src/librustc/infer/region_constraints/taint.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 use super::*;
  12
  13 #[derive(Debug)]
  14 pub(super) struct TaintSet<'tcx> {
  15     directions: TaintDirections,
  16     regions: FxHashSet<ty::Region<'tcx>>,
  17 }
  18
  19 impl<'tcx> TaintSet<'tcx> {
  20     pub(super) fn new(directions: TaintDirections, initial_region: ty::Region<'tcx>) -> Self {
  21         let mut regions = FxHashSet::default();
  22         regions.insert(initial_region);
  23         TaintSet {
  24             directions: directions,
  25             regions: regions,
  26         }
  27     }
  28
  29     pub(super) fn fixed_point(
  30         &mut self,
  31         tcx: TyCtxt<'_, '_, 'tcx>,
  32         undo_log: &[UndoLog<'tcx>],
  33         verifys: &[Verify<'tcx>],
  34     ) {
  35         let mut prev_len = 0;
  36         while prev_len < self.len() {
  37             debug!(
  38                 "tainted: prev_len = {:?} new_len = {:?}",
  39                 prev_len,
  40                 self.len()
  41             );
  42
  43             prev_len = self.len();
  44
  45             for undo_entry in undo_log {
  46                 match undo_entry {
  47                     &AddConstraint(Constraint::VarSubVar(a, b)) => {
  48                         self.add_edge(tcx.mk_region(ReVar(a)), tcx.mk_region(ReVar(b)));
  49                     }
  50                     &AddConstraint(Constraint::RegSubVar(a, b)) => {
  51                         self.add_edge(a, tcx.mk_region(ReVar(b)));
  52                     }
  53                     &AddConstraint(Constraint::VarSubReg(a, b)) => {
  54                         self.add_edge(tcx.mk_region(ReVar(a)), b);
  55                     }
  56                     &AddConstraint(Constraint::RegSubReg(a, b)) => {
  57                         self.add_edge(a, b);
  58                     }
  59                     &AddGiven(a, b) => {
  60                         self.add_edge(a, tcx.mk_region(ReVar(b)));
  61                     }
  62                     &AddVerify(i) => {
  63                         span_bug!(
  64                             verifys[i].origin.span(),
  65                             "we never add verifications while doing higher-ranked things",
  66                         )
  67                     }
  68                     &Purged | &AddCombination(..) | &AddVar(..) | &OpenSnapshot
  69                     | &CommitedSnapshot => {}
  70                 }
  71             }
  72         }
  73     }
  74
  75     pub(super) fn into_set(self) -> FxHashSet<ty::Region<'tcx>> {
  76         self.regions
  77     }
  78
  79     fn len(&self) -> usize {
  80         self.regions.len()
  81     }
  82
  83     fn add_edge(&mut self, source: ty::Region<'tcx>, target: ty::Region<'tcx>) {
  84         if self.directions.incoming {
  85             if self.regions.contains(&target) {
  86                 self.regions.insert(source);
  87             }
  88         }
  89
  90         if self.directions.outgoing {
  91             if self.regions.contains(&source) {
  92                 self.regions.insert(target);
  93             }
  94         }
  95     }
  96 }