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// Copyright 2017 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.
use encoder::EncodeContext;
use schema::{Lazy, LazySeq};
use rustc::ich::{StableHashingContext, Fingerprint};
use rustc::ty::TyCtxt;
use rustc_data_structures::accumulate_vec::AccumulateVec;
use rustc_data_structures::stable_hasher::{StableHasher, HashStable};
use rustc_serialize::Encodable;
/// The IsolatedEncoder provides facilities to write to crate metadata while
/// making sure that anything going through it is also feed into an ICH hasher.
pub struct IsolatedEncoder<'a, 'b: 'a, 'tcx: 'b> {
pub tcx: TyCtxt<'b, 'tcx, 'tcx>,
ecx: &'a mut EncodeContext<'b, 'tcx>,
hcx: Option<(StableHashingContext<'tcx>, StableHasher<Fingerprint>)>,
}
impl<'a, 'b: 'a, 'tcx: 'b> IsolatedEncoder<'a, 'b, 'tcx> {
pub fn new(ecx: &'a mut EncodeContext<'b, 'tcx>) -> Self {
let tcx = ecx.tcx;
let compute_ich = ecx.compute_ich;
IsolatedEncoder {
tcx,
ecx,
hcx: if compute_ich {
// We are always hashing spans for things in metadata because
// don't know if a downstream crate will use them or not.
// Except when -Zquery-dep-graph is specified because we don't
// want to mess up our tests.
let hcx = if tcx.sess.opts.debugging_opts.query_dep_graph {
tcx.create_stable_hashing_context()
} else {
tcx.create_stable_hashing_context().force_span_hashing()
};
Some((hcx, StableHasher::new()))
} else {
None
}
}
}
pub fn finish(self) -> (Option<Fingerprint>, &'a mut EncodeContext<'b, 'tcx>) {
if let Some((_, hasher)) = self.hcx {
(Some(hasher.finish()), self.ecx)
} else {
(None, self.ecx)
}
}
pub fn lazy<T>(&mut self, value: &T) -> Lazy<T>
where T: Encodable + HashStable<StableHashingContext<'tcx>>
{
if let Some((ref mut hcx, ref mut hasher)) = self.hcx {
value.hash_stable(hcx, hasher);
debug!("metadata-hash: {:?}", hasher);
}
self.ecx.lazy(value)
}
pub fn lazy_seq<I, T>(&mut self, iter: I) -> LazySeq<T>
where I: IntoIterator<Item = T>,
T: Encodable + HashStable<StableHashingContext<'tcx>>
{
if let Some((ref mut hcx, ref mut hasher)) = self.hcx {
let iter = iter.into_iter();
let (lower_bound, upper_bound) = iter.size_hint();
if upper_bound == Some(lower_bound) {
lower_bound.hash_stable(hcx, hasher);
let mut num_items_hashed = 0;
let ret = self.ecx.lazy_seq(iter.inspect(|item| {
item.hash_stable(hcx, hasher);
num_items_hashed += 1;
}));
// Sometimes items in a sequence are filtered out without being
// hashed (e.g. for &[ast::Attribute]) and this code path cannot
// handle that correctly, so we want to make sure we didn't hit
// it by accident.
if lower_bound != num_items_hashed {
bug!("Hashed a different number of items ({}) than expected ({})",
num_items_hashed,
lower_bound);
}
debug!("metadata-hash: {:?}", hasher);
ret
} else {
// Collect into a vec so we know the length of the sequence
let items: AccumulateVec<[T; 32]> = iter.collect();
items.hash_stable(hcx, hasher);
debug!("metadata-hash: {:?}", hasher);
self.ecx.lazy_seq(items)
}
} else {
self.ecx.lazy_seq(iter)
}
}
pub fn lazy_seq_ref<'x, I, T>(&mut self, iter: I) -> LazySeq<T>
where I: IntoIterator<Item = &'x T>,
T: 'x + Encodable + HashStable<StableHashingContext<'tcx>>
{
if let Some((ref mut hcx, ref mut hasher)) = self.hcx {
let iter = iter.into_iter();
let (lower_bound, upper_bound) = iter.size_hint();
if upper_bound == Some(lower_bound) {
lower_bound.hash_stable(hcx, hasher);
let mut num_items_hashed = 0;
let ret = self.ecx.lazy_seq_ref(iter.inspect(|item| {
item.hash_stable(hcx, hasher);
num_items_hashed += 1;
}));
// Sometimes items in a sequence are filtered out without being
// hashed (e.g. for &[ast::Attribute]) and this code path cannot
// handle that correctly, so we want to make sure we didn't hit
// it by accident.
if lower_bound != num_items_hashed {
bug!("Hashed a different number of items ({}) than expected ({})",
num_items_hashed,
lower_bound);
}
debug!("metadata-hash: {:?}", hasher);
ret
} else {
// Collect into a vec so we know the length of the sequence
let items: AccumulateVec<[&'x T; 32]> = iter.collect();
items.hash_stable(hcx, hasher);
debug!("metadata-hash: {:?}", hasher);
self.ecx.lazy_seq_ref(items.iter().map(|x| *x))
}
} else {
self.ecx.lazy_seq_ref(iter)
}
}
pub fn lazy_seq_from_slice<T>(&mut self, slice: &[T]) -> LazySeq<T>
where T: Encodable + HashStable<StableHashingContext<'tcx>>
{
if let Some((ref mut hcx, ref mut hasher)) = self.hcx {
slice.hash_stable(hcx, hasher);
debug!("metadata-hash: {:?}", hasher);
}
self.ecx.lazy_seq_ref(slice.iter())
}
pub fn lazy_seq_ref_from_slice<T>(&mut self, slice: &[&T]) -> LazySeq<T>
where T: Encodable + HashStable<StableHashingContext<'tcx>>
{
if let Some((ref mut hcx, ref mut hasher)) = self.hcx {
slice.hash_stable(hcx, hasher);
debug!("metadata-hash: {:?}", hasher);
}
self.ecx.lazy_seq_ref(slice.iter().map(|x| *x))
}
}
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