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| 1 | namespace Semantic.Types is | |
| 2 | use IO.Std; | |
| 3 | ||
| 4 | use Source.LOCATION; | |
| 5 | ||
| 6 | use Logging; | |
| 7 | ||
| 8 | use Ghul.Pipes; | |
| 9 | ||
| 10 | enum TypeVariance is | |
| 11 | INVARIANT, | |
| 12 | COVARIANT, | |
| 13 | CONTRAVARIANT | |
| 14 | si | |
| 15 | ||
| 16 | class GENERIC: NAMED is | |
| 17 | _is_wild: byte; | |
| 18 | ||
| 19 | arguments: Collections.List[Type] => symbol.arguments; | |
| 20 | ||
| 21 | is_error: bool => arguments |> any(a => a.is_error); | |
| 22 | ||
| 23 | // should be | |
| 24 | // is_wild: bool => arguments |> any(a => a.is_wild) | |
| 25 | // but the following shaves about 10% off compiler build time | |
| 26 | is_wild: bool is | |
| 27 | if _is_wild == 0b then | |
| 28 | let a = symbol.arguments; | |
| 29 | let c = a.count; | |
| 30 | ||
| 31 | let i mut = 0; | |
| 32 | ||
| 33 | while i < c do | |
| 34 | if a[i].is_wild then | |
| 35 | _is_wild = 1b; | |
| 36 | return true; | |
| 37 | fi | |
| 38 | ||
| 39 | i = i + 1; | |
| 40 | od | |
| 41 | ||
| 42 | _is_wild = 2b; | |
| 43 | return false; | |
| 44 | fi | |
| 45 | ||
| 46 | return _is_wild == 1b; | |
| 47 | si | |
| 48 | ||
| 49 | // Recurse into arguments — Function[placeholder, int] is | |
| 50 | // a GENERIC whose self.is_inferred is false but whose | |
| 51 | // arguments contain a placeholder. The iterative-inference | |
| 52 | // re-narrowing path uses this to decide whether a let-bound | |
| 53 | // symbol's type still needs updating after a body retry. | |
| 54 | contains_inferred: bool => arguments |> any(a => a.contains_inferred); | |
| 55 | ||
| 56 | contains_function_generic_argument: bool => | |
| 57 | arguments |> any(a => a.contains_function_generic_argument); | |
| 58 | ||
| 59 | short_description: string is | |
| 60 | let result = System.Text.StringBuilder(); | |
| 61 | ||
| 62 | result | |
| 63 | .append(symbol.name) | |
| 64 | .append('['); | |
| 65 | ||
| 66 | let seen_any mut = false; | |
| 67 | ||
| 68 | for a in arguments do | |
| 69 | if seen_any then | |
| 70 | result.append(','); | |
| 71 | fi | |
| 72 | ||
| 73 | result.append(a.short_description); | |
| 74 | ||
| 75 | seen_any = true; | |
| 76 | od | |
| 77 | ||
| 78 | result.append(']'); | |
| 79 | ||
| 80 | return result.to_string(); | |
| 81 | si | |
| 82 | ||
| 83 | is_function_with_any_implicit_argument_types: bool is | |
| 84 | if !is_function then | |
| 85 | return false; | |
| 86 | fi | |
| 87 | ||
| 88 | // is_inferred (today only INFERRED_RETURN_TYPE) rather | |
| 89 | // than is_sentinel: an ERROR-typed argument is a real failure, | |
| 90 | // not a deferred-inference placeholder, and shouldn't | |
| 91 | // trigger overload-resolver's "needs second pass to infer | |
| 92 | // formal-derived arg types" path. | |
| 93 | for i in 0..arguments.count -1 do | |
| 94 | if arguments[i].is_inferred then | |
| 95 | return true; | |
| 96 | fi | |
| 97 | od | |
| 98 | return false; | |
| 99 | si | |
| 100 | ||
| 101 | init( | |
| 102 | symbol: Symbols.GENERIC | |
| 103 | ) is | |
| 104 | super.init(symbol); | |
| 105 | si | |
| 106 | ||
| 107 | init( | |
| 108 | location: LOCATION, | |
| 109 | symbol: Symbols.Classy, | |
| 110 | arguments: Collections.List[Type] | |
| 111 | ) is | |
| 112 | super.init(Symbols.GENERIC(location, symbol, arguments)); | |
| 113 | si | |
| 114 | ||
| 115 | create( | |
| 116 | location: LOCATION, | |
| 117 | symbol: Symbols.Classy, | |
| 118 | arguments: Collections.List[Type] | |
| 119 | ) -> GENERIC => | |
| 120 | GENERIC(location, symbol, arguments); | |
| 121 | ||
| 122 | is_same_symbol(other: Type) -> bool is | |
| 123 | if !isa GENERIC(other) then | |
| 124 | return false; | |
| 125 | fi | |
| 126 | ||
| 127 | let other_generic = other; | |
| 128 | ||
| 129 | let generic_symbol = cast Symbols.GENERIC?(symbol)!; | |
| 130 | let generic_other_symbol = cast Symbols.GENERIC?(other_generic.symbol)!; | |
| 131 | ||
| 132 | return generic_symbol.symbol == generic_other_symbol.symbol; | |
| 133 | si | |
| 134 | ||
| 135 | // The declared variance at this type-argument position: whether | |
| 136 | // this position may vary at all, and in which direction. This is | |
| 137 | // purely a property of the generic type's own shape — read from | |
| 138 | // reflected .NET metadata for imported types (Symbols.Classy. | |
| 139 | // argument_variances) or, for FUNCTION/ACTION/ARRAY, fixed by | |
| 140 | // the kind of type they are. It says nothing about whether a | |
| 141 | // *specific* instantiation may use that variance — see | |
| 142 | // effective_argument_variance for that. | |
| 143 | get_argument_type_variance(index: int) -> TypeVariance is | |
| 144 | let generic_symbol = cast Symbols.GENERIC?(symbol); | |
| 145 | if !generic_symbol? then | |
| 146 | return TypeVariance.INVARIANT; | |
| 147 | fi | |
| 148 | return generic_symbol.symbol.get_argument_variance(index); | |
| 149 | si | |
| 150 | ||
| 151 | // The variance actually usable when converting from `other` to | |
| 152 | // self at this position. The CLR only allows a variant | |
| 153 | // conversion when the actual type argument at this position is | |
| 154 | // a reference type on both sides, so this downgrades a declared | |
| 155 | // covariant/contravariant position to invariant whenever either | |
| 156 | // side's actual argument is a value type. | |
| 157 | effective_argument_variance(other: GENERIC, index: int) -> TypeVariance is | |
| 158 | let declared = other.get_argument_type_variance(index); | |
| 159 | ||
| 160 | if declared == TypeVariance.INVARIANT then | |
| 161 | return TypeVariance.INVARIANT; | |
| 162 | fi | |
| 163 | ||
| 164 | if index >= 0 /\ index < arguments.count /\ (arguments[index].is_value_type \/ other.arguments[index].is_value_type) then | |
| 165 | return TypeVariance.INVARIANT; | |
| 166 | fi | |
| 167 | ||
| 168 | return declared; | |
| 169 | si | |
| 170 | ||
| 171 | get_element_type() -> Type => arguments[0]; | |
| 172 | ||
| 173 | specialize_generic(type_map: Collections.Map[string,Type]) -> Types.GENERIC is | |
| 174 | let context = IoC.CONTAINER.instance.symbol_table.current_instance_context; | |
| 175 | ||
| 176 | let we_are_generic = context? /\ context.arguments.count > 0; | |
| 177 | ||
| 178 | let seen_any_new mut = false; | |
| 179 | ||
| 180 | let generic_symbol = cast Symbols.GENERIC?(symbol)!; | |
| 181 | ||
| 182 | let new_arguments = Collections.LIST[Type](arguments.count); | |
| 183 | ||
| 184 | for i in 0..arguments.count do | |
| 185 | let argument_name | |
| 186 | = generic_symbol.symbol.argument_names[i]; | |
| 187 | ||
| 188 | let mapped_type: Type mut; | |
| 189 | ||
| 190 | if we_are_generic /\ type_map.try_get_value(argument_name, mapped_type ref) then | |
| 191 | new_arguments.add(mapped_type); | |
| 192 | ||
| 193 | seen_any_new = true; | |
| 194 | else | |
| 195 | let oa = generic_symbol.arguments[i]; | |
| 196 | let na = oa.specialize(type_map); | |
| 197 | ||
| 198 | new_arguments.add(na); | |
| 199 | ||
| 200 | if oa != na then | |
| 201 | seen_any_new = true; | |
| 202 | fi | |
| 203 | fi | |
| 204 | od | |
| 205 | ||
| 206 | if seen_any_new then | |
| 207 | let result = create(symbol.location, generic_symbol.symbol, new_arguments); | |
| 208 | ||
| 209 | return result; | |
| 210 | else | |
| 211 | return self; | |
| 212 | fi | |
| 213 | si | |
| 214 | ||
| 215 | specialize(type_map: Collections.Map[string,Type]) -> Type => | |
| 216 | specialize_generic(type_map); | |
| 217 | ||
| 218 | matches(other: Type) -> bool is | |
| 219 | if other.is_sentinel then | |
| 220 | return true; | |
| 221 | fi | |
| 222 | ||
| 223 | if !isa GENERIC(other) then | |
| 224 | return false; | |
| 225 | fi | |
| 226 | ||
| 227 | let generic_other = other; | |
| 228 | ||
| 229 | if symbol == generic_other.symbol then | |
| 230 | return true; | |
| 231 | fi | |
| 232 | ||
| 233 | let generic_symbol = cast Symbols.GENERIC?(symbol)!; | |
| 234 | let generic_other_symbol = cast Symbols.GENERIC?(generic_other.symbol)!; | |
| 235 | ||
| 236 | if generic_symbol.symbol != generic_other_symbol.symbol then | |
| 237 | return false; | |
| 238 | fi | |
| 239 | ||
| 240 | if generic_symbol.arguments.count != generic_other_symbol.arguments.count then | |
| 241 | return false; | |
| 242 | fi | |
| 243 | ||
| 244 | for i in 0..generic_symbol.arguments.count do | |
| 245 | if !generic_symbol.arguments[i].matches(generic_other_symbol.arguments[i]) then | |
| 246 | return false; | |
| 247 | fi | |
| 248 | od | |
| 249 | ||
| 250 | return true; | |
| 251 | si | |
| 252 | ||
| 253 | is_equivalent_to(other: Type) -> bool is | |
| 254 | if other.is_sentinel then | |
| 255 | return true; | |
| 256 | fi | |
| 257 | ||
| 258 | if !isa GENERIC(other) then | |
| 259 | return false; | |
| 260 | fi | |
| 261 | ||
| 262 | let generic_other = other; | |
| 263 | ||
| 264 | // Unlike `matches`, the outer optional flag participates: | |
| 265 | // LIST[cat]? is not equivalent to LIST[cat], whether or | |
| 266 | // not the two share a symbol instance. | |
| 267 | if is_optional != generic_other.is_optional then | |
| 268 | return false; | |
| 269 | fi | |
| 270 | ||
| 271 | if symbol == generic_other.symbol then | |
| 272 | return true; | |
| 273 | fi | |
| 274 | ||
| 275 | let generic_symbol = cast Symbols.GENERIC?(symbol)!; | |
| 276 | let generic_other_symbol = cast Symbols.GENERIC?(generic_other.symbol)!; | |
| 277 | ||
| 278 | if generic_symbol.symbol != generic_other_symbol.symbol then | |
| 279 | return false; | |
| 280 | fi | |
| 281 | ||
| 282 | if generic_symbol.arguments.count != generic_other_symbol.arguments.count then | |
| 283 | return false; | |
| 284 | fi | |
| 285 | ||
| 286 | for i in 0..generic_symbol.arguments.count do | |
| 287 | if !generic_symbol.arguments[i].is_equivalent_to(generic_other_symbol.arguments[i]) then | |
| 288 | return false; | |
| 289 | fi | |
| 290 | od | |
| 291 | ||
| 292 | return true; | |
| 293 | si | |
| 294 | ||
| 295 | compare_direct(other: Type) -> Types.MATCH is | |
| 296 | if other.is_sentinel then | |
| 297 | return Types.MATCH.SAME; | |
| 298 | fi | |
| 299 | ||
| 300 | if !isa GENERIC(other) then | |
| 301 | return Types.MATCH.DIFFERENT; | |
| 302 | fi | |
| 303 | ||
| 304 | let generic_other = other; | |
| 305 | ||
| 306 | if symbol == generic_other.symbol then | |
| 307 | // Structurally identical; the outer optional flag | |
| 308 | // decides the direction. `List[T]?` accepts `List[T]` | |
| 309 | // (widening); `List[T]` rejects `List[T]?` (would | |
| 310 | // lose the discriminator). | |
| 311 | if is_optional == generic_other.is_optional then | |
| 312 | return Types.MATCH.SAME; | |
| 313 | elif is_optional then | |
| 314 | return Types.MATCH.ASSIGNABLE; | |
| 315 | else | |
| 316 | return Types.MATCH.DIFFERENT; | |
| 317 | fi | |
| 318 | fi | |
| 319 | ||
| 320 | let generic_symbol = cast Symbols.GENERIC?(symbol)!; | |
| 321 | let generic_other_symbol = cast Symbols.GENERIC?(generic_other.symbol)!; | |
| 322 | ||
| 323 | if generic_symbol.symbol != generic_other_symbol.symbol then | |
| 324 | return Types.MATCH.DIFFERENT; | |
| 325 | fi | |
| 326 | ||
| 327 | if generic_symbol.arguments.count != generic_other_symbol.arguments.count then | |
| 328 | return Types.MATCH.DIFFERENT; | |
| 329 | fi | |
| 330 | ||
| 331 | // Same outer-flag rule as the shared-symbol fast path | |
| 332 | // above, for structurally-equal constructions that don't | |
| 333 | // share a symbol instance: a bare slot rejects an | |
| 334 | // optional value outright, and an optional slot accepting | |
| 335 | // a bare value is a widening, never an exact match. | |
| 336 | if !is_optional /\ generic_other.is_optional then | |
| 337 | return Types.MATCH.DIFFERENT; | |
| 338 | fi | |
| 339 | ||
| 340 | let result mut = | |
| 341 | if is_optional == generic_other.is_optional then | |
| 342 | Types.MATCH.SAME | |
| 343 | else | |
| 344 | Types.MATCH.ASSIGNABLE | |
| 345 | fi; | |
| 346 | ||
| 347 | for i in 0..generic_symbol.arguments.count do | |
| 348 | let variance = effective_argument_variance(generic_other, i); | |
| 349 | ||
| 350 | let argument_score: Types.MATCH mut; | |
| 351 | ||
| 352 | if variance == TypeVariance.COVARIANT then | |
| 353 | argument_score = generic_symbol.arguments[i].compare(generic_other_symbol.arguments[i]); | |
| 354 | elif variance == TypeVariance.CONTRAVARIANT then | |
| 355 | argument_score = generic_other_symbol.arguments[i].compare(generic_symbol.arguments[i]); | |
| 356 | elif generic_symbol.arguments[i].is_equivalent_to(generic_other_symbol.arguments[i]) then | |
| 357 | argument_score = Types.MATCH.SAME; | |
| 358 | else | |
| 359 | // `matches` would erase the optional flag here, and an | |
| 360 | // invariant position must not: reading from the | |
| 361 | // slot could surface a null its type denies, and | |
| 362 | // writing through it could store one. | |
| 363 | return Types.MATCH.DIFFERENT; | |
| 364 | fi | |
| 365 | ||
| 366 | if cast int(argument_score) > cast int(result) then | |
| 367 | result = argument_score; | |
| 368 | fi | |
| 369 | od | |
| 370 | ||
| 371 | return result; | |
| 372 | si | |
| 373 | ||
| 374 | compare(other: Type) -> Types.MATCH is | |
| 375 | if isa ONE_OF(other) /\ !isa ONE_OF(self) then | |
| 376 | // ONE_OF assignability is "value of underlying union | |
| 377 | // restricted to a variant subset" — delegate to the | |
| 378 | // underlying type so the narrowing target's | |
| 379 | // is_assignable_from check sees the same identity it | |
| 380 | // would for the plain union. NAMED.compare already | |
| 381 | // does the right thing for ONE_OF via symbol-match. | |
| 382 | let one_of = other; | |
| 383 | return self.compare(one_of.underlying_type); | |
| 384 | fi | |
| 385 | ||
| 386 | if other.is_null then | |
| 387 | return Types.MATCH.ASSIGNABLE; | |
| 388 | elif symbol == null \/ other == null then | |
| 389 | return Types.MATCH.DIFFERENT; | |
| 390 | elif other.is_named then | |
| 391 | // Strict non-nullable-by-default: a bare slot never | |
| 392 | // accepts a `T?` value, at every construction shape. | |
| 393 | // compare_direct already enforces this for the shared | |
| 394 | // symbol, but the ancestor walk below recurses on | |
| 395 | // `other.symbol.ancestors`, which are bare (see | |
| 396 | // `Symbol.ancestors`) — so without this guard an | |
| 397 | // optional generic silently widens to a non-optional | |
| 398 | // supertype and its null discriminator is lost. Wild | |
| 399 | // placeholders skip it, matching NAMED.compare. | |
| 400 | if !is_wild /\ !is_optional /\ other.is_optional then | |
| 401 | return Types.MATCH.DIFFERENT; | |
| 402 | fi | |
| 403 | ||
| 404 | let direct_score = compare_direct(other); | |
| 405 | ||
| 406 | if cast int(direct_score) <= cast int(Types.MATCH.ASSIGNABLE) then | |
| 407 | return direct_score; | |
| 408 | fi | |
| 409 | ||
| 410 | for i in 0..other.symbol.ancestors.count do | |
| 411 | let a = other.symbol.get_ancestor(i); | |
| 412 | ||
| 413 | let match = self.compare(a); | |
| 414 | ||
| 415 | if cast int(match) <= cast int(Types.MATCH.ASSIGNABLE) then | |
| 416 | return Types.MATCH.ASSIGNABLE; | |
| 417 | elif match == Types.MATCH.CONVERTABLE then | |
| 418 | return Types.MATCH.CONVERTABLE; | |
| 419 | fi | |
| 420 | od | |
| 421 | fi | |
| 422 | ||
| 423 | if is_wild \/ other.is_wild then | |
| 424 | return Types.MATCH.WILD; | |
| 425 | fi | |
| 426 | ||
| 427 | return Types.MATCH.DIFFERENT; | |
| 428 | si | |
| 429 | ||
| 430 | // attempt to bind type variables in this generic against concrete types in | |
| 431 | // other by pattern matching | |
| 432 | bind_type_variables(other: Type, results: GENERIC_ARGUMENT_BIND_RESULTS) -> bool is | |
| 433 | if other.is_null then | |
| 434 | return true; | |
| 435 | fi | |
| 436 | ||
| 437 | if let other_generic: GENERIC = other then | |
| 438 | let generic_symbol = cast Symbols.GENERIC?(symbol)!; | |
| 439 | let generic_other_symbol = cast Symbols.GENERIC?(other_generic.symbol)!; | |
| 440 | ||
| 441 | if generic_symbol.symbol == generic_other_symbol.symbol then | |
| 442 | let result mut = true; | |
| 443 | ||
| 444 | for i in 0..arguments.count do | |
| 445 | result = arguments[i].bind_type_variables(other.arguments[i], results) /\ result; | |
| 446 | od | |
| 447 | ||
| 448 | return result; | |
| 449 | else | |
| 450 | for i in 0..other_generic.ancestors.count do | |
| 451 | let a = other_generic.symbol.get_ancestor(i); | |
| 452 | ||
| 453 | if bind_type_variables(a, results) then | |
| 454 | return true; | |
| 455 | fi | |
| 456 | od | |
| 457 | ||
| 458 | return false; | |
| 459 | fi | |
| 460 | else | |
| 461 | for a in other.ancestors do | |
| 462 | if bind_type_variables(a, results) then | |
| 463 | return true; | |
| 464 | fi | |
| 465 | od | |
| 466 | ||
| 467 | return false; | |
| 468 | fi | |
| 469 | si | |
| 470 | ||
| 471 | get_type_arguments_into(results: Collections.LIST[GenericArgument]) is | |
| 472 | for a in arguments do | |
| 473 | a.get_type_arguments_into(results); | |
| 474 | od | |
| 475 | si | |
| 476 | ||
| 477 | walk(action: (Type) -> void) is | |
| 478 | for a in arguments do | |
| 479 | a.walk(action); | |
| 480 | od | |
| 481 | ||
| 482 | super.walk(action); | |
| 483 | si | |
| 484 | ||
| 485 | to_string() -> string => | |
| 486 | if is_optional then | |
| 487 | "{symbol.to_string()}?"; | |
| 488 | else | |
| 489 | symbol.to_string(); | |
| 490 | fi; | |
| 491 | si | |
| 492 | si |