compiler/rustc_hir/src/hir_id.rs

   1 use crate::def_id::{DefId, DefIndex, LocalDefId, CRATE_DEF_ID};
   2 use rustc_data_structures::stable_hasher::{HashStable, StableHasher, StableOrd, ToStableHashKey};
   3 use rustc_span::{def_id::DefPathHash, HashStableContext};
   4 use std::fmt;
   5
   6 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
   7 #[derive(Encodable, Decodable)]
   8 pub struct OwnerId {
   9     pub def_id: LocalDefId,
  10 }
  11
  12 impl From<OwnerId> for HirId {
  13     fn from(owner: OwnerId) -> HirId {
  14         HirId { owner, local_id: ItemLocalId::from_u32(0) }
  15     }
  16 }
  17
  18 impl OwnerId {
  19     #[inline]
  20     pub fn to_def_id(self) -> DefId {
  21         self.def_id.to_def_id()
  22     }
  23 }
  24
  25 impl rustc_index::vec::Idx for OwnerId {
  26     #[inline]
  27     fn new(idx: usize) -> Self {
  28         OwnerId { def_id: LocalDefId { local_def_index: DefIndex::from_usize(idx) } }
  29     }
  30
  31     #[inline]
  32     fn index(self) -> usize {
  33         self.def_id.local_def_index.as_usize()
  34     }
  35 }
  36
  37 impl<CTX: HashStableContext> HashStable<CTX> for OwnerId {
  38     #[inline]
  39     fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
  40         self.to_stable_hash_key(hcx).hash_stable(hcx, hasher);
  41     }
  42 }
  43
  44 impl<CTX: HashStableContext> ToStableHashKey<CTX> for OwnerId {
  45     type KeyType = DefPathHash;
  46
  47     #[inline]
  48     fn to_stable_hash_key(&self, hcx: &CTX) -> DefPathHash {
  49         hcx.def_path_hash(self.to_def_id())
  50     }
  51 }
  52
  53 /// Uniquely identifies a node in the HIR of the current crate. It is
  54 /// composed of the `owner`, which is the `LocalDefId` of the directly enclosing
  55 /// `hir::Item`, `hir::TraitItem`, or `hir::ImplItem` (i.e., the closest "item-like"),
  56 /// and the `local_id` which is unique within the given owner.
  57 ///
  58 /// This two-level structure makes for more stable values: One can move an item
  59 /// around within the source code, or add or remove stuff before it, without
  60 /// the `local_id` part of the `HirId` changing, which is a very useful property in
  61 /// incremental compilation where we have to persist things through changes to
  62 /// the code base.
  63 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
  64 #[derive(Encodable, Decodable, HashStable_Generic)]
  65 #[rustc_pass_by_value]
  66 pub struct HirId {
  67     pub owner: OwnerId,
  68     pub local_id: ItemLocalId,
  69 }
  70
  71 impl HirId {
  72     /// Signal local id which should never be used.
  73     pub const INVALID: HirId =
  74         HirId { owner: OwnerId { def_id: CRATE_DEF_ID }, local_id: ItemLocalId::INVALID };
  75
  76     #[inline]
  77     pub fn expect_owner(self) -> OwnerId {
  78         assert_eq!(self.local_id.index(), 0);
  79         self.owner
  80     }
  81
  82     #[inline]
  83     pub fn as_owner(self) -> Option<OwnerId> {
  84         if self.local_id.index() == 0 { Some(self.owner) } else { None }
  85     }
  86
  87     #[inline]
  88     pub fn is_owner(self) -> bool {
  89         self.local_id.index() == 0
  90     }
  91
  92     #[inline]
  93     pub fn make_owner(owner: LocalDefId) -> Self {
  94         Self { owner: OwnerId { def_id: owner }, local_id: ItemLocalId::from_u32(0) }
  95     }
  96
  97     pub fn index(self) -> (usize, usize) {
  98         (
  99             rustc_index::vec::Idx::index(self.owner.def_id),
 100             rustc_index::vec::Idx::index(self.local_id),
 101         )
 102     }
 103 }
 104
 105 impl fmt::Display for HirId {
 106     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 107         write!(f, "{:?}", self)
 108     }
 109 }
 110
 111 impl Ord for HirId {
 112     fn cmp(&self, other: &Self) -> std::cmp::Ordering {
 113         (self.index()).cmp(&(other.index()))
 114     }
 115 }
 116
 117 impl PartialOrd for HirId {
 118     fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
 119         Some(self.cmp(other))
 120     }
 121 }
 122
 123 rustc_data_structures::define_stable_id_collections!(HirIdMap, HirIdSet, HirIdMapEntry, HirId);
 124 rustc_data_structures::define_id_collections!(
 125     ItemLocalMap,
 126     ItemLocalSet,
 127     ItemLocalMapEntry,
 128     ItemLocalId
 129 );
 130
 131 rustc_index::newtype_index! {
 132     /// An `ItemLocalId` uniquely identifies something within a given "item-like";
 133     /// that is, within a `hir::Item`, `hir::TraitItem`, or `hir::ImplItem`. There is no
 134     /// guarantee that the numerical value of a given `ItemLocalId` corresponds to
 135     /// the node's position within the owning item in any way, but there is a
 136     /// guarantee that the `LocalItemId`s within an owner occupy a dense range of
 137     /// integers starting at zero, so a mapping that maps all or most nodes within
 138     /// an "item-like" to something else can be implemented by a `Vec` instead of a
 139     /// tree or hash map.
 140     #[derive(HashStable_Generic)]
 141     pub struct ItemLocalId { .. }
 142 }
 143
 144 impl ItemLocalId {
 145     /// Signal local id which should never be used.
 146     pub const INVALID: ItemLocalId = ItemLocalId::MAX;
 147 }
 148
 149 // Safety: Ord is implement as just comparing the LocalItemId's numerical
 150 // values and these are not changed by (de-)serialization.
 151 unsafe impl StableOrd for ItemLocalId {}
 152
 153 /// The `HirId` corresponding to `CRATE_NODE_ID` and `CRATE_DEF_ID`.
 154 pub const CRATE_HIR_ID: HirId =
 155     HirId { owner: OwnerId { def_id: CRATE_DEF_ID }, local_id: ItemLocalId::from_u32(0) };
 156
 157 pub const CRATE_OWNER_ID: OwnerId = OwnerId { def_id: CRATE_DEF_ID };