com.crankuptheamps.client.NVFIXBuilder Maven / Gradle / Ivy

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////////////////////////////////////////////////////////////////////////////
//
// Copyright (c) 2010-2021 60East Technologies Inc., All Rights Reserved.
//
// This computer software is owned by 60East Technologies Inc. and is
// protected by U.S. copyright laws and other laws and by international
// treaties.  This computer software is furnished by 60East Technologies
// Inc. pursuant to a written license agreement and may be used, copied,
// transmitted, and stored only in accordance with the terms of such
// license agreement and with the inclusion of the above copyright notice.
// This computer software or any other copies thereof may not be provided
// or otherwise made available to any other person.
//
// U.S. Government Restricted Rights.  This computer software: (a) was
// developed at private expense and is in all respects the proprietary
// information of 60East Technologies Inc.; (b) was not developed with
// government funds; (c) is a trade secret of 60East Technologies Inc.
// for all purposes of the Freedom of Information Act; and (d) is a
// commercial item and thus, pursuant to Section 12.212 of the Federal
// Acquisition Regulations (FAR) and DFAR Supplement Section 227.7202,
// Government's use, duplication or disclosure of the computer software
// is subject to the restrictions set forth by 60East Technologies Inc..
//
////////////////////////////////////////////////////////////////////////////

package com.crankuptheamps.client;

import java.nio.charset.StandardCharsets;
import com.crankuptheamps.client.exception.CommandException;

/**
 * Used to build up message strings for NVFIX.
 */

public class NVFIXBuilder
{
    /**
     * we'll repeatedly double capacity when growth is required.
     * starting at less than zero doesn't work,
     * capacity won't initialize to anything less than this value.
     */
    private static final int MIN_CAPACITY = 8;

    private byte[] _buffer   = null;
    private int    _size     = 0;
    private int    _capacity = 1024;
    private final byte   _fieldSeparator;

    public NVFIXBuilder(final int capacity, final byte fieldSeparator)
    {
        _fieldSeparator = fieldSeparator;
        _capacity = capacity < MIN_CAPACITY ? MIN_CAPACITY : capacity;
        this._buffer = new byte[_capacity];
    }

    /**
     * Clears the current builder, resetting it to empty.
     */
    public void clear()
    {
        _size = 0;
    }

    /**
     * Returns the number of bytes in the byte array containing the NVFIX message.
     *
     * @return number of valid bytes in the byte array
     */
    public int getSize()
    {
        return _size;
    }

    /**
     * Returns the byte array containing the NVFIX message. The number of valid
     * bytes within the buffer is returned from getSize().
     *
     * @return byte array containing the NVFIX message
     */
    public byte[] getBytes()
    {
        return _buffer;
    }

    private void checkCapacity(int bytesNeeded)
    {
        if(_capacity - _size < bytesNeeded)
        {
            // Not enough capacity left, must resize
            while (_capacity - _size < bytesNeeded)
            {
                _capacity = _capacity * 2;
            }

            byte[] newbuf = new byte[_capacity];
            System.arraycopy(_buffer, 0, newbuf, 0, _size);

            _buffer = newbuf;
        }
    }

    /**
     * Appends a tag and value pair contained within a byte buffer to the FIX message.
     *
     * @param tag
     *          the String NVFIX tag to append
     * @param value
     *          the byte buffer containing the FIX value to append.
     * @param offset
     *          the starting location of the value inside the byte buffer.
     * @param length
     *          the length of the value inside the byte buffer.
     * @throws CommandException
     *          if the tag or value argument is not convertible to ISO-8859-1.
     * @return a reference to this object.
     */
    public NVFIXBuilder append(String tag, byte[] value, int offset, int length)
    throws CommandException
    {
        return append(toBytes(tag), value, offset, length);
    }


    /**
     * Appends a tag and value pair to the FIX message.
     *
     * @param tag
     *           the string FIX tag to append
     * @param value
     *           the FIX value for the tag to append. The value will be converted
     *           to an ISO-8859-1 byte array for writing.
     * @throws CommandException
     *            if the tag or value argument is not convertible to ISO-8859-1.
     * @return a reference to this object.
     */
    public NVFIXBuilder append(String tag, String value) throws CommandException
    {
        return append(toBytes(tag), toBytes(value));
    }

// PRIVATE METHODS 

    private NVFIXBuilder append(final byte[] tag, final byte[] val)
    {
        return append(tag, val, 0, val.length);
    }

    private NVFIXBuilder append(final byte[] tag, final byte[] val, final int valOffset, int valLength)
    {
        // capacity
        final int sizeNeeded = tag.length + 1 + valLength + 1;
        checkCapacity(sizeNeeded);
        int writeIndex = _size;
        // tag
        System.arraycopy(tag, 0, _buffer, writeIndex, tag.length);
        writeIndex += tag.length;
        // equals
        _buffer[writeIndex] = '=';
        ++writeIndex;
        // value
        System.arraycopy(val, valOffset, _buffer, writeIndex, valLength);
        writeIndex += valLength;
        // delimiter
        _buffer[writeIndex] = _fieldSeparator;
        _size += sizeNeeded;
        return this;
    }

    private static byte[] toBytes(final String datum)
    {
        return datum.getBytes(StandardCharsets.ISO_8859_1);
    }

}