encoding.bend source

encoding.bend on the hub · documented module

import Base# Hex of each char as two nibbles. ASCII-oriented.def nibble(+n: U32) -> U32:  Bool.pick(U32, U32.is_le(n, 9), (48 + n : U32), (87 + n : U32))@unsafedef hi.go(+n: U32, +acc: U32, small: Bool) -> U32:  match small:    case True{}:      acc    case False{}:      hi.go((n - 16 : U32), (acc + 1 : U32), U32.is_le((n - 16 : U32), 15))def hi(+n: U32) -> U32:  hi.go(n, 0, U32.is_le(n, 15))def lo(+n: U32) -> U32:  (n - (hi(n) * 16 : U32) : U32)def encode.go(s: String, acc: String) -> String:  match s:    case SNil{}:      String.reverse(acc)    case SCon{Chr{+c}, t}:      encode.go(t, SCon{Chr{nibble(lo(c))}, SCon{Chr{nibble(hi(c))}, acc}})def encode(s: String) -> String:  encode.go(s, SNil{})def unhex.h(c: U32, hex: Bool) -> Maybe<&2, U32>:  match hex:    case True{}:      Some{(c - 87 : U32)}    case False{}:      None{}def unhex.d(+c: U32, dec: Bool, hex: Bool) -> Maybe<&2, U32>:  match dec:    case True{}:      Some{(c - 48 : U32)}    case False{}:      unhex.h(c, hex)def unhex(+c: U32) -> Maybe<&2, U32>:  unhex.d(c, Bool.and(U32.is_le(48, c), U32.is_le(c, 57)), Bool.and(U32.is_le(97, c), U32.is_le(c, 102)))def decode.cons(byte: U32, rest: Maybe<&2, String>) -> Maybe<&2, String>:  match rest:    case None{}:      None{}    case Some{s}:      Some{SCon{Chr{byte}, s}}def decode.join2(x: U32, b: Maybe<&2, U32>, rest: Maybe<&2, String>) -> Maybe<&2, String>:  match b:    case None{}:      None{}    case Some{y}:      decode.cons((x * 16 + y : U32), rest)def decode.join(a: Maybe<&2, U32>, b: Maybe<&2, U32>, rest: Maybe<&2, String>) -> Maybe<&2, String>:  match a:    case None{}:      None{}    case Some{x}:      decode.join2(x, b, rest)@unsafedef decode.go(s: String) -> Maybe<&2, String>:  match s:    case SNil{}:      Some{SNil{}}    case SCon{Chr{+c}, t}:      match t:        case SNil{}:          None{}        case SCon{Chr{+d}, r}:          decode.join(unhex(c), unhex(d), decode.go(r))def decode(s: String) -> Maybe<&2, String>:  decode.go(s)