-
Notifications
You must be signed in to change notification settings - Fork 12.1k
/
mod.rs
112 lines (95 loc) · 3.75 KB
/
mod.rs
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
// 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 rustc::ty::RegionVid;
use rustc_data_structures::indexed_vec::{Idx, IndexVec};
use borrow_check::nll::type_check::Locations;
use std::fmt;
use std::ops::Deref;
#[derive(Clone, Default)]
crate struct ConstraintSet {
constraints: IndexVec<ConstraintIndex, OutlivesConstraint>,
}
impl ConstraintSet {
pub fn push(&mut self, constraint: OutlivesConstraint) {
debug!(
"ConstraintSet::push({:?}: {:?} @ {:?}",
constraint.sup, constraint.sub, constraint.locations
);
if constraint.sup == constraint.sub {
// 'a: 'a is pretty uninteresting
return;
}
self.constraints.push(constraint);
}
}
impl Deref for ConstraintSet {
type Target = IndexVec<ConstraintIndex, OutlivesConstraint>;
fn deref(&self) -> &Self::Target { &self.constraints }
}
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub struct OutlivesConstraint {
// NB. The ordering here is not significant for correctness, but
// it is for convenience. Before we dump the constraints in the
// debugging logs, we sort them, and we'd like the "super region"
// to be first, etc. (In particular, span should remain last.)
/// The region SUP must outlive SUB...
pub sup: RegionVid,
/// Region that must be outlived.
pub sub: RegionVid,
/// Where did this constraint arise?
pub locations: Locations,
}
impl fmt::Debug for OutlivesConstraint {
fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
write!(
formatter,
"({:?}: {:?}) due to {:?}",
self.sup, self.sub, self.locations
)
}
}
newtype_index!(ConstraintIndex { DEBUG_FORMAT = "ConstraintIndex({})" });
crate struct ConstraintGraph {
first_constraints: IndexVec<RegionVid, Option<ConstraintIndex>>,
next_constraints: IndexVec<ConstraintIndex, Option<ConstraintIndex>>,
}
impl ConstraintGraph {
/// Constraint a graph where each region constraint `R1: R2` is
/// treated as an edge `R2 -> R1`. This is useful for cheaply
/// finding dirty constraints.
crate fn new(set: &ConstraintSet, num_region_vars: usize) -> Self {
let mut first_constraints = IndexVec::from_elem_n(None, num_region_vars);
let mut next_constraints = IndexVec::from_elem(None, &set.constraints);
for (idx, constraint) in set.constraints.iter_enumerated().rev() {
let mut head = &mut first_constraints[constraint.sub];
let mut next = &mut next_constraints[idx];
debug_assert!(next.is_none());
*next = *head;
*head = Some(idx);
}
ConstraintGraph { first_constraints, next_constraints }
}
/// Invokes `op` with the index of any constraints of the form
/// `region_sup: region_sub`. These are the constraints that must
/// be reprocessed when the value of `R1` changes. If you think of
/// each constraint `R1: R2` as an edge `R2 -> R1`, then this
/// gives the set of successors to R2.
crate fn for_each_dependent(
&self,
region_sub: RegionVid,
mut op: impl FnMut(ConstraintIndex),
) {
let mut p = self.first_constraints[region_sub];
while let Some(dep_idx) = p {
op(dep_idx);
p = self.next_constraints[dep_idx];
}
}
}