import gleam/list
import nibble/lexer.{type Token, Keep}

pub fn chars() -> lexer.Lexer(String, Nil) {
  lexer.simple([lexer.custom(fn(_, lexeme, _) { Keep(lexeme, Nil) })])
}

pub fn run(
  lexer: lexer.Lexer(String, Nil),
  on input: String,
) -> List(Token(String)) {
  let assert Ok(tokens) = lexer.run(input, lexer)

  // Nibble's lexer prepends an empty string at the start of each line.
  // Filter out all empty tokens.
  tokens
  |> list.filter(fn(token) { token.lexeme != "" })
}