1 use crate::build::expr::as_place::PlaceBase;
2 use crate::build::expr::as_place::PlaceBuilder;
3 use crate::build::matches::MatchPair;
4 use crate::build::Builder;
5 use rustc_middle::mir::*;
6 use rustc_middle::thir::*;
8 use rustc_middle::ty::TypeVisitable;
9 use smallvec::SmallVec;
10 use std::convert::TryInto;
12 impl<'a, 'tcx> Builder<'a, 'tcx> {
13 pub(crate) fn field_match_pairs<'pat>(
15 place: PlaceBuilder<'tcx>,
16 subpatterns: &'pat [FieldPat<'tcx>],
17 ) -> Vec<MatchPair<'pat, 'tcx>> {
21 let place = place.clone().field(fieldpat.field, fieldpat.pattern.ty);
22 MatchPair::new(place, &fieldpat.pattern, self)
27 pub(crate) fn prefix_slice_suffix<'pat>(
29 match_pairs: &mut SmallVec<[MatchPair<'pat, 'tcx>; 1]>,
30 place: &PlaceBuilder<'tcx>,
31 prefix: &'pat [Box<Pat<'tcx>>],
32 opt_slice: &'pat Option<Box<Pat<'tcx>>>,
33 suffix: &'pat [Box<Pat<'tcx>>],
36 let (min_length, exact_size) =
37 if let Ok(place_resolved) = place.clone().try_upvars_resolved(self) {
38 match place_resolved.into_place(self).ty(&self.local_decls, tcx).ty.kind() {
39 ty::Array(_, length) => (length.eval_usize(tcx, self.param_env), true),
40 _ => ((prefix.len() + suffix.len()).try_into().unwrap(), false),
43 ((prefix.len() + suffix.len()).try_into().unwrap(), false)
46 match_pairs.extend(prefix.iter().enumerate().map(|(idx, subpattern)| {
48 ProjectionElem::ConstantIndex { offset: idx as u64, min_length, from_end: false };
49 let place = place.clone().project(elem);
50 MatchPair::new(place, subpattern, self)
53 if let Some(subslice_pat) = opt_slice {
54 let suffix_len = suffix.len() as u64;
55 let subslice = place.clone().project(ProjectionElem::Subslice {
56 from: prefix.len() as u64,
57 to: if exact_size { min_length - suffix_len } else { suffix_len },
58 from_end: !exact_size,
60 match_pairs.push(MatchPair::new(subslice, subslice_pat, self));
63 match_pairs.extend(suffix.iter().rev().enumerate().map(|(idx, subpattern)| {
64 let end_offset = (idx + 1) as u64;
65 let elem = ProjectionElem::ConstantIndex {
66 offset: if exact_size { min_length - end_offset } else { end_offset },
68 from_end: !exact_size,
70 let place = place.clone().project(elem);
71 MatchPair::new(place, subpattern, self)
75 /// Creates a false edge to `imaginary_target` and a real edge to
76 /// real_target. If `imaginary_target` is none, or is the same as the real
77 /// target, a Goto is generated instead to simplify the generated MIR.
78 pub(crate) fn false_edges(
80 from_block: BasicBlock,
81 real_target: BasicBlock,
82 imaginary_target: Option<BasicBlock>,
83 source_info: SourceInfo,
85 match imaginary_target {
86 Some(target) if target != real_target => {
90 TerminatorKind::FalseEdge { real_target, imaginary_target: target },
93 _ => self.cfg.goto(from_block, source_info, real_target),
98 impl<'pat, 'tcx> MatchPair<'pat, 'tcx> {
99 pub(in crate::build) fn new(
100 place: PlaceBuilder<'tcx>,
101 pattern: &'pat Pat<'tcx>,
102 cx: &Builder<'_, 'tcx>,
103 ) -> MatchPair<'pat, 'tcx> {
104 // Force the place type to the pattern's type.
105 // FIXME(oli-obk): can we use this to simplify slice/array pattern hacks?
106 let mut place = match place.try_upvars_resolved(cx) {
107 Ok(val) | Err(val) => val,
110 // Only add the OpaqueCast projection if the given place is an opaque type and the
111 // expected type from the pattern is not.
112 let may_need_cast = match place.base() {
113 PlaceBase::Local(local) => {
114 let ty = Place::ty_from(local, place.projection(), &cx.local_decls, cx.tcx).ty;
115 ty != pattern.ty && ty.has_opaque_types()
120 place = place.project(ProjectionElem::OpaqueCast(pattern.ty));
122 MatchPair { place, pattern }