly one byte.
     */
    ERR_BOOLEAN_INVALID_LENGTH("ASN.1 Boolean elements must have a value whose length is exactly one byte."),


    /**
     * Unable to decode the provided byte array as an ASN.1 BER element:  {0}
     */
    ERR_ELEMENT_DECODE_EXCEPTION("Unable to decode the provided byte array as an ASN.1 BER element:  {0}"),;

    private String s;

    ASN1Messages(String s) {
        this.s = s;
    }

    /**
     * Retrieves a localized version of the message.
     * This method should only be used for messages which do not take any arguments.
     *
     * @return A localized version of the message.
     */
    public String get() {
        return s;
    }
}