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
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
|
/* NSC -- new Scala compiler
* Copyright 2005-2013 LAMP/EPFL
* @author Martin Odersky
*/
package scala.tools.nsc
package ast.parser
import symtab.Flags._
import scala.collection.mutable.ListBuffer
/** Methods for building trees, used in the parser. All the trees
* returned by this class must be untyped.
*/
abstract class TreeBuilder {
val global: Global
import global._
def freshName(): Name = freshName("x$")
def freshTermName(): TermName = freshTermName("x$")
def freshName(prefix: String): Name
def freshTermName(prefix: String): TermName
def freshTypeName(prefix: String): TypeName
def o2p(offset: Int): Position
def r2p(start: Int, point: Int, end: Int): Position
def rootId(name: Name) = gen.rootId(name)
def rootScalaDot(name: Name) = gen.rootScalaDot(name)
def scalaDot(name: Name) = gen.scalaDot(name)
def scalaAnyRefConstr = scalaDot(tpnme.AnyRef)
def scalaAnyValConstr = scalaDot(tpnme.AnyVal)
def scalaAnyConstr = scalaDot(tpnme.Any)
def scalaUnitConstr = scalaDot(tpnme.Unit)
def productConstr = scalaDot(tpnme.Product)
def productConstrN(n: Int) = scalaDot(newTypeName("Product" + n))
def serializableConstr = scalaDot(tpnme.Serializable)
def convertToTypeName(t: Tree) = gen.convertToTypeName(t)
/** Convert all occurrences of (lower-case) variables in a pattern as follows:
* x becomes x @ _
* x: T becomes x @ (_: T)
*/
private object patvarTransformer extends Transformer {
override def transform(tree: Tree): Tree = tree match {
case Ident(name) if (treeInfo.isVarPattern(tree) && name != nme.WILDCARD) =>
atPos(tree.pos)(Bind(name, atPos(tree.pos.focus) (Ident(nme.WILDCARD))))
case Typed(id @ Ident(name), tpt) if (treeInfo.isVarPattern(id) && name != nme.WILDCARD) =>
atPos(tree.pos.withPoint(id.pos.point)) {
Bind(name, atPos(tree.pos.withStart(tree.pos.point)) {
Typed(Ident(nme.WILDCARD), tpt)
})
}
case Apply(fn @ Apply(_, _), args) =>
treeCopy.Apply(tree, transform(fn), transformTrees(args))
case Apply(fn, args) =>
treeCopy.Apply(tree, fn, transformTrees(args))
case Typed(expr, tpt) =>
treeCopy.Typed(tree, transform(expr), tpt)
case Bind(name, body) =>
treeCopy.Bind(tree, name, transform(body))
case Alternative(_) | Star(_) =>
super.transform(tree)
case _ =>
tree
}
}
/** Traverse pattern and collect all variable names with their types in buffer
* The variables keep their positions; whereas the pattern is converted to be
* synthetic for all nodes that contain a variable position.
*/
class GetVarTraverser extends Traverser {
val buf = new ListBuffer[(Name, Tree, Position)]
def namePos(tree: Tree, name: Name): Position =
if (!tree.pos.isRange || name.containsName(nme.raw.DOLLAR)) tree.pos.focus
else {
val start = tree.pos.start
val end = start + name.decode.length
r2p(start, start, end)
}
override def traverse(tree: Tree): Unit = {
def seenName(name: Name) = buf exists (_._1 == name)
def add(name: Name, t: Tree) = if (!seenName(name)) buf += ((name, t, namePos(tree, name)))
val bl = buf.length
tree match {
case Bind(nme.WILDCARD, _) =>
super.traverse(tree)
case Bind(name, Typed(tree1, tpt)) =>
val newTree = if (treeInfo.mayBeTypePat(tpt)) TypeTree() else tpt.duplicate
add(name, newTree)
traverse(tree1)
case Bind(name, tree1) =>
// can assume only name range as position, as otherwise might overlap
// with binds embedded in pattern tree1
add(name, TypeTree())
traverse(tree1)
case _ =>
super.traverse(tree)
}
if (buf.length > bl)
tree setPos tree.pos.makeTransparent
}
def apply(tree: Tree) = {
traverse(tree)
buf.toList
}
}
/** Returns list of all pattern variables, possibly with their types,
* without duplicates
*/
private def getVariables(tree: Tree): List[(Name, Tree, Position)] =
new GetVarTraverser apply tree
def byNameApplication(tpe: Tree): Tree =
AppliedTypeTree(rootScalaDot(tpnme.BYNAME_PARAM_CLASS_NAME), List(tpe))
def repeatedApplication(tpe: Tree): Tree =
AppliedTypeTree(rootScalaDot(tpnme.REPEATED_PARAM_CLASS_NAME), List(tpe))
def makeImportSelector(name: Name, nameOffset: Int): ImportSelector =
ImportSelector(name, nameOffset, name, nameOffset)
private def makeTuple(trees: List[Tree], isType: Boolean): Tree = {
val tupString = "Tuple" + trees.length
Apply(scalaDot(if (isType) newTypeName(tupString) else newTermName(tupString)), trees)
}
def makeTupleTerm(trees: List[Tree], flattenUnary: Boolean): Tree = trees match {
case Nil => Literal(Constant())
case List(tree) if flattenUnary => tree
case _ => makeTuple(trees, false)
}
def makeTupleType(trees: List[Tree], flattenUnary: Boolean): Tree = trees match {
case Nil => scalaUnitConstr
case List(tree) if flattenUnary => tree
case _ => AppliedTypeTree(scalaDot(newTypeName("Tuple" + trees.length)), trees)
}
def stripParens(t: Tree) = t match {
case Parens(ts) => atPos(t.pos) { makeTupleTerm(ts, true) }
case _ => t
}
def makeAnnotated(t: Tree, annot: Tree): Tree =
atPos(annot.pos union t.pos)(Annotated(annot, t))
def makeSelfDef(name: TermName, tpt: Tree): ValDef =
ValDef(Modifiers(PRIVATE), name, tpt, EmptyTree)
/** If tree is a variable pattern, return Some("its name and type").
* Otherwise return none */
private def matchVarPattern(tree: Tree): Option[(Name, Tree)] = {
def wildType(t: Tree): Option[Tree] = t match {
case Ident(x) if x.toTermName == nme.WILDCARD => Some(TypeTree())
case Typed(Ident(x), tpt) if x.toTermName == nme.WILDCARD => Some(tpt)
case _ => None
}
tree match {
case Ident(name) => Some((name, TypeTree()))
case Bind(name, body) => wildType(body) map (x => (name, x))
case Typed(Ident(name), tpt) => Some((name, tpt))
case _ => None
}
}
/** Create tree representing (unencoded) binary operation expression or pattern. */
def makeBinop(isExpr: Boolean, left: Tree, op: TermName, right: Tree, opPos: Position): Tree = {
def mkNamed(args: List[Tree]) =
if (isExpr) args map {
case a @ Assign(id @ Ident(name), rhs) =>
atPos(a.pos) { AssignOrNamedArg(id, rhs) }
case e => e
} else args
val arguments = right match {
case Parens(args) => mkNamed(args)
case _ => List(right)
}
if (isExpr) {
if (treeInfo.isLeftAssoc(op)) {
Apply(atPos(opPos union left.pos) { Select(stripParens(left), op.encode) }, arguments)
} else {
val x = freshTermName()
Block(
List(ValDef(Modifiers(SYNTHETIC), x, TypeTree(), stripParens(left))),
Apply(atPos(opPos union right.pos) { Select(stripParens(right), op.encode) }, List(Ident(x))))
}
} else {
Apply(Ident(op.encode), stripParens(left) :: arguments)
}
}
/** Creates a tree representing new Object { stats }.
* To make sure an anonymous subclass of Object is created,
* if there are no stats, a () is added.
*/
def makeAnonymousNew(stats: List[Tree]): Tree = {
val stats1 = if (stats.isEmpty) List(Literal(Constant(()))) else stats
makeNew(Nil, emptyValDef, stats1, ListOfNil, NoPosition, NoPosition)
}
/** Create positioned tree representing an object creation <new parents { stats }
* @param npos the position of the new
* @param cpos the position of the anonymous class starting with parents
*/
def makeNew(parents: List[Tree], self: ValDef, stats: List[Tree], argss: List[List[Tree]],
npos: Position, cpos: Position): Tree =
if (parents.isEmpty)
makeNew(List(scalaAnyRefConstr), self, stats, argss, npos, cpos)
else if (parents.tail.isEmpty && stats.isEmpty)
atPos(npos union cpos) { New(parents.head, argss) }
else {
val x = tpnme.ANON_CLASS_NAME
atPos(npos union cpos) {
Block(
List(
atPos(cpos) {
ClassDef(
Modifiers(FINAL), x, Nil,
Template(parents, self, NoMods, ListOfNil, argss, stats, cpos.focus))
}),
atPos(npos) {
New(
Ident(x) setPos npos.focus,
ListOfNil)
}
)
}
}
/** Create a tree representing an assignment <lhs = rhs> */
def makeAssign(lhs: Tree, rhs: Tree): Tree = lhs match {
case Apply(fn, args) =>
Apply(atPos(fn.pos) { Select(fn, nme.update) }, args ::: List(rhs))
case _ =>
Assign(lhs, rhs)
}
/** Tree for `od op`, start is start0 if od.pos is borked. */
def makePostfixSelect(start0: Int, end: Int, od: Tree, op: Name): Tree = {
val start = if (od.pos.isDefined) od.pos.startOrPoint else start0
atPos(r2p(start, end, end)) { new PostfixSelect(od, op.encode) }
}
/** A type tree corresponding to (possibly unary) intersection type */
def makeIntersectionTypeTree(tps: List[Tree]): Tree =
if (tps.tail.isEmpty) tps.head
else CompoundTypeTree(Template(tps, emptyValDef, Nil))
/** Create tree representing a while loop */
def makeWhile(startPos: Int, cond: Tree, body: Tree): Tree = {
val lname = freshTermName(nme.WHILE_PREFIX)
def default = wrappingPos(List(cond, body)) match {
case p if p.isDefined => p.endOrPoint
case _ => startPos
}
val continu = atPos(o2p(body.pos pointOrElse default)) { Apply(Ident(lname), Nil) }
val rhs = If(cond, Block(List(body), continu), Literal(Constant()))
LabelDef(lname, Nil, rhs)
}
/** Create tree representing a do-while loop */
def makeDoWhile(lname: TermName, body: Tree, cond: Tree): Tree = {
val continu = Apply(Ident(lname), Nil)
val rhs = Block(List(body), If(cond, continu, Literal(Constant())))
LabelDef(lname, Nil, rhs)
}
/** Create block of statements `stats` */
def makeBlock(stats: List[Tree]): Tree =
if (stats.isEmpty) Literal(Constant())
else if (!stats.last.isTerm) Block(stats, Literal(Constant()))
else if (stats.length == 1) stats.head
else Block(stats.init, stats.last)
def makeFilter(tree: Tree, condition: Tree, scrutineeName: String): Tree = {
val cases = List(
CaseDef(condition, EmptyTree, Literal(Constant(true))),
CaseDef(Ident(nme.WILDCARD), EmptyTree, Literal(Constant(false)))
)
val matchTree = makeVisitor(cases, false, scrutineeName)
atPos(tree.pos)(Apply(Select(tree, nme.withFilter), matchTree :: Nil))
}
/** Create tree for for-comprehension generator <val pat0 <- rhs0> */
def makeGenerator(pos: Position, pat: Tree, valeq: Boolean, rhs: Tree): Enumerator = {
val pat1 = patvarTransformer.transform(pat)
val rhs1 =
if (valeq || treeInfo.isVarPatternDeep(pat)) rhs
else makeFilter(rhs, pat1.duplicate, nme.CHECK_IF_REFUTABLE_STRING)
if (valeq) ValEq(pos, pat1, rhs1)
else ValFrom(pos, pat1, rhs1)
}
def makeParam(pname: TermName, tpe: Tree) =
ValDef(Modifiers(PARAM), pname, tpe, EmptyTree)
def makeSyntheticParam(pname: TermName) =
ValDef(Modifiers(PARAM | SYNTHETIC), pname, TypeTree(), EmptyTree)
def makeSyntheticTypeParam(pname: TypeName, bounds: Tree) =
TypeDef(Modifiers(DEFERRED | SYNTHETIC), pname, Nil, bounds)
abstract class Enumerator { def pos: Position }
case class ValFrom(pos: Position, pat: Tree, rhs: Tree) extends Enumerator
case class ValEq(pos: Position, pat: Tree, rhs: Tree) extends Enumerator
case class Filter(pos: Position, test: Tree) extends Enumerator
/** Create tree for for-comprehension <for (enums) do body> or
* <for (enums) yield body> where mapName and flatMapName are chosen
* corresponding to whether this is a for-do or a for-yield.
* The creation performs the following rewrite rules:
*
* 1.
*
* for (P <- G) E ==> G.foreach (P => E)
*
* Here and in the following (P => E) is interpreted as the function (P => E)
* if P is a variable pattern and as the partial function { case P => E } otherwise.
*
* 2.
*
* for (P <- G) yield E ==> G.map (P => E)
*
* 3.
*
* for (P_1 <- G_1; P_2 <- G_2; ...) ...
* ==>
* G_1.flatMap (P_1 => for (P_2 <- G_2; ...) ...)
*
* 4.
*
* for (P <- G; E; ...) ...
* =>
* for (P <- G.filter (P => E); ...) ...
*
* 5. For N < MaxTupleArity:
*
* for (P_1 <- G; P_2 = E_2; val P_N = E_N; ...)
* ==>
* for (TupleN(P_1, P_2, ... P_N) <-
* for (x_1 @ P_1 <- G) yield {
* val x_2 @ P_2 = E_2
* ...
* val x_N & P_N = E_N
* TupleN(x_1, ..., x_N)
* } ...)
*
* If any of the P_i are variable patterns, the corresponding `x_i @ P_i' is not generated
* and the variable constituting P_i is used instead of x_i
*
* @param mapName The name to be used for maps (either map or foreach)
* @param flatMapName The name to be used for flatMaps (either flatMap or foreach)
* @param enums The enumerators in the for expression
* @param body The body of the for expression
*/
private def makeFor(mapName: TermName, flatMapName: TermName, enums: List[Enumerator], body: Tree): Tree = {
/** make a closure pat => body.
* The closure is assigned a transparent position with the point at pos.point and
* the limits given by pat and body.
*/
def makeClosure(pos: Position, pat: Tree, body: Tree): Tree = {
def splitpos = wrappingPos(List(pat, body)).withPoint(pos.point).makeTransparent
matchVarPattern(pat) match {
case Some((name, tpt)) =>
Function(
List(atPos(pat.pos) { ValDef(Modifiers(PARAM), name.toTermName, tpt, EmptyTree) }),
body) setPos splitpos
case None =>
atPos(splitpos) {
makeVisitor(List(CaseDef(pat, EmptyTree, body)), false)
}
}
}
/** Make an application qual.meth(pat => body) positioned at `pos`.
*/
def makeCombination(pos: Position, meth: TermName, qual: Tree, pat: Tree, body: Tree): Tree =
Apply(Select(qual, meth) setPos qual.pos, List(makeClosure(pos, pat, body))) setPos pos
/** Optionally, if pattern is a `Bind`, the bound name, otherwise None.
*/
def patternVar(pat: Tree): Option[Name] = pat match {
case Bind(name, _) => Some(name)
case _ => None
}
/** If `pat` is not yet a `Bind` wrap it in one with a fresh name
*/
def makeBind(pat: Tree): Tree = pat match {
case Bind(_, _) => pat
case _ => Bind(freshName(), pat) setPos pat.pos
}
/** A reference to the name bound in Bind `pat`.
*/
def makeValue(pat: Tree): Tree = pat match {
case Bind(name, _) => Ident(name) setPos pat.pos.focus
}
/** The position of the closure that starts with generator at position `genpos`.
*/
def closurePos(genpos: Position) = {
val end = body.pos match {
case NoPosition => genpos.point
case bodypos => bodypos.endOrPoint
}
r2p(genpos.startOrPoint, genpos.point, end)
}
// val result =
enums match {
case ValFrom(pos, pat, rhs) :: Nil =>
makeCombination(closurePos(pos), mapName, rhs, pat, body)
case ValFrom(pos, pat, rhs) :: (rest @ (ValFrom(_, _, _) :: _)) =>
makeCombination(closurePos(pos), flatMapName, rhs, pat,
makeFor(mapName, flatMapName, rest, body))
case ValFrom(pos, pat, rhs) :: Filter(_, test) :: rest =>
makeFor(mapName, flatMapName,
ValFrom(pos, pat, makeCombination(rhs.pos union test.pos, nme.withFilter, rhs, pat.duplicate, test)) :: rest,
body)
case ValFrom(pos, pat, rhs) :: rest =>
val valeqs = rest.take(definitions.MaxTupleArity - 1).takeWhile(_.isInstanceOf[ValEq]);
assert(!valeqs.isEmpty)
val rest1 = rest.drop(valeqs.length)
val pats = valeqs map { case ValEq(_, pat, _) => pat }
val rhss = valeqs map { case ValEq(_, _, rhs) => rhs }
val defpat1 = makeBind(pat)
val defpats = pats map makeBind
val pdefs = (defpats, rhss).zipped flatMap makePatDef
val ids = (defpat1 :: defpats) map makeValue
val rhs1 = makeForYield(
List(ValFrom(pos, defpat1, rhs)),
Block(pdefs, atPos(wrappingPos(ids)) { makeTupleTerm(ids, true) }) setPos wrappingPos(pdefs))
val allpats = (pat :: pats) map (_.duplicate)
val vfrom1 = ValFrom(r2p(pos.startOrPoint, pos.point, rhs1.pos.endOrPoint), atPos(wrappingPos(allpats)) { makeTuple(allpats, false) } , rhs1)
makeFor(mapName, flatMapName, vfrom1 :: rest1, body)
case _ =>
EmptyTree //may happen for erroneous input
}
// println("made for "+result)
// result
}
/** Create tree for for-do comprehension <for (enums) body> */
def makeFor(enums: List[Enumerator], body: Tree): Tree =
makeFor(nme.foreach, nme.foreach, enums, body)
/** Create tree for for-yield comprehension <for (enums) yield body> */
def makeForYield(enums: List[Enumerator], body: Tree): Tree =
makeFor(nme.map, nme.flatMap, enums, body)
/** Create tree for a lifted expression XX-LIFTING
*/
def makeLifted(gs: List[ValFrom], body: Tree): Tree = {
def combine(gs: List[ValFrom]): ValFrom = (gs: @unchecked) match {
case g :: Nil => g
case ValFrom(pos1, pat1, rhs1) :: gs2 =>
val ValFrom(pos2, pat2, rhs2) = combine(gs2)
ValFrom(pos1, makeTuple(List(pat1, pat2), false), Apply(Select(rhs1, nme.zip), List(rhs2)))
}
makeForYield(List(combine(gs)), body)
}
/** Create tree for a pattern alternative */
def makeAlternative(ts: List[Tree]): Tree = {
def alternatives(t: Tree): List[Tree] = t match {
case Alternative(ts) => ts
case _ => List(t)
}
Alternative(ts flatMap alternatives)
}
/** Create visitor <x => x match cases> */
def makeVisitor(cases: List[CaseDef], checkExhaustive: Boolean): Tree =
makeVisitor(cases, checkExhaustive, "x$")
/** Create visitor <x => x match cases> */
def makeVisitor(cases: List[CaseDef], checkExhaustive: Boolean, prefix: String): Tree = {
val x = freshTermName(prefix)
val id = Ident(x)
val sel = if (checkExhaustive) id else gen.mkUnchecked(id)
Function(List(makeSyntheticParam(x)), Match(sel, cases))
}
/** Create tree for case definition <case pat if guard => rhs> */
def makeCaseDef(pat: Tree, guard: Tree, rhs: Tree): CaseDef =
CaseDef(patvarTransformer.transform(pat), guard, rhs)
/** Creates tree representing:
* { case x: Throwable =>
* val catchFn = catchExpr
* if (catchFn isDefinedAt x) catchFn(x) else throw x
* }
*/
def makeCatchFromExpr(catchExpr: Tree): CaseDef = {
val binder = freshTermName("x")
val pat = Bind(binder, Typed(Ident(nme.WILDCARD), Ident(tpnme.Throwable)))
val catchDef = ValDef(NoMods, freshTermName("catchExpr"), TypeTree(), catchExpr)
val catchFn = Ident(catchDef.name)
val body = atPos(catchExpr.pos.makeTransparent)(Block(
List(catchDef),
If(
Apply(Select(catchFn, nme.isDefinedAt), List(Ident(binder))),
Apply(Select(catchFn, nme.apply), List(Ident(binder))),
Throw(Ident(binder))
)
))
makeCaseDef(pat, EmptyTree, body)
}
/** Create tree for pattern definition <val pat0 = rhs> */
def makePatDef(pat: Tree, rhs: Tree): List[Tree] =
makePatDef(Modifiers(0), pat, rhs)
/** Create tree for pattern definition <mods val pat0 = rhs> */
def makePatDef(mods: Modifiers, pat: Tree, rhs: Tree): List[Tree] = matchVarPattern(pat) match {
case Some((name, tpt)) =>
List(atPos(pat.pos union rhs.pos) {
ValDef(mods, name.toTermName, tpt, rhs)
})
case None =>
// in case there is exactly one variable x_1 in pattern
// val/var p = e ==> val/var x_1 = e.match (case p => (x_1))
//
// in case there are zero or more than one variables in pattern
// val/var p = e ==> private synthetic val t$ = e.match (case p => (x_1, ..., x_N))
// val/var x_1 = t$._1
// ...
// val/var x_N = t$._N
val rhsUnchecked = gen.mkUnchecked(rhs)
// TODO: clean this up -- there is too much information packked into makePatDef's `pat` argument
// when it's a simple identifier (case Some((name, tpt)) -- above),
// pat should have the type ascription that was specified by the user
// however, in `case None` (here), we must be careful not to generate illegal pattern trees (such as `(a, b): Tuple2[Int, String]`)
// i.e., this must hold: pat1 match { case Typed(expr, tp) => assert(expr.isInstanceOf[Ident]) case _ => }
// if we encounter such an erroneous pattern, we strip off the type ascription from pat and propagate the type information to rhs
val (pat1, rhs1) = patvarTransformer.transform(pat) match {
// move the Typed ascription to the rhs
case Typed(expr, tpt) if !expr.isInstanceOf[Ident] =>
val rhsTypedUnchecked =
if (tpt.isEmpty) rhsUnchecked
else Typed(rhsUnchecked, tpt) setPos (rhs.pos union tpt.pos)
(expr, rhsTypedUnchecked)
case ok =>
(ok, rhsUnchecked)
}
val vars = getVariables(pat1)
val matchExpr = atPos((pat1.pos union rhs.pos).makeTransparent) {
Match(
rhs1,
List(
atPos(pat1.pos) {
CaseDef(pat1, EmptyTree, makeTupleTerm(vars map (_._1) map Ident.apply, true))
}
))
}
vars match {
case List((vname, tpt, pos)) =>
List(atPos(pat.pos union pos union rhs.pos) {
ValDef(mods, vname.toTermName, tpt, matchExpr)
})
case _ =>
val tmp = freshTermName()
val firstDef =
atPos(matchExpr.pos) {
ValDef(Modifiers(PrivateLocal | SYNTHETIC | (mods.flags & LAZY)),
tmp, TypeTree(), matchExpr)
}
var cnt = 0
val restDefs = for ((vname, tpt, pos) <- vars) yield atPos(pos) {
cnt += 1
ValDef(mods, vname.toTermName, tpt, Select(Ident(tmp), newTermName("_" + cnt)))
}
firstDef :: restDefs
}
}
/** Create a tree representing the function type (argtpes) => restpe */
def makeFunctionTypeTree(argtpes: List[Tree], restpe: Tree): Tree =
AppliedTypeTree(rootScalaDot(newTypeName("Function" + argtpes.length)), argtpes ::: List(restpe))
/** Append implicit parameter section if `contextBounds` nonempty */
def addEvidenceParams(owner: Name, vparamss: List[List[ValDef]], contextBounds: List[Tree]): List[List[ValDef]] = {
if (contextBounds.isEmpty) vparamss
else {
val mods = Modifiers(if (owner.isTypeName) PARAMACCESSOR | LOCAL | PRIVATE else PARAM)
def makeEvidenceParam(tpt: Tree) = ValDef(mods | IMPLICIT | SYNTHETIC, freshTermName(nme.EVIDENCE_PARAM_PREFIX), tpt, EmptyTree)
val evidenceParams = contextBounds map makeEvidenceParam
val vparamssLast = if(vparamss.nonEmpty) vparamss.last else Nil
if(vparamssLast.nonEmpty && vparamssLast.head.mods.hasFlag(IMPLICIT))
vparamss.init ::: List(evidenceParams ::: vparamssLast)
else
vparamss ::: List(evidenceParams)
}
}
}
|