|
| 1 | +/* |
| 2 | + * Copyright © 2016-2025 The LmdbJava Open Source Project |
| 3 | + * |
| 4 | + * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | + * you may not use this file except in compliance with the License. |
| 6 | + * You may obtain a copy of the License at |
| 7 | + * |
| 8 | + * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | + * |
| 10 | + * Unless required by applicable law or agreed to in writing, software |
| 11 | + * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | + * See the License for the specific language governing permissions and |
| 14 | + * limitations under the License. |
| 15 | + */ |
| 16 | +package org.lmdbjava; |
| 17 | + |
| 18 | +import java.util.Collection; |
| 19 | +import java.util.Collections; |
| 20 | +import java.util.EnumSet; |
| 21 | +import java.util.Iterator; |
| 22 | +import java.util.Objects; |
| 23 | +import java.util.Set; |
| 24 | +import java.util.function.Function; |
| 25 | +import java.util.function.Supplier; |
| 26 | + |
| 27 | +/** |
| 28 | + * Encapsulates an immutable set of flags and the associated bit mask for the flags in the set. |
| 29 | + * |
| 30 | + * @param <T> The type of the flags in this set. Must extend {@link MaskedFlag} and {@link Enum<T>}. |
| 31 | + */ |
| 32 | +abstract class AbstractFlagSet<T extends Enum<T> & MaskedFlag> implements FlagSet<T> { |
| 33 | + |
| 34 | + private final Set<T> flags; |
| 35 | + private final int mask; |
| 36 | + |
| 37 | + protected AbstractFlagSet(final EnumSet<T> flags) { |
| 38 | + Objects.requireNonNull(flags); |
| 39 | + this.mask = MaskedFlag.mask(flags); |
| 40 | + this.flags = Collections.unmodifiableSet(Objects.requireNonNull(flags)); |
| 41 | + } |
| 42 | + |
| 43 | + @Override |
| 44 | + public int getMask() { |
| 45 | + return mask; |
| 46 | + } |
| 47 | + |
| 48 | + @Override |
| 49 | + public Set<T> getFlags() { |
| 50 | + return flags; |
| 51 | + } |
| 52 | + |
| 53 | + @Override |
| 54 | + public boolean isSet(final T flag) { |
| 55 | + // Probably cheaper to compare the masks than to use EnumSet.contains() |
| 56 | + return flag != null && MaskedFlag.isSet(mask, flag); |
| 57 | + } |
| 58 | + |
| 59 | + /** |
| 60 | + * @return The number of flags in this set. |
| 61 | + */ |
| 62 | + @Override |
| 63 | + public int size() { |
| 64 | + return flags.size(); |
| 65 | + } |
| 66 | + |
| 67 | + /** |
| 68 | + * @return True if this set is empty. |
| 69 | + */ |
| 70 | + @Override |
| 71 | + public boolean isEmpty() { |
| 72 | + return flags.isEmpty(); |
| 73 | + } |
| 74 | + |
| 75 | + /** |
| 76 | + * @return The {@link Iterator} for this set. |
| 77 | + */ |
| 78 | + @Override |
| 79 | + public Iterator<T> iterator() { |
| 80 | + return flags.iterator(); |
| 81 | + } |
| 82 | + |
| 83 | + @Override |
| 84 | + public boolean equals(Object object) { |
| 85 | + return FlagSet.equals(this, object); |
| 86 | + } |
| 87 | + |
| 88 | + @Override |
| 89 | + public int hashCode() { |
| 90 | + return Objects.hash(flags, mask); |
| 91 | + } |
| 92 | + |
| 93 | + @Override |
| 94 | + public String toString() { |
| 95 | + return FlagSet.asString(this); |
| 96 | + } |
| 97 | + |
| 98 | + abstract static class AbstractSingleFlagSet<T extends Enum<T> & MaskedFlag> |
| 99 | + implements FlagSet<T> { |
| 100 | + |
| 101 | + private final T flag; |
| 102 | + // Only holding this for iterator() and getFlags() so make it lazy. |
| 103 | + private EnumSet<T> enumSet; |
| 104 | + |
| 105 | + public AbstractSingleFlagSet(final T flag) { |
| 106 | + this.flag = Objects.requireNonNull(flag); |
| 107 | + } |
| 108 | + |
| 109 | + @Override |
| 110 | + public int getMask() { |
| 111 | + return flag.getMask(); |
| 112 | + } |
| 113 | + |
| 114 | + @Override |
| 115 | + public Set<T> getFlags() { |
| 116 | + if (enumSet == null) { |
| 117 | + return initSet(); |
| 118 | + } else { |
| 119 | + return this.enumSet; |
| 120 | + } |
| 121 | + } |
| 122 | + |
| 123 | + @Override |
| 124 | + public boolean isSet(final T flag) { |
| 125 | + return this.flag == flag; |
| 126 | + } |
| 127 | + |
| 128 | + @Override |
| 129 | + public boolean areAnySet(FlagSet<T> flags) { |
| 130 | + if (flags == null) { |
| 131 | + return false; |
| 132 | + } else { |
| 133 | + return flags.isSet(this.flag); |
| 134 | + } |
| 135 | + } |
| 136 | + |
| 137 | + @Override |
| 138 | + public int size() { |
| 139 | + return 1; |
| 140 | + } |
| 141 | + |
| 142 | + @Override |
| 143 | + public boolean isEmpty() { |
| 144 | + return false; |
| 145 | + } |
| 146 | + |
| 147 | + @Override |
| 148 | + public Iterator<T> iterator() { |
| 149 | + if (enumSet == null) { |
| 150 | + return initSet().iterator(); |
| 151 | + } else { |
| 152 | + return this.enumSet.iterator(); |
| 153 | + } |
| 154 | + } |
| 155 | + |
| 156 | + @Override |
| 157 | + public String toString() { |
| 158 | + return FlagSet.asString(this); |
| 159 | + } |
| 160 | + |
| 161 | + @Override |
| 162 | + public int hashCode() { |
| 163 | + return Objects.hash(flag, getFlags()); |
| 164 | + } |
| 165 | + |
| 166 | + private Set<T> initSet() { |
| 167 | + final EnumSet<T> set = EnumSet.of(this.flag); |
| 168 | + this.enumSet = set; |
| 169 | + return set; |
| 170 | + } |
| 171 | + } |
| 172 | + |
| 173 | + static class AbstractEmptyFlagSet<T extends MaskedFlag> implements FlagSet<T> { |
| 174 | + |
| 175 | + @Override |
| 176 | + public int getMask() { |
| 177 | + return MaskedFlag.EMPTY_MASK; |
| 178 | + } |
| 179 | + |
| 180 | + @Override |
| 181 | + public Set<T> getFlags() { |
| 182 | + return Collections.emptySet(); |
| 183 | + } |
| 184 | + |
| 185 | + @Override |
| 186 | + public boolean isSet(final T flag) { |
| 187 | + return false; |
| 188 | + } |
| 189 | + |
| 190 | + @Override |
| 191 | + public boolean areAnySet(final FlagSet<T> flags) { |
| 192 | + return false; |
| 193 | + } |
| 194 | + |
| 195 | + @Override |
| 196 | + public int size() { |
| 197 | + return 0; |
| 198 | + } |
| 199 | + |
| 200 | + @Override |
| 201 | + public boolean isEmpty() { |
| 202 | + return true; |
| 203 | + } |
| 204 | + |
| 205 | + @Override |
| 206 | + public Iterator<T> iterator() { |
| 207 | + return Collections.emptyIterator(); |
| 208 | + } |
| 209 | + |
| 210 | + @Override |
| 211 | + public String toString() { |
| 212 | + return FlagSet.asString(this); |
| 213 | + } |
| 214 | + |
| 215 | + @Override |
| 216 | + public boolean equals(Object object) { |
| 217 | + return FlagSet.equals(this, object); |
| 218 | + } |
| 219 | + |
| 220 | + @Override |
| 221 | + public int hashCode() { |
| 222 | + return Objects.hash(getMask(), getFlags()); |
| 223 | + } |
| 224 | + } |
| 225 | + |
| 226 | + /** |
| 227 | + * A builder for creating a {@link AbstractFlagSet}. |
| 228 | + * |
| 229 | + * @param <E> The type of flag to be held in the {@link AbstractFlagSet} |
| 230 | + * @param <S> The type of the {@link AbstractFlagSet} implementation. |
| 231 | + */ |
| 232 | + public static final class Builder<E extends Enum<E> & MaskedFlag, S extends FlagSet<E>> { |
| 233 | + |
| 234 | + final Class<E> type; |
| 235 | + final EnumSet<E> enumSet; |
| 236 | + final Function<EnumSet<E>, S> constructor; |
| 237 | + final Function<E, S> singletonSetConstructor; |
| 238 | + final Supplier<S> emptySetSupplier; |
| 239 | + |
| 240 | + Builder( |
| 241 | + final Class<E> type, |
| 242 | + final Function<EnumSet<E>, S> constructor, |
| 243 | + final Function<E, S> singletonSetConstructor, |
| 244 | + final Supplier<S> emptySetSupplier) { |
| 245 | + this.type = type; |
| 246 | + this.enumSet = EnumSet.noneOf(type); |
| 247 | + this.constructor = Objects.requireNonNull(constructor); |
| 248 | + this.singletonSetConstructor = Objects.requireNonNull(singletonSetConstructor); |
| 249 | + this.emptySetSupplier = Objects.requireNonNull(emptySetSupplier); |
| 250 | + } |
| 251 | + |
| 252 | + /** |
| 253 | + * Replaces any flags already set in the builder with the contents of the passed flags {@link |
| 254 | + * Collection} |
| 255 | + * |
| 256 | + * @param flags The flags to set in the builder. |
| 257 | + * @return this builder instance. |
| 258 | + */ |
| 259 | + public Builder<E, S> setFlags(final Collection<E> flags) { |
| 260 | + clear(); |
| 261 | + if (flags != null) { |
| 262 | + for (E flag : flags) { |
| 263 | + if (flag != null) { |
| 264 | + enumSet.add(flag); |
| 265 | + } |
| 266 | + } |
| 267 | + } |
| 268 | + return this; |
| 269 | + } |
| 270 | + |
| 271 | + /** |
| 272 | + * Replaces any flags already set in the builder with the passed flags. |
| 273 | + * |
| 274 | + * @param flags The flags to set in the builder. |
| 275 | + * @return this builder instance. |
| 276 | + */ |
| 277 | + @SafeVarargs |
| 278 | + public final Builder<E, S> setFlags(final E... flags) { |
| 279 | + clear(); |
| 280 | + if (flags != null) { |
| 281 | + for (E flag : flags) { |
| 282 | + if (flag != null) { |
| 283 | + if (!type.equals(flag.getClass())) { |
| 284 | + throw new IllegalArgumentException("Unexpected type " + flag.getClass()); |
| 285 | + } |
| 286 | + enumSet.add(flag); |
| 287 | + } |
| 288 | + } |
| 289 | + } |
| 290 | + return this; |
| 291 | + } |
| 292 | + |
| 293 | + /** |
| 294 | + * Adds a single flag in the builder. |
| 295 | + * |
| 296 | + * @param flag The flag to set in the builder. |
| 297 | + * @return this builder instance. |
| 298 | + */ |
| 299 | + public Builder<E, S> addFlag(final E flag) { |
| 300 | + if (flag != null) { |
| 301 | + enumSet.add(flag); |
| 302 | + } |
| 303 | + return this; |
| 304 | + } |
| 305 | + |
| 306 | + /** |
| 307 | + * Adds multiple flag in the builder. |
| 308 | + * |
| 309 | + * @param flags The flags to set in the builder. |
| 310 | + * @return this builder instance. |
| 311 | + */ |
| 312 | + public Builder<E, S> addFlags(final Collection<E> flags) { |
| 313 | + if (flags != null) { |
| 314 | + enumSet.addAll(flags); |
| 315 | + } |
| 316 | + return this; |
| 317 | + } |
| 318 | + |
| 319 | + /** |
| 320 | + * Clears any flags already set in this {@link Builder} |
| 321 | + * |
| 322 | + * @return this builder instance. |
| 323 | + */ |
| 324 | + public Builder<E, S> clear() { |
| 325 | + enumSet.clear(); |
| 326 | + return this; |
| 327 | + } |
| 328 | + |
| 329 | + /** |
| 330 | + * Build the {@link DbiFlagSet} |
| 331 | + * |
| 332 | + * @return A |
| 333 | + */ |
| 334 | + public S build() { |
| 335 | + final int size = enumSet.size(); |
| 336 | + if (size == 0) { |
| 337 | + return emptySetSupplier.get(); |
| 338 | + } else if (size == 1) { |
| 339 | + return singletonSetConstructor.apply(enumSet.stream().findFirst().get()); |
| 340 | + } else { |
| 341 | + return constructor.apply(enumSet); |
| 342 | + } |
| 343 | + } |
| 344 | + } |
| 345 | +} |
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