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use std::fmt::{self, Debug};
use std::hash::Hash;
use std::ops::RangeInclusive;
pub(crate) mod tree;
pub(crate) use tree::Tree;
pub(crate) mod dfa;
pub(crate) use dfa::Dfa;
#[derive(Debug)]
pub(crate) struct Uninhabited;
/// A range of byte values, or the uninit byte.
#[derive(Hash, Eq, PartialEq, Ord, PartialOrd, Clone, Copy)]
pub(crate) struct Byte {
// An inclusive-inclusive range. We use this instead of `RangeInclusive`
// because `RangeInclusive: !Copy`.
//
// `None` means uninit.
//
// FIXME(@joshlf): Optimize this representation. Some pairs of values (where
// `lo > hi`) are illegal, and we could use these to represent `None`.
range: Option<(u8, u8)>,
}
impl Byte {
fn new(range: RangeInclusive<u8>) -> Self {
Self { range: Some((*range.start(), *range.end())) }
}
fn from_val(val: u8) -> Self {
Self { range: Some((val, val)) }
}
pub(crate) fn uninit() -> Byte {
Byte { range: None }
}
/// Returns `None` if `self` is the uninit byte.
pub(crate) fn range(&self) -> Option<RangeInclusive<u8>> {
self.range.map(|(lo, hi)| lo..=hi)
}
/// Are any of the values in `self` transmutable into `other`?
///
/// Note two special cases: An uninit byte is only transmutable into another
/// uninit byte. Any byte is transmutable into an uninit byte.
pub(crate) fn transmutable_into(&self, other: &Byte) -> bool {
match (self.range, other.range) {
(None, None) => true,
(None, Some(_)) => false,
(Some(_), None) => true,
(Some((slo, shi)), Some((olo, ohi))) => slo <= ohi && olo <= shi,
}
}
}
impl fmt::Debug for Byte {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self.range {
None => write!(f, "uninit"),
Some((lo, hi)) => write!(f, "{lo}..={hi}"),
}
}
}
impl From<RangeInclusive<u8>> for Byte {
fn from(src: RangeInclusive<u8>) -> Self {
Self::new(src)
}
}
impl From<u8> for Byte {
fn from(src: u8) -> Self {
Self::from_val(src)
}
}
pub(crate) trait Def: Debug + Hash + Eq + PartialEq + Copy + Clone {
fn has_safety_invariants(&self) -> bool;
}
pub trait Ref: Debug + Hash + Eq + PartialEq + Copy + Clone {
fn min_align(&self) -> usize;
fn size(&self) -> usize;
fn is_mutable(&self) -> bool;
}
impl Def for ! {
fn has_safety_invariants(&self) -> bool {
unreachable!()
}
}
impl Ref for ! {
fn min_align(&self) -> usize {
unreachable!()
}
fn size(&self) -> usize {
unreachable!()
}
fn is_mutable(&self) -> bool {
unreachable!()
}
}
#[cfg(test)]
impl<const N: usize> Ref for [(); N] {
fn min_align(&self) -> usize {
N
}
fn size(&self) -> usize {
N
}
fn is_mutable(&self) -> bool {
false
}
}
#[cfg(feature = "rustc")]
pub mod rustc {
use std::fmt::{self, Write};
use rustc_abi::Layout;
use rustc_middle::mir::Mutability;
use rustc_middle::ty::layout::{HasTyCtxt, LayoutCx, LayoutError};
use rustc_middle::ty::{self, Ty};
/// A reference in the layout.
#[derive(Debug, Hash, Eq, PartialEq, Clone, Copy)]
pub struct Ref<'tcx> {
pub lifetime: ty::Region<'tcx>,
pub ty: Ty<'tcx>,
pub mutability: Mutability,
pub align: usize,
pub size: usize,
}
impl<'tcx> super::Ref for Ref<'tcx> {
fn min_align(&self) -> usize {
self.align
}
fn size(&self) -> usize {
self.size
}
fn is_mutable(&self) -> bool {
match self.mutability {
Mutability::Mut => true,
Mutability::Not => false,
}
}
}
impl<'tcx> Ref<'tcx> {}
impl<'tcx> fmt::Display for Ref<'tcx> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.write_char('&')?;
if self.mutability == Mutability::Mut {
f.write_str("mut ")?;
}
self.ty.fmt(f)
}
}
/// A visibility node in the layout.
#[derive(Debug, Hash, Eq, PartialEq, Clone, Copy)]
pub enum Def<'tcx> {
Adt(ty::AdtDef<'tcx>),
Variant(&'tcx ty::VariantDef),
Field(&'tcx ty::FieldDef),
Primitive,
}
impl<'tcx> super::Def for Def<'tcx> {
fn has_safety_invariants(&self) -> bool {
// Rust presently has no notion of 'unsafe fields', so for now we
// make the conservative assumption that everything besides
// primitive types carry safety invariants.
self != &Self::Primitive
}
}
pub(crate) fn layout_of<'tcx>(
cx: LayoutCx<'tcx>,
ty: Ty<'tcx>,
) -> Result<Layout<'tcx>, &'tcx LayoutError<'tcx>> {
use rustc_middle::ty::layout::LayoutOf;
let ty = cx.tcx().erase_regions(ty);
cx.layout_of(ty).map(|tl| tl.layout)
}
}
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