[9284] | 1 | // License: GPL. For details, see LICENSE file.
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| 2 | package org.openstreetmap.josm.gui.mappaint;
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| 3 |
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| 4 | import java.util.ArrayList;
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| 5 | import java.util.List;
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[9371] | 6 | import java.util.Objects;
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[9284] | 7 |
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| 8 | import org.openstreetmap.josm.gui.mappaint.styleelement.StyleElement;
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| 9 | import org.openstreetmap.josm.tools.Pair;
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| 10 |
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| 11 | /**
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| 12 | * Splits the range of possible scale values (0 < scale < +Infinity) into
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| 13 | * multiple subranges, for each scale range it keeps a data object of a certain
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| 14 | * type T (can be null).
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| 15 | *
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| 16 | * Used for caching style information for different zoom levels.
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| 17 | *
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| 18 | * Immutable class, equals & hashCode is required (the same for
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| 19 | * {@link StyleElementList}, {@link StyleElement} and its subclasses).
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| 20 | *
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| 21 | * @param <T> the type of the data objects
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| 22 | */
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| 23 | public class DividedScale<T> {
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| 24 |
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[10236] | 25 | /**
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| 26 | * This exception type is for debugging #8997 and can later be replaced by AssertionError
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| 27 | */
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| 28 | public static class RangeViolatedError extends RuntimeException {
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| 29 | /**
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| 30 | * Constructs a new {@code RangeViolatedError}
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| 31 | * @param message error message
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| 32 | */
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[9284] | 33 | public RangeViolatedError(String message) {
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| 34 | super(message);
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| 35 | }
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| 36 | }
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| 37 |
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| 38 | /* list of boundaries for the scale ranges */
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| 39 | private final List<Double> bd;
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| 40 | /* data objects for each scale range */
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| 41 | private final List<T> data;
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| 42 |
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| 43 | protected DividedScale() {
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| 44 | bd = new ArrayList<>();
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| 45 | bd.add(0.0);
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| 46 | bd.add(Double.POSITIVE_INFINITY);
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| 47 | data = new ArrayList<>();
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| 48 | data.add(null);
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| 49 | }
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| 50 |
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| 51 | protected DividedScale(DividedScale<T> s) {
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| 52 | bd = new ArrayList<>(s.bd);
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| 53 | data = new ArrayList<>(s.data);
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| 54 | }
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| 55 |
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| 56 | /**
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| 57 | * Looks up the data object for a certain scale value.
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| 58 | *
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| 59 | * @param scale scale
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| 60 | * @return the data object at the given scale, can be null
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| 61 | */
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| 62 | public T get(double scale) {
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| 63 | if (scale <= 0)
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| 64 | throw new IllegalArgumentException("scale must be <= 0 but is "+scale);
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| 65 | for (int i = 0; i < data.size(); ++i) {
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| 66 | if (bd.get(i) < scale && scale <= bd.get(i+1)) {
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| 67 | return data.get(i);
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| 68 | }
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| 69 | }
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| 70 | throw new AssertionError();
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| 71 | }
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| 72 |
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| 73 | /**
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| 74 | * Looks up the data object for a certain scale value and additionally returns
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| 75 | * the scale range where the object is valid.
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| 76 | *
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| 77 | * @param scale scale
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| 78 | * @return pair containing data object and range
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| 79 | */
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| 80 | public Pair<T, Range> getWithRange(double scale) {
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| 81 | if (scale <= 0)
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| 82 | throw new IllegalArgumentException("scale must be <= 0 but is "+scale);
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| 83 | for (int i = 0; i < data.size(); ++i) {
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| 84 | if (bd.get(i) < scale && scale <= bd.get(i+1)) {
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| 85 | return new Pair<>(data.get(i), new Range(bd.get(i), bd.get(i+1)));
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| 86 | }
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| 87 | }
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| 88 | throw new AssertionError();
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| 89 | }
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| 90 |
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| 91 | /**
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| 92 | * Add data object which is valid for the given range.
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| 93 | *
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| 94 | * This is only possible, if there is no data for the given range yet.
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| 95 | *
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| 96 | * @param o data object
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| 97 | * @param r the valid range
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| 98 | * @return a new, updated, <code>DividedScale</code> object
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| 99 | */
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| 100 | public DividedScale<T> put(T o, Range r) {
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| 101 | DividedScale<T> s = new DividedScale<>(this);
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| 102 | s.putImpl(o, r.getLower(), r.getUpper());
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| 103 | s.consistencyTest();
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| 104 | return s;
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| 105 | }
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| 106 |
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| 107 | /**
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| 108 | * Implementation of the <code>put</code> operation.
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| 109 | *
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| 110 | * ASCII-art explanation:
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| 111 | *
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| 112 | * data[i]
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| 113 | * --|-------|---------|--
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| 114 | * bd[i-1] bd[i] bd[i+1]
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| 115 | *
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| 116 | * (--------]
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| 117 | * lower upper
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| 118 | * @param o data object
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| 119 | * @param lower lower bound
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| 120 | * @param upper upper bound
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| 121 | */
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[10145] | 122 | private void putImpl(T o, double lower, double upper) {
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[9284] | 123 | int i = 0;
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| 124 | while (bd.get(i) < lower) {
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| 125 | ++i;
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| 126 | }
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| 127 | if (bd.get(i) == lower) {
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| 128 | if (upper > bd.get(i+1))
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[9341] | 129 | throw new RangeViolatedError("the new range must be within a single subrange (1)");
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[9284] | 130 | if (data.get(i) != null)
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[9341] | 131 | throw new RangeViolatedError("the new range must be within a subrange that has no data");
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[9284] | 132 |
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| 133 | if (bd.get(i+1) == upper) {
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| 134 | // --|-------|--------|--
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| 135 | // i-1 i i+1
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| 136 | // (--------]
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| 137 | data.set(i, o);
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| 138 | } else {
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| 139 | // --|-------|--------|--
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| 140 | // i-1 i i+1
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| 141 | // (-----]
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| 142 | bd.add(i+1, upper);
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| 143 | data.add(i, o);
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| 144 | }
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| 145 | } else {
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| 146 | if (bd.get(i) < upper)
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[9341] | 147 | throw new RangeViolatedError("the new range must be within a single subrange (2)");
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[9284] | 148 | if (data.get(i-1) != null)
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| 149 | throw new AssertionError();
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| 150 |
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| 151 | // --|-------|--------|--
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| 152 | // i-1 i i+1
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| 153 | // (--] or
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| 154 | // (----]
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| 155 | bd.add(i, lower);
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| 156 | data.add(i, o);
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| 157 |
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| 158 | // --|--|----|--------|--
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| 159 | // i-1 i i+1 i+2
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| 160 | // (--]
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| 161 | if (bd.get(i+1) > upper) {
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| 162 | bd.add(i+1, upper);
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| 163 | data.add(i+1, null);
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| 164 | }
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| 165 | }
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| 166 | }
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| 167 |
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[10145] | 168 | /**
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| 169 | * Runs a consistency test.
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| 170 | * @throws AssertionError When an invariant is broken.
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| 171 | */
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[9284] | 172 | public void consistencyTest() {
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| 173 | if (bd.size() < 2) throw new AssertionError(bd);
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| 174 | if (data.isEmpty()) throw new AssertionError(data);
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| 175 | if (bd.size() != data.size() + 1) throw new AssertionError();
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| 176 | if (bd.get(0) != 0) throw new AssertionError();
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| 177 | if (bd.get(bd.size() - 1) != Double.POSITIVE_INFINITY) throw new AssertionError();
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| 178 | for (int i = 0; i < data.size() - 1; ++i) {
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| 179 | if (bd.get(i) >= bd.get(i + 1)) throw new AssertionError();
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| 180 | }
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| 181 | }
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| 182 |
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| 183 | @Override
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| 184 | public boolean equals(Object obj) {
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[9371] | 185 | if (this == obj) return true;
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| 186 | if (obj == null || getClass() != obj.getClass()) return false;
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| 187 | DividedScale<?> that = (DividedScale<?>) obj;
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| 188 | return Objects.equals(bd, that.bd) &&
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| 189 | Objects.equals(data, that.data);
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[9284] | 190 | }
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| 191 |
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| 192 | @Override
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| 193 | public int hashCode() {
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[9371] | 194 | return Objects.hash(bd, data);
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[9284] | 195 | }
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| 196 |
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| 197 | @Override
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| 198 | public String toString() {
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| 199 | return "DS{" + bd + ' ' + data + '}';
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| 200 | }
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| 201 | }
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