src/metamodel/static_type.nit

   1 # This file is part of NIT ( http://www.nitlanguage.org ).
   2 #
   3 # Copyright 2004-2008 Jean Privat <jean@pryen.org>
   4 # Copyright 2006-2008 Floréal Morandat <morandat@lirmm.fr>
   5 #
   6 # Licensed under the Apache License, Version 2.0 (the "License");
   7 # you may not use this file except in compliance with the License.
   8 # You may obtain a copy of the License at
   9 #
  10 #     http://www.apache.org/licenses/LICENSE-2.0
  11 #
  12 # Unless required by applicable law or agreed to in writing, software
  13 # distributed under the License is distributed on an "AS IS" BASIS,
  14 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  15 # See the License for the specific language governing permissions and
  16 # limitations under the License.
  17
  18 # Static types and property signatures
  19 package static_type
  20
  21 intrude import abstractmetamodel
  22
  23 redef class MMLocalClass
  24         # Cached result of get_type
  25         attr _base_type_cache: MMType
  26
  27         # Return the type of self for this class
  28         meth get_type: MMType
  29         do
  30                 if _base_type_cache == null then _base_type_cache = new MMTypeSimpleClass(self)
  31                 return _base_type_cache
  32         end
  33
  34         # Register a new ancestor
  35         protected meth add_ancestor(a: MMAncestor)
  36         do
  37                 assert not _ancestors.has_key(a.local_class)
  38                 assert a.local_class != self
  39                 _ancestors[a.local_class] = a
  40         end
  41
  42         # Array of ancestor that associate each superclass with the corresponding ancestor
  43         readable attr _ancestors: Map[MMLocalClass, MMAncestor]
  44
  45         # The ancestor type for a given superclass
  46         meth ancestor(c: MMLocalClass): MMType
  47         do
  48                 return _ancestors[c].stype
  49         end
  50 end
  51
  52 redef class MMLocalProperty
  53         # The signature of the property (where it is declared)
  54         readable writable attr _signature: MMSignature
  55
  56         attr _signatures_cache: HashMap[MMType, MMSignature] = new HashMap[MMType, MMSignature]
  57
  58         # Return the adapted signature of self for a receiver of type t
  59         meth signature_for(t: MMType): MMSignature do
  60                 if t == local_class.get_type then return signature
  61
  62                 if _signatures_cache.has_key(t) then return _signatures_cache[t]
  63
  64                 var res = signature.adaptation_to(t)
  65                 _signatures_cache[t] = res
  66                 return res
  67         end
  68 end
  69
  70 # Signature for local properties
  71 class MMSignature
  72         # The type of the reveiver
  73         readable attr _recv: MMType
  74
  75         # The parameter types
  76         attr _params: Array[MMType]
  77
  78         # The return type
  79         readable attr _return_type: MMType
  80
  81         # The closure parameters
  82         readable attr _closures: Array[MMClosure] = new Array[MMClosure]
  83
  84         # Number of parameters
  85         meth arity: Int
  86         do
  87                 assert _params != null
  88                 return _params.length
  89         end
  90
  91         # Is self a valid subtype of an other signature
  92         meth <(s: MMSignature): Bool
  93         do
  94                 assert s != null
  95                 if self == s then
  96                         return true
  97                 end
  98                 assert _recv.module == s.recv.module
  99                 if arity != s.arity or (_return_type == null) != (s.return_type == null) then return false
 100                 if _return_type != null and not _return_type < s.return_type then
 101                         return false
 102                 end
 103
 104                 for i in [0..arity[ do
 105                         if not s[i] < self[i] then
 106                                 return false
 107                         end
 108                 end
 109
 110                 if closures.length != s.closures.length then return false
 111                 for i in [0..closures.length[ do
 112                         if not s.closures[i] < closures[i] then return false
 113                 end
 114                 return true
 115         end
 116
 117         # The type of the i-th parameter
 118         meth [](i: Int): MMType
 119         do
 120                 assert _params.length > i
 121                 return _params[i]
 122         end
 123
 124         redef meth to_s
 125         do
 126                 var s = new Buffer
 127                 if _params != null and _params.length > 0 then
 128                         var tmp: String
 129                         var a = new Array[String].with_capacity(_params.length)
 130                         for i in [0.._params.length[ do
 131                                 #var pn = _params_name[i]
 132                                 var p = _params[i]
 133                                 #a.add("{pn}: {p}")
 134                                 a.add(p.to_s)
 135                         end
 136                         s.append("({a.join(",")})")
 137                 end
 138                 if _return_type != null then
 139                         s.append(": {_return_type}")
 140                 end
 141                 return s.to_s
 142         end
 143
 144         # Adapt the signature to a different receiver
 145         meth adaptation_to(r: MMType): MMSignature
 146         do
 147                 if _recv == r then
 148                         return self
 149                 end
 150                 var mod = r.module
 151                 var p = _params
 152                 if p != null then
 153                         p = new Array[MMType]
 154                         for i in _params do
 155                                 p.add(i.for_module(mod).adapt_to(r))
 156                         end
 157                 end
 158                 var rv = _return_type
 159                 if rv != null then
 160                         rv = rv.for_module(mod).adapt_to(r)
 161                 end
 162                 var res = new MMSignature(p,rv,r)
 163                 for clos in _closures do
 164                         res.closures.add(clos.adaptation_to(r))
 165                 end
 166                 return res
 167         end
 168
 169         attr _not_for_self_cache: MMSignature = null
 170
 171         # Return a type approximation if the reveiver is not self
 172         # Useful for virtual types
 173         meth not_for_self: MMSignature
 174         do
 175                 var res = _not_for_self_cache
 176                 if res != null then return res
 177
 178                 var need_for_self = false
 179                 var p = _params
 180                 if p != null then
 181                         p = new Array[MMType]
 182                         for i in _params do
 183                                 var i2 = i.not_for_self
 184                                 if i != i2 then need_for_self = true
 185                                 p.add(i2)
 186                         end
 187                 end
 188
 189                 var rv = _return_type
 190                 if rv != null then
 191                         rv = rv.not_for_self
 192                         if rv != _return_type then need_for_self = true
 193                 end
 194
 195                 var clos = _closures
 196                 if clos != null then
 197                         clos = new Array[MMClosure]
 198                         for c in _closures do
 199                                 var c2 = c.not_for_self
 200                                 if c2 != c then need_for_self = true
 201                                 clos.add(c2)
 202                         end
 203                 end
 204
 205                 if need_for_self then
 206                         res = new MMSignature(p, rv, _recv)
 207                         res.closures.add_all(clos)
 208                 else
 209                         res = self
 210                 end
 211
 212                 _not_for_self_cache = res
 213                 return res
 214         end
 215
 216         init(params: Array[MMType], return_type: MMType, r: MMType)
 217         do
 218                 assert params != null
 219                 _params = params
 220                 _return_type = return_type
 221                 _recv = r
 222         end
 223 end
 224
 225 # A closure in a signature
 226 class MMClosure
 227         # The signature of the closure
 228         readable attr _signature: MMSignature
 229
 230         # Is the closure a brek one
 231         # aka is defined with the break keyword thus does not return
 232         readable attr _is_break: Bool
 233
 234         # Is the closure optional?
 235         # ie is there a default definition
 236         readable attr _is_optional: Bool
 237
 238         # Adapt the signature to a different receiver
 239         meth adaptation_to(r: MMType): MMClosure
 240         do
 241                 return new MMClosure(_signature.adaptation_to(r), _is_break, _is_optional)
 242         end
 243
 244         init(s: MMSignature, is_break: Bool, is_optional: Bool)
 245         do
 246                 _signature = s
 247                 _is_break = is_break
 248                 _is_optional = is_optional
 249         end
 250
 251         meth not_for_self: MMClosure
 252         do
 253                 var sig = _signature.not_for_self
 254                 if sig != _signature then
 255                         return new MMClosure(sig, _is_break, _is_optional)
 256                 else
 257                         return self
 258                 end
 259         end
 260
 261         meth <(c: MMClosure): Bool
 262         do
 263                 if c.is_optional and not is_optional then return false
 264                 if not c.is_break and is_break then return false
 265                 return c.signature < signature
 266         end
 267 end
 268
 269 # Inheritance relation between two types
 270 abstract class MMAncestor
 271         # The inherited type
 272         readable writable attr _stype: MMType = null
 273
 274         # The inheriter (heir) type
 275         readable writable attr _inheriter: MMType  = null
 276
 277         meth is_reffinement: Bool do
 278                 return stype.module != stype.module
 279         end
 280
 281         meth is_specialisation: Bool do
 282                 return stype.local_class.global != inheriter.local_class.global
 283         end
 284
 285         # The inherited class
 286         meth local_class: MMLocalClass is abstract
 287
 288         redef meth to_s
 289         do
 290                 if stype == null then
 291                         return local_class.to_s
 292                 else
 293                         return stype.to_s
 294                 end
 295         end
 296 end
 297
 298 # A static type
 299 # Note that static type a related to a specific module
 300 abstract class MMType
 301         # The module where self makes sence
 302         meth module: MMModule is abstract
 303
 304         # The local class that self direclty or indirectly refers to
 305         meth local_class: MMLocalClass is abstract
 306
 307         # Is the type a valid one
 308         # For instance, circular dependency on formal types is invalid
 309         meth is_valid: Bool do return true
 310
 311         # Is self a valid subtype of t
 312         meth <(t : MMType): Bool is abstract
 313
 314         # Is self a valid supertype of t
 315         # This method must be only called within definition of < if
 316         # a double dispatch is needed
 317         meth is_supertype(t: MMType): Bool is abstract
 318
 319         # Adapt self to another module
 320         meth for_module(mod: MMModule): MMType is abstract
 321
 322         # Get the type adapted to another receiver type
 323         # Useful for formal types
 324         meth adapt_to(recv: MMType): MMType is abstract
 325
 326         # Adapt self to another local class context
 327         # Useful for genericity
 328         # 'c' Must be a super-class of self
 329         # Example:
 330         #   class A[E]
 331         #   class B[F] special A[F]
 332         #   class C[G] special B[String]
 333         #   class D special C[Float]
 334         # 'A[Int]'.upcast_for('A') -> 'A[Int]'
 335         # 'A[Int]'.upcast_for('B') -> abort
 336         # 'B[Int]'.upcast_for('B') -> 'B[Int]'
 337         # 'B[Int]'.upcast_for('A') -> 'A[Int]'
 338         # 'B[Int]'.upcast_for('C') -> abort
 339         # 'C[Int]'.upcast_for('C') -> 'C[Int]'
 340         # 'C[Int]'.upcast_for('B') -> 'B[String]'
 341         # 'C[Int]'.upcast_for('A') -> 'A[String]'
 342         # 'D'.upcast_for('D') -> 'D'
 343         # 'D'.upcast_for('C') -> 'C[Float]'
 344         # 'D'.upcast_for('B') -> 'C[String]'
 345         # 'D'.upcast_for('A') -> 'A[String]'
 346         meth upcast_for(c: MMLocalClass): MMType is abstract
 347
 348         # Return a type approximation if the reveiver is not self
 349         # Useful for virtual types
 350         meth not_for_self: MMType do return self
 351
 352         # The nullable version of self (if needed)
 353         attr _as_nullable_cache: MMType = null
 354
 355         # IS the type can accept null?
 356         meth is_nullable: Bool do return false
 357
 358         # Return the nullable version of the type
 359         # Noop if already nullable
 360         meth as_nullable: MMType do
 361                 var cache = _as_nullable_cache
 362                 if cache != null then return cache
 363                 var res = new MMNullableType(self)
 364                 _as_nullable_cache = res
 365                 return res
 366         end
 367
 368         # Return the not null version of the type
 369         # Noop if already not null
 370         meth as_notnull: MMType do return self
 371 end
 372
 373 class MMNullableType
 374 special MMType
 375         attr _base_type: MMType
 376         redef meth is_nullable: Bool do return true
 377         redef meth as_notnull do return _base_type
 378         redef meth as_nullable do return self
 379         init(t: MMType) do _base_type = t
 380
 381         redef meth module do return _base_type.module
 382
 383         redef meth local_class do return _base_type.local_class
 384
 385         redef meth <(t)
 386         do
 387                 return t isa MMNullableType and _base_type < t.as_notnull
 388         end
 389
 390         redef meth to_s
 391         do
 392                 return "nullable {_base_type}"
 393         end
 394
 395         redef meth is_supertype(t)
 396         do
 397                 return _base_type.is_supertype(t)
 398         end
 399
 400         redef meth for_module(mod)
 401         do
 402                 return _base_type.for_module(mod).as_nullable
 403         end
 404
 405         redef meth adapt_to(recv)
 406         do
 407                 return _base_type.adapt_to(recv).as_nullable
 408         end
 409
 410         redef meth upcast_for(c)
 411         do
 412                 return _base_type.upcast_for(c)
 413         end
 414
 415         redef meth not_for_self
 416         do
 417                 return _base_type.not_for_self.as_nullable
 418         end
 419 end
 420
 421 class MMTypeClass
 422 special MMType
 423         redef readable attr _local_class: MMLocalClass
 424         redef meth module do return _local_class.module end
 425         redef meth <(t) do return t != null and t.is_supertype(self)
 426
 427         redef meth to_s
 428         do
 429                 return _local_class.to_s
 430         end
 431
 432         redef meth upcast_for(c)
 433         do
 434                 assert _local_class != null
 435                 assert c != null
 436
 437                 var t: MMType = self
 438                 if _local_class != c then
 439                         t = _local_class.ancestor(c)
 440                 end
 441                 assert t != null
 442                 return t
 443         end
 444
 445         init(c : MMLocalClass)
 446         do
 447                 _local_class = c
 448         end
 449 end
 450
 451 class MMTypeSimpleClass
 452 special MMTypeClass
 453         redef meth is_supertype(t)
 454         do
 455                 return  t.local_class.cshe <= _local_class
 456         end
 457
 458         redef meth for_module(mod)
 459         do
 460                 var t: MMType = self
 461                 if module != mod then
 462                         t = _local_class.for_module(mod).get_type
 463                 end
 464                 assert t != null
 465                 return t
 466         end
 467
 468         redef meth adapt_to(recv) do return self
 469
 470         init(c: MMLocalClass)
 471         do
 472                 super(c)
 473         end
 474 end
 475
 476 # The type of null
 477 class MMTypeNone
 478 special MMType
 479         redef readable attr _module: MMModule
 480         redef meth is_nullable: Bool do return true
 481         redef meth <(t) do return t isa MMTypeNone or t isa MMNullableType
 482         redef meth to_s do return "null"
 483         redef meth is_supertype(t) do return false
 484         redef meth local_class do abort
 485         redef meth upcast_for(c) do abort
 486         redef meth as_nullable do return self
 487         redef meth as_notnull do abort
 488
 489         private init(m: MMModule) do _module = m
 490 end
 491
 492 redef class MMModule
 493         # The type of null
 494         readable attr _type_none: MMTypeNone = new MMTypeNone(self)
 495 end