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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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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 sun.text;

import java.nio.BufferUnderflowException;
import java.nio.ByteBuffer;
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
 //=========================================================================

 BreakDictionary(String dictionaryName, byte[] dictionaryData) {
 try {
 setupDictionary(dictionaryName, dictionaryData);
 } catch (BufferUnderflowException bue) {
 MissingResourceException e;
 e = new MissingResourceException("Corrupted dictionary data",
 dictionaryName, "");
 e.initCause(bue);
 throw e;
 }
 }

 private void setupDictionary(String dictionaryName, byte[] dictionaryData) {
 ByteBuffer bb = ByteBuffer.wrap(dictionaryData);

 // check version
 int version = bb.getInt();
 if (version != supportedVersion) {
 throw new MissingResourceException("Dictionary version(" + version + ") is unsupported",
 dictionaryName, "");
 }

 // Check data size
 int len = bb.getInt();
 if (bb.position() + len != bb.limit()) {
 throw new MissingResourceException("Dictionary size is wrong: " + bb.limit(),
 dictionaryName, "");
 }

 // read in the column map for BMP characteres (this is serialized in
 // its internal form: an index array followed by a data array)
 len = bb.getInt();
 short[] temp = new short[len];
 for (int i = 0; i < len; i++) {
 temp[i] = bb.getShort();
 }
 len = bb.getInt();
 byte[] temp2 = new byte[len];
 bb.get(temp2);
 columnMap = new CompactByteArray(temp, temp2);

 // read in numCols and numColGroups
 numCols = bb.getInt();
 numColGroups = bb.getInt();

 // read in the row-number index
 len = bb.getInt();
 rowIndex = new short[len];
 for (int i = 0; i < len; i++) {
 rowIndex[i] = bb.getShort();
 }

 // load in the populated-cells bitmap: index first, then bitmap list
 len = bb.getInt();
 rowIndexFlagsIndex = new short[len];
 for (int i = 0; i < len; i++) {
 rowIndexFlagsIndex[i] = bb.getShort();
 }
 len = bb.getInt();
 rowIndexFlags = new int[len];
 for (int i = 0; i < len; i++) {
 rowIndexFlags[i] = bb.getInt();
 }

 // load in the row-shift index
 len = bb.getInt();
 rowIndexShifts = new byte[len];
 bb.get(rowIndexShifts);

 // load in the actual state table
 len = bb.getInt();
 table = new short[len];
 for (int i = 0; i < len; i++) {
 table[i] = bb.getShort();
 }

 // finally, prepare the column map for supplementary characters
 len = bb.getInt();
 int[] temp3 = new int[len];
 for (int i = 0; i < len; i++) {
 temp3[i] = bb.getInt();
 }
 assert bb.position() == bb.limit();

 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 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 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];
 }
}