strange behavior, last newline is being captured although MultiLineWhitespace is used

[dacr]

Using this script :

//> using scala "3.6.4"
//> using dep "com.lihaoyi::fastparse:3.1.1"
//> using dep "com.lihaoyi::pprint:0.9.0"

import fastparse.*, MultiLineWhitespace.*, pprint.pprintln

case class MatchNode(variableName: Option[String], labels: Seq[String])
case class MatchSection(matchNode: MatchNode)
case class ReturnSection(returnExpressions: String)
case class Statement(matchSection: MatchSection, returnSection: ReturnSection)

def pVariableName[$: P]: P[String] =
  P((CharIn("_a-zA-Z") ~ CharsWhileIn("_a-zA-Z0-9", 0)).!)

def pLabel[$: P]: P[String] =
  P((CharIn("_a-zA-Z") ~ CharsWhileIn("_a-zA-Z0-9", 0)).!)

def pMatchExpression[$: P]: P[MatchNode] =
  P("(" ~ pVariableName.!.? ~ (":" ~ pLabel.!).rep ~ ")")
    .map((variableName, labels) => MatchNode(variableName, labels))

def pMatchSection[$: P]: P[MatchSection] =
  P("MATCH" ~ pMatchExpression)
    .map(expression => MatchSection(expression))

def pReturnSection[$: P]: P[ReturnSection] =
  P("RETURN" ~ pVariableName.!)
    .map(v => ReturnSection(v))

def pStatement[$: P]: P[Statement] =
  P(pMatchSection ~ pReturnSection ~ End)
    .map((ms, rs) => Statement(ms, rs))


val input =
  """MATCH (n)
    |RETURN n
    |""".stripMargin

val result = parse(input, p => pStatement(using p))
pprintln(result)
pprintln(result.get.value.returnSection.returnExpressions)

I get "n\n" as response for the RETURN n part :

[dacr]

(Of course going to do .stripMargin.trim as workaround)

[dacr]

sorry found the issue, it is the way I've written my parser

[dacr]

for the posterity, the fix is to use ~~ (non-whitespace-consuming):

def pVariableName[$: P]: P[String] =
  P((CharIn("_a-zA-Z") ~~ CharsWhileIn("_a-zA-Z0-9", 0)).!)

def pLabel[$: P]: P[String] =
  P((CharIn("_a-zA-Z") ~~ CharsWhileIn("_a-zA-Z0-9", 0)).!)