src/librustdoc/clean/inline.rs

   1 // Copyright 2012-2013 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 //! Support for inlining external documentation into the current AST.
  12
  13 use std::collections::HashSet;
  14 use std::iter::once;
  15
  16 use syntax::ast;
  17 use syntax::attr::AttrMetaMethods;
  18 use rustc::hir;
  19
  20 use rustc::middle::cstore::{self, CrateStore};
  21 use rustc::hir::def::Def;
  22 use rustc::hir::def_id::DefId;
  23 use rustc::ty::{self, TyCtxt};
  24 use rustc::ty::subst;
  25 use rustc::middle::stability;
  26
  27 use rustc_const_eval::lookup_const_by_id;
  28
  29 use core::DocContext;
  30 use doctree;
  31 use clean::{self, Attributes, GetDefId};
  32
  33 use super::{Clean, ToSource};
  34
  35 /// Attempt to inline the definition of a local node id into this AST.
  36 ///
  37 /// This function will fetch the definition of the id specified, and if it is
  38 /// from another crate it will attempt to inline the documentation from the
  39 /// other crate into this crate.
  40 ///
  41 /// This is primarily used for `pub use` statements which are, in general,
  42 /// implementation details. Inlining the documentation should help provide a
  43 /// better experience when reading the documentation in this use case.
  44 ///
  45 /// The returned value is `None` if the `id` could not be inlined, and `Some`
  46 /// of a vector of items if it was successfully expanded.
  47 pub fn try_inline(cx: &DocContext, id: ast::NodeId, into: Option<ast::Name>)
  48                   -> Option<Vec<clean::Item>> {
  49     let tcx = match cx.tcx_opt() {
  50         Some(tcx) => tcx,
  51         None => return None,
  52     };
  53     let def = match tcx.def_map.borrow().get(&id) {
  54         Some(d) => d.full_def(),
  55         None => return None,
  56     };
  57     let did = def.def_id();
  58     if did.is_local() { return None }
  59     try_inline_def(cx, tcx, def).map(|vec| {
  60         vec.into_iter().map(|mut item| {
  61             match into {
  62                 Some(into) if item.name.is_some() => {
  63                     item.name = Some(into.clean(cx));
  64                 }
  65                 _ => {}
  66             }
  67             item
  68         }).collect()
  69     })
  70 }
  71
  72 fn try_inline_def(cx: &DocContext, tcx: &TyCtxt,
  73                   def: Def) -> Option<Vec<clean::Item>> {
  74     let mut ret = Vec::new();
  75     let did = def.def_id();
  76     let inner = match def {
  77         Def::Trait(did) => {
  78             record_extern_fqn(cx, did, clean::TypeTrait);
  79             clean::TraitItem(build_external_trait(cx, tcx, did))
  80         }
  81         Def::Fn(did) => {
  82             record_extern_fqn(cx, did, clean::TypeFunction);
  83             clean::FunctionItem(build_external_function(cx, tcx, did))
  84         }
  85         Def::Struct(did)
  86                 // If this is a struct constructor, we skip it
  87                 if tcx.sess.cstore.tuple_struct_definition_if_ctor(did).is_none() => {
  88             record_extern_fqn(cx, did, clean::TypeStruct);
  89             ret.extend(build_impls(cx, tcx, did));
  90             clean::StructItem(build_struct(cx, tcx, did))
  91         }
  92         Def::TyAlias(did) => {
  93             record_extern_fqn(cx, did, clean::TypeTypedef);
  94             ret.extend(build_impls(cx, tcx, did));
  95             build_type(cx, tcx, did)
  96         }
  97         Def::Enum(did) => {
  98             record_extern_fqn(cx, did, clean::TypeEnum);
  99             ret.extend(build_impls(cx, tcx, did));
 100             build_type(cx, tcx, did)
 101         }
 102         // Assume that the enum type is reexported next to the variant, and
 103         // variants don't show up in documentation specially.
 104         Def::Variant(..) => return Some(Vec::new()),
 105         Def::Mod(did) => {
 106             record_extern_fqn(cx, did, clean::TypeModule);
 107             clean::ModuleItem(build_module(cx, tcx, did))
 108         }
 109         Def::Static(did, mtbl) => {
 110             record_extern_fqn(cx, did, clean::TypeStatic);
 111             clean::StaticItem(build_static(cx, tcx, did, mtbl))
 112         }
 113         Def::Const(did) | Def::AssociatedConst(did) => {
 114             record_extern_fqn(cx, did, clean::TypeConst);
 115             clean::ConstantItem(build_const(cx, tcx, did))
 116         }
 117         _ => return None,
 118     };
 119     cx.inlined.borrow_mut().as_mut().unwrap().insert(did);
 120     ret.push(clean::Item {
 121         source: clean::Span::empty(),
 122         name: Some(tcx.item_name(did).to_string()),
 123         attrs: load_attrs(cx, tcx, did),
 124         inner: inner,
 125         visibility: Some(hir::Public),
 126         stability: stability::lookup_stability(tcx, did).clean(cx),
 127         deprecation: stability::lookup_deprecation(tcx, did).clean(cx),
 128         def_id: did,
 129     });
 130     Some(ret)
 131 }
 132
 133 pub fn load_attrs(cx: &DocContext, tcx: &TyCtxt,
 134                   did: DefId) -> Vec<clean::Attribute> {
 135     tcx.get_attrs(did).iter().map(|a| a.clean(cx)).collect()
 136 }
 137
 138 /// Record an external fully qualified name in the external_paths cache.
 139 ///
 140 /// These names are used later on by HTML rendering to generate things like
 141 /// source links back to the original item.
 142 pub fn record_extern_fqn(cx: &DocContext, did: DefId, kind: clean::TypeKind) {
 143     if let Some(tcx) = cx.tcx_opt() {
 144         let crate_name = tcx.sess.cstore.crate_name(did.krate).to_string();
 145         let relative = tcx.def_path(did).data.into_iter().map(|elem| {
 146             elem.data.to_string()
 147         });
 148         let fqn = once(crate_name).chain(relative).collect();
 149         cx.external_paths.borrow_mut().as_mut().unwrap().insert(did, (fqn, kind));
 150     }
 151 }
 152
 153 pub fn build_external_trait(cx: &DocContext, tcx: &TyCtxt,
 154                             did: DefId) -> clean::Trait {
 155     let def = tcx.lookup_trait_def(did);
 156     let trait_items = tcx.trait_items(did).clean(cx);
 157     let predicates = tcx.lookup_predicates(did);
 158     let generics = (&def.generics, &predicates, subst::TypeSpace).clean(cx);
 159     let generics = filter_non_trait_generics(did, generics);
 160     let (generics, supertrait_bounds) = separate_supertrait_bounds(generics);
 161     clean::Trait {
 162         unsafety: def.unsafety,
 163         generics: generics,
 164         items: trait_items,
 165         bounds: supertrait_bounds,
 166     }
 167 }
 168
 169 fn build_external_function(cx: &DocContext, tcx: &TyCtxt, did: DefId) -> clean::Function {
 170     let t = tcx.lookup_item_type(did);
 171     let (decl, style, abi) = match t.ty.sty {
 172         ty::TyFnDef(_, _, ref f) => ((did, &f.sig).clean(cx), f.unsafety, f.abi),
 173         _ => panic!("bad function"),
 174     };
 175
 176     let constness = if tcx.sess.cstore.is_const_fn(did) {
 177         hir::Constness::Const
 178     } else {
 179         hir::Constness::NotConst
 180     };
 181
 182     let predicates = tcx.lookup_predicates(did);
 183     clean::Function {
 184         decl: decl,
 185         generics: (&t.generics, &predicates, subst::FnSpace).clean(cx),
 186         unsafety: style,
 187         constness: constness,
 188         abi: abi,
 189     }
 190 }
 191
 192 fn build_struct(cx: &DocContext, tcx: &TyCtxt, did: DefId) -> clean::Struct {
 193     let t = tcx.lookup_item_type(did);
 194     let predicates = tcx.lookup_predicates(did);
 195     let variant = tcx.lookup_adt_def(did).struct_variant();
 196
 197     clean::Struct {
 198         struct_type: match &*variant.fields {
 199             [] => doctree::Unit,
 200             [_] if variant.kind == ty::VariantKind::Tuple => doctree::Newtype,
 201             [..] if variant.kind == ty::VariantKind::Tuple => doctree::Tuple,
 202             _ => doctree::Plain,
 203         },
 204         generics: (&t.generics, &predicates, subst::TypeSpace).clean(cx),
 205         fields: variant.fields.clean(cx),
 206         fields_stripped: false,
 207     }
 208 }
 209
 210 fn build_type(cx: &DocContext, tcx: &TyCtxt, did: DefId) -> clean::ItemEnum {
 211     let t = tcx.lookup_item_type(did);
 212     let predicates = tcx.lookup_predicates(did);
 213     match t.ty.sty {
 214         ty::TyEnum(edef, _) if !tcx.sess.cstore.is_typedef(did) => {
 215             return clean::EnumItem(clean::Enum {
 216                 generics: (&t.generics, &predicates, subst::TypeSpace).clean(cx),
 217                 variants_stripped: false,
 218                 variants: edef.variants.clean(cx),
 219             })
 220         }
 221         _ => {}
 222     }
 223
 224     clean::TypedefItem(clean::Typedef {
 225         type_: t.ty.clean(cx),
 226         generics: (&t.generics, &predicates, subst::TypeSpace).clean(cx),
 227     }, false)
 228 }
 229
 230 pub fn build_impls(cx: &DocContext,
 231                    tcx: &TyCtxt,
 232                    did: DefId) -> Vec<clean::Item> {
 233     tcx.populate_inherent_implementations_for_type_if_necessary(did);
 234     let mut impls = Vec::new();
 235
 236     if let Some(i) = tcx.inherent_impls.borrow().get(&did) {
 237         for &did in i.iter() {
 238             build_impl(cx, tcx, did, &mut impls);
 239         }
 240     }
 241
 242     // If this is the first time we've inlined something from this crate, then
 243     // we inline *all* impls from the crate into this crate. Note that there's
 244     // currently no way for us to filter this based on type, and we likely need
 245     // many impls for a variety of reasons.
 246     //
 247     // Primarily, the impls will be used to populate the documentation for this
 248     // type being inlined, but impls can also be used when generating
 249     // documentation for primitives (no way to find those specifically).
 250     if !cx.all_crate_impls.borrow_mut().contains_key(&did.krate) {
 251         let mut impls = Vec::new();
 252         for item in tcx.sess.cstore.crate_top_level_items(did.krate) {
 253             populate_impls(cx, tcx, item.def, &mut impls);
 254         }
 255         cx.all_crate_impls.borrow_mut().insert(did.krate, impls);
 256
 257         fn populate_impls(cx: &DocContext, tcx: &TyCtxt,
 258                           def: cstore::DefLike,
 259                           impls: &mut Vec<clean::Item>) {
 260             match def {
 261                 cstore::DlImpl(did) => build_impl(cx, tcx, did, impls),
 262                 cstore::DlDef(Def::Mod(did)) => {
 263                     // Don't recurse if this is a #[doc(hidden)] module
 264                     if load_attrs(cx, tcx, did).list("doc").has_word("hidden") {
 265                         return;
 266                     }
 267
 268                     for item in tcx.sess.cstore.item_children(did) {
 269                         populate_impls(cx, tcx, item.def, impls)
 270                     }
 271                 }
 272                 _ => {}
 273             }
 274         }
 275     }
 276
 277     let mut candidates = cx.all_crate_impls.borrow_mut();
 278     let candidates = candidates.get_mut(&did.krate).unwrap();
 279     for i in (0..candidates.len()).rev() {
 280         let remove = match candidates[i].inner {
 281             clean::ImplItem(ref i) => {
 282                 i.for_.def_id() == Some(did) || i.for_.primitive_type().is_some()
 283             }
 284             _ => continue,
 285         };
 286         if remove {
 287             impls.push(candidates.swap_remove(i));
 288         }
 289     }
 290
 291     return impls;
 292 }
 293
 294 pub fn build_impl(cx: &DocContext,
 295                   tcx: &TyCtxt,
 296                   did: DefId,
 297                   ret: &mut Vec<clean::Item>) {
 298     if !cx.inlined.borrow_mut().as_mut().unwrap().insert(did) {
 299         return
 300     }
 301
 302     let attrs = load_attrs(cx, tcx, did);
 303     let associated_trait = tcx.impl_trait_ref(did);
 304     if let Some(ref t) = associated_trait {
 305         // If this is an impl for a #[doc(hidden)] trait, be sure to not inline
 306         let trait_attrs = load_attrs(cx, tcx, t.def_id);
 307         if trait_attrs.list("doc").has_word("hidden") {
 308             return
 309         }
 310     }
 311
 312     // If this is a defaulted impl, then bail out early here
 313     if tcx.sess.cstore.is_default_impl(did) {
 314         return ret.push(clean::Item {
 315             inner: clean::DefaultImplItem(clean::DefaultImpl {
 316                 // FIXME: this should be decoded
 317                 unsafety: hir::Unsafety::Normal,
 318                 trait_: match associated_trait.as_ref().unwrap().clean(cx) {
 319                     clean::TraitBound(polyt, _) => polyt.trait_,
 320                     clean::RegionBound(..) => unreachable!(),
 321                 },
 322             }),
 323             source: clean::Span::empty(),
 324             name: None,
 325             attrs: attrs,
 326             visibility: Some(hir::Inherited),
 327             stability: stability::lookup_stability(tcx, did).clean(cx),
 328             deprecation: stability::lookup_deprecation(tcx, did).clean(cx),
 329             def_id: did,
 330         });
 331     }
 332
 333     let predicates = tcx.lookup_predicates(did);
 334     let trait_items = tcx.sess.cstore.impl_items(did)
 335             .iter()
 336             .filter_map(|did| {
 337         let did = did.def_id();
 338         let impl_item = tcx.impl_or_trait_item(did);
 339         match impl_item {
 340             ty::ConstTraitItem(ref assoc_const) => {
 341                 let did = assoc_const.def_id;
 342                 let type_scheme = tcx.lookup_item_type(did);
 343                 let default = if assoc_const.has_value {
 344                     Some(lookup_const_by_id(tcx, did, None)
 345                          .unwrap().0.span.to_src(cx))
 346                 } else {
 347                     None
 348                 };
 349                 Some(clean::Item {
 350                     name: Some(assoc_const.name.clean(cx)),
 351                     inner: clean::AssociatedConstItem(
 352                         type_scheme.ty.clean(cx),
 353                         default,
 354                     ),
 355                     source: clean::Span::empty(),
 356                     attrs: vec![],
 357                     visibility: None,
 358                     stability: stability::lookup_stability(tcx, did).clean(cx),
 359                     deprecation: stability::lookup_deprecation(tcx, did).clean(cx),
 360                     def_id: did
 361                 })
 362             }
 363             ty::MethodTraitItem(method) => {
 364                 if method.vis != ty::Visibility::Public && associated_trait.is_none() {
 365                     return None
 366                 }
 367                 let mut item = method.clean(cx);
 368                 item.inner = match item.inner.clone() {
 369                     clean::TyMethodItem(clean::TyMethod {
 370                         unsafety, decl, self_, generics, abi
 371                     }) => {
 372                         let constness = if tcx.sess.cstore.is_const_fn(did) {
 373                             hir::Constness::Const
 374                         } else {
 375                             hir::Constness::NotConst
 376                         };
 377
 378                         clean::MethodItem(clean::Method {
 379                             unsafety: unsafety,
 380                             constness: constness,
 381                             decl: decl,
 382                             self_: self_,
 383                             generics: generics,
 384                             abi: abi
 385                         })
 386                     }
 387                     _ => panic!("not a tymethod"),
 388                 };
 389                 Some(item)
 390             }
 391             ty::TypeTraitItem(ref assoc_ty) => {
 392                 let did = assoc_ty.def_id;
 393                 let type_scheme = ty::TypeScheme {
 394                     ty: assoc_ty.ty.unwrap(),
 395                     generics: ty::Generics::empty()
 396                 };
 397                 // Not sure the choice of ParamSpace actually matters here,
 398                 // because an associated type won't have generics on the LHS
 399                 let typedef = (type_scheme, ty::GenericPredicates::empty(),
 400                                subst::ParamSpace::TypeSpace).clean(cx);
 401                 Some(clean::Item {
 402                     name: Some(assoc_ty.name.clean(cx)),
 403                     inner: clean::TypedefItem(typedef, true),
 404                     source: clean::Span::empty(),
 405                     attrs: vec![],
 406                     visibility: None,
 407                     stability: stability::lookup_stability(tcx, did).clean(cx),
 408                     deprecation: stability::lookup_deprecation(tcx, did).clean(cx),
 409                     def_id: did
 410                 })
 411             }
 412         }
 413     }).collect::<Vec<_>>();
 414     let polarity = tcx.trait_impl_polarity(did);
 415     let ty = tcx.lookup_item_type(did);
 416     let trait_ = associated_trait.clean(cx).map(|bound| {
 417         match bound {
 418             clean::TraitBound(polyt, _) => polyt.trait_,
 419             clean::RegionBound(..) => unreachable!(),
 420         }
 421     });
 422     if trait_.def_id() == cx.deref_trait_did.get() {
 423         super::build_deref_target_impls(cx, &trait_items, ret);
 424     }
 425
 426     let provided = trait_.def_id().map(|did| {
 427         cx.tcx().provided_trait_methods(did)
 428                 .into_iter()
 429                 .map(|meth| meth.name.to_string())
 430                 .collect()
 431     }).unwrap_or(HashSet::new());
 432
 433     ret.push(clean::Item {
 434         inner: clean::ImplItem(clean::Impl {
 435             unsafety: hir::Unsafety::Normal, // FIXME: this should be decoded
 436             derived: clean::detect_derived(&attrs),
 437             provided_trait_methods: provided,
 438             trait_: trait_,
 439             for_: ty.ty.clean(cx),
 440             generics: (&ty.generics, &predicates, subst::TypeSpace).clean(cx),
 441             items: trait_items,
 442             polarity: polarity.map(|p| { p.clean(cx) }),
 443         }),
 444         source: clean::Span::empty(),
 445         name: None,
 446         attrs: attrs,
 447         visibility: Some(hir::Inherited),
 448         stability: stability::lookup_stability(tcx, did).clean(cx),
 449         deprecation: stability::lookup_deprecation(tcx, did).clean(cx),
 450         def_id: did,
 451     });
 452 }
 453
 454 fn build_module(cx: &DocContext, tcx: &TyCtxt,
 455                 did: DefId) -> clean::Module {
 456     let mut items = Vec::new();
 457     fill_in(cx, tcx, did, &mut items);
 458     return clean::Module {
 459         items: items,
 460         is_crate: false,
 461     };
 462
 463     fn fill_in(cx: &DocContext, tcx: &TyCtxt, did: DefId,
 464                items: &mut Vec<clean::Item>) {
 465         // If we're reexporting a reexport it may actually reexport something in
 466         // two namespaces, so the target may be listed twice. Make sure we only
 467         // visit each node at most once.
 468         let mut visited = HashSet::new();
 469         for item in tcx.sess.cstore.item_children(did) {
 470             match item.def {
 471                 cstore::DlDef(Def::ForeignMod(did)) => {
 472                     fill_in(cx, tcx, did, items);
 473                 }
 474                 cstore::DlDef(def) if item.vis == ty::Visibility::Public => {
 475                     if !visited.insert(def) { continue }
 476                     if let Some(i) = try_inline_def(cx, tcx, def) {
 477                         items.extend(i)
 478                     }
 479                 }
 480                 cstore::DlDef(..) => {}
 481                 // All impls were inlined above
 482                 cstore::DlImpl(..) => {}
 483                 cstore::DlField => panic!("unimplemented field"),
 484             }
 485         }
 486     }
 487 }
 488
 489 fn build_const(cx: &DocContext, tcx: &TyCtxt,
 490                did: DefId) -> clean::Constant {
 491     use rustc::hir::print as pprust;
 492
 493     let (expr, ty) = lookup_const_by_id(tcx, did, None).unwrap_or_else(|| {
 494         panic!("expected lookup_const_by_id to succeed for {:?}", did);
 495     });
 496     debug!("converting constant expr {:?} to snippet", expr);
 497     let sn = pprust::expr_to_string(expr);
 498     debug!("got snippet {}", sn);
 499
 500     clean::Constant {
 501         type_: ty.map(|t| t.clean(cx)).unwrap_or_else(|| tcx.lookup_item_type(did).ty.clean(cx)),
 502         expr: sn
 503     }
 504 }
 505
 506 fn build_static(cx: &DocContext, tcx: &TyCtxt,
 507                 did: DefId,
 508                 mutable: bool) -> clean::Static {
 509     clean::Static {
 510         type_: tcx.lookup_item_type(did).ty.clean(cx),
 511         mutability: if mutable {clean::Mutable} else {clean::Immutable},
 512         expr: "\n\n\n".to_string(), // trigger the "[definition]" links
 513     }
 514 }
 515
 516 /// A trait's generics clause actually contains all of the predicates for all of
 517 /// its associated types as well. We specifically move these clauses to the
 518 /// associated types instead when displaying, so when we're genering the
 519 /// generics for the trait itself we need to be sure to remove them.
 520 ///
 521 /// The inverse of this filtering logic can be found in the `Clean`
 522 /// implementation for `AssociatedType`
 523 fn filter_non_trait_generics(trait_did: DefId, mut g: clean::Generics)
 524                              -> clean::Generics {
 525     g.where_predicates.retain(|pred| {
 526         match *pred {
 527             clean::WherePredicate::BoundPredicate {
 528                 ty: clean::QPath {
 529                     self_type: box clean::Generic(ref s),
 530                     trait_: box clean::ResolvedPath { did, .. },
 531                     name: ref _name,
 532                 }, ..
 533             } => *s != "Self" || did != trait_did,
 534             _ => true,
 535         }
 536     });
 537     return g;
 538 }
 539
 540 /// Supertrait bounds for a trait are also listed in the generics coming from
 541 /// the metadata for a crate, so we want to separate those out and create a new
 542 /// list of explicit supertrait bounds to render nicely.
 543 fn separate_supertrait_bounds(mut g: clean::Generics)
 544                               -> (clean::Generics, Vec<clean::TyParamBound>) {
 545     let mut ty_bounds = Vec::new();
 546     g.where_predicates.retain(|pred| {
 547         match *pred {
 548             clean::WherePredicate::BoundPredicate {
 549                 ty: clean::Generic(ref s),
 550                 ref bounds
 551             } if *s == "Self" => {
 552                 ty_bounds.extend(bounds.iter().cloned());
 553                 false
 554             }
 555             _ => true,
 556         }
 557     });
 558     (g, ty_bounds)
 559 }