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use crate::build::expr::as_place::PlaceBuilder;
use crate::build::matches::MatchPair;
use crate::build::Builder;
use rustc_middle::mir::*;
use rustc_middle::thir::*;
use rustc_middle::ty;
use smallvec::SmallVec;
use std::convert::TryInto;
impl<'a, 'tcx> Builder<'a, 'tcx> {
pub(crate) fn field_match_pairs<'pat>(
&mut self,
place: PlaceBuilder<'tcx>,
subpatterns: &'pat [FieldPat<'tcx>],
) -> Vec<MatchPair<'pat, 'tcx>> {
subpatterns
.iter()
.map(|fieldpat| {
let place = place.clone().field(fieldpat.field, fieldpat.pattern.ty);
MatchPair::new(place, &fieldpat.pattern)
})
.collect()
}
pub(crate) fn prefix_slice_suffix<'pat>(
&mut self,
match_pairs: &mut SmallVec<[MatchPair<'pat, 'tcx>; 1]>,
place: &PlaceBuilder<'tcx>,
prefix: &'pat [Pat<'tcx>],
opt_slice: Option<&'pat Pat<'tcx>>,
suffix: &'pat [Pat<'tcx>],
) {
let tcx = self.tcx;
let (min_length, exact_size) = if let Ok(place_resolved) =
place.clone().try_upvars_resolved(tcx, self.typeck_results)
{
match place_resolved
.into_place(tcx, self.typeck_results)
.ty(&self.local_decls, tcx)
.ty
.kind()
{
ty::Array(_, length) => (length.eval_usize(tcx, self.param_env), true),
_ => ((prefix.len() + suffix.len()).try_into().unwrap(), false),
}
} else {
((prefix.len() + suffix.len()).try_into().unwrap(), false)
};
match_pairs.extend(prefix.iter().enumerate().map(|(idx, subpattern)| {
let elem =
ProjectionElem::ConstantIndex { offset: idx as u64, min_length, from_end: false };
let place = place.clone().project(elem);
MatchPair::new(place, subpattern)
}));
if let Some(subslice_pat) = opt_slice {
let suffix_len = suffix.len() as u64;
let subslice = place.clone().project(ProjectionElem::Subslice {
from: prefix.len() as u64,
to: if exact_size { min_length - suffix_len } else { suffix_len },
from_end: !exact_size,
});
match_pairs.push(MatchPair::new(subslice, subslice_pat));
}
match_pairs.extend(suffix.iter().rev().enumerate().map(|(idx, subpattern)| {
let end_offset = (idx + 1) as u64;
let elem = ProjectionElem::ConstantIndex {
offset: if exact_size { min_length - end_offset } else { end_offset },
min_length,
from_end: !exact_size,
};
let place = place.clone().project(elem);
MatchPair::new(place, subpattern)
}));
}
/// Creates a false edge to `imaginary_target` and a real edge to
/// real_target. If `imaginary_target` is none, or is the same as the real
/// target, a Goto is generated instead to simplify the generated MIR.
pub(crate) fn false_edges(
&mut self,
from_block: BasicBlock,
real_target: BasicBlock,
imaginary_target: Option<BasicBlock>,
source_info: SourceInfo,
) {
match imaginary_target {
Some(target) if target != real_target => {
self.cfg.terminate(
from_block,
source_info,
TerminatorKind::FalseEdge { real_target, imaginary_target: target },
);
}
_ => self.cfg.goto(from_block, source_info, real_target),
}
}
}
impl<'pat, 'tcx> MatchPair<'pat, 'tcx> {
pub(crate) fn new(
place: PlaceBuilder<'tcx>,
pattern: &'pat Pat<'tcx>,
) -> MatchPair<'pat, 'tcx> {
MatchPair { place, pattern }
}
}
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