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Merge pull request #7571 from dotty-staging/add-end-nested
Allow nested end marker scopes at same indentation width
2 parents 32a3781 + 957fbde commit 7c7fffa

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5 files changed

+93
-77
lines changed

5 files changed

+93
-77
lines changed

‎compiler/src/dotty/tools/dotc/parsing/Parsers.scala‎

Lines changed: 16 additions & 23 deletions
Original file line numberDiff line numberDiff line change
@@ -1278,15 +1278,8 @@ object Parsers {
12781278
if silentTemplateIndent && !isNew then in.observeIndented()
12791279
newLineOptWhenFollowedBy(LBRACE)
12801280

1281-
def indentRegion[T](tag: EndMarkerTag)(op: => T): T = {
1282-
val iw = in.currentRegion.indentWidth
1283-
val t = op
1284-
in.consumeEndMarker(tag, iw)
1285-
t
1286-
}
1287-
1288-
def indentRegion[T](pid: Tree)(op: => T): T = pid match {
1289-
case pid: RefTree => indentRegion(pid.name.toTermName)(op)
1281+
def endMarkerScope[T](pid: Tree)(op: => T): T = pid match {
1282+
case pid: RefTree => in.endMarkerScope(pid.name.toTermName)(op)
12901283
case _ => op
12911284
}
12921285

@@ -1789,9 +1782,9 @@ object Parsers {
17891782

17901783
def expr1(location: Location.Value = Location.ElseWhere): Tree = in.token match {
17911784
case IF =>
1792-
indentRegion(IF) { ifExpr(in.offset, If) }
1785+
in.endMarkerScope(IF) { ifExpr(in.offset, If) }
17931786
case WHILE =>
1794-
indentRegion(WHILE) {
1787+
in.endMarkerScope(WHILE) {
17951788
atSpan(in.skipToken()) {
17961789
val cond = condExpr(DO)
17971790
newLinesOpt()
@@ -1826,7 +1819,7 @@ object Parsers {
18261819
WhileDo(Block(body, cond), Literal(Constant(())))
18271820
}
18281821
case TRY =>
1829-
indentRegion(TRY) {
1822+
in.endMarkerScope(TRY) {
18301823
val tryOffset = in.offset
18311824
atSpan(in.skipToken()) {
18321825
val body = expr()
@@ -1961,7 +1954,7 @@ object Parsers {
19611954
/** `match' (`{' CaseClauses `}' | CaseClause)
19621955
*/
19631956
def matchExpr(t: Tree, start: Offset, mkMatch: (Tree, List[CaseDef]) => Match) =
1964-
indentRegion(MATCH) {
1957+
in.endMarkerScope(MATCH) {
19651958
atSpan(start, in.skipToken()) {
19661959
mkMatch(t, casesExpr(caseClause))
19671960
}
@@ -2157,7 +2150,7 @@ object Parsers {
21572150
* | ‘new’ TemplateBody
21582151
*/
21592152
def newExpr(): Tree =
2160-
indentRegion(NEW) {
2153+
in.endMarkerScope(NEW) {
21612154
val start = in.skipToken()
21622155
def reposition(t: Tree) = t.withSpan(Span(start, in.lastOffset))
21632156
possibleBracesStart()
@@ -2323,7 +2316,7 @@ object Parsers {
23232316
* {nl} [`yield'] Expr
23242317
* | `for' Enumerators (`do' Expr | `yield' Expr)
23252318
*/
2326-
def forExpr(): Tree = indentRegion(FOR) {
2319+
def forExpr(): Tree = in.endMarkerScope(FOR) {
23272320
atSpan(in.skipToken()) {
23282321
var wrappedEnums = true
23292322
val start = in.offset
@@ -3074,7 +3067,7 @@ object Parsers {
30743067
else emptyType
30753068
val rhs =
30763069
if (tpt.isEmpty || in.token == EQUALS)
3077-
indentRegion(first) {
3070+
endMarkerScope(first) {
30783071
accept(EQUALS)
30793072
if (in.token == USCORE && !tpt.isEmpty && mods.is(Mutable) &&
30803073
(lhs.toList forall (_.isInstanceOf[Ident])))
@@ -3166,7 +3159,7 @@ object Parsers {
31663159
if (in.isScala2CompatMode) newLineOptWhenFollowedBy(LBRACE)
31673160
val rhs =
31683161
if (in.token == EQUALS)
3169-
indentRegion(name) {
3162+
in.endMarkerScope(name) {
31703163
in.nextToken()
31713164
subExpr()
31723165
}
@@ -3298,7 +3291,7 @@ object Parsers {
32983291
}
32993292

33003293
def classDefRest(start: Offset, mods: Modifiers, name: TypeName): TypeDef =
3301-
indentRegion(name.toTermName) {
3294+
in.endMarkerScope(name.toTermName) {
33023295
val constr = classConstr(isCaseClass = mods.is(Case))
33033296
val templ = templateOpt(constr)
33043297
finalizeDef(TypeDef(name, templ), mods, start)
@@ -3322,7 +3315,7 @@ object Parsers {
33223315
*/
33233316
def objectDef(start: Offset, mods: Modifiers): ModuleDef = atSpan(start, nameStart) {
33243317
val name = ident()
3325-
indentRegion(name) {
3318+
in.endMarkerScope(name) {
33263319
val templ = templateOpt(emptyConstructor)
33273320
finalizeDef(ModuleDef(name, templ), mods, start)
33283321
}
@@ -3332,7 +3325,7 @@ object Parsers {
33323325
*/
33333326
def enumDef(start: Offset, mods: Modifiers): TypeDef = atSpan(start, nameStart) {
33343327
val modulName = ident()
3335-
indentRegion(modulName) {
3328+
in.endMarkerScope(modulName) {
33363329
val clsName = modulName.toTypeName
33373330
val constr = classConstr()
33383331
val templ = template(constr, isEnum = true)
@@ -3412,7 +3405,7 @@ object Parsers {
34123405
else
34133406
(EmptyTermName, isIdent(nme.extension))
34143407

3415-
val gdef = indentRegion(if name.isEmpty then GIVEN else name) {
3408+
val gdef = in.endMarkerScope(if name.isEmpty then GIVEN else name) {
34163409
if isExtension then
34173410
if (in.token == COLON) in.nextToken()
34183411
assert(ident() == nme.extension)
@@ -3597,7 +3590,7 @@ object Parsers {
35973590
*/
35983591
def packaging(start: Int): Tree = {
35993592
val pkg = qualId()
3600-
indentRegion(pkg) {
3593+
endMarkerScope(pkg) {
36013594
possibleTemplateStart()
36023595
val stats = inDefScopeBraces(topStatSeq())
36033596
makePackaging(start, pkg, stats)
@@ -3785,7 +3778,7 @@ object Parsers {
37853778
else
37863779
val pkg = qualId()
37873780
var continue = false
3788-
indentRegion(pkg) {
3781+
endMarkerScope(pkg) {
37893782
possibleTemplateStart()
37903783
if in.token == EOF then
37913784
ts += makePackaging(start, pkg, List())

‎compiler/src/dotty/tools/dotc/parsing/Scanners.scala‎

Lines changed: 36 additions & 45 deletions
Original file line numberDiff line numberDiff line change
@@ -226,8 +226,8 @@ object Scanners {
226226
/** The current region. This is initially an Indented region with indentation width. */
227227
var currentRegion: Region = Indented(IndentWidth.Zero, Set(), EMPTY, null)
228228

229-
/** The end marker that was skipped last */
230-
val endMarkers = new mutable.ListBuffer[EndMarker]
229+
/** The number of open end marker scopes */
230+
var openEndMarkers: List[(EndMarkerTag, IndentWidth)] = Nil
231231

232232
// Scala 2 compatibility
233233

@@ -324,48 +324,47 @@ object Scanners {
324324
this.token = token
325325
}
326326

327-
/** If this token and the next constitute an end marker, skip them and append a new EndMarker
328-
* value at the end of the endMarkers queue.
327+
/** What can be referred to in an end marker */
328+
type EndMarkerTag = TermName | Token
329+
330+
/** Establish a scope for a passible end-marker with given tag, parsed by `op` */
331+
def endMarkerScope[T](tag: EndMarkerTag)(op: => T): T =
332+
val saved = openEndMarkers
333+
openEndMarkers = (tag, currentRegion.indentWidth) :: openEndMarkers
334+
try op finally openEndMarkers = saved
335+
336+
/** If this token and the next constitute an end marker, skip them and check they
337+
* align with an opening construct with the same end marker tag.
329338
*/
330-
private def handleEndMarkers(width: IndentWidth): Unit =
331-
if (next.token == IDENTIFIER && next.name == nme.end && width == currentRegion.indentWidth) {
339+
protected def skipEndMarker(width: IndentWidth): Unit =
340+
if next.token == IDENTIFIER && next.name == nme.end then
332341
val lookahead = LookaheadScanner()
333-
lookahead.nextToken() // skip the `end`
342+
val start = lookahead.offset
343+
344+
def handle(tag: EndMarkerTag) =
345+
def checkAligned(): Unit = openEndMarkers match
346+
case (etag, ewidth) :: rest if width <= ewidth =>
347+
if width < ewidth || tag != etag then
348+
openEndMarkers = rest
349+
checkAligned()
350+
case _ =>
351+
lexical.println(i"misaligned end marker $tag, $width, $openEndMarkers")
352+
errorButContinue("misaligned end marker", start)
334353

335-
def handle(tag: EndMarkerTag) = {
336354
val skipTo = lookahead.charOffset
337355
lookahead.nextToken()
338-
if (lookahead.isAfterLineEnd || lookahead.token == EOF) {
339-
lexical.println(i"produce end marker $tag $width")
340-
endMarkers += EndMarker(tag, width, offset)
356+
if lookahead.isAfterLineEnd || lookahead.token == EOF then
357+
checkAligned()
341358
next.token = EMPTY
342-
while (charOffset < skipTo) nextChar()
343-
}
344-
}
359+
while charOffset < skipTo do nextChar()
360+
end handle
345361

346-
lookahead.token match {
362+
lookahead.nextToken() // skip the `end`
363+
lookahead.token match
347364
case IDENTIFIER | BACKQUOTED_IDENT => handle(lookahead.name)
348365
case IF | WHILE | FOR | MATCH | TRY | NEW | GIVEN => handle(lookahead.token)
349366
case _ =>
350-
}
351-
}
352-
353-
/** Consume and cancel the head of the end markers queue if it has the given `tag` and width.
354-
* Flag end markers with higher indent widths as errors.
355-
*/
356-
def consumeEndMarker(tag: EndMarkerTag, width: IndentWidth): Unit = {
357-
lexical.println(i"consume end marker $tag $width")
358-
if (endMarkers.nonEmpty) {
359-
val em = endMarkers.head
360-
if (width <= em.width) {
361-
if (em.tag != tag || em.width != width) {
362-
lexical.println(i"misaligned end marker ${em.tag}, ${em.width} at ${width}")
363-
errorButContinue("misaligned end marker", em.offset)
364-
}
365-
endMarkers.trimStart(1)
366-
}
367-
}
368-
}
367+
end skipEndMarker
369368

370369
/** A leading symbolic or backquoted identifier is treated as an infix operator if
371370
* - it does not follow a blank line, and
@@ -501,6 +500,7 @@ object Scanners {
501500
&& !isLeadingInfixOperator()
502501
then
503502
insert(if (pastBlankLine) NEWLINES else NEWLINE, lineOffset)
503+
skipEndMarker(nextWidth)
504504
else if indentIsSignificant then
505505
if nextWidth < lastWidth
506506
|| nextWidth == lastWidth && (indentPrefix == MATCH || indentPrefix == CATCH) && token != CASE then
@@ -511,7 +511,7 @@ object Scanners {
511511
case r: Indented =>
512512
currentRegion = r.enclosing
513513
insert(OUTDENT, offset)
514-
handleEndMarkers(nextWidth)
514+
skipEndMarker(nextWidth)
515515
case r: InBraces if !closingRegionTokens.contains(token) =>
516516
ctx.warning("Line is indented too far to the left, or a `}' is missing",
517517
source.atSpan(Span(offset)))
@@ -883,6 +883,7 @@ object Scanners {
883883

884884
class LookaheadScanner(indent: Boolean = false) extends Scanner(source, offset) {
885885
override val indentSyntax = indent
886+
override def skipEndMarker(width: IndentWidth) = ()
886887
override protected def printState() = {
887888
print("la:")
888889
super.printState()
@@ -1416,16 +1417,6 @@ object Scanners {
14161417
val Zero = Run(' ', 0)
14171418
}
14181419

1419-
/** What can be referred to in an end marker */
1420-
type EndMarkerTag = TermName | Token
1421-
1422-
/** A processed end marker
1423-
* @param tag The name or token referred to in the marker
1424-
* @param width The indentation width where the marker occurred
1425-
* @param offset The offset of the `end`
1426-
*/
1427-
case class EndMarker(tag: EndMarkerTag, width: IndentWidth, offset: Int)
1428-
14291420
// ------------- keyword configuration -----------------------------------
14301421

14311422
private val (lastKeywordStart, kwArray) = buildKeywordArray(keywords)

‎tests/neg/endmarkers.scala‎

Lines changed: 9 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -3,14 +3,14 @@ object Test
33
locally {
44
var x = 0
55
while x < 10 do x += 1
6-
end while // error: end of statement expected but while found // error: not found: end
7-
val f = 10 // error: ';' expected, but 'val' found
6+
end while
7+
val f = 10
88
while
99
x += 1
1010
x < 10
1111
do ()
12-
end while // error: misaligned end marker // error: not found : end
13-
} // error: ';' expected, but '}' found
12+
end while // error: misaligned end marker
13+
}
1414

1515
def f(x: Int): Int =
1616
val y =
@@ -50,24 +50,24 @@ class Test2
5050
object x
5151
new Test2 {
5252
override def foo = 2
53-
end new // error: end of statement expected but new found // error: not found: end
54-
} // error: ';' expected, but '}' found
53+
end new // error: misaligned end marker
54+
}
5555
def bar = 2
5656
end Test2 // error: misaligned end marker
5757
end Test2
5858

5959
class Test3
6060
self =>
6161
def foo = 1
62-
end Test3 // error: not found: end
62+
end Test3 // error: misaligned end marker
6363

6464
import collection.mutable.HashMap
6565

6666
class Coder(words: List[String])
6767

6868
class Foo
6969
println()
70-
end Foo // error: not found: end
70+
end Foo // error: misaligned end marker
7171

7272
(2 -> "ABC", new ArrowAssoc('3') -> "DEF")
7373

@@ -101,4 +101,4 @@ class Coder(words: List[String])
101101
.flatMap {
102102
case (digit, str) => str map (ltr => ltr -> digit)
103103
}
104-
end Coder // error: The start of this line does not match any of the previous indentation widths.
104+
end Coder // error: misaligned end marker

‎tests/neg/endmarkers1.scala‎

Lines changed: 18 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,18 @@
1+
2+
def f7[T](x: Option[T]) = x match
3+
case Some(y) =>
4+
case None =>
5+
end if // error: misaligned end marker
6+
7+
object Test4 with
8+
def f[T](x: Option[T]) = x match
9+
case Some(y) =>
10+
case None =>
11+
end if // error: misaligned end marker
12+
end Test // error: misaligned end marker
13+
14+
def f[T](x: Option[T]) = x match
15+
case Some(y) =>
16+
case None => "hello"
17+
end f // error: misaligned end marker
18+

‎tests/pos/end-nested.scala‎

Lines changed: 14 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,14 @@
1+
def f[T](x: Option[T]) = x match
2+
case Some(y) =>
3+
case None =>
4+
end f
5+
6+
object Test with
7+
try List(1, 2, 3) match
8+
case x :: xs => println(x)
9+
case Nil => println("Nil")
10+
catch
11+
case ex: java.io.IOException => println(ex)
12+
case ex: Throwable => throw ex
13+
end try
14+

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