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fix RFC #341: dot-like operators are now parsed with same precedence as . (#18711)

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* fix RFC #341: dot-like operators are now parsed with same precedence as `.`

* fixup

* [skip ci] address comment in changelog

* address comment

* update grammmar

* add manual entry

* fixup

* -d:nimPreviewDotLikeOps

* address comment to unblock PR: move nimPreviewDotLikeOps out of config/config.nims
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Timothee Cour 2021-08-24 21:50:40 -07:00 • committed by GitHub
commit 3aa16c1de0
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7 changed files with 74 additions and 5 deletions
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2
compiler/lineinfos.nim
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@ -46,6 +46,7 @@ type
warnCannotOpenFile = "CannotOpenFile", warnOctalEscape = "OctalEscape",
warnXIsNeverRead = "XIsNeverRead", warnXmightNotBeenInit = "XmightNotBeenInit",
warnDeprecated = "Deprecated", warnConfigDeprecated = "ConfigDeprecated",
warnDotLikeOps = "DotLikeOps",
warnSmallLshouldNotBeUsed = "SmallLshouldNotBeUsed", warnUnknownMagic = "UnknownMagic",
warnRstRedefinitionOfLabel = "RedefinitionOfLabel",
warnRstUnknownSubstitutionX = "UnknownSubstitutionX",
@ -116,6 +117,7 @@ const
warnXmightNotBeenInit: "'$1' might not have been initialized",
warnDeprecated: "$1",
warnConfigDeprecated: "config file '$1' is deprecated",
warnDotLikeOps: "$1",
warnSmallLshouldNotBeUsed: "'l' should not be used as an identifier; may look like '1' (one)",
warnUnknownMagic: "unknown magic '$1' might crash the compiler",
warnRstRedefinitionOfLabel: "redefinition of label '$1'",

34
compiler/parser.nim
View file

@ -466,6 +466,17 @@ proc dotExpr(p: var Parser, a: PNode): PNode =
exprColonEqExprListAux(p, tkParRi, y)
result = y
proc dotLikeExpr(p: var Parser, a: PNode): PNode =
#| dotLikeExpr = expr DOTLIKEOP optInd symbol
var info = p.parLineInfo
result = newNodeI(nkInfix, info)
optInd(p, result)
var opNode = newIdentNodeP(p.tok.ident, p)
getTok(p)
result.add(opNode)
result.add(a)
result.add(parseSymbol(p, smAfterDot))
proc qualifiedIdent(p: var Parser): PNode =
#| qualifiedIdent = symbol ('.' optInd symbol)?
result = parseSymbol(p)
@ -788,10 +799,15 @@ proc commandExpr(p: var Parser; r: PNode; mode: PrimaryMode): PNode =
p.hasProgress = false
result.add commandParam(p, isFirstParam, mode)
proc isDotLike(tok: Token): bool =
result = tok.tokType == tkOpr and tok.ident.s.len > 1 and
tok.ident.s[0] == '.' and tok.ident.s[1] != '.'
proc primarySuffix(p: var Parser, r: PNode,
baseIndent: int, mode: PrimaryMode): PNode =
#| primarySuffix = '(' (exprColonEqExpr comma?)* ')'
#| | '.' optInd symbol generalizedLit?
#| | DOTLIKEOP optInd symbol generalizedLit?
#| | '[' optInd exprColonEqExprList optPar ']'
#| | '{' optInd exprColonEqExprList optPar '}'
#| | &( '`'|IDENT|literal|'cast'|'addr'|'type') expr # command syntax
@ -840,11 +856,19 @@ proc primarySuffix(p: var Parser, r: PNode,
# `foo ref` or `foo ptr`. Unfortunately, these two are also
# used as infix operators for the memory regions feature and
# the current parsing rules don't play well here.
if p.inPragma == 0 and (isUnary(p.tok) or p.tok.tokType notin {tkOpr, tkDotDot}):
# actually parsing {.push hints:off.} as {.push(hints:off).} is a sweet
# solution, but pragmas.nim can't handle that
result = commandExpr(p, result, mode)
break
let isDotLike2 = p.tok.isDotLike
if isDotLike2 and p.lex.config.isDefined("nimPreviewDotLikeOps"):
# synchronize with `tkDot` branch
result = dotLikeExpr(p, result)
result = parseGStrLit(p, result)
else:
if isDotLike2:
parMessage(p, warnDotLikeOps, "dot-like operators will be parsed differently with `-d:nimPreviewDotLikeOps`")
if p.inPragma == 0 and (isUnary(p.tok) or p.tok.tokType notin {tkOpr, tkDotDot}):
# actually parsing {.push hints:off.} as {.push(hints:off).} is a sweet
# solution, but pragmas.nim can't handle that
result = commandExpr(p, result, mode)
break
else:
break