com-lihaoyi fastparse basic usage examples - new line issue ? / published by https://github.com/dacr/code-examples-manager #ec19b756-24fa-49b6-8654-1113b9e2fd6b/f4e34ffc37cad4b80adec8d6c115828e4387619c

com-lihaoyi-fastparse-last-newline-issue.sc

// summary : com-lihaoyi fastparse basic usage examples - new line issue ?
// keywords : scala, lihaoyi, fastparse, @testable
// publish : gist
// authors : David Crosson
// license : Apache NON-AI License Version 2.0 (https://raw.githubusercontent.com/non-ai-licenses/non-ai-licenses/main/NON-AI-APACHE2)
// id : ec19b756-24fa-49b6-8654-1113b9e2fd6b
// created-on : 2025-03-12T13:45:14+01:00
// managed-by : https://github.com/dacr/code-examples-manager
// run-with : scala-cli $file

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

// https://github.com/com-lihaoyi/fastparse/issues/327
// IN FACT NOT A BUG => Use ~~ instead of ~ non-whitespace-consuming

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)