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
|
/*
* Copyright (C) 2012 Typesafe Inc. <http://www.typesafe.com>
*/
package scala.async
import scala.reflect.macros.Context
private[async] final case class AnfTransform[C <: Context](c: C) {
import c.universe._
val utils = TransformUtils[c.type](c)
import utils._
def apply(tree: Tree): List[Tree] = {
val unique = uniqueNames(tree)
// Must prepend the () for issue #31.
anf.transformToList(Block(List(c.literalUnit.tree), unique))
}
private def uniqueNames(tree: Tree): Tree = {
new UniqueNames(tree).transform(tree)
}
/** Assigns unique names to all definitions in a tree, and adjusts references to use the new name.
* Only modifies names that appear more than once in the tree.
*
* This step is needed to allow us to safely merge blocks during the `inline` transform below.
*/
private final class UniqueNames(tree: Tree) extends Transformer {
val repeatedNames: Set[Symbol] = {
class DuplicateNameTraverser extends AsyncTraverser {
val result = collection.mutable.Buffer[Symbol]()
override def traverse(tree: Tree) {
tree match {
case dt: DefTree => result += dt.symbol
case _ => super.traverse(tree)
}
}
}
val dupNameTraverser = new DuplicateNameTraverser
dupNameTraverser.traverse(tree)
dupNameTraverser.result.groupBy(x => x.name).filter(_._2.size > 1).values.flatten.toSet[Symbol]
}
/** Stepping outside of the public Macro API to call [[scala.reflect.internal.Symbols.Symbol.name_=]] */
val symtab = c.universe.asInstanceOf[reflect.internal.SymbolTable]
val renamed = collection.mutable.Set[Symbol]()
override def transform(tree: Tree): Tree = {
tree match {
case defTree: DefTree if repeatedNames(defTree.symbol) =>
val trans = super.transform(defTree)
val origName = defTree.symbol.name
val sym = defTree.symbol.asInstanceOf[symtab.Symbol]
val fresh = name.fresh(sym.name.toString)
sym.name = defTree.symbol.name match {
case _: TermName => symtab.newTermName(fresh)
case _: TypeName => symtab.newTypeName(fresh)
}
renamed += trans.symbol
val newName = trans.symbol.name
trans match {
case ValDef(mods, name, tpt, rhs) =>
treeCopy.ValDef(trans, mods, newName, tpt, rhs)
case Bind(name, body) =>
treeCopy.Bind(trans, newName, body)
case DefDef(mods, name, tparams, vparamss, tpt, rhs) =>
treeCopy.DefDef(trans, mods, newName, tparams, vparamss, tpt, rhs)
case TypeDef(mods, name, tparams, rhs) =>
treeCopy.TypeDef(tree, mods, newName, tparams, transform(rhs))
// If we were to allow local classes / objects, we would need to rename here.
case ClassDef(mods, name, tparams, impl) =>
treeCopy.ClassDef(tree, mods, newName, tparams, transform(impl).asInstanceOf[Template])
case ModuleDef(mods, name, impl) =>
treeCopy.ModuleDef(tree, mods, newName, transform(impl).asInstanceOf[Template])
case x => super.transform(x)
}
case Ident(name) =>
if (renamed(tree.symbol)) treeCopy.Ident(tree, tree.symbol.name)
else tree
case Select(fun, name) =>
if (renamed(tree.symbol)) {
treeCopy.Select(tree, transform(fun), tree.symbol.name)
} else super.transform(tree)
case _ => super.transform(tree)
}
}
}
private object trace {
private var indent = -1
def indentString = " " * indent
def apply[T](prefix: String, args: Any)(t: => T): T = {
indent += 1
def oneLine(s: Any) = s.toString.replaceAll( """\n""", "\\\\n").take(127)
try {
AsyncUtils.trace(s"${
indentString
}$prefix(${oneLine(args)})")
val result = t
AsyncUtils.trace(s"${indentString}= ${oneLine(result)}")
result
} finally {
indent -= 1
}
}
}
private object inline {
def transformToList(tree: Tree): List[Tree] = trace("inline", tree) {
val stats :+ expr = anf.transformToList(tree)
expr match {
case Apply(fun, args) if isAwait(fun) =>
val valDef = defineVal(name.await, expr, tree.pos)
stats :+ valDef :+ Ident(valDef.name)
case If(cond, thenp, elsep) =>
// if type of if-else is Unit don't introduce assignment,
// but add Unit value to bring it into form expected by async transform
if (expr.tpe =:= definitions.UnitTpe) {
stats :+ expr :+ Literal(Constant(()))
} else {
val varDef = defineVar(name.ifRes, expr.tpe, tree.pos)
def branchWithAssign(orig: Tree) = orig match {
case Block(thenStats, thenExpr) => Block(thenStats, Assign(Ident(varDef.name), thenExpr))
case _ => Assign(Ident(varDef.name), orig)
}
val ifWithAssign = If(cond, branchWithAssign(thenp), branchWithAssign(elsep))
stats :+ varDef :+ ifWithAssign :+ Ident(varDef.name)
}
case Match(scrut, cases) =>
// if type of match is Unit don't introduce assignment,
// but add Unit value to bring it into form expected by async transform
if (expr.tpe =:= definitions.UnitTpe) {
stats :+ expr :+ Literal(Constant(()))
}
else {
val varDef = defineVar(name.matchRes, expr.tpe, tree.pos)
val casesWithAssign = cases map {
case cd@CaseDef(pat, guard, Block(caseStats, caseExpr)) =>
attachCopy(cd)(CaseDef(pat, guard, Block(caseStats, Assign(Ident(varDef.name), caseExpr))))
case cd@CaseDef(pat, guard, body) =>
attachCopy(cd)(CaseDef(pat, guard, Assign(Ident(varDef.name), body)))
}
val matchWithAssign = attachCopy(tree)(Match(scrut, casesWithAssign))
stats :+ varDef :+ matchWithAssign :+ Ident(varDef.name)
}
case _ =>
stats :+ expr
}
}
def transformToList(trees: List[Tree]): List[Tree] = trees flatMap transformToList
def transformToBlock(tree: Tree): Block = transformToList(tree) match {
case stats :+ expr => Block(stats, expr)
}
private def defineVar(prefix: String, tp: Type, pos: Position): ValDef = {
val vd = ValDef(Modifiers(Flag.MUTABLE), name.fresh(prefix), TypeTree(tp), defaultValue(tp))
vd.setPos(pos)
vd
}
private def defineVal(prefix: String, lhs: Tree, pos: Position): ValDef = {
val vd = ValDef(NoMods, name.fresh(prefix), TypeTree(), lhs)
vd.setPos(pos)
vd
}
}
private object anf {
private[AnfTransform] def transformToList(tree: Tree): List[Tree] = trace("anf", tree) {
def containsAwait = tree exists isAwait
tree match {
case Select(qual, sel) if containsAwait =>
val stats :+ expr = inline.transformToList(qual)
stats :+ attachCopy(tree)(Select(expr, sel).setSymbol(tree.symbol))
case Apply(fun, args) if containsAwait =>
// we an assume that no await call appears in a by-name argument position,
// this has already been checked.
val funStats :+ simpleFun = inline.transformToList(fun)
val argLists = args map inline.transformToList
val allArgStats = argLists flatMap (_.init)
val simpleArgs = argLists map (_.last)
funStats ++ allArgStats :+ attachCopy(tree)(Apply(simpleFun, simpleArgs).setSymbol(tree.symbol))
case Block(stats, expr) if containsAwait =>
inline.transformToList(stats :+ expr)
case ValDef(mods, name, tpt, rhs) if containsAwait =>
if (rhs exists isAwait) {
val stats :+ expr = inline.transformToList(rhs)
stats :+ attachCopy(tree)(ValDef(mods, name, tpt, expr).setSymbol(tree.symbol))
} else List(tree)
case Assign(lhs, rhs) if containsAwait =>
val stats :+ expr = inline.transformToList(rhs)
stats :+ attachCopy(tree)(Assign(lhs, expr))
case If(cond, thenp, elsep) if containsAwait =>
val condStats :+ condExpr = inline.transformToList(cond)
val thenBlock = inline.transformToBlock(thenp)
val elseBlock = inline.transformToBlock(elsep)
// Typechecking with `condExpr` as the condition fails if the condition
// contains an await. `ifTree.setType(tree.tpe)` also fails; it seems
// we rely on this call to `typeCheck` descending into the branches.
// But, we can get away with typechecking a throwaway `If` tree with the
// original scrutinee and the new branches, and setting that type on
// the real `If` tree.
val ifType = c.typeCheck(If(cond, thenBlock, elseBlock)).tpe
condStats :+
attachCopy(tree)(If(condExpr, thenBlock, elseBlock)).setType(ifType)
case Match(scrut, cases) if containsAwait =>
val scrutStats :+ scrutExpr = inline.transformToList(scrut)
val caseDefs = cases map {
case CaseDef(pat, guard, body) =>
// extract local variables for all names bound in `pat`, and rewrite `body`
// to refer to these.
// TODO we can move this into ExprBuilder once we get rid of `AsyncDefinitionUseAnalyzer`.
val block = inline.transformToBlock(body)
val (valDefs, mappings) = (pat collect {
case b@Bind(name, _) =>
val newName = newTermName(utils.name.fresh(name.toTermName + utils.name.bindSuffix))
val vd = ValDef(NoMods, newName, TypeTree(), Ident(b.symbol))
(vd, (b.symbol, newName))
}).unzip
val Block(stats1, expr1) = utils.substituteNames(block, mappings.toMap).asInstanceOf[Block]
attachCopy(tree)(CaseDef(pat, guard, Block(valDefs ++ stats1, expr1)))
}
// Refer to comments the translation of `If` above.
val matchType = c.typeCheck(Match(scrut, caseDefs)).tpe
val typedMatch = attachCopy(tree)(Match(scrutExpr, caseDefs)).setType(tree.tpe)
scrutStats :+ typedMatch
case LabelDef(name, params, rhs) if containsAwait =>
List(LabelDef(name, params, Block(inline.transformToList(rhs), Literal(Constant(())))).setSymbol(tree.symbol))
case TypeApply(fun, targs) if containsAwait =>
val funStats :+ simpleFun = inline.transformToList(fun)
funStats :+ attachCopy(tree)(TypeApply(simpleFun, targs).setSymbol(tree.symbol))
case _ =>
List(tree)
}
}
}
}
|
