src/librustc_mir/util/collect_writes.rs

   1 use rustc::mir::{Local, Location};
   2 use rustc::mir::Body;
   3 use rustc::mir::visit::PlaceContext;
   4 use rustc::mir::visit::Visitor;
   5
   6 crate trait FindAssignments {
   7     // Finds all statements that assign directly to local (i.e., X = ...)
   8     // and returns their locations.
   9     fn find_assignments(&self, local: Local) -> Vec<Location>;
  10 }
  11
  12 impl<'tcx> FindAssignments for Body<'tcx>{
  13     fn find_assignments(&self, local: Local) -> Vec<Location>{
  14             let mut visitor = FindLocalAssignmentVisitor{ needle: local, locations: vec![]};
  15             visitor.visit_body(self);
  16             visitor.locations
  17     }
  18 }
  19
  20 // The Visitor walks the MIR to return the assignment statements corresponding
  21 // to a Local.
  22 struct FindLocalAssignmentVisitor {
  23     needle: Local,
  24     locations: Vec<Location>,
  25 }
  26
  27 impl<'tcx> Visitor<'tcx> for FindLocalAssignmentVisitor {
  28     fn visit_local(&mut self,
  29                    local: &Local,
  30                    place_context: PlaceContext,
  31                    location: Location) {
  32         if self.needle != *local {
  33             return;
  34         }
  35
  36         if place_context.is_place_assignment() {
  37             self.locations.push(location);
  38         }
  39     }
  40 }