src/librustc/hir/svh.rs

   1 // Copyright 2012-2014 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 //! Calculation and management of a Strict Version Hash for crates
  12 //!
  13 //! The SVH is used for incremental compilation to track when HIR
  14 //! nodes have changed between compilations, and also to detect
  15 //! mismatches where we have two versions of the same crate that were
  16 //! compiled from distinct sources.
  17
  18 use std::fmt;
  19 use std::hash::{Hash, Hasher};
  20 use serialize::{Encodable, Decodable, Encoder, Decoder};
  21
  22 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
  23 pub struct Svh {
  24     hash: u64,
  25 }
  26
  27 impl Svh {
  28     /// Create a new `Svh` given the hash. If you actually want to
  29     /// compute the SVH from some HIR, you want the `calculate_svh`
  30     /// function found in `librustc_incremental`.
  31     pub fn new(hash: u64) -> Svh {
  32         Svh { hash: hash }
  33     }
  34
  35     pub fn as_u64(&self) -> u64 {
  36         self.hash
  37     }
  38
  39     pub fn to_string(&self) -> String {
  40         format!("{:016x}", self.hash)
  41     }
  42 }
  43
  44 impl Hash for Svh {
  45     fn hash<H>(&self, state: &mut H) where H: Hasher {
  46         self.hash.to_le().hash(state);
  47     }
  48 }
  49
  50 impl fmt::Display for Svh {
  51     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
  52         f.pad(&self.to_string())
  53     }
  54 }
  55
  56 impl Encodable for Svh {
  57     fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
  58         s.emit_u64(self.as_u64().to_le())
  59     }
  60 }
  61
  62 impl Decodable for Svh {
  63     fn decode<D: Decoder>(d: &mut D) -> Result<Svh, D::Error> {
  64         d.read_u64()
  65          .map(u64::from_le)
  66          .map(Svh::new)
  67     }
  68 }
  69
  70 impl_stable_hash_for!(struct Svh {
  71     hash
  72 });