src/librustc_incremental/ich/fingerprint.rs

   1 // Copyright 2016 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 use rustc_serialize::{Encodable, Decodable, Encoder, Decoder};
  12
  13 const FINGERPRINT_LENGTH: usize = 16;
  14
  15 #[derive(Eq, PartialEq, Ord, PartialOrd, Hash, Debug, Clone, Copy)]
  16 pub struct Fingerprint(pub [u8; FINGERPRINT_LENGTH]);
  17
  18 impl Fingerprint {
  19     #[inline]
  20     pub fn zero() -> Fingerprint {
  21         Fingerprint([0; FINGERPRINT_LENGTH])
  22     }
  23
  24     pub fn from_smaller_hash(hash: u64) -> Fingerprint {
  25         let mut result = Fingerprint::zero();
  26         result.0[0] = (hash >>  0) as u8;
  27         result.0[1] = (hash >>  8) as u8;
  28         result.0[2] = (hash >> 16) as u8;
  29         result.0[3] = (hash >> 24) as u8;
  30         result.0[4] = (hash >> 32) as u8;
  31         result.0[5] = (hash >> 40) as u8;
  32         result.0[6] = (hash >> 48) as u8;
  33         result.0[7] = (hash >> 56) as u8;
  34         result
  35     }
  36
  37     pub fn to_smaller_hash(&self) -> u64 {
  38         ((self.0[0] as u64) <<  0) |
  39         ((self.0[1] as u64) <<  8) |
  40         ((self.0[2] as u64) << 16) |
  41         ((self.0[3] as u64) << 24) |
  42         ((self.0[4] as u64) << 32) |
  43         ((self.0[5] as u64) << 40) |
  44         ((self.0[6] as u64) << 48) |
  45         ((self.0[7] as u64) << 56)
  46     }
  47 }
  48
  49 impl Encodable for Fingerprint {
  50     #[inline]
  51     fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
  52         for &byte in &self.0[..] {
  53             s.emit_u8(byte)?;
  54         }
  55         Ok(())
  56     }
  57 }
  58
  59 impl Decodable for Fingerprint {
  60     #[inline]
  61     fn decode<D: Decoder>(d: &mut D) -> Result<Fingerprint, D::Error> {
  62         let mut result = Fingerprint([0u8; FINGERPRINT_LENGTH]);
  63         for byte in &mut result.0[..] {
  64             *byte = d.read_u8()?;
  65         }
  66         Ok(result)
  67     }
  68 }
  69
  70 impl ::std::fmt::Display for Fingerprint {
  71     fn fmt(&self, formatter: &mut ::std::fmt::Formatter) -> Result<(), ::std::fmt::Error> {
  72         for i in 0 .. self.0.len() {
  73             if i > 0 {
  74                 write!(formatter, "::")?;
  75             }
  76
  77             write!(formatter, "{}", self.0[i])?;
  78         }
  79         Ok(())
  80     }
  81 }