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syntax.md: update syntax of for-expressions #11624

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Jul 8, 2021
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syntax.md: update syntax of for-expressions #11624

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6 changes: 3 additions & 3 deletions compiler/src/dotty/tools/dotc/parsing/Parsers.scala
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Expand Up @@ -2509,9 +2509,9 @@ object Parsers {
GenFrom(pat, subExpr(), checkMode)
}

/** ForExpr ::= `for' (`(' Enumerators `)' | `{' Enumerators `}')
* {nl} [`yield'] Expr
* | `for' Enumerators (`do' Expr | `yield' Expr)
/** ForExpr ::= ‘for’ ‘(’ Enumerators ‘)’ {nl} [‘do‘ | ‘yield’] Expr
* | ‘for’ ‘{’ Enumerators ‘}’ {nl} [‘do‘ | ‘yield’] Expr
* | ‘for’ Enumerators (‘do‘ | ‘yield’) Expr
*/
def forExpr(): Tree =
atSpan(in.skipToken()) {
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7 changes: 4 additions & 3 deletions docs/docs/internals/syntax.md
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Expand Up @@ -272,9 +272,10 @@ BlockStat ::= Import
| Expr1
| EndMarker

ForExpr ::= ‘for’ (‘(’ Enumerators ‘)’ | ‘{’ Enumerators ‘}’) ForYield(enums, expr)
{nl} [‘yield’] Expr
| ‘for’ Enumerators (‘do’ Expr | ‘yield’ Expr) ForDo(enums, expr)
ForExpr ::= ‘for’ ‘(’ Enumerators0 ‘)’ {nl} [‘do‘ | ‘yield’] Expr ForYield(enums, expr) / ForDo(enums, expr)
| ‘for’ ‘{’ Enumerators0 ‘}’ {nl} [‘do‘ | ‘yield’] Expr
| ‘for’ Enumerators0 (‘do‘ | ‘yield’) Expr
Enumerators0 ::= {nl} Enumerators [semi]
Enumerators ::= Generator {semi Enumerator | Guard}
Enumerator ::= Generator
| Guard
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6 changes: 4 additions & 2 deletions docs/docs/reference/syntax.md
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Expand Up @@ -263,8 +263,10 @@ BlockStat ::= Import
| Expr1
| EndMarker

ForExpr ::= ‘for’ (‘(’ Enumerators ‘)’ | ‘{’ Enumerators ‘}’) {nl} [‘yield’] Expr
| ‘for’ Enumerators (‘do’ Expr | ‘yield’ Expr)
ForExpr ::= ‘for’ ‘(’ Enumerators0 ‘)’ {nl} [‘do‘ | ‘yield’] Expr
| ‘for’ ‘{’ Enumerators0 ‘}’ {nl} [‘do‘ | ‘yield’] Expr
| ‘for’ Enumerators0 (‘do‘ | ‘yield’) Expr
Enumerators0 ::= {nl} Enumerators [semi]
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No {nl} needs to be inserted here.

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Enumerators themselves do not accept new line before them.

No {nl} needs to be inserted here.

Is it because it's kinda "obvious" that here can go an arbitrary amount of new lines?
For me, it's as obvious as {nl} after ) in for / if / while, still they contain {nl} in rules.

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No, nl means an newline token inserted by the lexer. But there is never a newline inserted in front of a do or yield.

Enumerators ::= Generator {semi Enumerator | Guard}
Enumerator ::= Generator
| Guard
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