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