src/librustc_resolve/build_reduced_graph.rs

   1 // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 //! Reduced graph building
  12 //!
  13 //! Here we build the "reduced graph": the graph of the module tree without
  14 //! any imports resolved.
  15
  16 use resolve_imports::ImportDirectiveSubclass::{self, GlobImport};
  17 use Module;
  18 use Namespace::{self, TypeNS, ValueNS};
  19 use {NameBinding, NameBindingKind};
  20 use ParentLink::{ModuleParentLink, BlockParentLink};
  21 use Resolver;
  22 use {resolve_error, resolve_struct_error, ResolutionError};
  23
  24 use rustc::middle::cstore::{ChildItem, DlDef};
  25 use rustc::hir::def::*;
  26 use rustc::hir::def_id::{CRATE_DEF_INDEX, DefId};
  27 use rustc::ty::{self, VariantKind};
  28
  29 use syntax::ast::Name;
  30 use syntax::attr;
  31 use syntax::parse::token;
  32
  33 use syntax::ast::{Block, Crate};
  34 use syntax::ast::{ForeignItem, ForeignItemKind, Item, ItemKind};
  35 use syntax::ast::{Mutability, PathListItemKind};
  36 use syntax::ast::{StmtKind, TraitItemKind};
  37 use syntax::ast::{Variant, ViewPathGlob, ViewPathList, ViewPathSimple};
  38 use syntax::visit::{self, Visitor};
  39
  40 use syntax_pos::{Span, DUMMY_SP};
  41
  42 trait ToNameBinding<'a> {
  43     fn to_name_binding(self) -> NameBinding<'a>;
  44 }
  45
  46 impl<'a> ToNameBinding<'a> for (Module<'a>, Span, ty::Visibility) {
  47     fn to_name_binding(self) -> NameBinding<'a> {
  48         NameBinding { kind: NameBindingKind::Module(self.0), span: self.1, vis: self.2 }
  49     }
  50 }
  51
  52 impl<'a> ToNameBinding<'a> for (Def, Span, ty::Visibility) {
  53     fn to_name_binding(self) -> NameBinding<'a> {
  54         NameBinding { kind: NameBindingKind::Def(self.0), span: self.1, vis: self.2 }
  55     }
  56 }
  57
  58 impl<'b> Resolver<'b> {
  59     /// Constructs the reduced graph for the entire crate.
  60     pub fn build_reduced_graph(&mut self, krate: &Crate) {
  61         let no_implicit_prelude = attr::contains_name(&krate.attrs, "no_implicit_prelude");
  62         self.graph_root.no_implicit_prelude.set(no_implicit_prelude);
  63
  64         let mut visitor = BuildReducedGraphVisitor {
  65             parent: self.graph_root,
  66             resolver: self,
  67         };
  68         visit::walk_crate(&mut visitor, krate);
  69     }
  70
  71     /// Defines `name` in namespace `ns` of module `parent` to be `def` if it is not yet defined.
  72     fn try_define<T>(&self, parent: Module<'b>, name: Name, ns: Namespace, def: T)
  73         where T: ToNameBinding<'b>
  74     {
  75         let _ = parent.try_define_child(name, ns, def.to_name_binding());
  76     }
  77
  78     /// Defines `name` in namespace `ns` of module `parent` to be `def` if it is not yet defined;
  79     /// otherwise, reports an error.
  80     fn define<T: ToNameBinding<'b>>(&self, parent: Module<'b>, name: Name, ns: Namespace, def: T) {
  81         let binding = def.to_name_binding();
  82         if let Err(old_binding) = parent.try_define_child(name, ns, binding.clone()) {
  83             self.report_conflict(parent, name, ns, old_binding, &binding);
  84         }
  85     }
  86
  87     fn block_needs_anonymous_module(&mut self, block: &Block) -> bool {
  88         // If any statements are items, we need to create an anonymous module
  89         block.stmts.iter().any(|statement| match statement.node {
  90             StmtKind::Item(_) => true,
  91             _ => false,
  92         })
  93     }
  94
  95     /// Constructs the reduced graph for one item.
  96     fn build_reduced_graph_for_item(&mut self, item: &Item, parent_ref: &mut Module<'b>) {
  97         let parent = *parent_ref;
  98         let name = item.ident.name;
  99         let sp = item.span;
 100         self.current_module = parent;
 101         let vis = self.resolve_visibility(&item.vis);
 102
 103         match item.node {
 104             ItemKind::Use(ref view_path) => {
 105                 // Extract and intern the module part of the path. For
 106                 // globs and lists, the path is found directly in the AST;
 107                 // for simple paths we have to munge the path a little.
 108                 let module_path: Vec<Name> = match view_path.node {
 109                     ViewPathSimple(_, ref full_path) => {
 110                         full_path.segments
 111                                  .split_last()
 112                                  .unwrap()
 113                                  .1
 114                                  .iter()
 115                                  .map(|seg| seg.identifier.name)
 116                                  .collect()
 117                     }
 118
 119                     ViewPathGlob(ref module_ident_path) |
 120                     ViewPathList(ref module_ident_path, _) => {
 121                         module_ident_path.segments
 122                                          .iter()
 123                                          .map(|seg| seg.identifier.name)
 124                                          .collect()
 125                     }
 126                 };
 127
 128                 // Build up the import directives.
 129                 let is_prelude = attr::contains_name(&item.attrs, "prelude_import");
 130
 131                 match view_path.node {
 132                     ViewPathSimple(binding, ref full_path) => {
 133                         let source_name = full_path.segments.last().unwrap().identifier.name;
 134                         if source_name.as_str() == "mod" || source_name.as_str() == "self" {
 135                             resolve_error(self,
 136                                           view_path.span,
 137                                           ResolutionError::SelfImportsOnlyAllowedWithin);
 138                         }
 139
 140                         let subclass = ImportDirectiveSubclass::single(binding.name, source_name);
 141                         let span = view_path.span;
 142                         parent.add_import_directive(module_path, subclass, span, item.id, vis);
 143                         self.unresolved_imports += 1;
 144                     }
 145                     ViewPathList(_, ref source_items) => {
 146                         // Make sure there's at most one `mod` import in the list.
 147                         let mod_spans = source_items.iter().filter_map(|item| {
 148                             match item.node {
 149                                 PathListItemKind::Mod { .. } => Some(item.span),
 150                                 _ => None,
 151                             }
 152                         }).collect::<Vec<Span>>();
 153
 154                         if mod_spans.len() > 1 {
 155                             let mut e = resolve_struct_error(self,
 156                                           mod_spans[0],
 157                                           ResolutionError::SelfImportCanOnlyAppearOnceInTheList);
 158                             for other_span in mod_spans.iter().skip(1) {
 159                                 e.span_note(*other_span, "another `self` import appears here");
 160                             }
 161                             e.emit();
 162                         }
 163
 164                         for source_item in source_items {
 165                             let (module_path, name, rename) = match source_item.node {
 166                                 PathListItemKind::Ident { name, rename, .. } =>
 167                                     (module_path.clone(), name.name, rename.unwrap_or(name).name),
 168                                 PathListItemKind::Mod { rename, .. } => {
 169                                     let name = match module_path.last() {
 170                                         Some(name) => *name,
 171                                         None => {
 172                                             resolve_error(
 173                                                 self,
 174                                                 source_item.span,
 175                                                 ResolutionError::
 176                                                 SelfImportOnlyInImportListWithNonEmptyPrefix
 177                                             );
 178                                             continue;
 179                                         }
 180                                     };
 181                                     let module_path = module_path.split_last().unwrap().1;
 182                                     let rename = rename.map(|i| i.name).unwrap_or(name);
 183                                     (module_path.to_vec(), name, rename)
 184                                 }
 185                             };
 186                             let subclass = ImportDirectiveSubclass::single(rename, name);
 187                             let (span, id) = (source_item.span, source_item.node.id());
 188                             parent.add_import_directive(module_path, subclass, span, id, vis);
 189                             self.unresolved_imports += 1;
 190                         }
 191                     }
 192                     ViewPathGlob(_) => {
 193                         let subclass = GlobImport { is_prelude: is_prelude };
 194                         let span = view_path.span;
 195                         parent.add_import_directive(module_path, subclass, span, item.id, vis);
 196                         self.unresolved_imports += 1;
 197                     }
 198                 }
 199             }
 200
 201             ItemKind::ExternCrate(_) => {
 202                 // n.b. we don't need to look at the path option here, because cstore already
 203                 // did
 204                 if let Some(crate_id) = self.session.cstore.extern_mod_stmt_cnum(item.id) {
 205                     let def_id = DefId {
 206                         krate: crate_id,
 207                         index: CRATE_DEF_INDEX,
 208                     };
 209                     let parent_link = ModuleParentLink(parent, name);
 210                     let def = Def::Mod(def_id);
 211                     let module = self.new_extern_crate_module(parent_link, def, item.id);
 212                     self.define(parent, name, TypeNS, (module, sp, vis));
 213
 214                     self.build_reduced_graph_for_external_crate(module);
 215                 }
 216             }
 217
 218             ItemKind::Mod(..) => {
 219                 let parent_link = ModuleParentLink(parent, name);
 220                 let def = Def::Mod(self.definitions.local_def_id(item.id));
 221                 let module = self.new_module(parent_link, Some(def), false);
 222                 module.no_implicit_prelude.set({
 223                     parent.no_implicit_prelude.get() ||
 224                         attr::contains_name(&item.attrs, "no_implicit_prelude")
 225                 });
 226                 self.define(parent, name, TypeNS, (module, sp, vis));
 227                 self.module_map.insert(item.id, module);
 228                 *parent_ref = module;
 229             }
 230
 231             ItemKind::ForeignMod(..) => {}
 232
 233             // These items live in the value namespace.
 234             ItemKind::Static(_, m, _) => {
 235                 let mutbl = m == Mutability::Mutable;
 236                 let def = Def::Static(self.definitions.local_def_id(item.id), mutbl);
 237                 self.define(parent, name, ValueNS, (def, sp, vis));
 238             }
 239             ItemKind::Const(_, _) => {
 240                 let def = Def::Const(self.definitions.local_def_id(item.id));
 241                 self.define(parent, name, ValueNS, (def, sp, vis));
 242             }
 243             ItemKind::Fn(_, _, _, _, _, _) => {
 244                 let def = Def::Fn(self.definitions.local_def_id(item.id));
 245                 self.define(parent, name, ValueNS, (def, sp, vis));
 246             }
 247
 248             // These items live in the type namespace.
 249             ItemKind::Ty(..) => {
 250                 let def = Def::TyAlias(self.definitions.local_def_id(item.id));
 251                 self.define(parent, name, TypeNS, (def, sp, vis));
 252             }
 253
 254             ItemKind::Enum(ref enum_definition, _) => {
 255                 let parent_link = ModuleParentLink(parent, name);
 256                 let def = Def::Enum(self.definitions.local_def_id(item.id));
 257                 let module = self.new_module(parent_link, Some(def), false);
 258                 self.define(parent, name, TypeNS, (module, sp, vis));
 259
 260                 for variant in &(*enum_definition).variants {
 261                     let item_def_id = self.definitions.local_def_id(item.id);
 262                     self.build_reduced_graph_for_variant(variant, item_def_id, module, vis);
 263                 }
 264             }
 265
 266             // These items live in both the type and value namespaces.
 267             ItemKind::Struct(ref struct_def, _) => {
 268                 // Define a name in the type namespace.
 269                 let def = Def::Struct(self.definitions.local_def_id(item.id));
 270                 self.define(parent, name, TypeNS, (def, sp, vis));
 271
 272                 // If this is a newtype or unit-like struct, define a name
 273                 // in the value namespace as well
 274                 if !struct_def.is_struct() {
 275                     let def = Def::Struct(self.definitions.local_def_id(struct_def.id()));
 276                     self.define(parent, name, ValueNS, (def, sp, vis));
 277                 }
 278
 279                 // Record the def ID and fields of this struct.
 280                 let field_names = struct_def.fields().iter().enumerate().map(|(index, field)| {
 281                     self.resolve_visibility(&field.vis);
 282                     field.ident.map(|ident| ident.name)
 283                                .unwrap_or_else(|| token::intern(&index.to_string()))
 284                 }).collect();
 285                 let item_def_id = self.definitions.local_def_id(item.id);
 286                 self.structs.insert(item_def_id, field_names);
 287             }
 288
 289             ItemKind::DefaultImpl(_, _) | ItemKind::Impl(..) => {}
 290
 291             ItemKind::Trait(_, _, _, ref items) => {
 292                 let def_id = self.definitions.local_def_id(item.id);
 293
 294                 // Add all the items within to a new module.
 295                 let parent_link = ModuleParentLink(parent, name);
 296                 let def = Def::Trait(def_id);
 297                 let module_parent = self.new_module(parent_link, Some(def), false);
 298                 self.define(parent, name, TypeNS, (module_parent, sp, vis));
 299
 300                 // Add the names of all the items to the trait info.
 301                 for item in items {
 302                     let item_def_id = self.definitions.local_def_id(item.id);
 303                     let mut is_static_method = false;
 304                     let (def, ns) = match item.node {
 305                         TraitItemKind::Const(..) => (Def::AssociatedConst(item_def_id), ValueNS),
 306                         TraitItemKind::Method(ref sig, _) => {
 307                             is_static_method = !sig.decl.has_self();
 308                             (Def::Method(item_def_id), ValueNS)
 309                         }
 310                         TraitItemKind::Type(..) => (Def::AssociatedTy(def_id, item_def_id), TypeNS),
 311                         TraitItemKind::Macro(_) => panic!("unexpanded macro in resolve!"),
 312                     };
 313
 314                     self.define(module_parent, item.ident.name, ns, (def, item.span, vis));
 315
 316                     self.trait_item_map.insert((item.ident.name, def_id), is_static_method);
 317                 }
 318             }
 319             ItemKind::Mac(_) => panic!("unexpanded macro in resolve!"),
 320         }
 321     }
 322
 323     // Constructs the reduced graph for one variant. Variants exist in the
 324     // type and value namespaces.
 325     fn build_reduced_graph_for_variant(&mut self,
 326                                        variant: &Variant,
 327                                        item_id: DefId,
 328                                        parent: Module<'b>,
 329                                        vis: ty::Visibility) {
 330         let name = variant.node.name.name;
 331         if variant.node.data.is_struct() {
 332             // Not adding fields for variants as they are not accessed with a self receiver
 333             let variant_def_id = self.definitions.local_def_id(variant.node.data.id());
 334             self.structs.insert(variant_def_id, Vec::new());
 335         }
 336
 337         // Variants are always treated as importable to allow them to be glob used.
 338         // All variants are defined in both type and value namespaces as future-proofing.
 339         let def = Def::Variant(item_id, self.definitions.local_def_id(variant.node.data.id()));
 340         self.define(parent, name, ValueNS, (def, variant.span, vis));
 341         self.define(parent, name, TypeNS, (def, variant.span, vis));
 342     }
 343
 344     /// Constructs the reduced graph for one foreign item.
 345     fn build_reduced_graph_for_foreign_item(&mut self,
 346                                             foreign_item: &ForeignItem,
 347                                             parent: Module<'b>) {
 348         let name = foreign_item.ident.name;
 349
 350         let def = match foreign_item.node {
 351             ForeignItemKind::Fn(..) => {
 352                 Def::Fn(self.definitions.local_def_id(foreign_item.id))
 353             }
 354             ForeignItemKind::Static(_, m) => {
 355                 Def::Static(self.definitions.local_def_id(foreign_item.id), m)
 356             }
 357         };
 358         self.current_module = parent;
 359         let vis = self.resolve_visibility(&foreign_item.vis);
 360         self.define(parent, name, ValueNS, (def, foreign_item.span, vis));
 361     }
 362
 363     fn build_reduced_graph_for_block(&mut self, block: &Block, parent: &mut Module<'b>) {
 364         if self.block_needs_anonymous_module(block) {
 365             let block_id = block.id;
 366
 367             debug!("(building reduced graph for block) creating a new anonymous module for block \
 368                     {}",
 369                    block_id);
 370
 371             let parent_link = BlockParentLink(parent, block_id);
 372             let new_module = self.new_module(parent_link, None, false);
 373             self.module_map.insert(block_id, new_module);
 374             *parent = new_module;
 375         }
 376     }
 377
 378     /// Builds the reduced graph for a single item in an external crate.
 379     fn build_reduced_graph_for_external_crate_def(&mut self, parent: Module<'b>, xcdef: ChildItem) {
 380         let def = match xcdef.def {
 381             DlDef(def) => def,
 382             _ => return,
 383         };
 384
 385         if let Def::ForeignMod(def_id) = def {
 386             // Foreign modules have no names. Recur and populate eagerly.
 387             for child in self.session.cstore.item_children(def_id) {
 388                 self.build_reduced_graph_for_external_crate_def(parent, child);
 389             }
 390             return;
 391         }
 392
 393         let name = xcdef.name;
 394         let vis = if parent.is_trait() { ty::Visibility::Public } else { xcdef.vis };
 395
 396         match def {
 397             Def::Mod(_) | Def::ForeignMod(_) | Def::Enum(..) => {
 398                 debug!("(building reduced graph for external crate) building module {} {:?}",
 399                        name, vis);
 400                 let parent_link = ModuleParentLink(parent, name);
 401                 let module = self.new_module(parent_link, Some(def), true);
 402                 self.try_define(parent, name, TypeNS, (module, DUMMY_SP, vis));
 403             }
 404             Def::Variant(_, variant_id) => {
 405                 debug!("(building reduced graph for external crate) building variant {}", name);
 406                 // Variants are always treated as importable to allow them to be glob used.
 407                 // All variants are defined in both type and value namespaces as future-proofing.
 408                 self.try_define(parent, name, TypeNS, (def, DUMMY_SP, vis));
 409                 self.try_define(parent, name, ValueNS, (def, DUMMY_SP, vis));
 410                 if self.session.cstore.variant_kind(variant_id) == Some(VariantKind::Struct) {
 411                     // Not adding fields for variants as they are not accessed with a self receiver
 412                     self.structs.insert(variant_id, Vec::new());
 413                 }
 414             }
 415             Def::Fn(..) |
 416             Def::Static(..) |
 417             Def::Const(..) |
 418             Def::AssociatedConst(..) |
 419             Def::Method(..) => {
 420                 debug!("(building reduced graph for external crate) building value (fn/static) {}",
 421                        name);
 422                 self.try_define(parent, name, ValueNS, (def, DUMMY_SP, vis));
 423             }
 424             Def::Trait(def_id) => {
 425                 debug!("(building reduced graph for external crate) building type {}", name);
 426
 427                 // If this is a trait, add all the trait item names to the trait
 428                 // info.
 429
 430                 let trait_item_def_ids = self.session.cstore.trait_item_def_ids(def_id);
 431                 for trait_item_def in &trait_item_def_ids {
 432                     let trait_item_name =
 433                         self.session.cstore.item_name(trait_item_def.def_id());
 434
 435                     debug!("(building reduced graph for external crate) ... adding trait item \
 436                             '{}'",
 437                            trait_item_name);
 438
 439                     self.trait_item_map.insert((trait_item_name, def_id), false);
 440                 }
 441
 442                 let parent_link = ModuleParentLink(parent, name);
 443                 let module = self.new_module(parent_link, Some(def), true);
 444                 self.try_define(parent, name, TypeNS, (module, DUMMY_SP, vis));
 445             }
 446             Def::TyAlias(..) | Def::AssociatedTy(..) => {
 447                 debug!("(building reduced graph for external crate) building type {}", name);
 448                 self.try_define(parent, name, TypeNS, (def, DUMMY_SP, vis));
 449             }
 450             Def::Struct(def_id)
 451                 if self.session.cstore.tuple_struct_definition_if_ctor(def_id).is_none() => {
 452                 debug!("(building reduced graph for external crate) building type and value for {}",
 453                        name);
 454                 self.try_define(parent, name, TypeNS, (def, DUMMY_SP, vis));
 455                 if let Some(ctor_def_id) = self.session.cstore.struct_ctor_def_id(def_id) {
 456                     let def = Def::Struct(ctor_def_id);
 457                     self.try_define(parent, name, ValueNS, (def, DUMMY_SP, vis));
 458                 }
 459
 460                 // Record the def ID and fields of this struct.
 461                 let fields = self.session.cstore.struct_field_names(def_id);
 462                 self.structs.insert(def_id, fields);
 463             }
 464             Def::Struct(..) => {}
 465             Def::Local(..) |
 466             Def::PrimTy(..) |
 467             Def::TyParam(..) |
 468             Def::Upvar(..) |
 469             Def::Label(..) |
 470             Def::SelfTy(..) |
 471             Def::Err => {
 472                 bug!("didn't expect `{:?}`", def);
 473             }
 474         }
 475     }
 476
 477     /// Builds the reduced graph rooted at the 'use' directive for an external
 478     /// crate.
 479     fn build_reduced_graph_for_external_crate(&mut self, root: Module<'b>) {
 480         let root_cnum = root.def_id().unwrap().krate;
 481         for child in self.session.cstore.crate_top_level_items(root_cnum) {
 482             self.build_reduced_graph_for_external_crate_def(root, child);
 483         }
 484     }
 485
 486     /// Ensures that the reduced graph rooted at the given external module
 487     /// is built, building it if it is not.
 488     pub fn populate_module_if_necessary(&mut self, module: Module<'b>) {
 489         if module.populated.get() { return }
 490         for child in self.session.cstore.item_children(module.def_id().unwrap()) {
 491             self.build_reduced_graph_for_external_crate_def(module, child);
 492         }
 493         module.populated.set(true)
 494     }
 495 }
 496
 497 struct BuildReducedGraphVisitor<'a, 'b: 'a> {
 498     resolver: &'a mut Resolver<'b>,
 499     parent: Module<'b>,
 500 }
 501
 502 impl<'a, 'b> Visitor for BuildReducedGraphVisitor<'a, 'b> {
 503     fn visit_item(&mut self, item: &Item) {
 504         let old_parent = self.parent;
 505         self.resolver.build_reduced_graph_for_item(item, &mut self.parent);
 506         visit::walk_item(self, item);
 507         self.parent = old_parent;
 508     }
 509
 510     fn visit_foreign_item(&mut self, foreign_item: &ForeignItem) {
 511         self.resolver.build_reduced_graph_for_foreign_item(foreign_item, &self.parent);
 512     }
 513
 514     fn visit_block(&mut self, block: &Block) {
 515         let old_parent = self.parent;
 516         self.resolver.build_reduced_graph_for_block(block, &mut self.parent);
 517         visit::walk_block(self, block);
 518         self.parent = old_parent;
 519     }
 520 }