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Java example source code file (BidiLine.java)

This example Java source code file (BidiLine.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

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Java - Java tags/keywords

bidi, bidibase, bidiline, bidirun, icu, illegalstateexception, internal, ltr, rtl, text, util

The BidiLine.java Java example source code

/*
 * Copyright (c) 2009, 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
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
/*
 *******************************************************************************
 * (C) Copyright IBM Corp. and others, 1996-2009 - All Rights Reserved         *
 *                                                                             *
 * The original version of this source code and documentation is copyrighted   *
 * and owned by IBM, These materials are provided under terms of a License     *
 * Agreement between IBM and Sun. This technology is protected by multiple     *
 * US and International patents. This notice and attribution to IBM may not    *
 * to removed.                                                                 *
 *******************************************************************************
 */
/* Written by Simon Montagu, Matitiahu Allouche
 * (ported from C code written by Markus W. Scherer)
 */

package sun.text.bidi;

import java.text.Bidi;
import java.util.Arrays;

public final class BidiLine {

    /*
     * General remarks about the functions in this file:
     *
     * These functions deal with the aspects of potentially mixed-directional
     * text in a single paragraph or in a line of a single paragraph
     * which has already been processed according to
     * the Unicode 3.0 Bidi algorithm as defined in
     * http://www.unicode.org/unicode/reports/tr9/ , version 13,
     * also described in The Unicode Standard, Version 4.0.1 .
     *
     * This means that there is a Bidi object with a levels
     * and a dirProps array.
     * paraLevel and direction are also set.
     * Only if the length of the text is zero, then levels==dirProps==NULL.
     *
     * The overall directionality of the paragraph
     * or line is used to bypass the reordering steps if possible.
     * Even purely RTL text does not need reordering there because
     * the getLogical/VisualIndex() methods can compute the
     * index on the fly in such a case.
     *
     * The implementation of the access to same-level-runs and of the reordering
     * do attempt to provide better performance and less memory usage compared to
     * a direct implementation of especially rule (L2) with an array of
     * one (32-bit) integer per text character.
     *
     * Here, the levels array is scanned as soon as necessary, and a vector of
     * same-level-runs is created. Reordering then is done on this vector.
     * For each run of text positions that were resolved to the same level,
     * only 8 bytes are stored: the first text position of the run and the visual
     * position behind the run after reordering.
     * One sign bit is used to hold the directionality of the run.
     * This is inefficient if there are many very short runs. If the average run
     * length is <2, then this uses more memory.
     *
     * In a further attempt to save memory, the levels array is never changed
     * after all the resolution rules (Xn, Wn, Nn, In).
     * Many methods have to consider the field trailingWSStart:
     * if it is less than length, then there is an implicit trailing run
     * at the paraLevel,
     * which is not reflected in the levels array.
     * This allows a line Bidi object to use the same levels array as
     * its paragraph parent object.
     *
     * When a Bidi object is created for a line of a paragraph, then the
     * paragraph's levels and dirProps arrays are reused by way of setting
     * a pointer into them, not by copying. This again saves memory and forbids to
     * change the now shared levels for (L1).
     */

    /* handle trailing WS (L1) -------------------------------------------------- */

    /*
     * setTrailingWSStart() sets the start index for a trailing
     * run of WS in the line. This is necessary because we do not modify
     * the paragraph's levels array that we just point into.
     * Using trailingWSStart is another form of performing (L1).
     *
     * To make subsequent operations easier, we also include the run
     * before the WS if it is at the paraLevel - we merge the two here.
     *
     * This method is called only from setLine(), so paraLevel is
     * set correctly for the line even when contextual multiple paragraphs.
     */

    static void setTrailingWSStart(BidiBase bidiBase)
    {
        byte[] dirProps = bidiBase.dirProps;
        byte[] levels = bidiBase.levels;
        int start = bidiBase.length;
        byte paraLevel = bidiBase.paraLevel;

        /* If the line is terminated by a block separator, all preceding WS etc...
           are already set to paragraph level.
           Setting trailingWSStart to pBidi->length will avoid changing the
           level of B chars from 0 to paraLevel in getLevels when
           orderParagraphsLTR==TRUE
        */
        if (BidiBase.NoContextRTL(dirProps[start - 1]) == BidiBase.B) {
            bidiBase.trailingWSStart = start;   /* currently == bidiBase.length */
            return;
        }
        /* go backwards across all WS, BN, explicit codes */
        while (start > 0 &&
                (BidiBase.DirPropFlagNC(dirProps[start - 1]) & BidiBase.MASK_WS) != 0) {
            --start;
        }

        /* if the WS run can be merged with the previous run then do so here */
        while (start > 0 && levels[start - 1] == paraLevel) {
            --start;
        }

        bidiBase.trailingWSStart=start;
    }

    public static Bidi setLine(Bidi bidi, BidiBase paraBidi,
                               Bidi newBidi, BidiBase newBidiBase,
                               int start, int limit) {
        int length;

        BidiBase lineBidi = newBidiBase;

        /* set the values in lineBidi from its paraBidi parent */
        /* class members are already initialized to 0 */
        // lineBidi.paraBidi = null;        /* mark unfinished setLine */
        // lineBidi.flags = 0;
        // lineBidi.controlCount = 0;

        length = lineBidi.length = lineBidi.originalLength =
                lineBidi.resultLength = limit - start;

        lineBidi.text = new char[length];
        System.arraycopy(paraBidi.text, start, lineBidi.text, 0, length);
        lineBidi.paraLevel = paraBidi.GetParaLevelAt(start);
        lineBidi.paraCount = paraBidi.paraCount;
        lineBidi.runs = new BidiRun[0];
        if (paraBidi.controlCount > 0) {
            int j;
            for (j = start; j < limit; j++) {
                if (BidiBase.IsBidiControlChar(paraBidi.text[j])) {
                    lineBidi.controlCount++;
                }
            }
            lineBidi.resultLength -= lineBidi.controlCount;
        }
        /* copy proper subset of DirProps */
        lineBidi.getDirPropsMemory(length);
        lineBidi.dirProps = lineBidi.dirPropsMemory;
        System.arraycopy(paraBidi.dirProps, start, lineBidi.dirProps, 0,
                         length);
        /* copy proper subset of Levels */
        lineBidi.getLevelsMemory(length);
        lineBidi.levels = lineBidi.levelsMemory;
        System.arraycopy(paraBidi.levels, start, lineBidi.levels, 0,
                         length);
        lineBidi.runCount = -1;

        if (paraBidi.direction != BidiBase.MIXED) {
            /* the parent is already trivial */
            lineBidi.direction = paraBidi.direction;

            /*
             * The parent's levels are all either
             * implicitly or explicitly ==paraLevel;
             * do the same here.
             */
            if (paraBidi.trailingWSStart <= start) {
                lineBidi.trailingWSStart = 0;
            } else if (paraBidi.trailingWSStart < limit) {
                lineBidi.trailingWSStart = paraBidi.trailingWSStart - start;
            } else {
                lineBidi.trailingWSStart = length;
            }
        } else {
            byte[] levels = lineBidi.levels;
            int i, trailingWSStart;
            byte level;

            setTrailingWSStart(lineBidi);
            trailingWSStart = lineBidi.trailingWSStart;

            /* recalculate lineBidi.direction */
            if (trailingWSStart == 0) {
                /* all levels are at paraLevel */
                lineBidi.direction = (byte)(lineBidi.paraLevel & 1);
            } else {
                /* get the level of the first character */
                level = (byte)(levels[0] & 1);

                /* if there is anything of a different level, then the line
                   is mixed */
                if (trailingWSStart < length &&
                    (lineBidi.paraLevel & 1) != level) {
                    /* the trailing WS is at paraLevel, which differs from
                       levels[0] */
                    lineBidi.direction = BidiBase.MIXED;
                } else {
                    /* see if levels[1..trailingWSStart-1] have the same
                       direction as levels[0] and paraLevel */
                    for (i = 1; ; i++) {
                        if (i == trailingWSStart) {
                            /* the direction values match those in level */
                            lineBidi.direction = level;
                            break;
                        } else if ((levels[i] & 1) != level) {
                            lineBidi.direction = BidiBase.MIXED;
                            break;
                        }
                    }
                }
            }

            switch(lineBidi.direction) {
                case Bidi.DIRECTION_LEFT_TO_RIGHT:
                    /* make sure paraLevel is even */
                    lineBidi.paraLevel = (byte)
                        ((lineBidi.paraLevel + 1) & ~1);

                    /* all levels are implicitly at paraLevel (important for
                       getLevels()) */
                    lineBidi.trailingWSStart = 0;
                    break;
                case Bidi.DIRECTION_RIGHT_TO_LEFT:
                    /* make sure paraLevel is odd */
                    lineBidi.paraLevel |= 1;

                    /* all levels are implicitly at paraLevel (important for
                       getLevels()) */
                    lineBidi.trailingWSStart = 0;
                    break;
                default:
                    break;
            }
        }

        newBidiBase.paraBidi = paraBidi; /* mark successful setLine */
        return newBidi;
    }

    static byte getLevelAt(BidiBase bidiBase, int charIndex)
    {
        /* return paraLevel if in the trailing WS run, otherwise the real level */
        if (bidiBase.direction != BidiBase.MIXED || charIndex >= bidiBase.trailingWSStart) {
            return bidiBase.GetParaLevelAt(charIndex);
        } else {
            return bidiBase.levels[charIndex];
        }
    }

    static byte[] getLevels(BidiBase bidiBase)
    {
        int start = bidiBase.trailingWSStart;
        int length = bidiBase.length;

        if (start != length) {
            /* the current levels array does not reflect the WS run */
            /*
             * After the previous if(), we know that the levels array
             * has an implicit trailing WS run and therefore does not fully
             * reflect itself all the levels.
             * This must be a Bidi object for a line, and
             * we need to create a new levels array.
             */
            /* bidiBase.paraLevel is ok even if contextual multiple paragraphs,
               since bidiBase is a line object                                     */
            Arrays.fill(bidiBase.levels, start, length, bidiBase.paraLevel);

            /* this new levels array is set for the line and reflects the WS run */
            bidiBase.trailingWSStart = length;
        }
        if (length < bidiBase.levels.length) {
            byte[] levels = new byte[length];
            System.arraycopy(bidiBase.levels, 0, levels, 0, length);
            return levels;
        }
        return bidiBase.levels;
    }

    static BidiRun getLogicalRun(BidiBase bidiBase, int logicalPosition)
    {
        /* this is done based on runs rather than on levels since levels have
           a special interpretation when REORDER_RUNS_ONLY
         */
        BidiRun newRun = new BidiRun(), iRun;
        getRuns(bidiBase);
        int runCount = bidiBase.runCount;
        int visualStart = 0, logicalLimit = 0;
        iRun = bidiBase.runs[0];

        for (int i = 0; i < runCount; i++) {
            iRun = bidiBase.runs[i];
            logicalLimit = iRun.start + iRun.limit - visualStart;
            if ((logicalPosition >= iRun.start) &&
                (logicalPosition < logicalLimit)) {
                break;
            }
            visualStart = iRun.limit;
        }
        newRun.start = iRun.start;
        newRun.limit = logicalLimit;
        newRun.level = iRun.level;
        return newRun;
    }

    /* in trivial cases there is only one trivial run; called by getRuns() */
    private static void getSingleRun(BidiBase bidiBase, byte level) {
        /* simple, single-run case */
        bidiBase.runs = bidiBase.simpleRuns;
        bidiBase.runCount = 1;

        /* fill and reorder the single run */
        bidiBase.runs[0] = new BidiRun(0, bidiBase.length, level);
    }

    /* reorder the runs array (L2) ---------------------------------------------- */

    /*
     * Reorder the same-level runs in the runs array.
     * Here, runCount>1 and maxLevel>=minLevel>=paraLevel.
     * All the visualStart fields=logical start before reordering.
     * The "odd" bits are not set yet.
     *
     * Reordering with this data structure lends itself to some handy shortcuts:
     *
     * Since each run is moved but not modified, and since at the initial maxLevel
     * each sequence of same-level runs consists of only one run each, we
     * don't need to do anything there and can predecrement maxLevel.
     * In many simple cases, the reordering is thus done entirely in the
     * index mapping.
     * Also, reordering occurs only down to the lowest odd level that occurs,
     * which is minLevel|1. However, if the lowest level itself is odd, then
     * in the last reordering the sequence of the runs at this level or higher
     * will be all runs, and we don't need the elaborate loop to search for them.
     * This is covered by ++minLevel instead of minLevel|=1 followed
     * by an extra reorder-all after the reorder-some loop.
     * About a trailing WS run:
     * Such a run would need special treatment because its level is not
     * reflected in levels[] if this is not a paragraph object.
     * Instead, all characters from trailingWSStart on are implicitly at
     * paraLevel.
     * However, for all maxLevel>paraLevel, this run will never be reordered
     * and does not need to be taken into account. maxLevel==paraLevel is only reordered
     * if minLevel==paraLevel is odd, which is done in the extra segment.
     * This means that for the main reordering loop we don't need to consider
     * this run and can --runCount. If it is later part of the all-runs
     * reordering, then runCount is adjusted accordingly.
     */
    private static void reorderLine(BidiBase bidiBase, byte minLevel, byte maxLevel) {

        /* nothing to do? */
        if (maxLevel<=(minLevel|1)) {
            return;
        }

        BidiRun[] runs;
        BidiRun tempRun;
        byte[] levels;
        int firstRun, endRun, limitRun, runCount;

        /*
         * Reorder only down to the lowest odd level
         * and reorder at an odd minLevel in a separate, simpler loop.
         * See comments above for why minLevel is always incremented.
         */
        ++minLevel;

        runs = bidiBase.runs;
        levels = bidiBase.levels;
        runCount = bidiBase.runCount;

        /* do not include the WS run at paraLevel<=old minLevel except in the simple loop */
        if (bidiBase.trailingWSStart < bidiBase.length) {
            --runCount;
        }

        while (--maxLevel >= minLevel) {
            firstRun = 0;

            /* loop for all sequences of runs */
            for ( ; ; ) {
                /* look for a sequence of runs that are all at >=maxLevel */
                /* look for the first run of such a sequence */
                while (firstRun < runCount && levels[runs[firstRun].start] < maxLevel) {
                    ++firstRun;
                }
                if (firstRun >= runCount) {
                    break;  /* no more such runs */
                }

                /* look for the limit run of such a sequence (the run behind it) */
                for (limitRun = firstRun; ++limitRun < runCount &&
                      levels[runs[limitRun].start]>=maxLevel; ) {}

                /* Swap the entire sequence of runs from firstRun to limitRun-1. */
                endRun = limitRun - 1;
                while (firstRun < endRun) {
                    tempRun = runs[firstRun];
                    runs[firstRun] = runs[endRun];
                    runs[endRun] = tempRun;
                    ++firstRun;
                    --endRun;
                }

                if (limitRun == runCount) {
                    break;  /* no more such runs */
                } else {
                    firstRun = limitRun + 1;
                }
            }
        }

        /* now do maxLevel==old minLevel (==odd!), see above */
        if ((minLevel & 1) == 0) {
            firstRun = 0;

            /* include the trailing WS run in this complete reordering */
            if (bidiBase.trailingWSStart == bidiBase.length) {
                --runCount;
            }

            /* Swap the entire sequence of all runs. (endRun==runCount) */
            while (firstRun < runCount) {
                tempRun = runs[firstRun];
                runs[firstRun] = runs[runCount];
                runs[runCount] = tempRun;
                ++firstRun;
                --runCount;
            }
        }
    }

    /* compute the runs array --------------------------------------------------- */

    static int getRunFromLogicalIndex(BidiBase bidiBase, int logicalIndex) {
        BidiRun[] runs = bidiBase.runs;
        int runCount = bidiBase.runCount, visualStart = 0, i, length, logicalStart;

        for (i = 0; i < runCount; i++) {
            length = runs[i].limit - visualStart;
            logicalStart = runs[i].start;
            if ((logicalIndex >= logicalStart) && (logicalIndex < (logicalStart+length))) {
                return i;
            }
            visualStart += length;
        }
        /* we should never get here */
        throw new IllegalStateException("Internal ICU error in getRunFromLogicalIndex");
    }

    /*
     * Compute the runs array from the levels array.
     * After getRuns() returns true, runCount is guaranteed to be >0
     * and the runs are reordered.
     * Odd-level runs have visualStart on their visual right edge and
     * they progress visually to the left.
     * If option OPTION_INSERT_MARKS is set, insertRemove will contain the
     * sum of appropriate LRM/RLM_BEFORE/AFTER flags.
     * If option OPTION_REMOVE_CONTROLS is set, insertRemove will contain the
     * negative number of BiDi control characters within this run.
     */
    static void getRuns(BidiBase bidiBase) {
        /*
         * This method returns immediately if the runs are already set. This
         * includes the case of length==0 (handled in setPara)..
         */
        if (bidiBase.runCount >= 0) {
            return;
        }
        if (bidiBase.direction != BidiBase.MIXED) {
            /* simple, single-run case - this covers length==0 */
            /* bidiBase.paraLevel is ok even for contextual multiple paragraphs */
            getSingleRun(bidiBase, bidiBase.paraLevel);
        } else /* BidiBase.MIXED, length>0 */ {
            /* mixed directionality */
            int length = bidiBase.length, limit;
            byte[] levels = bidiBase.levels;
            int i, runCount;
            byte level = BidiBase.INTERNAL_LEVEL_DEFAULT_LTR;   /* initialize with no valid level */
            /*
             * If there are WS characters at the end of the line
             * and the run preceding them has a level different from
             * paraLevel, then they will form their own run at paraLevel (L1).
             * Count them separately.
             * We need some special treatment for this in order to not
             * modify the levels array which a line Bidi object shares
             * with its paragraph parent and its other line siblings.
             * In other words, for the trailing WS, it may be
             * levels[]!=paraLevel but we have to treat it like it were so.
             */
            limit = bidiBase.trailingWSStart;
            /* count the runs, there is at least one non-WS run, and limit>0 */
            runCount = 0;
            for (i = 0; i < limit; ++i) {
                /* increment runCount at the start of each run */
                if (levels[i] != level) {
                    ++runCount;
                    level = levels[i];
                }
            }

            /*
             * We don't need to see if the last run can be merged with a trailing
             * WS run because setTrailingWSStart() would have done that.
             */
            if (runCount == 1 && limit == length) {
                /* There is only one non-WS run and no trailing WS-run. */
                getSingleRun(bidiBase, levels[0]);
            } else /* runCount>1 || limit<length */ {
                /* allocate and set the runs */
                BidiRun[] runs;
                int runIndex, start;
                byte minLevel = BidiBase.MAX_EXPLICIT_LEVEL + 1;
                byte maxLevel=0;

                /* now, count a (non-mergeable) WS run */
                if (limit < length) {
                    ++runCount;
                }

                /* runCount > 1 */
                bidiBase.getRunsMemory(runCount);
                runs = bidiBase.runsMemory;

                /* set the runs */
                /* FOOD FOR THOUGHT: this could be optimized, e.g.:
                 * 464->444, 484->444, 575->555, 595->555
                 * However, that would take longer. Check also how it would
                 * interact with BiDi control removal and inserting Marks.
                 */
                runIndex = 0;

                /* search for the run limits and initialize visualLimit values with the run lengths */
                i = 0;
                do {
                    /* prepare this run */
                    start = i;
                    level = levels[i];
                    if (level < minLevel) {
                        minLevel = level;
                    }
                    if (level > maxLevel) {
                        maxLevel = level;
                    }

                    /* look for the run limit */
                    while (++i < limit && levels[i] == level) {}

                    /* i is another run limit */
                    runs[runIndex] = new BidiRun(start, i - start, level);
                    ++runIndex;
                } while (i < limit);

                if (limit < length) {
                    /* there is a separate WS run */
                    runs[runIndex] = new BidiRun(limit, length - limit, bidiBase.paraLevel);
                    /* For the trailing WS run, bidiBase.paraLevel is ok even
                       if contextual multiple paragraphs.                   */
                    if (bidiBase.paraLevel < minLevel) {
                        minLevel = bidiBase.paraLevel;
                    }
                }

                /* set the object fields */
                bidiBase.runs = runs;
                bidiBase.runCount = runCount;

                reorderLine(bidiBase, minLevel, maxLevel);

                /* now add the direction flags and adjust the visualLimit's to be just that */
                /* this loop will also handle the trailing WS run */
                limit = 0;
                for (i = 0; i < runCount; ++i) {
                    runs[i].level = levels[runs[i].start];
                    limit = (runs[i].limit += limit);
                }

                /* Set the embedding level for the trailing WS run. */
                /* For a RTL paragraph, it will be the *first* run in visual order. */
                /* For the trailing WS run, bidiBase.paraLevel is ok even if
                   contextual multiple paragraphs.                          */
                if (runIndex < runCount) {
                    int trailingRun = ((bidiBase.paraLevel & 1) != 0)? 0 : runIndex;
                    runs[trailingRun].level = bidiBase.paraLevel;
                }
            }
        }

        /* handle insert LRM/RLM BEFORE/AFTER run */
        if (bidiBase.insertPoints.size > 0) {
            BidiBase.Point point;
            int runIndex, ip;
            for (ip = 0; ip < bidiBase.insertPoints.size; ip++) {
                point = bidiBase.insertPoints.points[ip];
                runIndex = getRunFromLogicalIndex(bidiBase, point.pos);
                bidiBase.runs[runIndex].insertRemove |= point.flag;
            }
        }

        /* handle remove BiDi control characters */
        if (bidiBase.controlCount > 0) {
            int runIndex, ic;
            char c;
            for (ic = 0; ic < bidiBase.length; ic++) {
                c = bidiBase.text[ic];
                if (BidiBase.IsBidiControlChar(c)) {
                    runIndex = getRunFromLogicalIndex(bidiBase, ic);
                    bidiBase.runs[runIndex].insertRemove--;
                }
            }
        }
    }

    static int[] prepareReorder(byte[] levels, byte[] pMinLevel, byte[] pMaxLevel)
    {
        int start;
        byte level, minLevel, maxLevel;

        if (levels == null || levels.length <= 0) {
            return null;
        }

        /* determine minLevel and maxLevel */
        minLevel = BidiBase.MAX_EXPLICIT_LEVEL + 1;
        maxLevel = 0;
        for (start = levels.length; start>0; ) {
            level = levels[--start];
            if (level > BidiBase.MAX_EXPLICIT_LEVEL + 1) {
                return null;
            }
            if (level < minLevel) {
                minLevel = level;
            }
            if (level > maxLevel) {
                maxLevel = level;
            }
        }
        pMinLevel[0] = minLevel;
        pMaxLevel[0] = maxLevel;

        /* initialize the index map */
        int[] indexMap = new int[levels.length];
        for (start = levels.length; start > 0; ) {
            --start;
            indexMap[start] = start;
        }

        return indexMap;
    }

    static int[] reorderVisual(byte[] levels)
    {
        byte[] aMinLevel = new byte[1];
        byte[] aMaxLevel = new byte[1];
        int start, end, limit, temp;
        byte minLevel, maxLevel;

        int[] indexMap = prepareReorder(levels, aMinLevel, aMaxLevel);
        if (indexMap == null) {
            return null;
        }

        minLevel = aMinLevel[0];
        maxLevel = aMaxLevel[0];

        /* nothing to do? */
        if (minLevel == maxLevel && (minLevel & 1) == 0) {
            return indexMap;
        }

        /* reorder only down to the lowest odd level */
        minLevel |= 1;

        /* loop maxLevel..minLevel */
        do {
            start = 0;

            /* loop for all sequences of levels to reorder at the current maxLevel */
            for ( ; ; ) {
                /* look for a sequence of levels that are all at >=maxLevel */
                /* look for the first index of such a sequence */
                while (start < levels.length && levels[start] < maxLevel) {
                    ++start;
                }
                if (start >= levels.length) {
                    break;  /* no more such runs */
                }

                /* look for the limit of such a sequence (the index behind it) */
                for (limit = start; ++limit < levels.length && levels[limit] >= maxLevel; ) {}

                /*
                 * Swap the entire interval of indexes from start to limit-1.
                 * We don't need to swap the levels for the purpose of this
                 * algorithm: the sequence of levels that we look at does not
                 * move anyway.
                 */
                end = limit - 1;
                while (start < end) {
                    temp = indexMap[start];
                    indexMap[start] = indexMap[end];
                    indexMap[end] = temp;

                    ++start;
                    --end;
                }

                if (limit == levels.length) {
                    break;  /* no more such sequences */
                } else {
                    start = limit + 1;
                }
            }
        } while (--maxLevel >= minLevel);

        return indexMap;
    }

    static int[] getVisualMap(BidiBase bidiBase)
    {
        /* fill a visual-to-logical index map using the runs[] */
        BidiRun[] runs = bidiBase.runs;
        int logicalStart, visualStart, visualLimit;
        int allocLength = bidiBase.length > bidiBase.resultLength ? bidiBase.length
                                                          : bidiBase.resultLength;
        int[] indexMap = new int[allocLength];

        visualStart = 0;
        int idx = 0;
        for (int j = 0; j < bidiBase.runCount; ++j) {
            logicalStart = runs[j].start;
            visualLimit = runs[j].limit;
            if (runs[j].isEvenRun()) {
                do { /* LTR */
                    indexMap[idx++] = logicalStart++;
                } while (++visualStart < visualLimit);
            } else {
                logicalStart += visualLimit - visualStart;  /* logicalLimit */
                do { /* RTL */
                    indexMap[idx++] = --logicalStart;
                } while (++visualStart < visualLimit);
            }
            /* visualStart==visualLimit; */
        }

        if (bidiBase.insertPoints.size > 0) {
            int markFound = 0, runCount = bidiBase.runCount;
            int insertRemove, i, j, k;
            runs = bidiBase.runs;
            /* count all inserted marks */
            for (i = 0; i < runCount; i++) {
                insertRemove = runs[i].insertRemove;
                if ((insertRemove & (BidiBase.LRM_BEFORE|BidiBase.RLM_BEFORE)) > 0) {
                    markFound++;
                }
                if ((insertRemove & (BidiBase.LRM_AFTER|BidiBase.RLM_AFTER)) > 0) {
                    markFound++;
                }
            }
            /* move back indexes by number of preceding marks */
            k = bidiBase.resultLength;
            for (i = runCount - 1; i >= 0 && markFound > 0; i--) {
                insertRemove = runs[i].insertRemove;
                if ((insertRemove & (BidiBase.LRM_AFTER|BidiBase.RLM_AFTER)) > 0) {
                    indexMap[--k] = BidiBase.MAP_NOWHERE;
                    markFound--;
                }
                visualStart = i > 0 ? runs[i-1].limit : 0;
                for (j = runs[i].limit - 1; j >= visualStart && markFound > 0; j--) {
                    indexMap[--k] = indexMap[j];
                }
                if ((insertRemove & (BidiBase.LRM_BEFORE|BidiBase.RLM_BEFORE)) > 0) {
                    indexMap[--k] = BidiBase.MAP_NOWHERE;
                    markFound--;
                }
            }
        }
        else if (bidiBase.controlCount > 0) {
            int runCount = bidiBase.runCount, logicalEnd;
            int insertRemove, length, i, j, k, m;
            char uchar;
            boolean evenRun;
            runs = bidiBase.runs;
            visualStart = 0;
            /* move forward indexes by number of preceding controls */
            k = 0;
            for (i = 0; i < runCount; i++, visualStart += length) {
                length = runs[i].limit - visualStart;
                insertRemove = runs[i].insertRemove;
                /* if no control found yet, nothing to do in this run */
                if ((insertRemove == 0) && (k == visualStart)) {
                    k += length;
                    continue;
                }
                /* if no control in this run */
                if (insertRemove == 0) {
                    visualLimit = runs[i].limit;
                    for (j = visualStart; j < visualLimit; j++) {
                        indexMap[k++] = indexMap[j];
                    }
                    continue;
                }
                logicalStart = runs[i].start;
                evenRun = runs[i].isEvenRun();
                logicalEnd = logicalStart + length - 1;
                for (j = 0; j < length; j++) {
                    m = evenRun ? logicalStart + j : logicalEnd - j;
                    uchar = bidiBase.text[m];
                    if (!BidiBase.IsBidiControlChar(uchar)) {
                        indexMap[k++] = m;
                    }
                }
            }
        }
        if (allocLength == bidiBase.resultLength) {
            return indexMap;
        }
        int[] newMap = new int[bidiBase.resultLength];
        System.arraycopy(indexMap, 0, newMap, 0, bidiBase.resultLength);
        return newMap;
    }

}

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