swift3/Sources/printer.swift

   1
   2 func pr_str(_ obj: MalVal, _ print_readably: Bool = true) -> String {
   3     switch obj {
   4     case MalVal.MalList(let lst, _):
   5         let elems = lst.map { pr_str($0, print_readably) }
   6         return "(" + elems.joined(separator: " ")  + ")"
   7     case MalVal.MalVector(let lst, _):
   8         let elems = lst.map { pr_str($0, print_readably) }
   9         return "[" + elems.joined(separator: " ")  + "]"
  10     case MalVal.MalHashMap(let dict, _):
  11         let elems = dict.map {
  12             pr_str(MalVal.MalString($0), print_readably) +
  13             " " + pr_str($1, print_readably)
  14         }
  15         return "{" + elems.joined(separator: " ")  + "}"
  16     case MalVal.MalString(let str):
  17         //print("kw: '\(str[str.startIndex])'")
  18         if str.characters.count > 0 && str[str.startIndex] == "\u{029e}" {
  19             return ":" + str[str.index(after: str.startIndex)..<str.endIndex]
  20         } else if print_readably {
  21             let s1 = str.replacingOccurrences(of: "\\", with: "\\\\")
  22             let s2 = s1.replacingOccurrences(of: "\"", with: "\\\"")
  23             let s3 = s2.replacingOccurrences(of: "\n", with: "\\n")
  24             return "\"" + s3 + "\""
  25         } else {
  26             return str
  27         }
  28     case MalVal.MalSymbol(let str):
  29         return str
  30     case MalVal.MalInt(let i): return String(i)
  31     case MalVal.MalNil:        return "nil"
  32     case MalVal.MalFalse:      return "false"
  33     case MalVal.MalTrue:       return "true"
  34     case MalVal.MalFunc(_, nil, _, _, _, _):
  35         return "#<native function>"
  36     case MalVal.MalFunc(_, let ast, _, let params, _, _):
  37         return "(fn* \(pr_str(params![0])) \(pr_str(ast![0])))"
  38     case MalVal.MalAtom(let ma):
  39         return "(atom \(pr_str(ma.val, print_readably)))"
  40     default:
  41         return String(describing:obj)
  42     }
  43 }