src/librustc/hir/map/definitions.rs

   1 //! For each definition, we track the following data. A definition
   2 //! here is defined somewhat circularly as "something with a `DefId`",
   3 //! but it generally corresponds to things like structs, enums, etc.
   4 //! There are also some rather random cases (like const initializer
   5 //! expressions) that are mostly just leftovers.
   6
   7 use crate::hir;
   8 use crate::hir::def_id::{CrateNum, DefId, DefIndex, CRATE_DEF_INDEX, LOCAL_CRATE};
   9 use crate::ich::Fingerprint;
  10 use crate::session::CrateDisambiguator;
  11 use crate::util::nodemap::NodeMap;
  12
  13 use rustc_data_structures::fx::FxHashMap;
  14 use rustc_data_structures::stable_hasher::StableHasher;
  15 use rustc_index::vec::IndexVec;
  16 use std::borrow::Borrow;
  17 use std::fmt::Write;
  18 use std::hash::Hash;
  19 use syntax::ast;
  20 use syntax_pos::hygiene::ExpnId;
  21 use syntax_pos::symbol::{sym, Symbol};
  22 use syntax_pos::Span;
  23
  24 /// The `DefPathTable` maps `DefIndex`es to `DefKey`s and vice versa.
  25 /// Internally the `DefPathTable` holds a tree of `DefKey`s, where each `DefKey`
  26 /// stores the `DefIndex` of its parent.
  27 /// There is one `DefPathTable` for each crate.
  28 #[derive(Clone, Default, RustcDecodable, RustcEncodable)]
  29 pub struct DefPathTable {
  30     index_to_key: IndexVec<DefIndex, DefKey>,
  31     def_path_hashes: IndexVec<DefIndex, DefPathHash>,
  32 }
  33
  34 impl DefPathTable {
  35     fn allocate(&mut self, key: DefKey, def_path_hash: DefPathHash) -> DefIndex {
  36         let index = {
  37             let index = DefIndex::from(self.index_to_key.len());
  38             debug!("DefPathTable::insert() - {:?} <-> {:?}", key, index);
  39             self.index_to_key.push(key);
  40             index
  41         };
  42         self.def_path_hashes.push(def_path_hash);
  43         debug_assert!(self.def_path_hashes.len() == self.index_to_key.len());
  44         index
  45     }
  46
  47     pub fn next_id(&self) -> DefIndex {
  48         DefIndex::from(self.index_to_key.len())
  49     }
  50
  51     #[inline(always)]
  52     pub fn def_key(&self, index: DefIndex) -> DefKey {
  53         self.index_to_key[index]
  54     }
  55
  56     #[inline(always)]
  57     pub fn def_path_hash(&self, index: DefIndex) -> DefPathHash {
  58         let hash = self.def_path_hashes[index];
  59         debug!("def_path_hash({:?}) = {:?}", index, hash);
  60         hash
  61     }
  62
  63     pub fn add_def_path_hashes_to(&self, cnum: CrateNum, out: &mut FxHashMap<DefPathHash, DefId>) {
  64         out.extend(self.def_path_hashes.iter().enumerate().map(|(index, &hash)| {
  65             let def_id = DefId { krate: cnum, index: DefIndex::from(index) };
  66             (hash, def_id)
  67         }));
  68     }
  69
  70     pub fn size(&self) -> usize {
  71         self.index_to_key.len()
  72     }
  73 }
  74
  75 /// The definition table containing node definitions.
  76 /// It holds the `DefPathTable` for local `DefId`s/`DefPath`s and it also stores a
  77 /// mapping from `NodeId`s to local `DefId`s.
  78 #[derive(Clone, Default)]
  79 pub struct Definitions {
  80     table: DefPathTable,
  81     node_to_def_index: NodeMap<DefIndex>,
  82     def_index_to_node: IndexVec<DefIndex, ast::NodeId>,
  83     pub(super) node_to_hir_id: IndexVec<ast::NodeId, hir::HirId>,
  84     /// If `ExpnId` is an ID of some macro expansion,
  85     /// then `DefId` is the normal module (`mod`) in which the expanded macro was defined.
  86     parent_modules_of_macro_defs: FxHashMap<ExpnId, DefId>,
  87     /// Item with a given `DefIndex` was defined during macro expansion with ID `ExpnId`.
  88     expansions_that_defined: FxHashMap<DefIndex, ExpnId>,
  89     next_disambiguator: FxHashMap<(DefIndex, DefPathData), u32>,
  90     def_index_to_span: FxHashMap<DefIndex, Span>,
  91     /// When collecting definitions from an AST fragment produced by a macro invocation `ExpnId`
  92     /// we know what parent node that fragment should be attached to thanks to this table.
  93     invocation_parents: FxHashMap<ExpnId, DefIndex>,
  94     /// Indices of unnamed struct or variant fields with unresolved attributes.
  95     placeholder_field_indices: NodeMap<usize>,
  96 }
  97
  98 /// A unique identifier that we can use to lookup a definition
  99 /// precisely. It combines the index of the definition's parent (if
 100 /// any) with a `DisambiguatedDefPathData`.
 101 #[derive(Copy, Clone, PartialEq, Debug, RustcEncodable, RustcDecodable)]
 102 pub struct DefKey {
 103     /// The parent path.
 104     pub parent: Option<DefIndex>,
 105
 106     /// The identifier of this node.
 107     pub disambiguated_data: DisambiguatedDefPathData,
 108 }
 109
 110 impl DefKey {
 111     fn compute_stable_hash(&self, parent_hash: DefPathHash) -> DefPathHash {
 112         let mut hasher = StableHasher::new();
 113
 114         // We hash a `0u8` here to disambiguate between regular `DefPath` hashes,
 115         // and the special "root_parent" below.
 116         0u8.hash(&mut hasher);
 117         parent_hash.hash(&mut hasher);
 118
 119         let DisambiguatedDefPathData { ref data, disambiguator } = self.disambiguated_data;
 120
 121         ::std::mem::discriminant(data).hash(&mut hasher);
 122         if let Some(name) = data.get_opt_name() {
 123             // Get a stable hash by considering the symbol chars rather than
 124             // the symbol index.
 125             name.as_str().hash(&mut hasher);
 126         }
 127
 128         disambiguator.hash(&mut hasher);
 129
 130         DefPathHash(hasher.finish())
 131     }
 132
 133     fn root_parent_stable_hash(
 134         crate_name: &str,
 135         crate_disambiguator: CrateDisambiguator,
 136     ) -> DefPathHash {
 137         let mut hasher = StableHasher::new();
 138         // Disambiguate this from a regular `DefPath` hash; see `compute_stable_hash()` above.
 139         1u8.hash(&mut hasher);
 140         crate_name.hash(&mut hasher);
 141         crate_disambiguator.hash(&mut hasher);
 142         DefPathHash(hasher.finish())
 143     }
 144 }
 145
 146 /// A pair of `DefPathData` and an integer disambiguator. The integer is
 147 /// normally `0`, but in the event that there are multiple defs with the
 148 /// same `parent` and `data`, we use this field to disambiguate
 149 /// between them. This introduces some artificial ordering dependency
 150 /// but means that if you have, e.g., two impls for the same type in
 151 /// the same module, they do get distinct `DefId`s.
 152 #[derive(Copy, Clone, PartialEq, Debug, RustcEncodable, RustcDecodable)]
 153 pub struct DisambiguatedDefPathData {
 154     pub data: DefPathData,
 155     pub disambiguator: u32,
 156 }
 157
 158 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
 159 pub struct DefPath {
 160     /// The path leading from the crate root to the item.
 161     pub data: Vec<DisambiguatedDefPathData>,
 162
 163     /// The crate root this path is relative to.
 164     pub krate: CrateNum,
 165 }
 166
 167 impl DefPath {
 168     pub fn is_local(&self) -> bool {
 169         self.krate == LOCAL_CRATE
 170     }
 171
 172     pub fn make<FN>(krate: CrateNum, start_index: DefIndex, mut get_key: FN) -> DefPath
 173     where
 174         FN: FnMut(DefIndex) -> DefKey,
 175     {
 176         let mut data = vec![];
 177         let mut index = Some(start_index);
 178         loop {
 179             debug!("DefPath::make: krate={:?} index={:?}", krate, index);
 180             let p = index.unwrap();
 181             let key = get_key(p);
 182             debug!("DefPath::make: key={:?}", key);
 183             match key.disambiguated_data.data {
 184                 DefPathData::CrateRoot => {
 185                     assert!(key.parent.is_none());
 186                     break;
 187                 }
 188                 _ => {
 189                     data.push(key.disambiguated_data);
 190                     index = key.parent;
 191                 }
 192             }
 193         }
 194         data.reverse();
 195         DefPath { data: data, krate: krate }
 196     }
 197
 198     /// Returns a string representation of the `DefPath` without
 199     /// the crate-prefix. This method is useful if you don't have
 200     /// a `TyCtxt` available.
 201     pub fn to_string_no_crate(&self) -> String {
 202         let mut s = String::with_capacity(self.data.len() * 16);
 203
 204         for component in &self.data {
 205             write!(s, "::{}[{}]", component.data.as_symbol(), component.disambiguator).unwrap();
 206         }
 207
 208         s
 209     }
 210
 211     /// Returns a filename-friendly string for the `DefPath`, with the
 212     /// crate-prefix.
 213     pub fn to_string_friendly<F>(&self, crate_imported_name: F) -> String
 214     where
 215         F: FnOnce(CrateNum) -> Symbol,
 216     {
 217         let crate_name_str = crate_imported_name(self.krate).as_str();
 218         let mut s = String::with_capacity(crate_name_str.len() + self.data.len() * 16);
 219
 220         write!(s, "::{}", crate_name_str).unwrap();
 221
 222         for component in &self.data {
 223             if component.disambiguator == 0 {
 224                 write!(s, "::{}", component.data.as_symbol()).unwrap();
 225             } else {
 226                 write!(s, "{}[{}]", component.data.as_symbol(), component.disambiguator).unwrap();
 227             }
 228         }
 229
 230         s
 231     }
 232
 233     /// Returns a filename-friendly string of the `DefPath`, without
 234     /// the crate-prefix. This method is useful if you don't have
 235     /// a `TyCtxt` available.
 236     pub fn to_filename_friendly_no_crate(&self) -> String {
 237         let mut s = String::with_capacity(self.data.len() * 16);
 238
 239         let mut opt_delimiter = None;
 240         for component in &self.data {
 241             opt_delimiter.map(|d| s.push(d));
 242             opt_delimiter = Some('-');
 243             if component.disambiguator == 0 {
 244                 write!(s, "{}", component.data.as_symbol()).unwrap();
 245             } else {
 246                 write!(s, "{}[{}]", component.data.as_symbol(), component.disambiguator).unwrap();
 247             }
 248         }
 249         s
 250     }
 251 }
 252
 253 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
 254 pub enum DefPathData {
 255     // Root: these should only be used for the root nodes, because
 256     // they are treated specially by the `def_path` function.
 257     /// The crate root (marker).
 258     CrateRoot,
 259     // Catch-all for random `DefId` things like `DUMMY_NODE_ID`.
 260     Misc,
 261
 262     // Different kinds of items and item-like things:
 263     /// An impl.
 264     Impl,
 265     /// Something in the type namespace.
 266     TypeNs(Symbol),
 267     /// Something in the value namespace.
 268     ValueNs(Symbol),
 269     /// Something in the macro namespace.
 270     MacroNs(Symbol),
 271     /// Something in the lifetime namespace.
 272     LifetimeNs(Symbol),
 273     /// A closure expression.
 274     ClosureExpr,
 275
 276     // Subportions of items:
 277     /// Implicit constructor for a unit or tuple-like struct or enum variant.
 278     Ctor,
 279     /// A constant expression (see `{ast,hir}::AnonConst`).
 280     AnonConst,
 281     /// An `impl Trait` type node.
 282     ImplTrait,
 283 }
 284
 285 #[derive(
 286     Copy,
 287     Clone,
 288     Hash,
 289     PartialEq,
 290     Eq,
 291     PartialOrd,
 292     Ord,
 293     Debug,
 294     RustcEncodable,
 295     RustcDecodable,
 296     HashStable,
 297 )]
 298 pub struct DefPathHash(pub Fingerprint);
 299
 300 impl Borrow<Fingerprint> for DefPathHash {
 301     #[inline]
 302     fn borrow(&self) -> &Fingerprint {
 303         &self.0
 304     }
 305 }
 306
 307 impl Definitions {
 308     pub fn def_path_table(&self) -> &DefPathTable {
 309         &self.table
 310     }
 311
 312     /// Gets the number of definitions.
 313     pub fn def_index_count(&self) -> usize {
 314         self.table.index_to_key.len()
 315     }
 316
 317     pub fn def_key(&self, index: DefIndex) -> DefKey {
 318         self.table.def_key(index)
 319     }
 320
 321     #[inline(always)]
 322     pub fn def_path_hash(&self, index: DefIndex) -> DefPathHash {
 323         self.table.def_path_hash(index)
 324     }
 325
 326     /// Returns the path from the crate root to `index`. The root
 327     /// nodes are not included in the path (i.e., this will be an
 328     /// empty vector for the crate root). For an inlined item, this
 329     /// will be the path of the item in the external crate (but the
 330     /// path will begin with the path to the external crate).
 331     pub fn def_path(&self, index: DefIndex) -> DefPath {
 332         DefPath::make(LOCAL_CRATE, index, |p| self.def_key(p))
 333     }
 334
 335     #[inline]
 336     pub fn opt_def_index(&self, node: ast::NodeId) -> Option<DefIndex> {
 337         self.node_to_def_index.get(&node).copied()
 338     }
 339
 340     #[inline]
 341     pub fn opt_local_def_id(&self, node: ast::NodeId) -> Option<DefId> {
 342         self.opt_def_index(node).map(DefId::local)
 343     }
 344
 345     #[inline]
 346     pub fn local_def_id(&self, node: ast::NodeId) -> DefId {
 347         self.opt_local_def_id(node).unwrap()
 348     }
 349
 350     #[inline]
 351     pub fn as_local_node_id(&self, def_id: DefId) -> Option<ast::NodeId> {
 352         if def_id.krate == LOCAL_CRATE {
 353             let node_id = self.def_index_to_node[def_id.index];
 354             if node_id != ast::DUMMY_NODE_ID {
 355                 return Some(node_id);
 356             }
 357         }
 358         None
 359     }
 360
 361     #[inline]
 362     pub fn as_local_hir_id(&self, def_id: DefId) -> Option<hir::HirId> {
 363         if def_id.krate == LOCAL_CRATE {
 364             let hir_id = self.def_index_to_hir_id(def_id.index);
 365             if hir_id != hir::DUMMY_HIR_ID { Some(hir_id) } else { None }
 366         } else {
 367             None
 368         }
 369     }
 370
 371     #[inline]
 372     pub fn node_to_hir_id(&self, node_id: ast::NodeId) -> hir::HirId {
 373         self.node_to_hir_id[node_id]
 374     }
 375
 376     #[inline]
 377     pub fn def_index_to_hir_id(&self, def_index: DefIndex) -> hir::HirId {
 378         let node_id = self.def_index_to_node[def_index];
 379         self.node_to_hir_id[node_id]
 380     }
 381
 382     /// Retrieves the span of the given `DefId` if `DefId` is in the local crate, the span exists
 383     /// and it's not `DUMMY_SP`.
 384     #[inline]
 385     pub fn opt_span(&self, def_id: DefId) -> Option<Span> {
 386         if def_id.krate == LOCAL_CRATE {
 387             self.def_index_to_span.get(&def_id.index).copied()
 388         } else {
 389             None
 390         }
 391     }
 392
 393     /// Adds a root definition (no parent) and a few other reserved definitions.
 394     pub fn create_root_def(
 395         &mut self,
 396         crate_name: &str,
 397         crate_disambiguator: CrateDisambiguator,
 398     ) -> DefIndex {
 399         let key = DefKey {
 400             parent: None,
 401             disambiguated_data: DisambiguatedDefPathData {
 402                 data: DefPathData::CrateRoot,
 403                 disambiguator: 0,
 404             },
 405         };
 406
 407         let parent_hash = DefKey::root_parent_stable_hash(crate_name, crate_disambiguator);
 408         let def_path_hash = key.compute_stable_hash(parent_hash);
 409
 410         // Create the definition.
 411         let root_index = self.table.allocate(key, def_path_hash);
 412         assert_eq!(root_index, CRATE_DEF_INDEX);
 413         assert!(self.def_index_to_node.is_empty());
 414         self.def_index_to_node.push(ast::CRATE_NODE_ID);
 415         self.node_to_def_index.insert(ast::CRATE_NODE_ID, root_index);
 416         self.set_invocation_parent(ExpnId::root(), root_index);
 417
 418         root_index
 419     }
 420
 421     /// Adds a definition with a parent definition.
 422     pub fn create_def_with_parent(
 423         &mut self,
 424         parent: DefIndex,
 425         node_id: ast::NodeId,
 426         data: DefPathData,
 427         expn_id: ExpnId,
 428         span: Span,
 429     ) -> DefIndex {
 430         debug!(
 431             "create_def_with_parent(parent={:?}, node_id={:?}, data={:?})",
 432             parent, node_id, data
 433         );
 434
 435         assert!(
 436             !self.node_to_def_index.contains_key(&node_id),
 437             "adding a def'n for node-id {:?} and data {:?} but a previous def'n exists: {:?}",
 438             node_id,
 439             data,
 440             self.table.def_key(self.node_to_def_index[&node_id])
 441         );
 442
 443         // The root node must be created with `create_root_def()`.
 444         assert!(data != DefPathData::CrateRoot);
 445
 446         // Find the next free disambiguator for this key.
 447         let disambiguator = {
 448             let next_disamb = self.next_disambiguator.entry((parent, data)).or_insert(0);
 449             let disambiguator = *next_disamb;
 450             *next_disamb = next_disamb.checked_add(1).expect("disambiguator overflow");
 451             disambiguator
 452         };
 453
 454         let key = DefKey {
 455             parent: Some(parent),
 456             disambiguated_data: DisambiguatedDefPathData { data, disambiguator },
 457         };
 458
 459         let parent_hash = self.table.def_path_hash(parent);
 460         let def_path_hash = key.compute_stable_hash(parent_hash);
 461
 462         debug!("create_def_with_parent: after disambiguation, key = {:?}", key);
 463
 464         // Create the definition.
 465         let index = self.table.allocate(key, def_path_hash);
 466         assert_eq!(index.index(), self.def_index_to_node.len());
 467         self.def_index_to_node.push(node_id);
 468
 469         // Some things for which we allocate `DefIndex`es don't correspond to
 470         // anything in the AST, so they don't have a `NodeId`. For these cases
 471         // we don't need a mapping from `NodeId` to `DefIndex`.
 472         if node_id != ast::DUMMY_NODE_ID {
 473             debug!("create_def_with_parent: def_index_to_node[{:?} <-> {:?}", index, node_id);
 474             self.node_to_def_index.insert(node_id, index);
 475         }
 476
 477         if expn_id != ExpnId::root() {
 478             self.expansions_that_defined.insert(index, expn_id);
 479         }
 480
 481         // The span is added if it isn't dummy.
 482         if !span.is_dummy() {
 483             self.def_index_to_span.insert(index, span);
 484         }
 485
 486         index
 487     }
 488
 489     /// Initializes the `ast::NodeId` to `HirId` mapping once it has been generated during
 490     /// AST to HIR lowering.
 491     pub fn init_node_id_to_hir_id_mapping(&mut self, mapping: IndexVec<ast::NodeId, hir::HirId>) {
 492         assert!(
 493             self.node_to_hir_id.is_empty(),
 494             "trying to initialize `NodeId` -> `HirId` mapping twice"
 495         );
 496         self.node_to_hir_id = mapping;
 497     }
 498
 499     pub fn expansion_that_defined(&self, index: DefIndex) -> ExpnId {
 500         self.expansions_that_defined.get(&index).copied().unwrap_or(ExpnId::root())
 501     }
 502
 503     pub fn parent_module_of_macro_def(&self, expn_id: ExpnId) -> DefId {
 504         self.parent_modules_of_macro_defs[&expn_id]
 505     }
 506
 507     pub fn add_parent_module_of_macro_def(&mut self, expn_id: ExpnId, module: DefId) {
 508         self.parent_modules_of_macro_defs.insert(expn_id, module);
 509     }
 510
 511     pub fn invocation_parent(&self, invoc_id: ExpnId) -> DefIndex {
 512         self.invocation_parents[&invoc_id]
 513     }
 514
 515     pub fn set_invocation_parent(&mut self, invoc_id: ExpnId, parent: DefIndex) {
 516         let old_parent = self.invocation_parents.insert(invoc_id, parent);
 517         assert!(old_parent.is_none(), "parent `DefIndex` is reset for an invocation");
 518     }
 519
 520     pub fn placeholder_field_index(&self, node_id: ast::NodeId) -> usize {
 521         self.placeholder_field_indices[&node_id]
 522     }
 523
 524     pub fn set_placeholder_field_index(&mut self, node_id: ast::NodeId, index: usize) {
 525         let old_index = self.placeholder_field_indices.insert(node_id, index);
 526         assert!(old_index.is_none(), "placeholder field index is reset for a node ID");
 527     }
 528 }
 529
 530 impl DefPathData {
 531     pub fn get_opt_name(&self) -> Option<Symbol> {
 532         use self::DefPathData::*;
 533         match *self {
 534             TypeNs(name) | ValueNs(name) | MacroNs(name) | LifetimeNs(name) => Some(name),
 535
 536             Impl | CrateRoot | Misc | ClosureExpr | Ctor | AnonConst | ImplTrait => None,
 537         }
 538     }
 539
 540     pub fn as_symbol(&self) -> Symbol {
 541         use self::DefPathData::*;
 542         match *self {
 543             TypeNs(name) | ValueNs(name) | MacroNs(name) | LifetimeNs(name) => name,
 544             // Note that this does not show up in user print-outs.
 545             CrateRoot => sym::double_braced_crate,
 546             Impl => sym::double_braced_impl,
 547             Misc => sym::double_braced_misc,
 548             ClosureExpr => sym::double_braced_closure,
 549             Ctor => sym::double_braced_constructor,
 550             AnonConst => sym::double_braced_constant,
 551             ImplTrait => sym::double_braced_opaque,
 552         }
 553     }
 554
 555     pub fn to_string(&self) -> String {
 556         self.as_symbol().to_string()
 557     }
 558 }