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Syntax change for single cases #7507

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Merged
merged 3 commits into from
Nov 7, 2019
Merged

Syntax change for single cases #7507

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28b33fd
Syntax change for single cases
odersky Nov 6, 2019
85e062f
Fix test
odersky Nov 6, 2019
c878c01
Add test
odersky Nov 7, 2019
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33 changes: 19 additions & 14 deletions compiler/src/dotty/tools/dotc/parsing/Parsers.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -1248,6 +1248,9 @@ object Parsers {
// note: next is defined here because current == NEWLINE
if (in.token == NEWLINE && in.next.token == token) in.nextToken()

def newLinesOptWhenFollowedBy(token: Int): Unit =
if in.isNewLine && in.next.token == token then in.nextToken()

def newLinesOptWhenFollowedBy(name: Name): Unit =
if in.isNewLine && in.next.token == IDENTIFIER && in.next.name == name then
in.nextToken()
Expand Down Expand Up @@ -1742,8 +1745,7 @@ object Parsers {
* | [SimpleExpr `.'] id `=' Expr
* | SimpleExpr1 ArgumentExprs `=' Expr
* | Expr2
* | [‘inline’] Expr2 `match' `{' CaseClauses `}'
* | `given' `match' `{' ImplicitCaseClauses `}'
* | [‘inline’] Expr2 `match' (`{' CaseClauses `}' | CaseClause)
* Bindings ::= `(' [Binding {`,' Binding}] `)'
* Binding ::= (id | `_') [`:' Type]
* Expr2 ::= PostfixExpr [Ascription]
Expand Down Expand Up @@ -1829,11 +1831,12 @@ object Parsers {
atSpan(in.skipToken()) {
val body = expr()
val (handler, handlerStart) =
if (in.token == CATCH) {
if in.token == CATCH then
val span = in.offset
in.nextToken()
(subExpr(), span)
}
(if in.token == CASE then Match(EmptyTree, caseClause() :: Nil)
else subExpr(),
span)
else (EmptyTree, -1)

handler match {
Expand Down Expand Up @@ -1955,20 +1958,20 @@ object Parsers {
mkIf(cond, thenp, elsep)
}

/** `match' { CaseClauses }
/** `match' (`{' CaseClauses `}' | CaseClause)
*/
def matchExpr(t: Tree, start: Offset, mkMatch: (Tree, List[CaseDef]) => Match) =
indentRegion(MATCH) {
atSpan(start, in.skipToken()) {
mkMatch(t, inBracesOrIndented(caseClauses(caseClause)))
mkMatch(t, casesExpr(caseClause))
}
}

/** `match' { TypeCaseClauses }
/** `match' (`{' TypeCaseClauses `}' | TypeCaseClause)
*/
def matchType(t: Tree): MatchTypeTree =
atSpan(t.span.start, accept(MATCH)) {
inBracesOrIndented(MatchTypeTree(EmptyTree, t, caseClauses(typeCaseClause)))
MatchTypeTree(EmptyTree, t, casesExpr(typeCaseClause))
}

/** FunParams ::= Bindings
Expand Down Expand Up @@ -2399,8 +2402,11 @@ object Parsers {
}
}

def casesExpr(clause: () => CaseDef): List[CaseDef] =
if in.token == CASE then clause() :: Nil
else inBracesOrIndented(caseClauses(clause))

/** CaseClauses ::= CaseClause {CaseClause}
* ImplicitCaseClauses ::= ImplicitCaseClause {ImplicitCaseClause}
* TypeCaseClauses ::= TypeCaseClause {TypeCaseClause}
*/
def caseClauses(clause: () => CaseDef): List[CaseDef] = {
Expand All @@ -2410,9 +2416,8 @@ object Parsers {
buf.toList
}

/** CaseClause ::= ‘case’ Pattern [Guard] `=>' Block
* ImplicitCaseClause ::= ‘case’ PatVar [Ascription] [Guard] `=>' Block
*/
/** CaseClause ::= ‘case’ Pattern [Guard] `=>' Block
*/
val caseClause: () => CaseDef = () => atSpan(in.offset) {
val (pat, grd) = inSepRegion(LPAREN, RPAREN) {
accept(CASE)
Expand All @@ -2430,7 +2435,7 @@ object Parsers {
}
CaseDef(pat, EmptyTree, atSpan(accept(ARROW)) {
val t = typ()
if (isStatSep) in.nextToken()
newLinesOptWhenFollowedBy(CASE)
t
})
}
Expand Down
9 changes: 5 additions & 4 deletions docs/docs/internals/syntax.md
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Expand Up @@ -147,7 +147,8 @@ FunArgTypes ::= InfixType
| ‘(’ [ ‘[given]’ FunArgType {‘,’ FunArgType } ] ‘)’
| ‘(’ ‘[given]’ TypedFunParam {‘,’ TypedFunParam } ‘)’
TypedFunParam ::= id ‘:’ Type
MatchType ::= InfixType `match` TypeCaseClauses
MatchType ::= InfixType `match`
(‘{’ TypeCaseClauses ‘}’ | TypeCaseClause)
InfixType ::= RefinedType {id [nl] RefinedType} InfixOp(t1, op, t2)
RefinedType ::= WithType {[nl | ‘with’] Refinement} RefinedTypeTree(t, ds)
WithType ::= AnnotType {‘with’ AnnotType} (deprecated)
Expand Down Expand Up @@ -198,12 +199,12 @@ Expr1 ::= ‘if’ ‘(’ Expr ‘)’ {nl}
| [SimpleExpr ‘.’] id ‘=’ Expr Assign(expr, expr)
| SimpleExpr1 ArgumentExprs ‘=’ Expr Assign(expr, expr)
| Expr2
| [‘inline’] Expr2 ‘match’ ‘{’ CaseClauses ‘}’ Match(expr, cases) -- point on match
| ‘given’ ‘match’ ‘{’ ImplicitCaseClauses ‘}’
| [‘inline’] Expr2 ‘match’
(‘{’ CaseClauses ‘}’ | CaseClause) Match(expr, cases) -- point on match
Expr2 ::= PostfixExpr [Ascription]
Ascription ::= ‘:’ InfixType Typed(expr, tp)
| ‘:’ Annotation {Annotation} Typed(expr, Annotated(EmptyTree, annot)*)
Catches ::= ‘catch’ Expr
Catches ::= ‘catch’ (Expr | CaseClause)
PostfixExpr ::= InfixExpr [id] PostfixOp(expr, op)
InfixExpr ::= PrefixExpr
| InfixExpr id [nl] InfixExpr InfixOp(expr, op, expr)
Expand Down
9 changes: 9 additions & 0 deletions tests/neg/case-semi.scala
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@@ -0,0 +1,9 @@
object Test with
type X = Int
val x: X = 1

type T2 = X match { case Int => String case String => Int }
x match { case 1 => 3; case 2 => 4 }
x match { case 1 => 3 case 2 => 4 }

type T1 = X match { case Int => String; case String => Int } // error // error
11 changes: 11 additions & 0 deletions tests/pos/single-case.scala
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@@ -0,0 +1,11 @@
object test with

type T[X] = X match case Int => X

try
println("hi")
catch case ex: java.io.IOException => println("ho")

1 match case x: Int => println(x)


2 changes: 1 addition & 1 deletion tests/run-macros/tasty-tree-map/quoted_2.scala
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Expand Up @@ -42,7 +42,7 @@ object Test {
println(identityMaped({ val x: Int | Any = 60; x }))
println(identityMaped({ def f(x: => Int): Int = x; f(61) }))
println(identityMaped({ type T[X] = X; val x: T[Int] = 62; x }))
println(identityMaped({ type T[X] = X match { case Int => String; case String => Int }; val x: T[String] = 63; x }))
println(identityMaped({ type T[X] = X match { case Int => String case String => Int }; val x: T[String] = 63; x }))
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What is the current state of matches without semicolons? We should have neg/pos tests with at least the folowing cases

X match { case Int => String; case String => Int }
X match { case Int => String case String => Int }
x match { case 1 => 3; case 2 => 4 }
x match { case 1 => 3 case 2 => 4 }

println(identityMaped((Nil: List[Int]) match { case _: List[t] => 64 }))
println(identityMaped({ object F { type T = Int }; val x: F.T = 65; x }))
println(identityMaped({ val x: Foo { type T = Int } = new Foo { type T = Int; def y: Int = 66 }; x.y }))
Expand Down