Matthias Andreas Benkard | 261532a | 2021-12-12 20:09:27 +0100 | [diff] [blame^] | 1 | package eu.mulk.jgvariant.core; |
| 2 | |
| 3 | import static java.nio.ByteOrder.LITTLE_ENDIAN; |
| 4 | |
| 5 | import eu.mulk.jgvariant.core.Value.Array; |
| 6 | import eu.mulk.jgvariant.core.Value.Bool; |
| 7 | import eu.mulk.jgvariant.core.Value.Float64; |
| 8 | import eu.mulk.jgvariant.core.Value.Int16; |
| 9 | import eu.mulk.jgvariant.core.Value.Int32; |
| 10 | import eu.mulk.jgvariant.core.Value.Int64; |
| 11 | import eu.mulk.jgvariant.core.Value.Int8; |
| 12 | import eu.mulk.jgvariant.core.Value.Maybe; |
| 13 | import eu.mulk.jgvariant.core.Value.Str; |
| 14 | import eu.mulk.jgvariant.core.Value.Structure; |
| 15 | import eu.mulk.jgvariant.core.Value.Variant; |
| 16 | import java.lang.reflect.InvocationTargetException; |
| 17 | import java.lang.reflect.RecordComponent; |
| 18 | import java.nio.ByteBuffer; |
| 19 | import java.nio.ByteOrder; |
| 20 | import java.nio.charset.Charset; |
| 21 | import java.util.ArrayList; |
| 22 | import java.util.Arrays; |
| 23 | import java.util.List; |
| 24 | import java.util.Optional; |
| 25 | import org.jetbrains.annotations.Nullable; |
| 26 | |
| 27 | /** |
| 28 | * Type class for decodable {@link Value} types. |
| 29 | * |
| 30 | * <p>Use the {@code of*} family of constructor methods to acquire a suitable {@link Decoder} for |
| 31 | * the type you wish to decode. |
| 32 | * |
| 33 | * @param <T> the type that the {@link Decoder} can decode. |
| 34 | */ |
| 35 | @SuppressWarnings("java:S1610") |
| 36 | public abstract class Decoder<T extends Value> { |
| 37 | |
| 38 | private Decoder() {} |
| 39 | |
| 40 | /** |
| 41 | * @throws java.nio.BufferUnderflowException if the byte buffer is shorter than the requested |
| 42 | * data. |
| 43 | */ |
| 44 | public abstract T decode(ByteBuffer byteSlice); |
| 45 | |
| 46 | abstract byte alignment(); |
| 47 | |
| 48 | @Nullable |
| 49 | abstract Integer fixedSize(); |
| 50 | |
| 51 | final boolean hasFixedSize() { |
| 52 | return fixedSize() != null; |
| 53 | } |
| 54 | |
| 55 | public Decoder<T> withByteOrder(ByteOrder byteOrder) { |
| 56 | var delegate = this; |
| 57 | |
| 58 | return new Decoder<>() { |
| 59 | @Override |
| 60 | public byte alignment() { |
| 61 | return delegate.alignment(); |
| 62 | } |
| 63 | |
| 64 | @Override |
| 65 | public @Nullable Integer fixedSize() { |
| 66 | return delegate.fixedSize(); |
| 67 | } |
| 68 | |
| 69 | @Override |
| 70 | public T decode(ByteBuffer byteSlice) { |
| 71 | byteSlice.order(byteOrder); |
| 72 | return delegate.decode(byteSlice); |
| 73 | } |
| 74 | }; |
| 75 | } |
| 76 | |
| 77 | public static <U extends Value> Decoder<Array<U>> ofArray(Decoder<U> elementDecoder) { |
| 78 | return new Decoder<>() { |
| 79 | @Override |
| 80 | public byte alignment() { |
| 81 | return elementDecoder.alignment(); |
| 82 | } |
| 83 | |
| 84 | @Override |
| 85 | @Nullable |
| 86 | Integer fixedSize() { |
| 87 | return null; |
| 88 | } |
| 89 | |
| 90 | @Override |
| 91 | public Array<U> decode(ByteBuffer byteSlice) { |
| 92 | List<U> elements; |
| 93 | |
| 94 | var elementSize = elementDecoder.fixedSize(); |
| 95 | if (elementSize != null) { |
| 96 | // A simple C-style array. |
| 97 | elements = new ArrayList<>(byteSlice.limit() / elementSize); |
| 98 | for (int i = 0; i < byteSlice.limit(); i += elementSize) { |
| 99 | var element = elementDecoder.decode(byteSlice.slice(i, elementSize)); |
| 100 | elements.add(element); |
| 101 | } |
| 102 | } else { |
| 103 | // An array with aligned elements and a vector of framing offsets in the end. |
| 104 | int framingOffsetSize = byteCount(byteSlice.limit()); |
| 105 | int lastFramingOffset = |
| 106 | getIntN(byteSlice.slice(byteSlice.limit() - framingOffsetSize, framingOffsetSize)); |
| 107 | int elementCount = (byteSlice.limit() - lastFramingOffset) / framingOffsetSize; |
| 108 | |
| 109 | elements = new ArrayList<>(elementCount); |
| 110 | int position = 0; |
| 111 | for (int i = 0; i < elementCount; i++) { |
| 112 | int framingOffset = |
| 113 | getIntN( |
| 114 | byteSlice.slice(lastFramingOffset + i * framingOffsetSize, framingOffsetSize)); |
| 115 | elements.add( |
| 116 | elementDecoder.decode(byteSlice.slice(position, framingOffset - position))); |
| 117 | position = align(framingOffset, alignment()); |
| 118 | } |
| 119 | } |
| 120 | |
| 121 | return new Array<>(elements); |
| 122 | } |
| 123 | }; |
| 124 | } |
| 125 | |
| 126 | private static int align(int offset, byte alignment) { |
| 127 | return offset % alignment == 0 ? offset : offset + alignment - (offset % alignment); |
| 128 | } |
| 129 | |
| 130 | private static int getIntN(ByteBuffer byteSlice) { |
| 131 | var intBytes = new byte[4]; |
| 132 | byteSlice.get(intBytes, 0, Math.min(4, byteSlice.limit())); |
| 133 | return ByteBuffer.wrap(intBytes).order(LITTLE_ENDIAN).getInt(); |
| 134 | } |
| 135 | |
| 136 | @SuppressWarnings("java:S3358") |
| 137 | private static int byteCount(int n) { |
| 138 | return n < (1 << 8) ? 1 : n < (1 << 16) ? 2 : 4; |
| 139 | } |
| 140 | |
| 141 | public static <U extends Value> Decoder<Maybe<U>> ofMaybe(Decoder<U> elementDecoder) { |
| 142 | return new Decoder<>() { |
| 143 | @Override |
| 144 | public byte alignment() { |
| 145 | return elementDecoder.alignment(); |
| 146 | } |
| 147 | |
| 148 | @Override |
| 149 | @Nullable |
| 150 | Integer fixedSize() { |
| 151 | return null; |
| 152 | } |
| 153 | |
| 154 | @Override |
| 155 | public Maybe<U> decode(ByteBuffer byteSlice) { |
| 156 | if (!byteSlice.hasRemaining()) { |
| 157 | return new Maybe<>(Optional.empty()); |
| 158 | } else { |
| 159 | if (!elementDecoder.hasFixedSize()) { |
| 160 | // Remove trailing zero byte. |
| 161 | byteSlice.limit(byteSlice.limit() - 1); |
| 162 | } |
| 163 | |
| 164 | return new Maybe<>(Optional.of(elementDecoder.decode(byteSlice))); |
| 165 | } |
| 166 | } |
| 167 | }; |
| 168 | } |
| 169 | |
| 170 | @SafeVarargs |
| 171 | public static <U extends Record> Decoder<Structure<U>> ofStructure( |
| 172 | Class<U> recordType, Decoder<? extends Value>... componentDecoders) { |
| 173 | var recordComponents = recordType.getRecordComponents(); |
| 174 | if (componentDecoders.length != recordComponents.length) { |
| 175 | throw new IllegalArgumentException( |
| 176 | "number of decoders (%d) does not match number of structure components (%d)" |
| 177 | .formatted(componentDecoders.length, recordComponents.length)); |
| 178 | } |
| 179 | |
| 180 | return new Decoder<>() { |
| 181 | @Override |
| 182 | public byte alignment() { |
| 183 | return (byte) Arrays.stream(componentDecoders).mapToInt(Decoder::alignment).max().orElse(1); |
| 184 | } |
| 185 | |
| 186 | @Override |
| 187 | public Integer fixedSize() { |
| 188 | int position = 0; |
| 189 | for (var componentDecoder : componentDecoders) { |
| 190 | var fixedComponentSize = componentDecoder.fixedSize(); |
| 191 | if (fixedComponentSize == null) { |
| 192 | return null; |
| 193 | } |
| 194 | |
| 195 | position = align(position, componentDecoder.alignment()); |
| 196 | position += fixedComponentSize; |
| 197 | } |
| 198 | |
| 199 | if (position == 0) { |
| 200 | return 1; |
| 201 | } |
| 202 | |
| 203 | return align(position, alignment()); |
| 204 | } |
| 205 | |
| 206 | @Override |
| 207 | public Structure<U> decode(ByteBuffer byteSlice) { |
| 208 | int framingOffsetSize = byteCount(byteSlice.limit()); |
| 209 | |
| 210 | var recordConstructorArguments = new Object[recordComponents.length]; |
| 211 | |
| 212 | int position = 0; |
| 213 | int framingOffsetIndex = 0; |
| 214 | int componentIndex = 0; |
| 215 | for (var componentDecoder : componentDecoders) { |
| 216 | position = align(position, componentDecoder.alignment()); |
| 217 | |
| 218 | var fixedComponentSize = componentDecoder.fixedSize(); |
| 219 | if (fixedComponentSize != null) { |
| 220 | recordConstructorArguments[componentIndex] = |
| 221 | componentDecoder.decode(byteSlice.slice(position, fixedComponentSize)); |
| 222 | position += fixedComponentSize; |
| 223 | } else { |
| 224 | if (componentIndex == recordComponents.length - 1) { |
| 225 | // The last component never has a framing offset. |
| 226 | int endPosition = byteSlice.limit() - framingOffsetIndex * framingOffsetSize; |
| 227 | recordConstructorArguments[componentIndex] = |
| 228 | componentDecoder.decode(byteSlice.slice(position, endPosition - position)); |
| 229 | position = endPosition; |
| 230 | } else { |
| 231 | int framingOffset = |
| 232 | getIntN( |
| 233 | byteSlice.slice( |
| 234 | byteSlice.limit() - (1 + framingOffsetIndex) * framingOffsetSize, |
| 235 | framingOffsetSize)); |
| 236 | recordConstructorArguments[componentIndex] = |
| 237 | componentDecoder.decode(byteSlice.slice(position, framingOffset - position)); |
| 238 | position = framingOffset; |
| 239 | ++framingOffsetIndex; |
| 240 | } |
| 241 | } |
| 242 | |
| 243 | ++componentIndex; |
| 244 | } |
| 245 | |
| 246 | try { |
| 247 | var recordComponentTypes = |
| 248 | Arrays.stream(recordType.getRecordComponents()) |
| 249 | .map(RecordComponent::getType) |
| 250 | .toArray(Class<?>[]::new); |
| 251 | var recordConstructor = recordType.getDeclaredConstructor(recordComponentTypes); |
| 252 | return new Structure<>(recordConstructor.newInstance(recordConstructorArguments)); |
| 253 | } catch (NoSuchMethodException |
| 254 | | InstantiationException |
| 255 | | IllegalAccessException |
| 256 | | InvocationTargetException e) { |
| 257 | throw new IllegalStateException(e); |
| 258 | } |
| 259 | } |
| 260 | }; |
| 261 | } |
| 262 | |
| 263 | public static Decoder<Variant> ofVariant() { |
| 264 | return new Decoder<>() { |
| 265 | @Override |
| 266 | public byte alignment() { |
| 267 | return 8; |
| 268 | } |
| 269 | |
| 270 | @Override |
| 271 | @Nullable |
| 272 | Integer fixedSize() { |
| 273 | return null; |
| 274 | } |
| 275 | |
| 276 | @Override |
| 277 | public Variant decode(ByteBuffer byteSlice) { |
| 278 | // TODO |
| 279 | throw new UnsupportedOperationException("not implemented"); |
| 280 | } |
| 281 | }; |
| 282 | } |
| 283 | |
| 284 | public static Decoder<Bool> ofBoolean() { |
| 285 | return new Decoder<>() { |
| 286 | @Override |
| 287 | public byte alignment() { |
| 288 | return 1; |
| 289 | } |
| 290 | |
| 291 | @Override |
| 292 | public Integer fixedSize() { |
| 293 | return 1; |
| 294 | } |
| 295 | |
| 296 | @Override |
| 297 | public Bool decode(ByteBuffer byteSlice) { |
| 298 | return new Bool(byteSlice.get() != 0); |
| 299 | } |
| 300 | }; |
| 301 | } |
| 302 | |
| 303 | public static Decoder<Int8> ofInt8() { |
| 304 | return new Decoder<>() { |
| 305 | @Override |
| 306 | public byte alignment() { |
| 307 | return 1; |
| 308 | } |
| 309 | |
| 310 | @Override |
| 311 | public Integer fixedSize() { |
| 312 | return 1; |
| 313 | } |
| 314 | |
| 315 | @Override |
| 316 | public Int8 decode(ByteBuffer byteSlice) { |
| 317 | return new Int8(byteSlice.get()); |
| 318 | } |
| 319 | }; |
| 320 | } |
| 321 | |
| 322 | public static Decoder<Int16> ofInt16() { |
| 323 | return new Decoder<>() { |
| 324 | @Override |
| 325 | public byte alignment() { |
| 326 | return 2; |
| 327 | } |
| 328 | |
| 329 | @Override |
| 330 | public Integer fixedSize() { |
| 331 | return 2; |
| 332 | } |
| 333 | |
| 334 | @Override |
| 335 | public Int16 decode(ByteBuffer byteSlice) { |
| 336 | return new Int16(byteSlice.getShort()); |
| 337 | } |
| 338 | }; |
| 339 | } |
| 340 | |
| 341 | public static Decoder<Int32> ofInt32() { |
| 342 | return new Decoder<>() { |
| 343 | @Override |
| 344 | public byte alignment() { |
| 345 | return 4; |
| 346 | } |
| 347 | |
| 348 | @Override |
| 349 | public Integer fixedSize() { |
| 350 | return 4; |
| 351 | } |
| 352 | |
| 353 | @Override |
| 354 | public Int32 decode(ByteBuffer byteSlice) { |
| 355 | return new Int32(byteSlice.getInt()); |
| 356 | } |
| 357 | }; |
| 358 | } |
| 359 | |
| 360 | public static Decoder<Int64> ofInt64() { |
| 361 | return new Decoder<>() { |
| 362 | @Override |
| 363 | public byte alignment() { |
| 364 | return 8; |
| 365 | } |
| 366 | |
| 367 | @Override |
| 368 | public Integer fixedSize() { |
| 369 | return 8; |
| 370 | } |
| 371 | |
| 372 | @Override |
| 373 | public Int64 decode(ByteBuffer byteSlice) { |
| 374 | return new Int64(byteSlice.getLong()); |
| 375 | } |
| 376 | }; |
| 377 | } |
| 378 | |
| 379 | public static Decoder<Float64> ofFloat64() { |
| 380 | return new Decoder<>() { |
| 381 | @Override |
| 382 | public byte alignment() { |
| 383 | return 8; |
| 384 | } |
| 385 | |
| 386 | @Override |
| 387 | public Integer fixedSize() { |
| 388 | return 8; |
| 389 | } |
| 390 | |
| 391 | @Override |
| 392 | public Float64 decode(ByteBuffer byteSlice) { |
| 393 | return new Float64(byteSlice.getDouble()); |
| 394 | } |
| 395 | }; |
| 396 | } |
| 397 | |
| 398 | public static Decoder<Str> ofStr(Charset charset) { |
| 399 | return new Decoder<>() { |
| 400 | @Override |
| 401 | public byte alignment() { |
| 402 | return 1; |
| 403 | } |
| 404 | |
| 405 | @Override |
| 406 | @Nullable |
| 407 | Integer fixedSize() { |
| 408 | return null; |
| 409 | } |
| 410 | |
| 411 | @Override |
| 412 | public Str decode(ByteBuffer byteSlice) { |
| 413 | byteSlice.limit(byteSlice.limit() - 1); |
| 414 | return new Str(charset.decode(byteSlice).toString()); |
| 415 | } |
| 416 | }; |
| 417 | } |
| 418 | } |