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Allow primes at the end of identifiers. #29

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Sep 6, 2014
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Allow primes at the end of identifiers. #29

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11 changes: 11 additions & 0 deletions src/compiler/scala/tools/nsc/ast/parser/Scanners.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -637,6 +637,10 @@ trait Scanners extends ScannersCommon {
putChar(ch)
nextChar()
getIdentOrOperatorRest()
case '\'' =>
putChar(ch)
nextChar()
getPrimeRest()
case SU => // strangely enough, Character.isUnicodeIdentifierPart(SU) returns true!
finishNamed()
case _ =>
Expand All @@ -649,6 +653,13 @@ trait Scanners extends ScannersCommon {
}
}

private def getPrimeRest(): Unit =
if (ch == '\'') {
putChar(ch)
nextChar()
getPrimeRest()
} else finishNamed()

private def getOperatorRest(): Unit = (ch: @switch) match {
case '~' | '!' | '@' | '#' | '%' |
'^' | '*' | '+' | '-' | '<' |
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1 change: 1 addition & 0 deletions src/library/scala/reflect/NameTransformer.scala
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Expand Up @@ -54,6 +54,7 @@ object NameTransformer {
enterOp('\\', "$bslash")
enterOp('?', "$qmark")
enterOp('@', "$at")
enterOp('\'', "$prime")

/** Replace operator symbols by corresponding `\$opname`.
*
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7 changes: 7 additions & 0 deletions test/files/neg/primed-identifiers.check
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@@ -0,0 +1,7 @@
primed-identifiers.scala:4: error: value b' is not a member of object a1
a1 b'c' // parses as a1 b' c'
^
primed-identifiers.scala:4: error: not found: value c'
a1 b'c' // parses as a1 b' c'
^
two errors found
13 changes: 13 additions & 0 deletions test/files/neg/primed-identifiers.scala
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@@ -0,0 +1,13 @@
object a1 {
def b(c: Char) = ???

a1 b'c' // parses as a1 b' c'
}

object a2 {
def b'(c: Int) = ???
def b(c: Char) = ???

val c' = 23
a2 b'c' // parses as a2 b' c'
}
48 changes: 48 additions & 0 deletions test/files/pos/primed-identifiers.scala
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@@ -0,0 +1,48 @@
object Test {
val l = List("Identifiers", "with", "primes", "!")

val l' = l map(_.length)

val l'' = l zip l'

val l''' = l''.reverse

object a1 {
def b(c: Char) = ???

a1 b 'c'
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scalac would parse a1 b'c' as a1.b('c'), while the Typelevel compiler would parse it as a1.b'(c'). Not sure if this is something permitted under your compatibility guidelines, but you should probably warn this (or require a language import).

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a1 b'c' parsing correctly sort of strikes me as a bug, though? Shouldn't it require a space?

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Good catch, Iulian! It's also an issue with symbol literals, unsurprisingly.

Regardless of whether it's considered a bug (in Scalac) or not, it's a
difference, so we'll need to put it under a -Z flag.

Given there are likely to be several very subtle parsing differences like
this -- which in all likelihood don't affect anyone that much -- would it
make sense to group them under a single -Z flag?

On 18 September 2014 13:15, Nami-Doc notifications@github.com wrote:

In test/files/pos/primed-identifiers.scala:

@@ -0,0 +1,48 @@
+object Test {

  • val l = List("Identifiers", "with", "primes", "!")
  • val l' = l map(_.length)
  • val l'' = l zip l'
  • val l''' = l''.reverse
  • object a1 {
  • def b(c: Char) = ???
  • a1 b 'c'

a1 b'c' parsing correctly sort of strikes me as a bug, though? Shouldn't
it require a space?

—
Reply to this email directly or view it on GitHub
https://github.com/typelevel/scala/pull/29/files#r17723052.

Jon Pretty | @propensive

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@Nami-Doc it's not a bug, according to the grammar in the SLS. Generally, space is not required between tokens (that's why you can write foo(x) without any space between the 4 tokens).

@propensive a -Z flag would work, but why not an import language.typelevel.syntax, or something like that?

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@dragos language flags work by using implicits, they're not in scope during the parser (i.e. it hasn't even gotten to typing, yet) - we need to figure out a solution for this.

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We've only got my/Martin's suggestion of passing both possible parsings
through to the typer, somehow. But I can't imagine how this could be any
less terrible than it sounds.
On 18 Sep 2014 15:14, "Brian McKenna" notifications@github.com wrote:

In test/files/pos/primed-identifiers.scala:

@@ -0,0 +1,48 @@
+object Test {

  • val l = List("Identifiers", "with", "primes", "!")
  • val l' = l map(_.length)
  • val l'' = l zip l'
  • val l''' = l''.reverse
  • object a1 {
  • def b(c: Char) = ???
  • a1 b 'c'

@dragos https://github.com/dragos language flags work by using
implicits, they're not in scope during the parser (i.e. it hasn't even
gotten to typing, yet) - we need to figure out a solution for this.

—
Reply to this email directly or view it on GitHub
https://github.com/typelevel/scala/pull/29/files#r17728891.

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Well, I'm pretty certain that aint gonna happen.

Notice that the name is MutableSettings, though. What if the Parser were to... mutate them? 👿

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For the record, the name MutableSettings was intended as documentation, not as guidance.

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@puffnfresh spot on about imports... too bad.

}

object a2 {
def b'(c: Int) = ???
def b(c: Char) = ???

a2 b' 23
a2 b'23

val i = 23
a2 b'i

val c' = 23
a2 b'c' // parses as a2 b' c'

a2 b 'c'
}

case object Foo'
case class Bar'(i: Int)

((): Any) match {
case foo': String => ???
case Foo' => ???
case Bar'(foo') => ???
}

val (x', y') = (13, 23)

for (z' <- List(x', y')) x'*2

type T' = Int
def foo[U', F'[_]](ft: F'[T'], fu: F'[U']) = (ft, fu)
}