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| 1 | namespace Syntax.Parsers.Expressions is | |
| 2 | use IO.Std | |
| 3 | use Ghul.Disposable | |
| 4 | ||
| 5 | use Source | |
| 6 | ||
| 7 | use Logging | |
| 8 | ||
| 9 | class PRIMARY( | |
| 10 | identifier_parser: Parser[Trees.Identifiers.Identifier], | |
| 11 | type_parser: Parser[Trees.TypeExpressions.TypeExpression], | |
| 12 | expression_parser: Parser[Trees.Expressions.Expression], | |
| 13 | expression_list_parser: Parser[Trees.Expressions.LIST], | |
| 14 | expression_tuple_parser: Parser[Trees.Expressions.Expression], | |
| 15 | statement_parser: Parser[Trees.Statements.Statement], | |
| 16 | statement_list_parser: Parser[Trees.Statements.LIST], | |
| 17 | variable_list_parser: Parser[Trees.Variables.LIST], | |
| 18 | pragma_parser: Parser[Trees.Pragmas.PRAGMA] | |
| 19 | ): Base[Trees.Expressions.Expression] is | |
| 20 | description: string => "primary expression" | |
| 21 | ||
| 22 | super() | |
| 23 | ||
| 24 | init(..) is | |
| 25 | add_parsers() | |
| 26 | si | |
| 27 | ||
| 28 | // `@Foo() name: T` — an attribute pragma on a lambda-literal | |
| 29 | // parameter. Recognised only where a tuple element (and so | |
| 30 | // potentially a lambda parameter) can start — everywhere else | |
| 31 | // `@` falls through to the base dispatch and its ordinary | |
| 32 | // "unexpected token" error, so it never shows up as a spurious | |
| 33 | // option in an unrelated "expected ..." diagnostic. Whether | |
| 34 | // this position genuinely turns out to be a lambda parameter | |
| 35 | // (as opposed to an element of a value tuple that was never | |
| 36 | // rewritten into one) is checked once the enclosing construct | |
| 37 | // is known — see COMPILE_TUPLES.visit_tuple and | |
| 38 | // TUPLE_ELEMENT.rewrite_as_expression. | |
| 39 | parse(context: CONTEXT) -> Trees.Expressions.Expression? is | |
| 40 | if context.current.token == Lexical.TOKEN.AT /\ context.allow_tuple_element then | |
| 41 | return _parse_pragma_variable(context) | |
| 42 | fi | |
| 43 | ||
| 44 | return super.parse(context) | |
| 45 | si | |
| 46 | ||
| 47 | _parse_pragma_variable(context: CONTEXT) -> Trees.Expressions.Expression is | |
| 48 | let start = context.location | |
| 49 | ||
| 50 | let pragmas = Collections.LIST[Trees.Pragmas.PRAGMA]() | |
| 51 | ||
| 52 | while context.current.token == Lexical.TOKEN.AT do | |
| 53 | let pragma = pragma_parser.parse(context) | |
| 54 | ||
| 55 | if !pragma? then | |
| 56 | break | |
| 57 | fi | |
| 58 | ||
| 59 | pragmas.add(pragma) | |
| 60 | od | |
| 61 | ||
| 62 | context.allow_tuple_element = false | |
| 63 | ||
| 64 | let identifier = identifier_parser.parse(context)! | |
| 65 | ||
| 66 | if identifier.is_qualified then | |
| 67 | context.error(identifier.location, "expected a simple parameter name here") | |
| 68 | fi | |
| 69 | ||
| 70 | let end mut = identifier.location | |
| 71 | let type_expression: Trees.TypeExpressions.TypeExpression mut = Trees.TypeExpressions.INFER(identifier.location) | |
| 72 | let initializer: Trees.Expressions.Expression? mut = null | |
| 73 | ||
| 74 | if context.current.token == Lexical.TOKEN.COLON then | |
| 75 | context.next_token() | |
| 76 | let parsed_type = type_parser.parse(context) | |
| 77 | ||
| 78 | if parsed_type? then | |
| 79 | type_expression = parsed_type | |
| 80 | end = parsed_type.location | |
| 81 | fi | |
| 82 | fi | |
| 83 | ||
| 84 | if context.current.token == Lexical.TOKEN.ASSIGN then | |
| 85 | context.next_token() | |
| 86 | initializer = expression_parser.parse(context) | |
| 87 | ||
| 88 | if initializer? then | |
| 89 | end = initializer.location | |
| 90 | fi | |
| 91 | fi | |
| 92 | ||
| 93 | let result = Trees.Expressions.VARIABLE(start::end, identifier, type_expression, initializer) | |
| 94 | result.set_pragmas(pragmas) | |
| 95 | ||
| 96 | return result | |
| 97 | si | |
| 98 | ||
| 99 | // The target type of a `cast`, or null when it is elided and | |
| 100 | // comes from the context instead. Tuple types are | |
| 101 | // parenthesised, so `cast (int, string)(v)` opens with the same | |
| 102 | // token as `cast(v)`: a type is only taken as the target when | |
| 103 | // one parses cleanly *and* the argument list's `(` follows it. | |
| 104 | // Cleanly is what separates the two - `cast(f(3))` reaches a | |
| 105 | // `(` where the type expression wanted a `)`, and taking the | |
| 106 | // half-parsed `f` as the target loses the call and leaves the | |
| 107 | // type parse's own errors behind. `cast (f)(x)` still reads as | |
| 108 | // a cast to the parenthesised type `(f)`, as it did before the | |
| 109 | // elided form existed. | |
| 110 | _try_parse_cast_type(context: CONTEXT) -> Trees.TypeExpressions.TypeExpression? is | |
| 111 | if context.current.token != Lexical.TOKEN.PAREN_OPEN then | |
| 112 | return type_parser.parse(context)! | |
| 113 | fi | |
| 114 | ||
| 115 | let use diagnostics_snapshot = context.diagnostics_speculate_then_backtrack() | |
| 116 | let use snapshot = context.tokenizer_speculate_then_backtrack() | |
| 117 | ||
| 118 | let errors_before = context.logger.error_count | |
| 119 | ||
| 120 | let type_expression = type_parser.parse(context) | |
| 121 | ||
| 122 | if | |
| 123 | type_expression? /\ | |
| 124 | !type_expression.is_poisoned /\ | |
| 125 | context.logger.error_count == errors_before /\ | |
| 126 | context.current.token == Lexical.TOKEN.PAREN_OPEN | |
| 127 | then | |
| 128 | snapshot.commit() | |
| 129 | diagnostics_snapshot.commit() | |
| 130 | ||
| 131 | return type_expression | |
| 132 | fi | |
| 133 | ||
| 134 | return null | |
| 135 | si | |
| 136 | ||
| 137 | add_parsers() is | |
| 138 | add_parser( | |
| 139 | (context) -> Trees.Expressions.Expression is | |
| 140 | let start = context.location | |
| 141 | let identifier = identifier_parser.parse(context)! | |
| 142 | ||
| 143 | // A bare unqualified `_` in a value position is the | |
| 144 | // default-value expression. The `: T` and `= init` | |
| 145 | // guards keep the typed-discard formal `_: T` on the | |
| 146 | // identifier path. Binding and pattern positions | |
| 147 | // (`let _ =`, destructure leaves, `for _`, `if let`) | |
| 148 | // never reach this parser — they parse identifiers | |
| 149 | // directly — so the discard meanings don't collide | |
| 150 | // with the value meaning. Inside a `(...)` group the | |
| 151 | // speculative tuple/pattern rewrite converts a `_` | |
| 152 | // element back to a discard leaf via DEFAULT's | |
| 153 | // try_copy_as_*. | |
| 154 | if | |
| 155 | identifier.name =~ "_" /\ | |
| 156 | !identifier.is_qualified /\ | |
| 157 | context.current.token != Lexical.TOKEN.COLON /\ | |
| 158 | context.current.token != Lexical.TOKEN.ASSIGN | |
| 159 | then | |
| 160 | // `_(args)` constructs the type the context | |
| 161 | // expects. `_` is never callable, so a `(` here | |
| 162 | // opens a constructor argument list, by the same | |
| 163 | // reasoning that makes `[` a type argument below. | |
| 164 | if context.current_token == Lexical.TOKEN.PAREN_OPEN then | |
| 165 | context.next_token() | |
| 166 | ||
| 167 | let arguments: Trees.Expressions.LIST? mut = null | |
| 168 | ||
| 169 | if context.current.token != Lexical.TOKEN.PAREN_CLOSE then | |
| 170 | arguments = expression_list_parser.parse(context) | |
| 171 | fi | |
| 172 | ||
| 173 | context.next_token(Lexical.TOKEN.PAREN_CLOSE, syntax_error_message) | |
| 174 | ||
| 175 | if !arguments? then | |
| 176 | arguments = | |
| 177 | Trees.Expressions.LIST( | |
| 178 | context.location, | |
| 179 | Collections.LIST[Trees.Expressions.Expression]() | |
| 180 | ) | |
| 181 | fi | |
| 182 | ||
| 183 | return Trees.Expressions.CONSTRUCT(start::arguments.location, arguments) | |
| 184 | fi | |
| 185 | ||
| 186 | // `_[T]` pins the type explicitly. `_` is | |
| 187 | // never indexable, so a `[` here is the type | |
| 188 | // argument, not an indexer. | |
| 189 | let type_expression: Trees.TypeExpressions.TypeExpression? mut = null | |
| 190 | ||
| 191 | if context.current_token == Lexical.TOKEN.SQUARE_OPEN then | |
| 192 | context.next_token() | |
| 193 | type_expression = type_parser.parse(context) | |
| 194 | context.next_token(Lexical.TOKEN.SQUARE_CLOSE) | |
| 195 | fi | |
| 196 | ||
| 197 | return Trees.Expressions.DEFAULT(start::context.location, type_expression) | |
| 198 | fi | |
| 199 | ||
| 200 | if context.allow_tuple_element /\ !identifier.is_qualified then | |
| 201 | context.allow_tuple_element = false | |
| 202 | let end mut = identifier.location | |
| 203 | let type_expression: Trees.TypeExpressions.TypeExpression? mut = null | |
| 204 | let initializer: Trees.Expressions.Expression? mut = null | |
| 205 | ||
| 206 | if context.current.token == Lexical.TOKEN.COLON then | |
| 207 | context.next_token() | |
| 208 | type_expression = type_parser.parse(context) | |
| 209 | end = type_expression!.location | |
| 210 | fi | |
| 211 | ||
| 212 | if context.current.token == Lexical.TOKEN.ASSIGN then | |
| 213 | context.next_token() | |
| 214 | initializer = expression_parser.parse(context) | |
| 215 | end = initializer!.location | |
| 216 | fi | |
| 217 | ||
| 218 | if initializer? then | |
| 219 | if type_expression == null then | |
| 220 | type_expression = Trees.TypeExpressions.INFER(context.location) | |
| 221 | fi | |
| 222 | fi | |
| 223 | ||
| 224 | if type_expression? then | |
| 225 | return Trees.Expressions.VARIABLE(start::end, identifier, type_expression, initializer) | |
| 226 | fi | |
| 227 | fi | |
| 228 | ||
| 229 | return Trees.Expressions.IDENTIFIER(identifier.location, identifier) | |
| 230 | si, Lexical.TOKEN.IDENTIFIER | |
| 231 | ) | |
| 232 | ||
| 233 | add_parser( | |
| 234 | (context) is | |
| 235 | let start = context.location | |
| 236 | context.next_token() | |
| 237 | ||
| 238 | // `[ ]` with the brackets tokenized separately is the | |
| 239 | // empty list literal, the same as the `[]` single token; | |
| 240 | // its element type comes from the surrounding context. | |
| 241 | let elements = | |
| 242 | if context.current.token == Lexical.TOKEN.SQUARE_CLOSE then | |
| 243 | Trees.Expressions.LIST(context.location, Collections.LIST[Trees.Expressions.Expression]()) | |
| 244 | else | |
| 245 | expression_list_parser.parse(context)! | |
| 246 | fi | |
| 247 | ||
| 248 | let end mut = context.location | |
| 249 | context.next_token(Lexical.TOKEN.SQUARE_CLOSE) | |
| 250 | let type_expression: Trees.TypeExpressions.TypeExpression = | |
| 251 | if context.current.token == Lexical.TOKEN.COLON then | |
| 252 | context.next_token() | |
| 253 | let parsed = type_parser.parse(context)! | |
| 254 | end = parsed.location | |
| 255 | parsed | |
| 256 | else | |
| 257 | Trees.TypeExpressions.INFER(start::end) | |
| 258 | fi | |
| 259 | ||
| 260 | return Trees.Expressions.SEQUENCE(start::end, elements, type_expression) | |
| 261 | si, | |
| 262 | Lexical.TOKEN.SQUARE_OPEN | |
| 263 | ) | |
| 264 | ||
| 265 | add_parser( | |
| 266 | (context) is | |
| 267 | // `[]` is a single token. As a value it is the empty | |
| 268 | // list literal: the element type can't come from the | |
| 269 | // (absent) elements, so it relies on a constraint pushed | |
| 270 | // down by the surrounding context — a typed initializer, | |
| 271 | // a call argument with a known formal type, and so on. | |
| 272 | // With no such constraint compile_tuples reports | |
| 273 | // "cannot infer type of list literal with no elements". | |
| 274 | let location = context.location | |
| 275 | ||
| 276 | context.next_token() | |
| 277 | ||
| 278 | return Trees.Expressions.SEQUENCE( | |
| 279 | location, | |
| 280 | Trees.Expressions.LIST(location, Collections.LIST[Trees.Expressions.Expression]()), | |
| 281 | Trees.TypeExpressions.INFER(location) | |
| 282 | ) | |
| 283 | si, | |
| 284 | Lexical.TOKEN.ARRAY_DEF | |
| 285 | ) | |
| 286 | ||
| 287 | add_parser( | |
| 288 | (context) is | |
| 289 | return expression_tuple_parser.parse(context)! | |
| 290 | si, | |
| 291 | Lexical.TOKEN.PAREN_OPEN | |
| 292 | ) | |
| 293 | ||
| 294 | // `new` is no longer part of the language, but it stays a | |
| 295 | // reserved token so that reaching one here can say so. Freed | |
| 296 | // as an identifier it would instead report a symbol that does | |
| 297 | // not exist, which says nothing about what to write instead. | |
| 298 | // Consuming just the keyword and parsing on leaves | |
| 299 | // `TYPE(args)`, which is what the construction should have | |
| 300 | // been written as, so the rest of the expression analyses | |
| 301 | // normally and the reader gets this error alone rather than a | |
| 302 | // cascade behind it. | |
| 303 | add_parser( | |
| 304 | (context) is | |
| 305 | let location = context.location | |
| 306 | ||
| 307 | context.next_token(Lexical.TOKEN.NEW) | |
| 308 | ||
| 309 | context.logger.error( | |
| 310 | location, | |
| 311 | "new is not supported", | |
| 312 | location, | |
| 313 | "help: construct by calling the type, as in TYPE(arguments)" | |
| 314 | ) | |
| 315 | ||
| 316 | let expression = parse(context) | |
| 317 | ||
| 318 | if !expression? then | |
| 319 | return Trees.Expressions.Literals.STRING(location, "") | |
| 320 | fi | |
| 321 | ||
| 322 | return expression | |
| 323 | si, | |
| 324 | Lexical.TOKEN.NEW | |
| 325 | ) | |
| 326 | ||
| 327 | add_parser( | |
| 328 | (context) -> Trees.Expressions.Expression is | |
| 329 | let start = context.location | |
| 330 | ||
| 331 | context.next_token(Lexical.TOKEN.CAST) | |
| 332 | ||
| 333 | let opens_with_group = context.current.token == Lexical.TOKEN.PAREN_OPEN | |
| 334 | ||
| 335 | let type_expression = _try_parse_cast_type(context) | |
| 336 | ||
| 337 | context.next_token(Lexical.TOKEN.PAREN_OPEN) | |
| 338 | ||
| 339 | // A parenthesised target reads two ways whenever it | |
| 340 | // is also a value: as the cast's target type with | |
| 341 | // the parentheses that follow holding its value, or | |
| 342 | // as the cast's value with those parentheses | |
| 343 | // calling the result. Both readings are carried to | |
| 344 | // resolve-type-expressions, which can ask the scope | |
| 345 | // which of the two the name is. A target that only | |
| 346 | // reads as a type - a tuple, a function type - is | |
| 347 | // unambiguous: its value reading could not be | |
| 348 | // called. A name is the only target shape whose | |
| 349 | // value reading is callable, so it is the only one | |
| 350 | // taken as ambiguous. | |
| 351 | let called_value = | |
| 352 | if | |
| 353 | opens_with_group /\ | |
| 354 | isa Trees.TypeExpressions.NAMED(type_expression) | |
| 355 | then | |
| 356 | type_expression.try_copy_as_value_expression() | |
| 357 | else | |
| 358 | null | |
| 359 | fi | |
| 360 | ||
| 361 | if called_value? /\ type_expression? then | |
| 362 | let arguments = | |
| 363 | if context.current.token != Lexical.TOKEN.PAREN_CLOSE then | |
| 364 | expression_list_parser.parse(context)! | |
| 365 | else | |
| 366 | Trees.Expressions.LIST( | |
| 367 | context.location, | |
| 368 | Collections.LIST[Trees.Expressions.Expression]() | |
| 369 | ) | |
| 370 | fi | |
| 371 | ||
| 372 | let end = context.location | |
| 373 | ||
| 374 | context.next_token(Lexical.TOKEN.PAREN_CLOSE) | |
| 375 | ||
| 376 | // A cast takes one value, so an argument list of | |
| 377 | // any other length settles the reading here: only | |
| 378 | // the call can be meant, and it is built as one. | |
| 379 | if arguments.expressions.count != 1 then | |
| 380 | return Trees.Expressions.CALL( | |
| 381 | start::end, | |
| 382 | Trees.Expressions.CAST(start::end, null, called_value, true), | |
| 383 | arguments | |
| 384 | ) | |
| 385 | fi | |
| 386 | ||
| 387 | let result = | |
| 388 | Trees.Expressions.CAST( | |
| 389 | start::end, | |
| 390 | type_expression, | |
| 391 | arguments.expressions[0], | |
| 392 | true | |
| 393 | ) | |
| 394 | ||
| 395 | result.set_ambiguous_readings( | |
| 396 | Trees.Expressions.CALL( | |
| 397 | start::end, | |
| 398 | Trees.Expressions.CAST(start::end, null, called_value, true), | |
| 399 | arguments | |
| 400 | ), | |
| 401 | arguments | |
| 402 | ) | |
| 403 | ||
| 404 | return result | |
| 405 | fi | |
| 406 | ||
| 407 | let value = expression_parser.parse(context)! | |
| 408 | let result = Trees.Expressions.CAST(start::context.location, type_expression, value, true) | |
| 409 | ||
| 410 | context.next_token(Lexical.TOKEN.PAREN_CLOSE) | |
| 411 | return result | |
| 412 | si, | |
| 413 | Lexical.TOKEN.CAST | |
| 414 | ) | |
| 415 | ||
| 416 | add_parser( | |
| 417 | (context) is | |
| 418 | let start = context.location | |
| 419 | context.next_token(Lexical.TOKEN.ISA) | |
| 420 | let type_expression = type_parser.parse(context)! | |
| 421 | context.next_token(Lexical.TOKEN.PAREN_OPEN) | |
| 422 | let value = expression_parser.parse(context)! | |
| 423 | let result = Trees.Expressions.ISA(start::context.location, type_expression, value) | |
| 424 | context.next_token(Lexical.TOKEN.PAREN_CLOSE) | |
| 425 | return result | |
| 426 | si, | |
| 427 | Lexical.TOKEN.ISA | |
| 428 | ) | |
| 429 | ||
| 430 | add_parser( | |
| 431 | (context) is | |
| 432 | let start = context.location | |
| 433 | context.next_token(Lexical.TOKEN.TYPEOF) | |
| 434 | let type_expression = type_parser.parse(context)! | |
| 435 | let result = Trees.Expressions.TYPEOF(start::context.location, type_expression) | |
| 436 | return result | |
| 437 | si, | |
| 438 | Lexical.TOKEN.TYPEOF | |
| 439 | ) | |
| 440 | ||
| 441 | add_parser( | |
| 442 | (context) is | |
| 443 | let location = context.location | |
| 444 | let value_string = context.current.value_string | |
| 445 | context.next_token() | |
| 446 | return Trees.Expressions.Literals.INTEGER(location, value_string) | |
| 447 | si, | |
| 448 | Lexical.TOKEN.INT_LITERAL | |
| 449 | ) | |
| 450 | ||
| 451 | add_parser( | |
| 452 | (context) is | |
| 453 | let location = context.location | |
| 454 | let value_string = context.current.value_string | |
| 455 | context.next_token() | |
| 456 | return Trees.Expressions.Literals.FLOAT(location, value_string) | |
| 457 | si, | |
| 458 | Lexical.TOKEN.FLOAT_LITERAL | |
| 459 | ) | |
| 460 | ||
| 461 | add_parser( | |
| 462 | (context) is | |
| 463 | let location = context.location | |
| 464 | let value_string = context.current.value_string | |
| 465 | context.next_token() | |
| 466 | return Trees.Expressions.Literals.STRING(location, value_string) | |
| 467 | si, | |
| 468 | Lexical.TOKEN.STRING_LITERAL | |
| 469 | ) | |
| 470 | ||
| 471 | add_parser( | |
| 472 | (context) is | |
| 473 | let location = context.location | |
| 474 | let value_string = context.current.value_string | |
| 475 | context.next_token() | |
| 476 | return Trees.Expressions.Literals.CHARACTER(location, value_string) | |
| 477 | si, | |
| 478 | Lexical.TOKEN.CHAR_LITERAL | |
| 479 | ) | |
| 480 | ||
| 481 | add_parser( | |
| 482 | (context) => parse_string_with_interpolations(context), | |
| 483 | Lexical.TOKEN.ENTER_STRING | |
| 484 | ) | |
| 485 | ||
| 486 | add_parser( | |
| 487 | (context) is | |
| 488 | let location = context.location | |
| 489 | let value_string = context.current.value_string | |
| 490 | context.next_token() | |
| 491 | return Trees.Expressions.Literals.BOOLEAN(location, value_string) | |
| 492 | si, | |
| 493 | [Lexical.TOKEN.TRUE, Lexical.TOKEN.FALSE] | |
| 494 | ) | |
| 495 | ||
| 496 | add_parser( | |
| 497 | (context) is | |
| 498 | let location = context.location | |
| 499 | context.next_token() | |
| 500 | return Trees.Expressions.NULL(location) | |
| 501 | si, | |
| 502 | Lexical.TOKEN.NULL | |
| 503 | ) | |
| 504 | ||
| 505 | add_parser( | |
| 506 | (context) is | |
| 507 | let location = context.location | |
| 508 | context.next_token() | |
| 509 | return Trees.Expressions.SELF(location) | |
| 510 | si, | |
| 511 | Lexical.TOKEN.SELF | |
| 512 | ) | |
| 513 | ||
| 514 | add_parser( | |
| 515 | (context) is | |
| 516 | let location = context.location | |
| 517 | context.next_token() | |
| 518 | return Trees.Expressions.SUPER(location) | |
| 519 | si, Lexical.TOKEN.SUPER | |
| 520 | ) | |
| 521 | ||
| 522 | add_parser( | |
| 523 | (context) is | |
| 524 | let location = context.location | |
| 525 | context.next_token() | |
| 526 | return Trees.Expressions.RECURSE(location) | |
| 527 | si, Lexical.TOKEN.REC | |
| 528 | ) | |
| 529 | ||
| 530 | add_parser( | |
| 531 | (context) -> Trees.Expressions.Expression is | |
| 532 | // A compound statement in element position settles | |
| 533 | // the element: it is never a lambda's formal | |
| 534 | // parameter. The flag has to be cleared before the | |
| 535 | // body is parsed, not merely when the element is | |
| 536 | // complete - inside the body, `name = e` is an | |
| 537 | // assignment statement, while the flag says to read | |
| 538 | // it as a named element, which declares a local | |
| 539 | // shadowing the one being assigned. | |
| 540 | context.allow_tuple_element = false | |
| 541 | ||
| 542 | let statement = statement_parser.parse(context)! | |
| 543 | ||
| 544 | return Trees.Expressions.STATEMENT(statement.location, statement) | |
| 545 | si, Lexical.TOKEN.IF | |
| 546 | ) | |
| 547 | ||
| 548 | add_parser( | |
| 549 | (context) -> Trees.Expressions.Expression is | |
| 550 | context.allow_tuple_element = false | |
| 551 | ||
| 552 | let statement = statement_parser.parse(context)! | |
| 553 | ||
| 554 | return Trees.Expressions.STATEMENT(statement.location, statement) | |
| 555 | si, Lexical.TOKEN.CASE | |
| 556 | ) | |
| 557 | ||
| 558 | // Loops in expression position: same delegation as `if` / | |
| 559 | // `case`. The wrapped statement produces a value only when a | |
| 560 | // valued `break` targets it; compile-expressions reports the | |
| 561 | // value-less forms. | |
| 562 | add_parser( | |
| 563 | (context) -> Trees.Expressions.Expression is | |
| 564 | context.allow_tuple_element = false | |
| 565 | ||
| 566 | let statement = statement_parser.parse(context)! | |
| 567 | ||
| 568 | return Trees.Expressions.STATEMENT(statement.location, statement) | |
| 569 | si, Lexical.TOKEN.DO | |
| 570 | ) | |
| 571 | ||
| 572 | add_parser( | |
| 573 | (context) -> Trees.Expressions.Expression is | |
| 574 | context.allow_tuple_element = false | |
| 575 | ||
| 576 | let statement = statement_parser.parse(context)! | |
| 577 | ||
| 578 | return Trees.Expressions.STATEMENT(statement.location, statement) | |
| 579 | si, Lexical.TOKEN.FOR | |
| 580 | ) | |
| 581 | ||
| 582 | add_parser( | |
| 583 | (context) -> Trees.Expressions.Expression is | |
| 584 | context.allow_tuple_element = false | |
| 585 | ||
| 586 | let statement = statement_parser.parse(context)! | |
| 587 | ||
| 588 | return Trees.Expressions.STATEMENT(statement.location, statement) | |
| 589 | si, Lexical.TOKEN.WHILE | |
| 590 | ) | |
| 591 | ||
| 592 | // `val ... lav` — a value-producing block. The block's | |
| 593 | // value is the LUB of its tail expression (if it provides | |
| 594 | // one) and every `return E` whose target is this block; | |
| 595 | // `return E` inside a `val ... lav` exits the innermost | |
| 596 | // enclosing val-block rather than the enclosing function. | |
| 597 | add_parser( | |
| 598 | (context) -> Trees.Expressions.Expression is | |
| 599 | let start = context.location | |
| 600 | context.next_token(Lexical.TOKEN.VAL) | |
| 601 | ||
| 602 | let use open = context.open_construct(Lexical.TOKEN.LAV) | |
| 603 | let statements = statement_list_parser.parse(context)! | |
| 604 | let end = context.location | |
| 605 | context.expect_closer(Lexical.TOKEN.LAV, syntax_error_message) | |
| 606 | return Trees.Expressions.VAL_BLOCK(start::end, statements) | |
| 607 | si, Lexical.TOKEN.VAL | |
| 608 | ) | |
| 609 | ||
| 610 | add_parser( | |
| 611 | (context) is | |
| 612 | let start = context.location | |
| 613 | context.next_token() | |
| 614 | let want_dispose = false | |
| 615 | if context.current_token == Lexical.TOKEN.USE then | |
| 616 | // TODO it's not totally clear what the scope of the | |
| 617 | // use should be - just the expression? There may not | |
| 618 | // be a clear statement block given that we're in an | |
| 619 | // expression context | |
| 620 | context.error(context.location, "use is not supported in this context") | |
| 621 | ||
| 622 | context.next_token() | |
| 623 | ||
| 624 | // want_dispose = true; | |
| 625 | fi | |
| 626 | ||
| 627 | let variable_list = variable_list_parser.parse(context)! | |
| 628 | ||
| 629 | let expression = | |
| 630 | if context.next_token(Lexical.TOKEN.IN) then | |
| 631 | expression_parser.parse(context)! | |
| 632 | else | |
| 633 | Trees.Expressions.Literals.NONE(start::variable_list.location) | |
| 634 | fi | |
| 635 | ||
| 636 | let location = start::expression.location | |
| 637 | ||
| 638 | return Trees.Expressions.LET_IN( | |
| 639 | location, | |
| 640 | want_dispose, | |
| 641 | variable_list, | |
| 642 | expression | |
| 643 | ) | |
| 644 | si, | |
| 645 | Lexical.TOKEN.LET | |
| 646 | ) | |
| 647 | ||
| 648 | add_parser( | |
| 649 | (context) is | |
| 650 | let start = context.location | |
| 651 | context.next_token() | |
| 652 | ||
| 653 | let condition = expression_parser.parse(context)! | |
| 654 | ||
| 655 | let message: Trees.Expressions.Expression? mut = null | |
| 656 | ||
| 657 | if context.current_token == Lexical.TOKEN.ELSE /\ context.continues(start) then | |
| 658 | context.next_token() | |
| 659 | message = expression_parser.parse(context) | |
| 660 | fi | |
| 661 | ||
| 662 | let expression = | |
| 663 | if context.next_token(Lexical.TOKEN.IN, syntax_error_message) then | |
| 664 | expression_parser.parse(context)! | |
| 665 | else | |
| 666 | Trees.Expressions.Literals.NONE(start::condition.location) | |
| 667 | fi | |
| 668 | ||
| 669 | let location = start::expression.location | |
| 670 | ||
| 671 | return Trees.Expressions.ASSERT_IN( | |
| 672 | location, | |
| 673 | condition, | |
| 674 | message, | |
| 675 | expression | |
| 676 | ) | |
| 677 | si, | |
| 678 | Lexical.TOKEN.ASSERT | |
| 679 | ) | |
| 680 | si | |
| 681 | ||
| 682 | parse_string_with_interpolations(context: CONTEXT) -> Trees.Expressions.Expression is | |
| 683 | // ENTER_STRING expression (':' FORMAT_STRING)? (CONTINUE_STRING expression (':' FORMAT_STRING)? )* (EXIT_STRING | CANCEL_STRING) | |
| 684 | // ^ we're here | |
| 685 | ||
| 686 | let start = context.location | |
| 687 | ||
| 688 | let fragments = Collections.LIST[Trees.Expressions.INTERPOLATION_FRAGMENT]() | |
| 689 | ||
| 690 | let is_first mut = true | |
| 691 | let success mut = false | |
| 692 | let line mut = start.start_line | |
| 693 | ||
| 694 | while | |
| 695 | context.current_token != Lexical.TOKEN.EXIT_STRING | |
| 696 | do | |
| 697 | // a newline in the string part will result in a CANCEL_STRING token | |
| 698 | // we should stop parsing the string and return immediately | |
| 699 | // TODO: return the interpolation that we've assembled so far | |
| 700 | ||
| 701 | if context.current_token == Lexical.TOKEN.CANCEL_STRING then | |
| 702 | // TODO might want to skip to end of line, as the input could be garbled | |
| 703 | context.next_token() | |
| 704 | return Trees.Expressions.Literals.STRING(start::context.location, "") | |
| 705 | fi | |
| 706 | ||
| 707 | // we've either just entered a string interpolation, or we've just passed a closing curly bracket | |
| 708 | // either way we're expecting a string fragment | |
| 709 | ||
| 710 | line = context.location.start_line | |
| 711 | ||
| 712 | let success_line = parse_single_interpolated_string_fragment(context, is_first, fragments) | |
| 713 | success = success_line.success | |
| 714 | line = success_line.line | |
| 715 | ||
| 716 | if !success then | |
| 717 | skip_to_end_of_string_with_interpolations(context, line) | |
| 718 | ||
| 719 | return Trees.Expressions.Literals.STRING(start::context.location, "") | |
| 720 | fi | |
| 721 | ||
| 722 | if context.current_token == Lexical.TOKEN.CANCEL_STRING then | |
| 723 | // TODO might want to skip to end of line, as the input could be garbled | |
| 724 | context.next_token() | |
| 725 | return Trees.Expressions.Literals.STRING(start::context.location, "") | |
| 726 | fi | |
| 727 | ||
| 728 | (success, line) = parse_single_interpolated_expression(context, fragments) | |
| 729 | ||
| 730 | if !success then | |
| 731 | skip_to_end_of_string_with_interpolations(context, line) | |
| 732 | ||
| 733 | return Trees.Expressions.Literals.STRING(start::context.location, "") | |
| 734 | fi | |
| 735 | ||
| 736 | is_first = false | |
| 737 | od | |
| 738 | ||
| 739 | if context.current_token == Lexical.TOKEN.CANCEL_STRING then | |
| 740 | context.next_token() | |
| 741 | elif context.current_token != Lexical.TOKEN.EXIT_STRING then | |
| 742 | context.error(context.location, "unexpected token in string interpolation") | |
| 743 | ||
| 744 | if context.location.start_line == start.start_line then | |
| 745 | skip_to_end_of_string_with_interpolations(context, line) | |
| 746 | fi | |
| 747 | else | |
| 748 | parse_single_interpolated_string_fragment(context, is_first, fragments) | |
| 749 | fi | |
| 750 | ||
| 751 | let end = context.location | |
| 752 | ||
| 753 | let expression_count mut = 0 | |
| 754 | let should_poison mut = false | |
| 755 | let total_fragment_length mut = 0 | |
| 756 | ||
| 757 | for e in fragments do | |
| 758 | if e.is_expression then | |
| 759 | expression_count = expression_count + 1 | |
| 760 | if e.expression.is_poisoned then | |
| 761 | should_poison = true | |
| 762 | fi | |
| 763 | else | |
| 764 | let fragment = cast Trees.Expressions.Literals.STRING?(e.expression)! | |
| 765 | let fragment_length = fragment.value_string.length | |
| 766 | ||
| 767 | total_fragment_length = total_fragment_length + fragment_length | |
| 768 | fi | |
| 769 | od | |
| 770 | ||
| 771 | let result = Trees.Expressions.STRING_INTERPOLATION(start::end, fragments, total_fragment_length, expression_count) | |
| 772 | ||
| 773 | return result | |
| 774 | si | |
| 775 | ||
| 776 | skip_to_end_of_string_with_interpolations(context: CONTEXT, line: int) is | |
| 777 | let retries mut = 50 | |
| 778 | ||
| 779 | while | |
| 780 | context.current_token != Lexical.TOKEN.EXIT_STRING /\ | |
| 781 | context.current_token != Lexical.TOKEN.CANCEL_STRING /\ | |
| 782 | context.location.start_line == line /\ | |
| 783 | !context.is_end_of_file /\ | |
| 784 | retries > 0 | |
| 785 | do | |
| 786 | context.next_token() | |
| 787 | retries = retries - 1 | |
| 788 | od | |
| 789 | si | |
| 790 | ||
| 791 | parse_single_interpolated_string_fragment( | |
| 792 | context: CONTEXT, | |
| 793 | is_first: bool, | |
| 794 | into: Collections.MutableList[Trees.Expressions.INTERPOLATION_FRAGMENT] | |
| 795 | ) -> | |
| 796 | (success: bool, line: int) | |
| 797 | is | |
| 798 | // ENTER_STRING expression (':' FORMAT_STRING)? (CONTINUE_STRING expression (':' FORMAT_STRING)? )* (EXIT_STRING | CANCEL_STRING) | |
| 799 | // ^ we're here ^ or here ^ or here | |
| 800 | ||
| 801 | // we've either just entered a string interpolation, or we've just passed a closing curly bracket | |
| 802 | // either way we're expecting a string fragment | |
| 803 | ||
| 804 | if is_first then | |
| 805 | if !context.expect_token(Lexical.TOKEN.ENTER_STRING) then | |
| 806 | return (false, 0) | |
| 807 | fi | |
| 808 | else | |
| 809 | if | |
| 810 | context.current_token != Lexical.TOKEN.CONTINUE_STRING /\ | |
| 811 | context.current_token != Lexical.TOKEN.EXIT_STRING | |
| 812 | then | |
| 813 | context.logger.error(context.location, "syntax error: expected }} but found {context.current_token_name}") | |
| 814 | ||
| 815 | return (false, 0) | |
| 816 | fi | |
| 817 | fi | |
| 818 | ||
| 819 | into.add( | |
| 820 | Trees.Expressions.INTERPOLATION_FRAGMENT( | |
| 821 | false, | |
| 822 | Trees.Expressions.Literals.STRING(context.location, context.current_string!), | |
| 823 | null, | |
| 824 | null | |
| 825 | ) | |
| 826 | ) | |
| 827 | ||
| 828 | let line = context.location.start_line | |
| 829 | ||
| 830 | context.next_token() | |
| 831 | ||
| 832 | return (true, line) | |
| 833 | si | |
| 834 | ||
| 835 | parse_single_interpolated_expression(context: CONTEXT, into: Collections.MutableList[Trees.Expressions.INTERPOLATION_FRAGMENT]) -> (success: bool, line: int) is | |
| 836 | // ENTER_STRING expression (':' FORMAT_STRING)? (CONTINUE_STRING expression (':' FORMAT_STRING)? )* (EXIT_STRING | CANCEL_STRING) | |
| 837 | // ^ we're here ^ or here | |
| 838 | ||
| 839 | let start = context.location | |
| 840 | ||
| 841 | let expression: Trees.Expressions.Expression mut | |
| 842 | ||
| 843 | // Neither an interpolated expression nor the alignment | |
| 844 | // after it is ever a formal-argument list, and the `:` that | |
| 845 | // can follow either opens a format specifier rather than a | |
| 846 | // type. Clear the flag the enclosing expression list may | |
| 847 | // have left set for the whole fragment, so nothing inside | |
| 848 | // it consumes that `:`. | |
| 849 | let previous_allow_tuple_element = context.allow_tuple_element | |
| 850 | context.allow_tuple_element = false | |
| 851 | ||
| 852 | if context.current_token != Lexical.TOKEN.CONTINUE_STRING then | |
| 853 | expression = expression_parser.parse(context)! | |
| 854 | else | |
| 855 | expression = Trees.Expressions.Literals.STRING(context.location, "") | |
| 856 | context.logger.error(context.location, "expected an expression") | |
| 857 | context.next_token() | |
| 858 | fi | |
| 859 | ||
| 860 | if expression.is_poisoned then | |
| 861 | if | |
| 862 | context.current_token != Lexical.TOKEN.COMMA /\ | |
| 863 | context.current_token != Lexical.TOKEN.COLON /\ | |
| 864 | context.current_token != Lexical.TOKEN.CONTINUE_STRING /\ | |
| 865 | context.current_token != Lexical.TOKEN.EXIT_STRING | |
| 866 | then | |
| 867 | context.allow_tuple_element = previous_allow_tuple_element | |
| 868 | return (false, 0) | |
| 869 | fi | |
| 870 | fi | |
| 871 | ||
| 872 | let alignment: Trees.Expressions.Expression? mut = null | |
| 873 | let format: string? mut = null | |
| 874 | ||
| 875 | let line mut = 0 | |
| 876 | ||
| 877 | if context.current_token == Lexical.TOKEN.COMMA then | |
| 878 | context.next_token() | |
| 879 | ||
| 880 | alignment = expression_parser.parse(context)! | |
| 881 | ||
| 882 | if alignment.is_poisoned then | |
| 883 | if | |
| 884 | context.current_token != Lexical.TOKEN.COLON /\ | |
| 885 | context.current_token != Lexical.TOKEN.CONTINUE_STRING /\ | |
| 886 | context.current_token != Lexical.TOKEN.EXIT_STRING | |
| 887 | then | |
| 888 | context.allow_tuple_element = previous_allow_tuple_element | |
| 889 | return (false, 0) | |
| 890 | fi | |
| 891 | fi | |
| 892 | ||
| 893 | line = alignment.location.end_line | |
| 894 | fi | |
| 895 | ||
| 896 | if context.current_token == Lexical.TOKEN.COLON then | |
| 897 | context.expect_format_specifier() | |
| 898 | ||
| 899 | context.next_token() | |
| 900 | ||
| 901 | if context.expect_token(Lexical.TOKEN.FORMAT_STRING) then | |
| 902 | format = context.current_string | |
| 903 | line = context.location.end_line | |
| 904 | ||
| 905 | context.next_token() | |
| 906 | fi | |
| 907 | fi | |
| 908 | ||
| 909 | context.allow_tuple_element = previous_allow_tuple_element | |
| 910 | ||
| 911 | into.add(Trees.Expressions.INTERPOLATION_FRAGMENT(true, expression, alignment, format)) | |
| 912 | ||
| 913 | return (true, line) | |
| 914 | si | |
| 915 | ||
| 916 | other_token(context: CONTEXT) -> Trees.Expressions.Expression is | |
| 917 | super.other_token(context) | |
| 918 | ||
| 919 | let result = Trees.Expressions.Literals.NONE(context.location) | |
| 920 | ||
| 921 | result.poison() | |
| 922 | ||
| 923 | return result | |
| 924 | si | |
| 925 | ||
| 926 | si | |
| 927 | si |