nom 7.0.0-alpha2

#[cfg(feature = "std")]
#[cfg_attr(feature = "docsrs", doc(cfg(feature = "std")))]
/// Helper trait to show a byte slice as a hex dump
pub trait HexDisplay {
  /// Converts the value of `self` to a hex dump, returning the owned
  /// `String`.
  fn to_hex(&self, chunk_size: usize) -> String;

  /// Converts the value of `self` to a hex dump beginning at `from` address, returning the owned
  /// `String`.
  fn to_hex_from(&self, chunk_size: usize, from: usize) -> String;
}

#[cfg(feature = "std")]
static CHARS: &[u8] = b"0123456789abcdef";

#[cfg(feature = "std")]
impl HexDisplay for [u8] {
  #[allow(unused_variables)]
  fn to_hex(&self, chunk_size: usize) -> String {
    self.to_hex_from(chunk_size, 0)
  }

  #[allow(unused_variables)]
  fn to_hex_from(&self, chunk_size: usize, from: usize) -> String {
    let mut v = Vec::with_capacity(self.len() * 3);
    let mut i = from;
    for chunk in self.chunks(chunk_size) {
      let s = format!("{:08x}", i);
      for &ch in s.as_bytes().iter() {
        v.push(ch);
      }
      v.push(b'\t');

      i += chunk_size;

      for &byte in chunk {
        v.push(CHARS[(byte >> 4) as usize]);
        v.push(CHARS[(byte & 0xf) as usize]);
        v.push(b' ');
      }
      if chunk_size > chunk.len() {
        for j in 0..(chunk_size - chunk.len()) {
          v.push(b' ');
          v.push(b' ');
          v.push(b' ');
        }
      }
      v.push(b'\t');

      for &byte in chunk {
        if (byte >= 32 && byte <= 126) || byte >= 128 {
          v.push(byte);
        } else {
          v.push(b'.');
        }
      }
      v.push(b'\n');
    }

    String::from_utf8_lossy(&v[..]).into_owned()
  }
}

#[cfg(feature = "std")]
impl HexDisplay for str {
  #[allow(unused_variables)]
  fn to_hex(&self, chunk_size: usize) -> String {
    self.to_hex_from(chunk_size, 0)
  }

  #[allow(unused_variables)]
  fn to_hex_from(&self, chunk_size: usize, from: usize) -> String {
    self.as_bytes().to_hex_from(chunk_size, from)
  }
}