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1 package fj;
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2
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3 import fj.data.Array;
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4 import fj.data.Either;
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5 import fj.data.List;
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6 import fj.data.Natural;
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7 import fj.data.NonEmptyList;
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8 import fj.data.Option;
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9 import fj.data.Set;
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10 import fj.data.Stream;
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11 import fj.data.Validation;
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12
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13 import java.math.BigDecimal;
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14 import java.math.BigInteger;
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15
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16 import static fj.Function.curry;
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17
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18 /**
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19 * Tests for ordering between two objects.
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20 *
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21 * @version %build.number%
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22 */
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23 public final class Ord<A> {
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24 private final F<A, F<A, Ordering>> f;
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25
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26 private Ord(final F<A, F<A, Ordering>> f) {
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27 this.f = f;
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28 }
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29
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30 /**
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31 * First-class ordering.
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32 *
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33 * @return A function that returns an ordering for its arguments.
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34 */
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35 public F<A, F<A, Ordering>> compare() {
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36 return f;
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37 }
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38
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39 /**
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40 * Returns an ordering for the given arguments.
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41 *
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42 * @param a1 An instance to compare for ordering to another.
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43 * @param a2 An instance to compare for ordering to another.
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44 * @return An ordering for the given arguments.
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45 */
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46 public Ordering compare(final A a1, final A a2) {
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47 return f.f(a1).f(a2);
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48 }
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49
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50 /**
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51 * Returns <code>true</code> if the given arguments are equal, <code>false</code> otherwise.
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52 *
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53 * @param a1 An instance to compare for equality to another.
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54 * @param a2 An instance to compare for equality to another.
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55 * @return <code>true</code> if the given arguments are equal, <code>false</code> otherwise.
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56 */
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57 public boolean eq(final A a1, final A a2) {
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58 return compare(a1, a2) == Ordering.EQ;
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59 }
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60
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61 /**
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62 * Returns an <code>Equal</code> for this order.
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63 *
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64 * @return An <code>Equal</code> for this order.
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65 */
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66 public Equal<A> equal() {
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67 return Equal.equal(curry(new F2<A, A, Boolean>() {
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68 public Boolean f(final A a1, final A a2) {
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69 return eq(a1, a2);
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70 }
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71 }));
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72 }
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73
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74 /**
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75 * Maps the given function across this ord as a contra-variant functor.
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76 *
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77 * @param f The function to map.
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78 * @return A new ord.
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79 */
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80 public <B> Ord<B> comap(final F<B, A> f) {
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81 return ord(F1Functions.o(F1Functions.o(F1Functions.<B, A, Ordering>andThen(f), this.f), f));
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82 }
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83
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84 /**
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85 * Returns <code>true</code> if the first given argument is less than the second given argument,
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86 * <code>false</code> otherwise.
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87 *
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88 * @param a1 An instance to compare for ordering to another.
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89 * @param a2 An instance to compare for ordering to another.
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90 * @return <code>true</code> if the first given argument is less than the second given argument,
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91 * <code>false</code> otherwise.
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92 */
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93 public boolean isLessThan(final A a1, final A a2) {
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94 return compare(a1, a2) == Ordering.LT;
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95 }
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96
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97 /**
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98 * Returns <code>true</code> if the first given argument is greater than the second given
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99 * argument, <code>false</code> otherwise.
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100 *
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101 * @param a1 An instance to compare for ordering to another.
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102 * @param a2 An instance to compare for ordering to another.
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103 * @return <code>true</code> if the first given argument is greater than the second given
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104 * argument, <code>false</code> otherwise.
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105 */
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106 public boolean isGreaterThan(final A a1, final A a2) {
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107 return compare(a1, a2) == Ordering.GT;
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108 }
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109
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110 /**
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111 * Returns a function that returns true if its argument is less than the argument to this method.
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112 *
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113 * @param a A value to compare against.
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114 * @return A function that returns true if its argument is less than the argument to this method.
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115 */
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116 public F<A, Boolean> isLessThan(final A a) {
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117 return new F<A, Boolean>() {
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118 public Boolean f(final A a2) {
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119 return compare(a2, a) == Ordering.LT;
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120 }
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121 };
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122 }
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123
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124 /**
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125 * Returns a function that returns true if its argument is greater than than the argument to this method.
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126 *
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127 * @param a A value to compare against.
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128 * @return A function that returns true if its argument is greater than the argument to this method.
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129 */
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130 public F<A, Boolean> isGreaterThan(final A a) {
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131 return new F<A, Boolean>() {
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132 public Boolean f(final A a2) {
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133 return compare(a2, a) == Ordering.GT;
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134 }
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135 };
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136 }
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137
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138 /**
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139 * Returns the greater of its two arguments.
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140 *
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141 * @param a1 A value to compare with another.
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142 * @param a2 A value to compare with another.
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143 * @return The greater of the two values.
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144 */
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145 public A max(final A a1, final A a2) {
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146 return isGreaterThan(a1, a2) ? a1 : a2;
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147 }
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148
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149
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150 /**
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151 * Returns the lesser of its two arguments.
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152 *
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153 * @param a1 A value to compare with another.
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154 * @param a2 A value to compare with another.
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155 * @return The lesser of the two values.
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156 */
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157 public A min(final A a1, final A a2) {
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158 return isLessThan(a1, a2) ? a1 : a2;
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159 }
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160
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161 /**
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162 * A function that returns the greater of its two arguments.
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163 */
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164 public final F<A, F<A, A>> max = curry(new F2<A, A, A>() {
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165 public A f(final A a, final A a1) {
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166 return max(a, a1);
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167 }
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168 });
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169
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170 /**
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171 * A function that returns the lesser of its two arguments.
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172 */
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173 public final F<A, F<A, A>> min = curry(new F2<A, A, A>() {
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174 public A f(final A a, final A a1) {
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175 return min(a, a1);
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176 }
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177 });
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178
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179 /**
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180 * Returns an order instance that uses the given equality test and ordering function.
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181 *
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182 * @param f The order function.
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183 * @return An order instance.
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184 */
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185 public static <A> Ord<A> ord(final F<A, F<A, Ordering>> f) {
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186 return new Ord<A>(f);
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187 }
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188
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189 /**
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190 * An order instance for the <code>boolean</code> type.
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191 */
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192 public static final Ord<Boolean> booleanOrd = new Ord<Boolean>(
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193 new F<Boolean, F<Boolean, Ordering>>() {
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194 public F<Boolean, Ordering> f(final Boolean a1) {
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195 return new F<Boolean, Ordering>() {
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196 public Ordering f(final Boolean a2) {
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197 final int x = a1.compareTo(a2);
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198 return x < 0 ? Ordering.LT : x == 0 ? Ordering.EQ : Ordering.GT;
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199 }
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200 };
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201 }
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202 });
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203
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204 /**
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205 * An order instance for the <code>byte</code> type.
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206 */
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207 public static final Ord<Byte> byteOrd = new Ord<Byte>(
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208 new F<Byte, F<Byte, Ordering>>() {
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209 public F<Byte, Ordering> f(final Byte a1) {
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210 return new F<Byte, Ordering>() {
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211 public Ordering f(final Byte a2) {
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212 final int x = a1.compareTo(a2);
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213 return x < 0 ? Ordering.LT : x == 0 ? Ordering.EQ : Ordering.GT;
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214 }
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215 };
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216 }
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217 });
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218
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219 /**
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220 * An order instance for the <code>char</code> type.
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221 */
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222 public static final Ord<Character> charOrd = new Ord<Character>(
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223 new F<Character, F<Character, Ordering>>() {
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224 public F<Character, Ordering> f(final Character a1) {
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225 return new F<Character, Ordering>() {
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226 public Ordering f(final Character a2) {
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227 final int x = a1.compareTo(a2);
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228 return x < 0 ? Ordering.LT : x == 0 ? Ordering.EQ : Ordering.GT;
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229 }
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230 };
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231 }
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232 });
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233
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234 /**
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235 * An order instance for the <code>double</code> type.
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236 */
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237 public static final Ord<Double> doubleOrd = new Ord<Double>(
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238 new F<Double, F<Double, Ordering>>() {
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239 public F<Double, Ordering> f(final Double a1) {
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240 return new F<Double, Ordering>() {
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241 public Ordering f(final Double a2) {
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242 final int x = a1.compareTo(a2);
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243 return x < 0 ? Ordering.LT : x == 0 ? Ordering.EQ : Ordering.GT;
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244 }
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245 };
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246 }
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247 });
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248
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249 /**
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250 * An order instance for the <code>float</code> type.
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251 */
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252 public static final Ord<Float> floatOrd = new Ord<Float>(
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253 new F<Float, F<Float, Ordering>>() {
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254 public F<Float, Ordering> f(final Float a1) {
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255 return new F<Float, Ordering>() {
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256 public Ordering f(final Float a2) {
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257 final int x = a1.compareTo(a2);
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258 return x < 0 ? Ordering.LT : x == 0 ? Ordering.EQ : Ordering.GT;
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259 }
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260 };
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261 }
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262 });
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263
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264 /**
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265 * An order instance for the <code>int</code> type.
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266 */
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267 public static final Ord<Integer> intOrd = new Ord<Integer>(
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268 new F<Integer, F<Integer, Ordering>>() {
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269 public F<Integer, Ordering> f(final Integer a1) {
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270 return new F<Integer, Ordering>() {
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271 public Ordering f(final Integer a2) {
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272 final int x = a1.compareTo(a2);
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273 return x < 0 ? Ordering.LT : x == 0 ? Ordering.EQ : Ordering.GT;
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274 }
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275 };
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276 }
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277 });
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278
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279 /**
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280 * An order instance for the <code>BigInteger</code> type.
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281 */
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282 public static final Ord<BigInteger> bigintOrd = new Ord<BigInteger>(
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283 new F<BigInteger, F<BigInteger, Ordering>>() {
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284 public F<BigInteger, Ordering> f(final BigInteger a1) {
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285 return new F<BigInteger, Ordering>() {
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286 public Ordering f(final BigInteger a2) {
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287 final int x = a1.compareTo(a2);
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288 return x < 0 ? Ordering.LT : x == 0 ? Ordering.EQ : Ordering.GT;
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289 }
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290 };
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291 }
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292 });
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293
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294 /**
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295 * An order instance for the <code>BigDecimal</code> type.
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296 */
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297 public static final Ord<BigDecimal> bigdecimalOrd = new Ord<BigDecimal>(
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298 new F<BigDecimal, F<BigDecimal, Ordering>>() {
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299 public F<BigDecimal, Ordering> f(final BigDecimal a1) {
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300 return new F<BigDecimal, Ordering>() {
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301 public Ordering f(final BigDecimal a2) {
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302 final int x = a1.compareTo(a2);
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303 return x < 0 ? Ordering.LT : x == 0 ? Ordering.EQ : Ordering.GT;
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304 }
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305 };
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306 }
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307 });
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308
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309 /**
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310 * An order instance for the <code>long</code> type.
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311 */
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312 public static final Ord<Long> longOrd = new Ord<Long>(
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313 new F<Long, F<Long, Ordering>>() {
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314 public F<Long, Ordering> f(final Long a1) {
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315 return new F<Long, Ordering>() {
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316 public Ordering f(final Long a2) {
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317 final int x = a1.compareTo(a2);
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318 return x < 0 ? Ordering.LT : x == 0 ? Ordering.EQ : Ordering.GT;
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319 }
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320 };
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321 }
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322 });
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323
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324 /**
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325 * An order instance for the <code>short</code> type.
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326 */
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327 public static final Ord<Short> shortOrd = new Ord<Short>(
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328 new F<Short, F<Short, Ordering>>() {
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329 public F<Short, Ordering> f(final Short a1) {
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330 return new F<Short, Ordering>() {
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331 public Ordering f(final Short a2) {
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332 final int x = a1.compareTo(a2);
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333 return x < 0 ? Ordering.LT : x == 0 ? Ordering.EQ : Ordering.GT;
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334 }
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335 };
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336 }
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337 });
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338
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339 /**
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340 * An order instance for the {@link Ordering} type.
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341 */
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342 public static final Ord<Ordering> orderingOrd = new Ord<Ordering>(curry(new F2<Ordering, Ordering, Ordering>() {
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343 public Ordering f(final Ordering o1, final Ordering o2) {
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344 return o1 == o2 ?
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345 Ordering.EQ :
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346 o1 == Ordering.LT ?
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347 Ordering.LT :
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348 o2 == Ordering.LT ?
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349 Ordering.GT :
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350 o1 == Ordering.EQ ?
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351 Ordering.LT :
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352 Ordering.GT;
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353 }
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354 }));
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355
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356 /**
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357 * An order instance for the {@link String} type.
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358 */
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359 public static final Ord<String> stringOrd = new Ord<String>(
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360 new F<String, F<String, Ordering>>() {
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361 public F<String, Ordering> f(final String a1) {
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362 return new F<String, Ordering>() {
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363 public Ordering f(final String a2) {
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364 final int x = a1.compareTo(a2);
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365 return x < 0 ? Ordering.LT : x == 0 ? Ordering.EQ : Ordering.GT;
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366 }
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367 };
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368 }
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369 });
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370
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371 /**
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372 * An order instance for the {@link StringBuffer} type.
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373 */
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374 public static final Ord<StringBuffer> stringBufferOrd =
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375 new Ord<StringBuffer>(new F<StringBuffer, F<StringBuffer, Ordering>>() {
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376 public F<StringBuffer, Ordering> f(final StringBuffer a1) {
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377 return new F<StringBuffer, Ordering>() {
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378 public Ordering f(final StringBuffer a2) {
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379 return stringOrd.compare(a1.toString(), a2.toString());
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380 }
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381 };
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382 }
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383 });
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384
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385 /**
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386 * An order instance for the {@link StringBuffer} type.
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387 */
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388 public static final Ord<StringBuilder> stringBuilderOrd =
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389 new Ord<StringBuilder>(new F<StringBuilder, F<StringBuilder, Ordering>>() {
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390 public F<StringBuilder, Ordering> f(final StringBuilder a1) {
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391 return new F<StringBuilder, Ordering>() {
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392 public Ordering f(final StringBuilder a2) {
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393 return stringOrd.compare(a1.toString(), a2.toString());
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394 }
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395 };
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396 }
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397 });
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398
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399 /**
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400 * An order instance for the {@link Option} type.
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401 *
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402 * @param oa Order across the element of the option.
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403 * @return An order instance for the {@link Option} type.
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404 */
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405 public static <A> Ord<Option<A>> optionOrd(final Ord<A> oa) {
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406 return new Ord<Option<A>>(new F<Option<A>, F<Option<A>, Ordering>>() {
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407 public F<Option<A>, Ordering> f(final Option<A> o1) {
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408 return new F<Option<A>, Ordering>() {
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409 public Ordering f(final Option<A> o2) {
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410 return o1.isNone() ?
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411 o2.isNone() ?
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412 Ordering.EQ :
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413 Ordering.LT :
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414 o2.isNone() ?
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415 Ordering.GT :
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416 oa.f.f(o1.some()).f(o2.some());
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417 }
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418 };
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419 }
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420 });
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421 }
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422
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423 /**
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424 * An order instance for the {@link Either} type.
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425 *
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426 * @param oa Order across the left side of {@link Either}.
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427 * @param ob Order across the right side of {@link Either}.
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428 * @return An order instance for the {@link Either} type.
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429 */
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430 public static <A, B> Ord<Either<A, B>> eitherOrd(final Ord<A> oa, final Ord<B> ob) {
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431 return new Ord<Either<A, B>>(new F<Either<A, B>, F<Either<A, B>, Ordering>>() {
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432 public F<Either<A, B>, Ordering> f(final Either<A, B> e1) {
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433 return new F<Either<A, B>, Ordering>() {
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434 public Ordering f(final Either<A, B> e2) {
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435 return e1.isLeft() ?
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436 e2.isLeft() ?
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437 oa.f.f(e1.left().value()).f(e2.left().value()) :
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438 Ordering.LT :
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439 e2.isLeft() ?
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440 Ordering.GT :
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441 ob.f.f(e1.right().value()).f(e2.right().value());
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442 }
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443 };
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444 }
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445 });
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446 }
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447
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448 /**
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449 * An order instance for the {@link Validation} type.
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450 *
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451 * @param oa Order across the failing side of {@link Validation}.
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452 * @param ob Order across the succeeding side of {@link Validation}.
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453 * @return An order instance for the {@link Validation} type.
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454 */
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455 public static <A, B> Ord<Validation<A, B>> validationOrd(final Ord<A> oa, final Ord<B> ob) {
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456 return eitherOrd(oa, ob).comap(Validation.<A, B>either());
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457 }
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458
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459 /**
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460 * An order instance for the {@link List} type.
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461 *
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462 * @param oa Order across the elements of the list.
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463 * @return An order instance for the {@link List} type.
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464 */
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465 public static <A> Ord<List<A>> listOrd(final Ord<A> oa) {
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466 return new Ord<List<A>>(new F<List<A>, F<List<A>, Ordering>>() {
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467 public F<List<A>, Ordering> f(final List<A> l1) {
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468 return new F<List<A>, Ordering>() {
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469 public Ordering f(final List<A> l2) {
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470 if (l1.isEmpty())
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471 return l2.isEmpty() ? Ordering.EQ : Ordering.LT;
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472 else if (l2.isEmpty())
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473 return l1.isEmpty() ? Ordering.EQ : Ordering.GT;
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474 else {
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475 final Ordering c = oa.compare(l1.head(), l2.head());
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476 return c == Ordering.EQ ? listOrd(oa).f.f(l1.tail()).f(l2.tail()) : c;
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477 }
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478 }
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479 };
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480 }
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481 });
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482 }
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483
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484 /**
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485 * An order instance for the {@link NonEmptyList} type.
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486 *
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487 * @param oa Order across the elements of the non-empty list.
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488 * @return An order instance for the {@link NonEmptyList} type.
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489 */
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490 public static <A> Ord<NonEmptyList<A>> nonEmptyListOrd(final Ord<A> oa) {
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491 return listOrd(oa).comap(NonEmptyList.<A>toList_());
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492 }
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493
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494 /**
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495 * An order instance for the {@link Stream} type.
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496 *
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497 * @param oa Order across the elements of the stream.
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498 * @return An order instance for the {@link Stream} type.
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499 */
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500 public static <A> Ord<Stream<A>> streamOrd(final Ord<A> oa) {
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501 return new Ord<Stream<A>>(new F<Stream<A>, F<Stream<A>, Ordering>>() {
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502 public F<Stream<A>, Ordering> f(final Stream<A> s1) {
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503 return new F<Stream<A>, Ordering>() {
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504 public Ordering f(final Stream<A> s2) {
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505 if (s1.isEmpty())
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506 return s2.isEmpty() ? Ordering.EQ : Ordering.LT;
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507 else if (s2.isEmpty())
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508 return s1.isEmpty() ? Ordering.EQ : Ordering.GT;
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509 else {
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510 final Ordering c = oa.compare(s1.head(), s2.head());
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511 return c == Ordering.EQ ? streamOrd(oa).f.f(s1.tail()._1()).f(s2.tail()._1()) : c;
|
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512 }
|
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513 }
|
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|
514 };
|
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515 }
|
|
|
516 });
|
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|
517 }
|
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518
|
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|
519 /**
|
|
|
520 * An order instance for the {@link Array} type.
|
|
|
521 *
|
|
|
522 * @param oa Order across the elements of the array.
|
|
|
523 * @return An order instance for the {@link Array} type.
|
|
|
524 */
|
|
|
525 public static <A> Ord<Array<A>> arrayOrd(final Ord<A> oa) {
|
|
|
526 return new Ord<Array<A>>(new F<Array<A>, F<Array<A>, Ordering>>() {
|
|
|
527 public F<Array<A>, Ordering> f(final Array<A> a1) {
|
|
|
528 return new F<Array<A>, Ordering>() {
|
|
|
529 public Ordering f(final Array<A> a2) {
|
|
|
530 int i = 0;
|
|
|
531 //noinspection ForLoopWithMissingComponent
|
|
|
532 for (; i < a1.length() && i < a2.length(); i++) {
|
|
|
533 final Ordering c = oa.compare(a1.get(i), a2.get(i));
|
|
|
534 if (c == Ordering.GT || c == Ordering.LT)
|
|
|
535 return c;
|
|
|
536 }
|
|
|
537 return i == a1.length() ?
|
|
|
538 i == a2.length() ?
|
|
|
539 Ordering.EQ :
|
|
|
540 Ordering.LT :
|
|
|
541 i == a1.length() ?
|
|
|
542 Ordering.EQ :
|
|
|
543 Ordering.GT;
|
|
|
544 }
|
|
|
545 };
|
|
|
546 }
|
|
|
547 });
|
|
|
548 }
|
|
|
549
|
|
|
550 /**
|
|
|
551 * An order instance for the {@link Set} type.
|
|
|
552 *
|
|
|
553 * @param oa Order across the elements of the set.
|
|
|
554 * @return An order instance for the {@link Set} type.
|
|
|
555 */
|
|
|
556 public static <A> Ord<Set<A>> setOrd(final Ord<A> oa) {
|
|
|
557 return streamOrd(oa).comap(new F<Set<A>, Stream<A>>() {
|
|
|
558 public Stream<A> f(final Set<A> as) {
|
|
|
559 return as.toStream();
|
|
|
560 }
|
|
|
561 });
|
|
|
562 }
|
|
|
563
|
|
|
564 /**
|
|
|
565 * An order instance for the {@link Unit} type.
|
|
|
566 */
|
|
|
567 public static final Ord<Unit> unitOrd = ord(curry(new F2<Unit, Unit, Ordering>() {
|
|
|
568 public Ordering f(final Unit u1, final Unit u2) {
|
|
|
569 return Ordering.EQ;
|
|
|
570 }
|
|
|
571 }));
|
|
|
572
|
|
|
573 /**
|
|
|
574 * An order instance for a product-1.
|
|
|
575 *
|
|
|
576 * @param oa Order across the produced type.
|
|
|
577 * @return An order instance for a product-1.
|
|
|
578 */
|
|
|
579 public static <A> Ord<P1<A>> p1Ord(final Ord<A> oa) {
|
|
|
580 return oa.comap(P1.<A>__1());
|
|
|
581 }
|
|
|
582
|
|
|
583
|
|
|
584 /**
|
|
|
585 * An order instance for a product-2, with the first factor considered most significant.
|
|
|
586 *
|
|
|
587 * @param oa An order instance for the first factor.
|
|
|
588 * @param ob An order instance for the second factor.
|
|
|
589 * @return An order instance for a product-2, with the first factor considered most significant.
|
|
|
590 */
|
|
|
591 public static <A, B> Ord<P2<A, B>> p2Ord(final Ord<A> oa, final Ord<B> ob) {
|
|
|
592 return ord(curry(new F2<P2<A, B>, P2<A, B>, Ordering>() {
|
|
|
593 public Ordering f(final P2<A, B> a, final P2<A, B> b) {
|
|
|
594 return oa.eq(a._1(), b._1()) ? ob.compare(a._2(), b._2()) : oa.compare(a._1(), b._1());
|
|
|
595 }
|
|
|
596 }));
|
|
|
597 }
|
|
|
598
|
|
|
599 /**
|
|
|
600 * An order instance for a product-3, with the first factor considered most significant.
|
|
|
601 *
|
|
|
602 * @param oa An order instance for the first factor.
|
|
|
603 * @param ob An order instance for the second factor.
|
|
|
604 * @param oc An order instance for the third factor.
|
|
|
605 * @return An order instance for a product-3, with the first factor considered most significant.
|
|
|
606 */
|
|
|
607 public static <A, B, C> Ord<P3<A, B, C>> p3Ord(final Ord<A> oa, final Ord<B> ob, final Ord<C> oc) {
|
|
|
608 return ord(curry(new F2<P3<A, B, C>, P3<A, B, C>, Ordering>() {
|
|
|
609 public Ordering f(final P3<A, B, C> a, final P3<A, B, C> b) {
|
|
|
610 return oa.eq(a._1(), b._1()) ?
|
|
|
611 p2Ord(ob, oc).compare(P.p(a._2(), a._3()), P.p(b._2(), b._3()))
|
|
|
612 : oa.compare(a._1(), b._1());
|
|
|
613 }
|
|
|
614 }));
|
|
|
615 }
|
|
|
616
|
|
|
617 /**
|
|
|
618 * An order instance for the <code>Natural</code> type.
|
|
|
619 */
|
|
|
620 public static final Ord<Natural> naturalOrd = bigintOrd.comap(Natural.bigIntegerValue);
|
|
|
621
|
|
|
622
|
|
|
623 /**
|
|
|
624 * An order instance for the <code>Comparable</code> interface.
|
|
|
625 *
|
|
|
626 * @return An order instance for the <code>Comparable</code> interface.
|
|
|
627 */
|
|
|
628 public static <A extends Comparable<A>> Ord<A> comparableOrd() {
|
|
|
629 return ord(new F<A, F<A, Ordering>>() {
|
|
|
630 public F<A, Ordering> f(final A a1) {
|
|
|
631 return new F<A, Ordering>() {
|
|
|
632 public Ordering f(final A a2) {
|
|
|
633 return Ordering.fromInt(a1.compareTo(a2));
|
|
|
634 }
|
|
|
635 };
|
|
|
636 }
|
|
|
637 });
|
|
|
638 }
|
|
|
639
|
|
|
640 /**
|
|
|
641 * An order instance that uses {@link Object#hashCode()} for computing the order and equality,
|
|
|
642 * thus objects returning the same hashCode are considered to be equals (check {@link #hashEqualsOrd()}
|
|
|
643 * for an additional check on {@link Object#equals(Object)}).
|
|
|
644 *
|
|
|
645 * @return An order instance that is based on {@link Object#hashCode()}.
|
|
|
646 * @see #hashEqualsOrd()
|
|
|
647 */
|
|
|
648 public static <A> Ord<A> hashOrd() {
|
|
|
649 return Ord.<A> ord(new F<A, F<A, Ordering>>() {
|
|
|
650 @Override
|
|
|
651 public F<A, Ordering> f(final A a) {
|
|
|
652 return new F<A, Ordering>() {
|
|
|
653 @Override
|
|
|
654 public Ordering f(final A a2) {
|
|
|
655 final int x = a.hashCode() - a2.hashCode();
|
|
|
656 return x < 0 ? Ordering.LT : x == 0 ? Ordering.EQ : Ordering.GT;
|
|
|
657 }
|
|
|
658 };
|
|
|
659 }
|
|
|
660 });
|
|
|
661 }
|
|
|
662
|
|
|
663 /**
|
|
|
664 * An order instance that uses {@link Object#hashCode()} and {@link Object#equals} for computing
|
|
|
665 * the order and equality. First the hashCode is compared, if this is equal, objects are compared
|
|
|
666 * using {@link Object#equals}.
|
|
|
667 *
|
|
|
668 * @return An order instance that is based on {@link Object#hashCode()} and {@link Object#equals}.
|
|
|
669 */
|
|
|
670 public static <A> Ord<A> hashEqualsOrd() {
|
|
|
671 return Ord.<A> ord(new F<A, F<A, Ordering>>() {
|
|
|
672 @Override
|
|
|
673 public F<A, Ordering> f(final A a) {
|
|
|
674 return new F<A, Ordering>() {
|
|
|
675 @Override
|
|
|
676 public Ordering f(final A a2) {
|
|
|
677 final int x = a.hashCode() - a2.hashCode();
|
|
|
678 return x < 0 ? Ordering.LT : x == 0 && a.equals(a2) ? Ordering.EQ : Ordering.GT;
|
|
|
679 }
|
|
|
680 };
|
|
|
681 }
|
|
|
682 });
|
|
|
683 }
|
|
|
684
|
|
|
685 }
|
