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Rule for symbolic foldLeft(/:) and foldRight(:/) (fix #27) #35

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Merged
merged 1 commit into from
Jun 12, 2018
Merged

Rule for symbolic foldLeft(/:) and foldRight(:/) (fix #27) #35

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12 changes: 12 additions & 0 deletions scalafix/input/src/main/scala/fix/FoldSrc.scala
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Original file line number Diff line number Diff line change
@@ -0,0 +1,12 @@
/*
rule = "scala:fix.Scalacollectioncompat_NewCollections"
*/
package fix

class FoldSrc(xs: List[Int]){
val f: (Int, Int) => Int = (x, y) => x + y
val g: (Int, Int) => Int = (x, y) => x * y

(0 /: xs)(f)
(xs :\ 1)(g)
}
12 changes: 12 additions & 0 deletions scalafix/output/src/main/scala/fix/FoldSrc.scala
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@@ -0,0 +1,12 @@



package fix

class FoldSrc(xs: List[Int]){
val f: (Int, Int) => Int = (x, y) => x + y
val g: (Int, Int) => Int = (x, y) => x * y

xs.foldLeft(0)(f)
xs.foldRight(1)(g)
}
23 changes: 21 additions & 2 deletions scalafix/rules/src/main/scala/fix/Scalacollectioncompat_NewCollections.scala
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Expand Up @@ -29,6 +29,15 @@ case class Scalacollectioncompat_NewCollections(index: SemanticdbIndex)
Symbol("_root_.scala.runtime.Tuple2Zipped.Ops.zipped."),
Symbol("_root_.scala.runtime.Tuple3Zipped.Ops.zipped.")
)
def foldSymbol(isLeft: Boolean): SymbolMatcher = {
val op =
if (isLeft) "/:"
else ":\\"

SymbolMatcher.normalized(Symbol(s"_root_.scala.collection.TraversableOnce.`$op`."))
}
val foldLeftSymbol = foldSymbol(isLeft = true)
val foldRightSymbol = foldSymbol(isLeft = false)

val retainMap =
SymbolMatcher.normalized(
Expand Down Expand Up @@ -60,7 +69,16 @@ case class Scalacollectioncompat_NewCollections(index: SemanticdbIndex)
ctx.replaceToken(open, "{case ") +
ctx.replaceToken(close, "}") +
ctx.replaceTree(n, "filterInPlace")
).asPatch
).asPatch
}.asPatch

def replaceSymbolicFold(ctx: RuleCtx) =
ctx.tree.collect {
case Term.Apply(ap @ Term.ApplyInfix(rhs, foldRightSymbol(_), _, List(lhs)), _) =>
ctx.replaceTree(ap, s"$rhs.foldRight($lhs)")
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@julienrf this would remove formatting and delete comments inside the parenthesis of the infix apply.

ex:

/*1*/(/*2*/ 0 /*3*/ /: /*4*/ xs /*5*/)/*6*/(f)
/*1*/xs.foldLeft(0)/*6*/(f)

the best we can achieve is to preserve one side, since this refactoring swap them.

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I don’t think lot of people write comments at those places anyway. If someone raises the issue we should address it, but for now let’s stick to this simple solution.


case Term.Apply(ap @ Term.ApplyInfix(lhs, foldLeftSymbol(_), _, List(rhs)), _) =>
ctx.replaceTree(ap, s"$rhs.foldLeft($lhs)")
}.asPatch

def replaceToList(ctx: RuleCtx) =
Expand Down Expand Up @@ -147,6 +165,7 @@ case class Scalacollectioncompat_NewCollections(index: SemanticdbIndex)
replaceCopyToBuffer(ctx) +
replaceStreamAppend(ctx) +
replaceMutableMap(ctx) +
replaceMutableSet(ctx)
replaceMutableSet(ctx) +
replaceSymbolicFold(ctx)
}
}