/*

 * Copyright (c) 1999, 2003, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code 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

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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/*

 *

 * (C) Copyright Taligent, Inc. 1996, 1997 - All Rights Reserved

 * (C) Copyright IBM Corp. 1996 - 2002 - All Rights Reserved

 *

 * The original version of this source code and documentation

 * is copyrighted and owned by Taligent, Inc., a wholly-owned

 * subsidiary of IBM. These materials are provided under terms

 * of a License Agreement between Taligent and Sun. This technology

 * is protected by multiple US and International patents.

 *

 * This notice and attribution to Taligent may not be removed.

 * Taligent is a registered trademark of Taligent, Inc.

 */

package java.text;

import java.io.*;

import java.security.AccessController;

import java.security.PrivilegedActionException;

import java.security.PrivilegedExceptionAction;

import java.util.MissingResourceException;

import sun.text.CompactByteArray;

import sun.text.SupplementaryCharacterData;

/**

 * This is the class that represents the list of known words used by

 * DictionaryBasedBreakIterator.  The conceptual data structure used

 * here is a trie: there is a node hanging off the root node for every

 * letter that can start a word.  Each of these nodes has a node hanging

 * off of it for every letter that can be the second letter of a word

 * if this node is the first letter, and so on.  The trie is represented

 * as a two-dimensional array that can be treated as a table of state

 * transitions.  Indexes are used to compress this array, taking

 * advantage of the fact that this array will always be very sparse.

 */

class BreakDictionary {

    //=========================================================================

    // data members

    //=========================================================================

    /**

      * The version of the dictionary that was read in.

      */

    private static int supportedVersion = 1;

    /**

     * Maps from characters to column numbers.  The main use of this is to

     * avoid making room in the array for empty columns.

     */

    private CompactByteArray columnMap = null;

    private SupplementaryCharacterData supplementaryCharColumnMap = null;

    /**

     * The number of actual columns in the table

     */

    private int numCols;

    /**

     * Columns are organized into groups of 32.  This says how many

     * column groups.  (We could calculate this, but we store the

     * value to avoid having to repeatedly calculate it.)

     */

    private int numColGroups;

    /**

     * The actual compressed state table.  Each conceptual row represents

     * a state, and the cells in it contain the row numbers of the states

     * to transition to for each possible letter.  0 is used to indicate

     * an illegal combination of letters (i.e., the error state).  The

     * table is compressed by eliminating all the unpopulated (i.e., zero)

     * cells.  Multiple conceptual rows can then be doubled up in a single

     * physical row by sliding them up and possibly shifting them to one

     * side or the other so the populated cells don't collide.  Indexes

     * are used to identify unpopulated cells and to locate populated cells.

     */

    private short[] table = null;

    /**

     * This index maps logical row numbers to physical row numbers

     */

    private short[] rowIndex = null;

    /**

     * A bitmap is used to tell which cells in the comceptual table are

     * populated.  This array contains all the unique bit combinations

     * in that bitmap.  If the table is more than 32 columns wide,

     * successive entries in this array are used for a single row.

     */

    private int[] rowIndexFlags = null;

    /**

     * This index maps from a logical row number into the bitmap table above.

     * (This keeps us from storing duplicate bitmap combinations.)  Since there

     * are a lot of rows with only one populated cell, instead of wasting space

     * in the bitmap table, we just store a negative number in this index for

     * rows with one populated cell.  The absolute value of that number is

     * the column number of the populated cell.

     */

    private short[] rowIndexFlagsIndex = null;

    /**

     * For each logical row, this index contains a constant that is added to

     * the logical column number to get the physical column number

     */

    private byte[] rowIndexShifts = null;

    //=========================================================================

    // deserialization

    //=========================================================================

    public BreakDictionary(String dictionaryName)

        throws IOException, MissingResourceException {

        readDictionaryFile(dictionaryName);

    }

    private void readDictionaryFile(final String dictionaryName)

        throws IOException, MissingResourceException {

        BufferedInputStream in;

        try {

            in = (BufferedInputStream)AccessController.doPrivileged(

                new PrivilegedExceptionAction() {

                    public Object run() throws Exception {

                        return new BufferedInputStream(getClass().getResourceAsStream("/sun/text/resources/" + dictionaryName));

                    }

                }

            );

        }

        catch (PrivilegedActionException e) {

            throw new InternalError(e.toString());

        }

        byte[] buf = new byte[8];

        if (in.read(buf) != 8) {

            throw new MissingResourceException("Wrong data length",

                                               dictionaryName, "");

        }

        // check vesion

        int version = BreakIterator.getInt(buf, 0);

        if (version != supportedVersion) {

            throw new MissingResourceException("Dictionary version(" + version + ") is unsupported",

                                                           dictionaryName, "");

        }

        // get data size

        int len = BreakIterator.getInt(buf, 4);

        buf = new byte[len];

        if (in.read(buf) != len) {

            throw new MissingResourceException("Wrong data length",

                                               dictionaryName, "");

        }

        // close the stream

        in.close();

        int l;

        int offset = 0;

        // read in the column map for BMP characteres (this is serialized in

        // its internal form: an index array followed by a data array)

        l = BreakIterator.getInt(buf, offset);

        offset += 4;

        short[] temp = new short[l];

        for (int i = 0; i < l; i++, offset+=2) {

            temp[i] = BreakIterator.getShort(buf, offset);

        }

        l = BreakIterator.getInt(buf, offset);

        offset += 4;

        byte[] temp2 = new byte[l];

        for (int i = 0; i < l; i++, offset++) {

            temp2[i] = buf[offset];

        }

        columnMap = new CompactByteArray(temp, temp2);

        // read in numCols and numColGroups

        numCols = BreakIterator.getInt(buf, offset);

        offset += 4;

        numColGroups = BreakIterator.getInt(buf, offset);

        offset += 4;

        // read in the row-number index

        l = BreakIterator.getInt(buf, offset);

        offset += 4;

        rowIndex = new short[l];

        for (int i = 0; i < l; i++, offset+=2) {

            rowIndex[i] = BreakIterator.getShort(buf, offset);

        }

        // load in the populated-cells bitmap: index first, then bitmap list

        l = BreakIterator.getInt(buf, offset);

        offset += 4;

        rowIndexFlagsIndex = new short[l];

        for (int i = 0; i < l; i++, offset+=2) {

            rowIndexFlagsIndex[i] = BreakIterator.getShort(buf, offset);

        }

        l = BreakIterator.getInt(buf, offset);

        offset += 4;

        rowIndexFlags = new int[l];

        for (int i = 0; i < l; i++, offset+=4) {

            rowIndexFlags[i] = BreakIterator.getInt(buf, offset);

        }

        // load in the row-shift index

        l = BreakIterator.getInt(buf, offset);

        offset += 4;

        rowIndexShifts = new byte[l];

        for (int i = 0; i < l; i++, offset++) {

            rowIndexShifts[i] = buf[offset];

        }

        // load in the actual state table

        l = BreakIterator.getInt(buf, offset);

        offset += 4;

        table = new short[l];

        for (int i = 0; i < l; i++, offset+=2) {

            table[i] = BreakIterator.getShort(buf, offset);

        }

        // finally, prepare the column map for supplementary characters

        l = BreakIterator.getInt(buf, offset);

        offset += 4;

        int[] temp3 = new int[l];

        for (int i = 0; i < l; i++, offset+=4) {

            temp3[i] = BreakIterator.getInt(buf, offset);

        }

        supplementaryCharColumnMap = new SupplementaryCharacterData(temp3);

    }

    //=========================================================================

    // access to the words

    //=========================================================================

    /**

     * Uses the column map to map the character to a column number, then

     * passes the row and column number to getNextState()

     * @param row The current state

     * @param ch The character whose column we're interested in

     * @return The new state to transition to

     */

    public final short getNextStateFromCharacter(int row, int ch) {

        int col;

        if (ch < Character.MIN_SUPPLEMENTARY_CODE_POINT) {

            col = columnMap.elementAt((char)ch);

        } else {

            col = supplementaryCharColumnMap.getValue(ch);

        }

        return getNextState(row, col);

    }

    /**

     * Returns the value in the cell with the specified (logical) row and

     * column numbers.  In DictionaryBasedBreakIterator, the row number is

     * a state number, the column number is an input, and the return value

     * is the row number of the new state to transition to.  (0 is the

     * "error" state, and -1 is the "end of word" state in a dictionary)

     * @param row The row number of the current state

     * @param col The column number of the input character (0 means "not a

     * dictionary character")

     * @return The row number of the new state to transition to

     */

    public final short getNextState(int row, int col) {

        if (cellIsPopulated(row, col)) {

            // we map from logical to physical row number by looking up the

            // mapping in rowIndex; we map from logical column number to

            // physical column number by looking up a shift value for this

            // logical row and offsetting the logical column number by

            // the shift amount.  Then we can use internalAt() to actually

            // get the value out of the table.

            return internalAt(rowIndex[row], col + rowIndexShifts[row]);

        }

        else {

            return 0;

        }

    }

    /**

     * Given (logical) row and column numbers, returns true if the

     * cell in that position is populated

     */

    private final boolean cellIsPopulated(int row, int col) {

        // look up the entry in the bitmap index for the specified row.

        // If it's a negative number, it's the column number of the only

        // populated cell in the row

        if (rowIndexFlagsIndex[row] < 0) {

            return col == -rowIndexFlagsIndex[row];

        }

        // if it's a positive number, it's the offset of an entry in the bitmap

        // list.  If the table is more than 32 columns wide, the bitmap is stored

        // successive entries in the bitmap list, so we have to divide the column

        // number by 32 and offset the number we got out of the index by the result.

        // Once we have the appropriate piece of the bitmap, test the appropriate

        // bit and return the result.

        else {

            int flags = rowIndexFlags[rowIndexFlagsIndex[row] + (col >> 5)];

            return (flags & (1 << (col & 0x1f))) != 0;

        }

    }

    /**

     * Implementation of getNextState() when we know the specified cell is

     * populated.

     * @param row The PHYSICAL row number of the cell

     * @param col The PHYSICAL column number of the cell

     * @return The value stored in the cell

     */

    private final short internalAt(int row, int col) {

        // the table is a one-dimensional array, so this just does the math necessary

        // to treat it as a two-dimensional array (we don't just use a two-dimensional

        // array because two-dimensional arrays are inefficient in Java)

        return table[row * numCols + col];

    }

}