package wacc

import parsley.Parsley
import parsley.token.{Basic, Lexer}
import parsley.token.descriptions.*

object lexer {
  private val desc = LexicalDesc.plain.copy(
    nameDesc = NameDesc.plain.copy(
      identifierStart = Basic(c => c.isLetter || c == '_'),
      identifierLetter = Basic(c => c.isLetterOrDigit || c == '_')
    ),
    symbolDesc = SymbolDesc.plain.copy(
      hardKeywords = Set(
        "begin", "end", "is", "skip", "if", "then", "else", "fi", "while", "do", "done", "read",
        "free", "return", "exit", "print", "println", "true", "false", "int", "bool", "char",
        "string", "pair", "newpair", "fst", "snd", "call", "chr", "ord", "len", "null"
      ),
      hardOperators = Set(
        "+", "-", "*", "/", "%", ">", "<", ">=", "<=", "==", "!=", "&&", "||", "!"
      )
    ),
    spaceDesc = SpaceDesc.plain.copy(
      lineCommentStart = "#"
    ),
    textDesc = TextDesc.plain.copy(
      graphicCharacter = Basic(c => c >= ' ' && c != '\\' && c != '\'' && c != '"'),
      escapeSequences = EscapeDesc.plain.copy(
        literals = Set('\\', '"', '\''),
        mapping = Map(
          "0" -> '\u0000',
          "b" -> '\b',
          "t" -> '\t',
          "n" -> '\n',
          "f" -> '\f',
          "r" -> '\r'
        )
      )
    ),
    numericDesc = NumericDesc.plain.copy(
      decimalExponentDesc = ExponentDesc.NoExponents
    )
  )

  private val lexer = Lexer(desc)
  val ident = lexer.lexeme.names.identifier
  val integer = lexer.lexeme.integer.decimal32[Int]
  val charLit = lexer.lexeme.character.ascii
  val stringLit = lexer.lexeme.string.ascii
  val implicits = lexer.lexeme.symbol.implicits

  def fully[A](p: Parsley[A]): Parsley[A] = lexer.fully(p)
}