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 * 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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package com.sun.java.util.jar.pack;

import java.io.IOException;

import java.io.InputStream;

import java.io.PrintStream;

import java.util.Arrays;

/**

 * Histogram derived from an integer array of events (int[]).

 * @author John Rose

 */

final class Histogram {

    // Compact histogram representation:  4 bytes per distinct value,

    // plus 5 words per distinct count.

    protected final int[][] matrix;  // multi-row matrix {{counti,valueij...}}

    protected final int     totalWeight;  // sum of all counts

    // These are created eagerly also, since that saves work.

    // They cost another 8 bytes per distinct value.

    protected final int[]   values;  // unique values, sorted by value

    protected final int[]   counts;  // counts, same order as values

    private static final long LOW32 = (long)-1 >>> 32;

    /** Build a histogram given a sequence of values.

     *  To save work, the input should be sorted, but need not be.

     */

    public

    Histogram(int[] valueSequence) {

        long[] hist2col = computeHistogram2Col(maybeSort(valueSequence));

        int[][] table = makeTable(hist2col);

        values = table[0];

        counts = table[1];

        this.matrix = makeMatrix(hist2col);

        this.totalWeight = valueSequence.length;

        assert(assertWellFormed(valueSequence));

    }

    public

    Histogram(int[] valueSequence, int start, int end) {

        this(sortedSlice(valueSequence, start, end));

    }

    /** Build a histogram given a compact matrix of counts and values. */

    public

    Histogram(int[][] matrix) {

        // sort the rows

        matrix = normalizeMatrix(matrix);  // clone and sort

        this.matrix = matrix;

        int length = 0;

        int weight = 0;

        for (int i = 0; i < matrix.length; i++) {

            int rowLength = matrix[i].length-1;

            length += rowLength;

            weight += matrix[i][0] * rowLength;

        }

        this.totalWeight = weight;

        long[] hist2col = new long[length];

        int fillp = 0;

        for (int i = 0; i < matrix.length; i++) {

            for (int j = 1; j < matrix[i].length; j++) {

                // sort key is value, so put it in the high 32!

                hist2col[fillp++] = ((long) matrix[i][j] << 32)

                                  | (LOW32 & matrix[i][0]);

            }

        }

        assert(fillp == hist2col.length);

        Arrays.sort(hist2col);

        int[][] table = makeTable(hist2col);

        values = table[1]; //backwards

        counts = table[0]; //backwards

        assert(assertWellFormed(null));

    }

    /** Histogram of int values, reported compactly as a ragged matrix,

     *  indexed by descending frequency rank.

     *  <p>

     *  Format of matrix:

     *  Each row in the matrix begins with an occurrence count,

     *  and continues with all int values that occur at that frequency.

     *  <pre>

     *  int[][] matrix = {

     *    { count1, value11, value12, value13, ...  },

     *    { count2, value21, value22, ... },

     *    ...

     *  }

     *  </pre>

     *  The first column of the matrix { count1, count2, ... }

     *  is sorted in descending order, and contains no duplicates.

     *  Each row of the matrix (apart from its first element)

     *  is sorted in ascending order, and contains no duplicates.

     *  That is, each sequence { valuei1, valuei2, ... } is sorted.

     */

    public

    int[][] getMatrix() { return matrix; }

    public

    int getRowCount() { return matrix.length; }

    public

    int getRowFrequency(int rn) { return matrix[rn][0]; }

    public

    int getRowLength(int rn) { return matrix[rn].length-1; }

    public

    int getRowValue(int rn, int vn) { return matrix[rn][vn+1]; }

    public

    int getRowWeight(int rn) {

        return getRowFrequency(rn) * getRowLength(rn);

    }

    public

    int getTotalWeight() {

        return totalWeight;

    }

    public

    int getTotalLength() {

        return values.length;

    }

    /** Returns an array of all values, sorted. */

    public

    int[] getAllValues() {

        return values;

    }

    /** Returns an array parallel with {@link #getValues},

     *  with a frequency for each value.

     */

    public

    int[] getAllFrequencies() {

        return counts;

    }

    private static double log2 = Math.log(2);

    public

    int getFrequency(int value) {

        int pos = Arrays.binarySearch(values, value);

        if (pos < 0)  return 0;

        assert(values[pos] == value);

        return counts[pos];

    }

    public

    double getBitLength(int value) {

        double prob = (double) getFrequency(value) / getTotalWeight();

        return - Math.log(prob) / log2;

    }

    public

    double getRowBitLength(int rn) {

        double prob = (double) getRowFrequency(rn) / getTotalWeight();

        return - Math.log(prob) / log2;

    }

    public

    interface BitMetric {

        public double getBitLength(int value);

    }

    private final BitMetric bitMetric = new BitMetric() {

        public double getBitLength(int value) {

            return Histogram.this.getBitLength(value);

        }

    };

    public BitMetric getBitMetric() {

        return bitMetric;

    }

    /** bit-length is negative entropy:  -H(matrix). */

    public

    double getBitLength() {

        double sum = 0;

        for (int i = 0; i < matrix.length; i++) {

            sum += getRowBitLength(i) * getRowWeight(i);

        }

        assert(0.1 > Math.abs(sum - getBitLength(bitMetric)));

        return sum;

    }

    /** bit-length in to another coding (cross-entropy) */

    public

    double getBitLength(BitMetric len) {

        double sum = 0;

        for (int i = 0; i < matrix.length; i++) {

            for (int j = 1; j < matrix[i].length; j++) {

                sum += matrix[i][0] * len.getBitLength(matrix[i][j]);

            }

        }

        return sum;

    }

    private static

    double round(double x, double scale) {

        return Math.round(x * scale) / scale;

    }

    /** Sort rows and columns.

     *  Merge adjacent rows with the same key element [0].

     *  Make a fresh copy of all of it.

     */

    public int[][] normalizeMatrix(int[][] matrix) {

        long[] rowMap = new long[matrix.length];

        for (int i = 0; i < matrix.length; i++) {

            if (matrix[i].length <= 1)  continue;

            int count = matrix[i][0];

            if (count <= 0)  continue;

            rowMap[i] = (long) count << 32 | i;

        }

        Arrays.sort(rowMap);

        int[][] newMatrix = new int[matrix.length][];

        int prevCount = -1;

        int fillp1 = 0;

        int fillp2 = 0;

        for (int i = 0; ; i++) {

            int[] row;

            if (i < matrix.length) {

                long rowMapEntry = rowMap[rowMap.length-i-1];

                if (rowMapEntry == 0)  continue;

                row = matrix[(int)rowMapEntry];

                assert(rowMapEntry>>>32 == row[0]);

            } else {

                row = new int[]{ -1 };  // close it off

            }

            if (row[0] != prevCount && fillp2 > fillp1) {

                // Close off previous run.

                int length = 0;

                for (int p = fillp1; p < fillp2; p++) {

                    int[] row0 = newMatrix[p];  // previously visited row

                    assert(row0[0] == prevCount);

                    length += row0.length-1;

                }

                int[] row1 = new int[1+length];  // cloned & consolidated row

                row1[0] = prevCount;

                int rfillp = 1;

                for (int p = fillp1; p < fillp2; p++) {

                    int[] row0 = newMatrix[p];  // previously visited row

                    assert(row0[0] == prevCount);

                    System.arraycopy(row0, 1, row1, rfillp, row0.length-1);

                    rfillp += row0.length-1;

                }

                if (!isSorted(row1, 1, true)) {

                    Arrays.sort(row1, 1, row1.length);

                    int jfillp = 2;

                    // Detect and squeeze out duplicates.

                    for (int j = 2; j < row1.length; j++) {

                        if (row1[j] != row1[j-1])

                            row1[jfillp++] = row1[j];

                    }

                    if (jfillp < row1.length) {

                        // Reallocate because of lost duplicates.

                        int[] newRow1 = new int[jfillp];

                        System.arraycopy(row1, 0, newRow1, 0, jfillp);

                        row1 = newRow1;

                    }

                }

                newMatrix[fillp1++] = row1;

                fillp2 = fillp1;

            }

            if (i == matrix.length)

                break;

            prevCount = row[0];

            newMatrix[fillp2++] = row;

        }

        assert(fillp1 == fillp2);  // no unfinished business

        // Now drop missing rows.

        matrix = newMatrix;

        if (fillp1 < matrix.length) {

            newMatrix = new int[fillp1][];

            System.arraycopy(matrix, 0, newMatrix, 0, fillp1);

            matrix = newMatrix;

        }

        return matrix;

    }

    public

    String[] getRowTitles(String name) {

        int totalUnique = getTotalLength();

        int ltotalWeight = getTotalWeight();

        String[] histTitles = new String[matrix.length];

        int cumWeight = 0;

        int cumUnique = 0;

        for (int i = 0; i < matrix.length; i++) {

            int count  = getRowFrequency(i);

            int unique = getRowLength(i);

            int weight = getRowWeight(i);

            cumWeight += weight;

            cumUnique += unique;

            long wpct = ((long)cumWeight * 100 + ltotalWeight/2) / ltotalWeight;

            long upct = ((long)cumUnique * 100 + totalUnique/2) / totalUnique;

            double len = getRowBitLength(i);

            assert(0.1 > Math.abs(len - getBitLength(matrix[i][1])));

            histTitles[i] = name+"["+i+"]"

                +" len="+round(len,10)

                +" ("+count+"*["+unique+"])"

                +" ("+cumWeight+":"+wpct+"%)"

                +" ["+cumUnique+":"+upct+"%]";

        }

        return histTitles;

    }

    /** Print a report of this histogram.

     */

    public

    void print(PrintStream out) {

        print("hist", out);

    }

    /** Print a report of this histogram.

     */

    public

    void print(String name, PrintStream out) {

        print(name, getRowTitles(name), out);

    }

    /** Print a report of this histogram.

     */

    public

    void print(String name, String[] histTitles, PrintStream out) {

        int totalUnique = getTotalLength();

        int ltotalWeight = getTotalWeight();

        double tlen = getBitLength();

        double avgLen = tlen / ltotalWeight;

        double avg = (double) ltotalWeight / totalUnique;

        String title = (name

                        +" len="+round(tlen,10)

                        +" avgLen="+round(avgLen,10)

                        +" weight("+ltotalWeight+")"

                        +" unique["+totalUnique+"]"

                        +" avgWeight("+round(avg,100)+")");

        if (histTitles == null) {

            out.println(title);

        } else {

            out.println(title+" {");

            StringBuffer buf = new StringBuffer();

            for (int i = 0; i < matrix.length; i++) {

                buf.setLength(0);

                buf.append("  ").append(histTitles[i]).append(" {");

                for (int j = 1; j < matrix[i].length; j++) {

                    buf.append(" ").append(matrix[i][j]);

                }

                buf.append(" }");

                out.println(buf);

            }

            out.println("}");

        }

    }

/*

    public static

    int[][] makeHistogramMatrix(int[] values) {

        // Make sure they are sorted.

        values = maybeSort(values);

        long[] hist2col = computeHistogram2Col(values);

        int[][] matrix = makeMatrix(hist2col);

        return matrix;

    }

*/

    private static

    int[][] makeMatrix(long[] hist2col) {

        // Sort by increasing count, then by increasing value.

        Arrays.sort(hist2col);

        int[] counts = new int[hist2col.length];

        for (int i = 0; i < counts.length; i++) {

            counts[i] = (int)( hist2col[i] >>> 32 );

        }

        long[] countHist = computeHistogram2Col(counts);

        int[][] matrix = new int[countHist.length][];

        int histp = 0;  // cursor into hist2col (increasing count, value)

        int countp = 0; // cursor into countHist (increasing count)

        // Do a join between hist2col (resorted) and countHist.

        for (int i = matrix.length; --i >= 0; ) {

            long countAndRep = countHist[countp++];

            int count  = (int) (countAndRep);  // what is the value count?

            int repeat = (int) (countAndRep >>> 32);  // # times repeated?

            int[] row = new int[1+repeat];

            row[0] = count;

            for (int j = 0; j < repeat; j++) {

                long countAndValue = hist2col[histp++];

                assert(countAndValue >>> 32 == count);

                row[1+j] = (int) countAndValue;

            }

            matrix[i] = row;

        }

        assert(histp == hist2col.length);

        return matrix;

    }

    private static

    int[][] makeTable(long[] hist2col) {

        int[][] table = new int[2][hist2col.length];

        // Break apart the entries in hist2col.

        // table[0] gets values, table[1] gets entries.

        for (int i = 0; i < hist2col.length; i++) {

            table[0][i] = (int)( hist2col[i] );

            table[1][i] = (int)( hist2col[i] >>> 32 );

        }

        return table;

    }

    /** Simple two-column histogram.  Contains repeated counts.

     *  Assumes input is sorted.  Does not sort output columns.

     *  <p>

     *  Format of result:

     *  <pre>

     *  long[] hist = {

     *    (count1 << 32) | (value1),

     *    (count2 << 32) | (value2),

     *    ...

     *  }

     *  </pre>

     *  In addition, the sequence {valuei...} is guaranteed to be sorted.

     *  Note that resorting this using Arrays.sort() will reorder the

     *  entries by increasing count.

     */

    private static

    long[] computeHistogram2Col(int[] sortedValues) {

        switch (sortedValues.length) {

        case 0:

            return new long[]{ };

        case 1:

            return new long[]{ ((long)1 << 32) | (LOW32 & sortedValues[0]) };

        }

        long[] hist = null;

        for (boolean sizeOnly = true; ; sizeOnly = false) {

            int prevIndex = -1;

            int prevValue = sortedValues[0] ^ -1;  // force a difference

            int prevCount = 0;

            for (int i = 0; i <= sortedValues.length; i++) {

                int thisValue;

                if (i < sortedValues.length)

                    thisValue = sortedValues[i];

                else

                    thisValue = prevValue ^ -1;  // force a difference at end

                if (thisValue == prevValue) {

                    prevCount += 1;

                } else {

                    // Found a new value.

                    if (!sizeOnly && prevCount != 0) {

                        // Save away previous value.

                        hist[prevIndex] = ((long)prevCount << 32)

                                        | (LOW32 & prevValue);

                    }

                    prevValue = thisValue;

                    prevCount = 1;

                    prevIndex += 1;

                }

            }

            if (sizeOnly) {

                // Finished the sizing pass.  Allocate the histogram.

                hist = new long[prevIndex];

            } else {

                break;  // done

            }

        }

        return hist;

    }

    /** Regroup the histogram, so that it becomes an approximate histogram

     *  whose rows are of the given lengths.

     *  If matrix rows must be split, the latter parts (larger values)

     *  are placed earlier in the new matrix.

     *  If matrix rows are joined, they are resorted into ascending order.

     *  In the new histogram, the counts are averaged over row entries.

     */

    private static

    int[][] regroupHistogram(int[][] matrix, int[] groups) {

        long oldEntries = 0;

        for (int i = 0; i < matrix.length; i++) {

            oldEntries += matrix[i].length-1;

        }

        long newEntries = 0;

        for (int ni = 0; ni < groups.length; ni++) {

            newEntries += groups[ni];

        }

        if (newEntries > oldEntries) {

            int newlen = groups.length;

            long ok = oldEntries;

            for (int ni = 0; ni < groups.length; ni++) {

                if (ok < groups[ni]) {

                    int[] newGroups = new int[ni+1];

                    System.arraycopy(groups, 0, newGroups, 0, ni+1);

                    groups = newGroups;

                    groups[ni] = (int) ok;

                    ok = 0;

                    break;

                }

                ok -= groups[ni];

            }

        } else {

            long excess = oldEntries - newEntries;

            int[] newGroups = new int[groups.length+1];

            System.arraycopy(groups, 0, newGroups, 0, groups.length);

            newGroups[groups.length] = (int) excess;

            groups = newGroups;

        }

        int[][] newMatrix = new int[groups.length][];