rust/src/librustc/hir/svh.rs

73 lines
1.9 KiB
Rust

// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
//! Calculation and management of a Strict Version Hash for crates
//!
//! The SVH is used for incremental compilation to track when HIR
//! nodes have changed between compilations, and also to detect
//! mismatches where we have two versions of the same crate that were
//! compiled from distinct sources.
use std::fmt;
use std::hash::{Hash, Hasher};
use serialize::{Encodable, Decodable, Encoder, Decoder};
#[derive(Copy, Clone, PartialEq, Eq, Debug)]
pub struct Svh {
hash: u64,
}
impl Svh {
/// Create a new `Svh` given the hash. If you actually want to
/// compute the SVH from some HIR, you want the `calculate_svh`
/// function found in `librustc_incremental`.
pub fn new(hash: u64) -> Svh {
Svh { hash: hash }
}
pub fn as_u64(&self) -> u64 {
self.hash
}
pub fn to_string(&self) -> String {
format!("{:016x}", self.hash)
}
}
impl Hash for Svh {
fn hash<H>(&self, state: &mut H) where H: Hasher {
self.hash.to_le().hash(state);
}
}
impl fmt::Display for Svh {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.pad(&self.to_string())
}
}
impl Encodable for Svh {
fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
s.emit_u64(self.as_u64().to_le())
}
}
impl Decodable for Svh {
fn decode<D: Decoder>(d: &mut D) -> Result<Svh, D::Error> {
d.read_u64()
.map(u64::from_le)
.map(Svh::new)
}
}
impl_stable_hash_for!(struct Svh {
hash
});