1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
|
/* NSC -- new Scala compiler
* Copyright 2005-2013 LAMP/EPFL
* @author Martin Odersky
*/
package scala.tools.nsc
package typechecker
import symtab.Flags._
/*
* @author Martin Odersky
* @version 1.0
*/
trait Unapplies extends ast.TreeDSL {
self: Analyzer =>
import global._
import definitions._
import CODE.{ CASE => _, _ }
import treeInfo.{ isRepeatedParamType, isByNameParamType }
private def unapplyParamName = nme.x_0
private def caseMods = Modifiers(SYNTHETIC | CASE)
// In the typeCompleter (templateSig) of a case class (resp it's module),
// synthetic `copy` (reps `apply`, `unapply`) methods are added. To compute
// their signatures, the corresponding ClassDef is needed. During naming (in
// `enterClassDef`), the case class ClassDef is added as an attachment to the
// moduleClass symbol of the companion module.
class ClassForCaseCompanionAttachment(val caseClass: ClassDef)
/** Returns unapply or unapplySeq if available, without further checks.
*/
def directUnapplyMember(tp: Type): Symbol = (tp member nme.unapply) orElse (tp member nme.unapplySeq)
/** Filters out unapplies with multiple (non-implicit) parameter lists,
* as they cannot be used as extractors
*/
def unapplyMember(tp: Type): Symbol = directUnapplyMember(tp) filter (sym => !hasMultipleNonImplicitParamLists(sym))
object HasUnapply {
def unapply(tp: Type): Option[Symbol] = unapplyMember(tp).toOption
}
private def toIdent(x: DefTree) = Ident(x.name) setPos x.pos.focus
private def classType(cdef: ClassDef, tparams: List[TypeDef]): Tree = {
// SI-7033 Unattributed to avoid forcing `cdef.symbol.info`.
val tycon = Ident(cdef.symbol)
if (tparams.isEmpty) tycon else AppliedTypeTree(tycon, tparams map toIdent)
}
private def constrParamss(cdef: ClassDef): List[List[ValDef]] = {
val ClassDef(_, _, _, Template(_, _, body)) = resetLocalAttrs(cdef.duplicate)
val DefDef(_, _, _, vparamss, _, _) = treeInfo firstConstructor body
vparamss
}
private def constrTparamsInvariant(cdef: ClassDef): List[TypeDef] = {
val ClassDef(_, _, tparams, _) = resetLocalAttrs(cdef.duplicate)
val tparamsInvariant = tparams.map(tparam => copyTypeDef(tparam)(mods = tparam.mods &~ (COVARIANT | CONTRAVARIANT)))
tparamsInvariant
}
/** The return value of an unapply method of a case class C[Ts]
* @param param The name of the parameter of the unapply method, assumed to be of type C[Ts]
* @param caseclazz The case class C[Ts]
*/
private def caseClassUnapplyReturnValue(param: Name, caseclazz: ClassDef) = {
def caseFieldAccessorValue(selector: ValDef): Tree = {
// Selecting by name seems to be the most straight forward way here to
// avoid forcing the symbol of the case class in order to list the accessors.
def selectByName = Ident(param) DOT caseAccessorName(caseclazz.symbol, selector.name)
// But, that gives a misleading error message in neg/t1422.scala, where a case
// class has an illegal private[this] parameter. We can detect this by checking
// the modifiers on the param accessors.
// We just generate a call to that param accessor here, which gives us an inaccessible
// symbol error, as before.
def localAccessor = caseclazz.impl.body find {
case t @ ValOrDefDef(mods, selector.name, _, _) => mods.isPrivateLocal
case _ => false
}
localAccessor.fold(selectByName)(Ident(param) DOT _.symbol)
}
// Working with trees, rather than symbols, to avoid cycles like SI-5082
constrParamss(caseclazz).take(1).flatten match {
case Nil => TRUE
case xs => SOME(xs map caseFieldAccessorValue: _*)
}
}
/** The module corresponding to a case class; overrides toString to show the module's name
*/
def caseModuleDef(cdef: ClassDef): ModuleDef = {
val params = constrParamss(cdef)
def inheritFromFun = !cdef.mods.hasAbstractFlag && cdef.tparams.isEmpty && (params match {
case List(ps) if ps.length <= MaxFunctionArity => true
case _ => false
})
def createFun = {
def primaries = params.head map (_.tpt)
gen.scalaFunctionConstr(primaries, toIdent(cdef), abstractFun = true)
}
def parents = if (inheritFromFun) List(createFun) else Nil
def toString = DefDef(
Modifiers(OVERRIDE | FINAL | SYNTHETIC),
nme.toString_,
Nil,
ListOfNil,
TypeTree(),
Literal(Constant(cdef.name.decode)))
companionModuleDef(cdef, parents, List(toString))
}
def companionModuleDef(cdef: ClassDef, parents: List[Tree] = Nil, body: List[Tree] = Nil): ModuleDef = atPos(cdef.pos.focus) {
ModuleDef(
Modifiers(cdef.mods.flags & AccessFlags | SYNTHETIC, cdef.mods.privateWithin),
cdef.name.toTermName,
gen.mkTemplate(parents, noSelfType, NoMods, Nil, body, cdef.impl.pos.focus))
}
/** The apply method corresponding to a case class
*/
def factoryMeth(mods: Modifiers, name: TermName, cdef: ClassDef): DefDef = {
val tparams = constrTparamsInvariant(cdef)
val cparamss = constrParamss(cdef)
def classtpe = classType(cdef, tparams)
atPos(cdef.pos.focus)(
DefDef(mods, name, tparams, cparamss, classtpe,
New(classtpe, mmap(cparamss)(gen.paramToArg)))
)
}
/** The apply method corresponding to a case class
*/
def caseModuleApplyMeth(cdef: ClassDef): DefDef = factoryMeth(caseMods, nme.apply, cdef)
/** The unapply method corresponding to a case class
*/
def caseModuleUnapplyMeth(cdef: ClassDef): DefDef = {
val tparams = constrTparamsInvariant(cdef)
val method = constrParamss(cdef) match {
case xs :: _ if xs.nonEmpty && isRepeatedParamType(xs.last.tpt) => nme.unapplySeq
case _ => nme.unapply
}
val cparams = List(ValDef(Modifiers(PARAM | SYNTHETIC), unapplyParamName, classType(cdef, tparams), EmptyTree))
val ifNull = if (constrParamss(cdef).head.isEmpty) FALSE else REF(NoneModule)
val body = nullSafe({ case Ident(x) => caseClassUnapplyReturnValue(x, cdef) }, ifNull)(Ident(unapplyParamName))
atPos(cdef.pos.focus)(
DefDef(caseMods, method, tparams, List(cparams), TypeTree(), body)
)
}
/**
* Generates copy methods for case classes. Copy only has defaults on the first
* parameter list, as of SI-5009.
*
* The parameter types of the copy method need to be exactly the same as the parameter
* types of the primary constructor. Just copying the TypeTree is not enough: a type `C`
* might refer to something else *inside* the class (i.e. as parameter type of `copy`)
* than *outside* the class (i.e. in the class parameter list).
*
* One such example is t0054.scala:
* class A {
* case class B(x: C) extends A { def copy(x: C = x) = ... }
* class C {} ^ ^
* } (1) (2)
*
* The reference (1) to C is `A.this.C`. The reference (2) is `B.this.C` - not the same.
*
* This is fixed with a hack currently. `Unapplies.caseClassCopyMeth`, which creates the
* copy method, uses empty `TypeTree()` nodes for parameter types.
*
* In `Namers.enterDefDef`, the copy method gets a special type completer (`enterCopyMethod`).
* Before computing the body type of `copy`, the class parameter types are assigned the copy
* method parameters.
*
* This attachment class stores the copy method parameter ValDefs as an attachment in the
* ClassDef of the case class.
*/
def caseClassCopyMeth(cdef: ClassDef): Option[DefDef] = {
def isDisallowed(vd: ValDef) = isRepeatedParamType(vd.tpt) || isByNameParamType(vd.tpt)
val classParamss = constrParamss(cdef)
if (cdef.symbol.hasAbstractFlag || mexists(classParamss)(isDisallowed)) None
else {
def makeCopyParam(vd: ValDef, putDefault: Boolean) = {
val rhs = if (putDefault) toIdent(vd) else EmptyTree
val flags = PARAM | (vd.mods.flags & IMPLICIT) | (if (putDefault) DEFAULTPARAM else 0)
// empty tpt: see comment above
val tpt = atPos(vd.pos.focus)(TypeTree() setOriginal vd.tpt)
treeCopy.ValDef(vd, Modifiers(flags), vd.name, tpt, rhs)
}
val tparams = constrTparamsInvariant(cdef)
val paramss = classParamss match {
case Nil => Nil
case ps :: pss =>
ps.map(makeCopyParam(_, putDefault = true)) :: mmap(pss)(makeCopyParam(_, putDefault = false))
}
val classTpe = classType(cdef, tparams)
val argss = mmap(paramss)(toIdent)
val body: Tree = New(classTpe, argss)
val copyDefDef = atPos(cdef.pos.focus)(
DefDef(Modifiers(SYNTHETIC), nme.copy, tparams, paramss, TypeTree(), body)
)
Some(copyDefDef)
}
}
}
|