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1 // Copyright (c) 2015, the Dart project authors. Please see the AUTHORS file | |
2 // for details. All rights reserved. Use of this source code is governed by a | |
3 // BSD-style license that can be found in the LICENSE file. | |
4 | |
5 /* This library defines the representation of runtime types. | |
6 */ | |
7 | |
8 dart_library.library('dart/_types', null, /* Imports */[ | |
9 ], /* Lazy Imports */[ | |
10 'dart/_utils', | |
11 'dart/core', | |
12 'dart/_classes', | |
13 'dart/_rtti' | |
14 ], function(exports, dart_utils, core, classes, rtti) { | |
15 'use strict'; | |
16 | |
17 const getOwnPropertyNames = Object.getOwnPropertyNames; | |
18 | |
19 const assert = dart_utils.assert; | |
20 | |
21 /** | |
22 * Types in dart are represented at runtime as follows. | |
23 * - Normal nominal types, produced from classes, are represented | |
24 * at runtime by the JS class of which they are an instance. | |
25 * If the type is the result of instantiating a generic class, | |
26 * then the "classes" module manages the association between the | |
27 * instantiated class and the original class declaration | |
28 * and the type arguments with which it was instantiated. This | |
29 * assocation can be queried via the "classes" module". | |
30 * | |
31 * - All other types are represented as instances of class TypeRep, | |
32 * defined in this module. | |
33 * - Dynamic, Void, and Bottom are singleton instances of sentinal | |
34 * classes. | |
35 * - Function types are instances of subclasses of AbstractFunctionType. | |
36 * | |
37 * Function types are represented in one of two ways: | |
38 * - As an instance of FunctionType. These are eagerly computed. | |
39 * - As an instance of TypeDef. The TypeDef representation lazily | |
40 * computes an instance of FunctionType, and delegates to that instance. | |
41 * | |
42 * All types satisfy the following interface: | |
43 * get String name; | |
44 * String toString(); | |
45 * | |
46 */ | |
47 class TypeRep extends rtti.LazyTagged(() => core.Type) { | |
48 get name() {return this.toString();} | |
49 } | |
50 | |
51 class Dynamic extends TypeRep { | |
52 toString() { return "dynamic"; } | |
53 } | |
54 let dynamicR = new Dynamic(); | |
55 exports.dynamic = dynamicR; | |
56 | |
57 class Void extends TypeRep { | |
58 toString() { return "void"; } | |
59 } | |
60 | |
61 let voidR = new Void(); | |
62 exports.void = voidR; | |
63 | |
64 class Bottom extends TypeRep { | |
65 toString() { return "bottom"; } | |
66 } | |
67 let bottomR = new Bottom(); | |
68 exports.bottom = bottomR; | |
69 | |
70 class JSObject extends TypeRep { | |
71 toString() { return "NativeJavaScriptObject"; } | |
72 } | |
73 let jsobjectR = new JSObject(); | |
74 exports.jsobject = jsobjectR; | |
75 | |
76 class AbstractFunctionType extends TypeRep { | |
77 constructor() { | |
78 super(); | |
79 this._stringValue = null; | |
80 } | |
81 | |
82 toString() { return this.name; } | |
83 | |
84 get name() { | |
85 if (this._stringValue) return this._stringValue; | |
86 | |
87 let buffer = '('; | |
88 for (let i = 0; i < this.args.length; ++i) { | |
89 if (i > 0) { | |
90 buffer += ', '; | |
91 } | |
92 buffer += typeName(this.args[i]); | |
93 } | |
94 if (this.optionals.length > 0) { | |
95 if (this.args.length > 0) buffer += ', '; | |
96 buffer += '['; | |
97 for (let i = 0; i < this.optionals.length; ++i) { | |
98 if (i > 0) { | |
99 buffer += ', '; | |
100 } | |
101 buffer += typeName(this.optionals[i]); | |
102 } | |
103 buffer += ']'; | |
104 } else if (Object.keys(this.named).length > 0) { | |
105 if (this.args.length > 0) buffer += ', '; | |
106 buffer += '{'; | |
107 let names = getOwnPropertyNames(this.named).sort(); | |
108 for (let i = 0; i < names.length; ++i) { | |
109 if (i > 0) { | |
110 buffer += ', '; | |
111 } | |
112 buffer += names[i] + ': ' + typeName(this.named[names[i]]); | |
113 } | |
114 buffer += '}'; | |
115 } | |
116 | |
117 buffer += ') -> ' + typeName(this.returnType); | |
118 this._stringValue = buffer; | |
119 return buffer; | |
120 } | |
121 } | |
122 | |
123 class FunctionType extends AbstractFunctionType { | |
124 /** | |
125 * Construct a function type. There are two arrow constructors, | |
126 * distinguished by the "definite" flag. | |
127 * | |
128 * The fuzzy arrow (definite is false) treats any arguments | |
129 * of type dynamic as having type bottom, and will always be | |
130 * called with a dynamic invoke. | |
131 * | |
132 * The definite arrow (definite is true) leaves arguments unchanged. | |
133 * | |
134 * We eagerly canonize the argument types to avoid having to deal with | |
135 * this logic in multiple places. | |
136 * | |
137 * TODO(leafp): Figure out how to present this to the user. How | |
138 * should these be printed out? | |
139 */ | |
140 constructor(definite, returnType, args, optionals, named) { | |
141 super(); | |
142 this.definite = definite; | |
143 this.returnType = returnType; | |
144 this.args = args; | |
145 this.optionals = optionals; | |
146 this.named = named; | |
147 | |
148 // TODO(vsm): This is just parameter metadata for now. | |
149 this.metadata = []; | |
150 function process(array, metadata) { | |
151 var result = []; | |
152 for (var i = 0; i < array.length; ++i) { | |
153 var arg = array[i]; | |
154 if (arg instanceof Array) { | |
155 metadata.push(arg.slice(1)); | |
156 result.push(arg[0]); | |
157 } else { | |
158 metadata.push([]); | |
159 result.push(arg); | |
160 } | |
161 } | |
162 return result; | |
163 } | |
164 this.args = process(this.args, this.metadata); | |
165 this.optionals = process(this.optionals, this.metadata); | |
166 // TODO(vsm): Add named arguments. | |
167 this._canonize(); | |
168 } | |
169 _canonize() { | |
170 if (this.definite) return; | |
171 | |
172 function replace(a) { | |
173 return (a == dynamicR) ? bottomR : a; | |
174 } | |
175 | |
176 this.args = this.args.map(replace); | |
177 | |
178 if (this.optionals.length > 0) { | |
179 this.optionals = this.optionals.map(replace); | |
180 } | |
181 | |
182 if (Object.keys(this.named).length > 0) { | |
183 let r = {}; | |
184 for (let name of getOwnPropertyNames(this.named)) { | |
185 r[name] = replace(this.named[name]); | |
186 } | |
187 this.named = r; | |
188 } | |
189 } | |
190 } | |
191 | |
192 class Typedef extends AbstractFunctionType { | |
193 constructor(name, closure) { | |
194 super(); | |
195 this._name = name; | |
196 this._closure = closure; | |
197 this._functionType = null; | |
198 } | |
199 | |
200 get definite() { | |
201 return this._functionType.definite; | |
202 } | |
203 | |
204 get name() { | |
205 return this._name; | |
206 } | |
207 | |
208 get functionType() { | |
209 if (!this._functionType) { | |
210 this._functionType = this._closure(); | |
211 } | |
212 return this._functionType; | |
213 } | |
214 | |
215 get returnType() { | |
216 return this.functionType.returnType; | |
217 } | |
218 | |
219 get args() { | |
220 return this.functionType.args; | |
221 } | |
222 | |
223 get optionals() { | |
224 return this.functionType.optionals; | |
225 } | |
226 | |
227 get named() { | |
228 return this.functionType.named; | |
229 } | |
230 | |
231 get metadata() { | |
232 return this.functionType.metadata; | |
233 } | |
234 } | |
235 | |
236 function _functionType(definite, returnType, args, extra) { | |
237 // TODO(vsm): Cache / memomize? | |
238 let optionals; | |
239 let named; | |
240 if (extra === void 0) { | |
241 optionals = []; | |
242 named = {}; | |
243 } else if (extra instanceof Array) { | |
244 optionals = extra; | |
245 named = {}; | |
246 } else { | |
247 optionals = []; | |
248 named = extra; | |
249 } | |
250 return new FunctionType(definite, returnType, args, optionals, named); | |
251 } | |
252 | |
253 /** | |
254 * Create a "fuzzy" function type. If any arguments are dynamic | |
255 * they will be replaced with bottom. | |
256 */ | |
257 function functionType(returnType, args, extra) { | |
258 return _functionType(false, returnType, args, extra); | |
259 } | |
260 exports.functionType = functionType; | |
261 | |
262 /** | |
263 * Create a definite function type. No substitution of dynamic for | |
264 * bottom occurs. | |
265 */ | |
266 function definiteFunctionType(returnType, args, extra) { | |
267 return _functionType(true, returnType, args, extra); | |
268 } | |
269 exports.definiteFunctionType = definiteFunctionType; | |
270 | |
271 function typedef(name, closure) { | |
272 return new Typedef(name, closure); | |
273 } | |
274 exports.typedef = typedef; | |
275 | |
276 function isDartType(type) { | |
277 return rtti.read(type) === core.Type; | |
278 } | |
279 exports.isDartType = isDartType; | |
280 | |
281 function typeName(type) { | |
282 // Non-instance types | |
283 if (type instanceof TypeRep) return type.toString(); | |
284 // Instance types | |
285 let tag = rtti.read(type); | |
286 if (tag === core.Type) { | |
287 let name = type.name; | |
288 let args = classes.getGenericArgs(type); | |
289 if (args) { | |
290 name += '<'; | |
291 for (let i = 0; i < args.length; ++i) { | |
292 if (i > 0) name += ', '; | |
293 name += typeName(args[i]); | |
294 } | |
295 name += '>'; | |
296 } | |
297 return name; | |
298 } | |
299 if (tag) return "Not a type: " + tag.name; | |
300 return "JSObject<" + type.name + ">"; | |
301 } | |
302 exports.typeName = typeName; | |
303 | |
304 function isFunctionType(type) { | |
305 return type instanceof AbstractFunctionType || type == core.Function; | |
306 } | |
307 | |
308 function isFunctionSubType(ft1, ft2) { | |
309 if (ft2 == core.Function) { | |
310 return true; | |
311 } | |
312 | |
313 let ret1 = ft1.returnType; | |
314 let ret2 = ft2.returnType; | |
315 | |
316 if (!isSubtype_(ret1, ret2)) { | |
317 // Covariant return types | |
318 // Note, void (which can only appear as a return type) is effectively | |
319 // treated as dynamic. If the base return type is void, we allow any | |
320 // subtype return type. | |
321 // E.g., we allow: | |
322 // () -> int <: () -> void | |
323 if (ret2 != voidR) { | |
324 return false; | |
325 } | |
326 } | |
327 | |
328 let args1 = ft1.args; | |
329 let args2 = ft2.args; | |
330 | |
331 if (args1.length > args2.length) { | |
332 return false; | |
333 } | |
334 | |
335 for (let i = 0; i < args1.length; ++i) { | |
336 if (!isSubtype_(args2[i], args1[i])) { | |
337 return false; | |
338 } | |
339 } | |
340 | |
341 let optionals1 = ft1.optionals; | |
342 let optionals2 = ft2.optionals; | |
343 | |
344 if (args1.length + optionals1.length < args2.length + optionals2.length) { | |
345 return false; | |
346 } | |
347 | |
348 let j = 0; | |
349 for (let i = args1.length; i < args2.length; ++i, ++j) { | |
350 if (!isSubtype_(args2[i], optionals1[j])) { | |
351 return false; | |
352 } | |
353 } | |
354 | |
355 for (let i = 0; i < optionals2.length; ++i, ++j) { | |
356 if (!isSubtype_(optionals2[i], optionals1[j])) { | |
357 return false; | |
358 } | |
359 } | |
360 | |
361 let named1 = ft1.named; | |
362 let named2 = ft2.named; | |
363 | |
364 let names = getOwnPropertyNames(named2); | |
365 for (let i = 0; i < names.length; ++i) { | |
366 let name = names[i]; | |
367 let n1 = named1[name]; | |
368 let n2 = named2[name]; | |
369 if (n1 === void 0) { | |
370 return false; | |
371 } | |
372 if (!isSubtype_(n2, n1)) { | |
373 return false; | |
374 } | |
375 } | |
376 | |
377 return true; | |
378 } | |
379 | |
380 /** | |
381 * Computes the canonical type. | |
382 * This maps JS types onto their corresponding Dart Type. | |
383 */ | |
384 // TODO(jmesserly): lots more needs to be done here. | |
385 function canonicalType(t) { | |
386 if (t === Object) return core.Object; | |
387 if (t === Function) return core.Function; | |
388 if (t === Array) return core.List; | |
389 | |
390 // We shouldn't normally get here with these types, unless something strange | |
391 // happens like subclassing Number in JS and passing it to Dart. | |
392 if (t === String) return core.String; | |
393 if (t === Number) return core.double; | |
394 if (t === Boolean) return core.bool; | |
395 return t; | |
396 } | |
397 | |
398 const subtypeMap = new Map(); | |
399 function isSubtype(t1, t2) { | |
400 // See if we already know the answer | |
401 // TODO(jmesserly): general purpose memoize function? | |
402 let map = subtypeMap.get(t1); | |
403 let result; | |
404 if (map) { | |
405 result = map.get(t2); | |
406 if (result !== void 0) return result; | |
407 } else { | |
408 subtypeMap.set(t1, map = new Map()); | |
409 } | |
410 result = isSubtype_(t1, t2) | |
411 map.set(t2, result); | |
412 return result; | |
413 } | |
414 exports.isSubtype = isSubtype; | |
415 | |
416 function _isBottom(type) { | |
417 return type == bottomR; | |
418 } | |
419 | |
420 function _isTop(type) { | |
421 return type == core.Object || (type == dynamicR); | |
422 } | |
423 | |
424 function isSubtype_(t1, t2) { | |
425 t1 = canonicalType(t1); | |
426 t2 = canonicalType(t2); | |
427 if (t1 == t2) return true; | |
428 | |
429 // Trivially true. | |
430 if (_isTop(t2) || _isBottom(t1)) { | |
431 return true; | |
432 } | |
433 | |
434 // Trivially false. | |
435 if (_isTop(t1) || _isBottom(t2)) { | |
436 return false; | |
437 } | |
438 | |
439 // "Traditional" name-based subtype check. | |
440 if (isClassSubType(t1, t2)) { | |
441 return true; | |
442 } | |
443 | |
444 // Function subtyping. | |
445 // TODO(vsm): Handle Objects with call methods. Those are functions | |
446 // even if they do not *nominally* subtype core.Function. | |
447 if (isFunctionType(t1) && | |
448 isFunctionType(t2)) { | |
449 return isFunctionSubType(t1, t2); | |
450 } | |
451 return false; | |
452 } | |
453 | |
454 function isClassSubType(t1, t2) { | |
455 // We support Dart's covariant generics with the caveat that we do not | |
456 // substitute bottom for dynamic in subtyping rules. | |
457 // I.e., given T1, ..., Tn where at least one Ti != dynamic we disallow: | |
458 // - S !<: S<T1, ..., Tn> | |
459 // - S<dynamic, ..., dynamic> !<: S<T1, ..., Tn> | |
460 t1 = canonicalType(t1); | |
461 assert(t2 == canonicalType(t2)); | |
462 if (t1 == t2) return true; | |
463 | |
464 if (t1 == core.Object) return false; | |
465 | |
466 // If t1 is a JS Object, we may not hit core.Object. | |
467 if (t1 == null) return t2 == core.Object || t2 == dynamicR; | |
468 | |
469 // Check if t1 and t2 have the same raw type. If so, check covariance on | |
470 // type parameters. | |
471 let raw1 = classes.getGenericClass(t1); | |
472 let raw2 = classes.getGenericClass(t2); | |
473 if (raw1 != null && raw1 == raw2) { | |
474 let typeArguments1 = classes.getGenericArgs(t1); | |
475 let typeArguments2 = classes.getGenericArgs(t2); | |
476 let length = typeArguments1.length; | |
477 if (typeArguments2.length == 0) { | |
478 // t2 is the raw form of t1 | |
479 return true; | |
480 } else if (length == 0) { | |
481 // t1 is raw, but t2 is not | |
482 return false; | |
483 } | |
484 assert(length == typeArguments2.length); | |
485 for (let i = 0; i < length; ++i) { | |
486 if (!isSubtype(typeArguments1[i], typeArguments2[i])) { | |
487 return false; | |
488 } | |
489 } | |
490 return true; | |
491 } | |
492 | |
493 // Check superclass. | |
494 if (isClassSubType(t1.__proto__, t2)) return true; | |
495 | |
496 // Check mixins. | |
497 let mixins = classes.getMixins(t1); | |
498 if (mixins) { | |
499 for (let m1 of mixins) { | |
500 // TODO(jmesserly): remove the != null check once we can load core libs. | |
501 if (m1 != null && isClassSubType(m1, t2)) return true; | |
502 } | |
503 } | |
504 | |
505 // Check interfaces. | |
506 let getInterfaces = classes.getImplements(t1); | |
507 if (getInterfaces) { | |
508 for (let i1 of getInterfaces()) { | |
509 // TODO(jmesserly): remove the != null check once we can load core libs. | |
510 if (i1 != null && isClassSubType(i1, t2)) return true; | |
511 } | |
512 } | |
513 | |
514 return false; | |
515 } | |
516 | |
517 // TODO(jmesserly): this isn't currently used, but it could be if we want | |
518 // `obj is NonGroundType<T,S>` to be rejected at runtime instead of compile | |
519 // time. | |
520 function isGroundType(type) { | |
521 // TODO(vsm): Cache this if we start using it at runtime. | |
522 | |
523 if (type instanceof AbstractFunctionType) { | |
524 if (!_isTop(type.returnType)) return false; | |
525 for (let i = 0; i < type.args.length; ++i) { | |
526 if (!_isBottom(type.args[i])) return false; | |
527 } | |
528 for (let i = 0; i < type.optionals.length; ++i) { | |
529 if (!_isBottom(type.optionals[i])) return false; | |
530 } | |
531 let names = getOwnPropertyNames(type.named); | |
532 for (let i = 0; i < names.length; ++i) { | |
533 if (!_isBottom(type.named[names[i]])) return false; | |
534 } | |
535 return true; | |
536 } | |
537 | |
538 let typeArgs = classes.getGenericArgs(type); | |
539 if (!typeArgs) return true; | |
540 for (let t of typeArgs) { | |
541 if (t != core.Object && t != dynamicR) return false; | |
542 } | |
543 return true; | |
544 } | |
545 exports.isGroundType = isGroundType; | |
546 | |
547 }); | |
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