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/*
 ******************************************************************************
 * Copyright (C) 1996-2014, International Business Machines Corporation and
 * others. All Rights Reserved.
 ******************************************************************************
 */

package jdk.internal.icu.impl;

import jdk.internal.icu.text.UTF16;

import java.io.DataInputStream;
import java.io.InputStream;
import java.io.IOException;


Trie implementation which stores data in char, 16 bits.

Author:synwee
See Also:
  • Trie
Since:release 2.1, Jan 01 2002
/**
 * Trie implementation which stores data in char, 16 bits.
 * @author synwee
 * @see com.ibm.icu.impl.Trie
 * @since release 2.1, Jan 01 2002
 */

 // note that i need to handle the block calculations later, since chartrie
 // in icu4c uses the same index array.
public class CharTrie extends Trie
{
    // public constructors ---------------------------------------------

    
Creates a new Trie with the settings for the trie data.


Unserialize the 32-bit-aligned input stream and use the data for the
trie.


Params:
  • inputStream – file input stream to a ICU data file, containing
                   the trie
  • dataManipulate – object which provides methods to parse the char
                       data
Throws:
@draft2.1
/**
     * <p>Creates a new Trie with the settings for the trie data.</p>
     * <p>Unserialize the 32-bit-aligned input stream and use the data for the
     * trie.</p>
     * @param inputStream file input stream to a ICU data file, containing
     *                    the trie
     * @param dataManipulate object which provides methods to parse the char
     *                        data
     * @throws IOException thrown when data reading fails
     * @draft 2.1
     */
    public CharTrie(InputStream inputStream,
                    DataManipulate dataManipulate) throws IOException
    {
        super(inputStream, dataManipulate);

        if (!isCharTrie()) {
            throw new IllegalArgumentException(
                               "Data given does not belong to a char trie.");
        }
    }

    // public methods --------------------------------------------------

    
Gets the value associated with the codepoint.
If no value is associated with the codepoint, a default value will be
returned.

Params:
  • ch – codepoint
Returns:offset to data
/**
     * Gets the value associated with the codepoint.
     * If no value is associated with the codepoint, a default value will be
     * returned.
     * @param ch codepoint
     * @return offset to data
     */
    public final char getCodePointValue(int ch)
    {
        int offset;

        // fastpath for U+0000..U+D7FF
        if(0 <= ch && ch < UTF16.LEAD_SURROGATE_MIN_VALUE) {
            // copy of getRawOffset()
            offset = (m_index_[ch >> INDEX_STAGE_1_SHIFT_] << INDEX_STAGE_2_SHIFT_)
                    + (ch & INDEX_STAGE_3_MASK_);
            return m_data_[offset];
        }

        // handle U+D800..U+10FFFF
        offset = getCodePointOffset(ch);

        // return -1 if there is an error, in this case we return the default
        // value: m_initialValue_
        return (offset >= 0) ? m_data_[offset] : m_initialValue_;
    }

    
Gets the value to the data which this lead surrogate character points
to.
Returned data may contain folding offset information for the next
trailing surrogate character.
This method does not guarantee correct results for trail surrogates.

Params:
  • ch – lead surrogate character
Returns:data value
/**
     * Gets the value to the data which this lead surrogate character points
     * to.
     * Returned data may contain folding offset information for the next
     * trailing surrogate character.
     * This method does not guarantee correct results for trail surrogates.
     * @param ch lead surrogate character
     * @return data value
     */
    public final char getLeadValue(char ch)
    {
       return m_data_[getLeadOffset(ch)];
    }

    // protected methods -----------------------------------------------

    
Parses the input stream and stores its trie content into a index and
data array


Params:
  • inputStream – data input stream containing trie data
Throws:
/**
     * <p>Parses the input stream and stores its trie content into a index and
     * data array</p>
     * @param inputStream data input stream containing trie data
     * @exception IOException thrown when data reading fails
     */
    protected final void unserialize(InputStream inputStream)
                                                throws IOException
    {
        DataInputStream input = new DataInputStream(inputStream);
        int indexDataLength = m_dataOffset_ + m_dataLength_;
        m_index_ = new char[indexDataLength];
        for (int i = 0; i < indexDataLength; i ++) {
            m_index_[i] = input.readChar();
        }
        m_data_           = m_index_;
        m_initialValue_   = m_data_[m_dataOffset_];
    }

    
Gets the offset to the data which the surrogate pair points to.

Params:
  • lead – lead surrogate
  • trail – trailing surrogate
Returns:offset to data
@draft2.1
/**
     * Gets the offset to the data which the surrogate pair points to.
     * @param lead lead surrogate
     * @param trail trailing surrogate
     * @return offset to data
     * @draft 2.1
     */
    protected final int getSurrogateOffset(char lead, char trail)
    {
        if (m_dataManipulate_ == null) {
            throw new NullPointerException(
                             "The field DataManipulate in this Trie is null");
        }

        // get fold position for the next trail surrogate
        int offset = m_dataManipulate_.getFoldingOffset(getLeadValue(lead));

        // get the real data from the folded lead/trail units
        if (offset > 0) {
            return getRawOffset(offset, (char)(trail & SURROGATE_MASK_));
        }

        // return -1 if there is an error, in this case we return the default
        // value: m_initialValue_
        return -1;
    }

    // private data members --------------------------------------------

    
Default value

/**
     * Default value
     */
    private char m_initialValue_;
    
Array of char data

/**
     * Array of char data
     */
    private char m_data_[];
}