Move SVH structure to data structures

2 files changed, 86 insertions, 0 deletions

diff --git a/src/librustc_data_structures/lib.rs b/src/librustc_data_structures/lib.rs
index dd90cf7ae19..b8c21afc386 100644
--- a/src/librustc_data_structures/lib.rs
+++ b/src/librustc_data_structures/lib.rs
@@ -46,6 +46,7 @@ extern crate stable_deref_trait;
 extern crate rustc_rayon as rayon;
 extern crate rustc_rayon_core as rayon_core;
 extern crate rustc_hash;
+extern crate serialize;
 
 // See librustc_cratesio_shim/Cargo.toml for a comment explaining this.
 #[allow(unused_extern_crates)]
@@ -53,6 +54,7 @@ extern crate rustc_cratesio_shim;
 
 pub use rustc_serialize::hex::ToHex;
 
+pub mod svh;
 pub mod accumulate_vec;
 pub mod array_vec;
 pub mod base_n;
diff --git a/src/librustc_data_structures/svh.rs b/src/librustc_data_structures/svh.rs
new file mode 100644
index 00000000000..94f132562b5
--- /dev/null
+++ b/src/librustc_data_structures/svh.rs
@@ -0,0 +1,84 @@
+// 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};
+
+use stable_hasher;
+
+#[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<T> stable_hasher::HashStable<T> for Svh {
+    #[inline]
+    fn hash_stable<W: stable_hasher::StableHasherResult>(
+        &self,
+        ctx: &mut T,
+        hasher: &mut stable_hasher::StableHasher<W>
+    ) {
+        let Svh {
+            hash
+        } = *self;
+        hash.hash_stable(ctx, hasher);
+    }
+}