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 rustc::hir;
  18
  19 use rustc::middle::cstore;
  20 use rustc::hir::def::Def;
  21 use rustc::hir::def_id::DefId;
  22 use rustc::hir::print as pprust;
  23 use rustc::ty::{self, TyCtxt};
  24 use rustc::ty::subst;
  25
  26 use rustc_const_eval::lookup_const_by_id;
  27
  28 use core::{DocContext, DocAccessLevels};
  29 use doctree;
  30 use clean::{self, GetDefId};
  31
  32 use super::Clean;
  33
  34 /// Attempt to inline the definition of a local node id into this AST.
  35 ///
  36 /// This function will fetch the definition of the id specified, and if it is
  37 /// from another crate it will attempt to inline the documentation from the
  38 /// other crate into this crate.
  39 ///
  40 /// This is primarily used for `pub use` statements which are, in general,
  41 /// implementation details. Inlining the documentation should help provide a
  42 /// better experience when reading the documentation in this use case.
  43 ///
  44 /// The returned value is `None` if the `id` could not be inlined, and `Some`
  45 /// of a vector of items if it was successfully expanded.
  46 pub fn try_inline(cx: &DocContext, id: ast::NodeId, into: Option<ast::Name>)
  47                   -> Option<Vec<clean::Item>> {
  48     let tcx = match cx.tcx_opt() {
  49         Some(tcx) => tcx,
  50         None => return None,
  51     };
  52     let def = match tcx.expect_def_or_none(id) {
  53         Some(def) => def,
  54         None => return None,
  55     };
  56     let did = def.def_id();
  57     if did.is_local() { return None }
  58     try_inline_def(cx, tcx, def).map(|vec| {
  59         vec.into_iter().map(|mut item| {
  60             match into {
  61                 Some(into) if item.name.is_some() => {
  62                     item.name = Some(into.clean(cx));
  63                 }
  64                 _ => {}
  65             }
  66             item
  67         }).collect()
  68     })
  69 }
  70
  71 fn try_inline_def<'a, 'tcx>(cx: &DocContext, tcx: TyCtxt<'a, 'tcx, 'tcx>,
  72                             def: Def) -> Option<Vec<clean::Item>> {
  73     let mut ret = Vec::new();
  74     let did = def.def_id();
  75     let inner = match def {
  76         Def::Trait(did) => {
  77             record_extern_fqn(cx, did, clean::TypeTrait);
  78             ret.extend(build_impls(cx, tcx, did));
  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.renderinfo.borrow_mut().inlined.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(clean::Public),
 126         stability: tcx.lookup_stability(did).clean(cx),
 127         deprecation: tcx.lookup_deprecation(did).clean(cx),
 128         def_id: did,
 129     });
 130     Some(ret)
 131 }
 132
 133 pub fn load_attrs<'a, 'tcx>(cx: &DocContext, tcx: TyCtxt<'a, 'tcx, 'tcx>,
 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().filter_map(|elem| {
 146             // extern blocks have an empty name
 147             let s = elem.data.to_string();
 148             if !s.is_empty() {
 149                 Some(s)
 150             } else {
 151                 None
 152             }
 153         });
 154         let fqn = once(crate_name).chain(relative).collect();
 155         cx.renderinfo.borrow_mut().external_paths.insert(did, (fqn, kind));
 156     }
 157 }
 158
 159 pub fn build_external_trait<'a, 'tcx>(cx: &DocContext, tcx: TyCtxt<'a, 'tcx, 'tcx>,
 160                                       did: DefId) -> clean::Trait {
 161     let def = tcx.lookup_trait_def(did);
 162     let trait_items = tcx.trait_items(did).clean(cx);
 163     let predicates = tcx.lookup_predicates(did);
 164     let generics = (&def.generics, &predicates, subst::TypeSpace).clean(cx);
 165     let generics = filter_non_trait_generics(did, generics);
 166     let (generics, supertrait_bounds) = separate_supertrait_bounds(generics);
 167     clean::Trait {
 168         unsafety: def.unsafety,
 169         generics: generics,
 170         items: trait_items,
 171         bounds: supertrait_bounds,
 172     }
 173 }
 174
 175 fn build_external_function<'a, 'tcx>(cx: &DocContext, tcx: TyCtxt<'a, 'tcx, 'tcx>,
 176                                      did: DefId) -> clean::Function {
 177     let t = tcx.lookup_item_type(did);
 178     let (decl, style, abi) = match t.ty.sty {
 179         ty::TyFnDef(_, _, ref f) => ((did, &f.sig).clean(cx), f.unsafety, f.abi),
 180         _ => panic!("bad function"),
 181     };
 182
 183     let constness = if tcx.sess.cstore.is_const_fn(did) {
 184         hir::Constness::Const
 185     } else {
 186         hir::Constness::NotConst
 187     };
 188
 189     let predicates = tcx.lookup_predicates(did);
 190     clean::Function {
 191         decl: decl,
 192         generics: (&t.generics, &predicates, subst::FnSpace).clean(cx),
 193         unsafety: style,
 194         constness: constness,
 195         abi: abi,
 196     }
 197 }
 198
 199 fn build_struct<'a, 'tcx>(cx: &DocContext, tcx: TyCtxt<'a, 'tcx, 'tcx>,
 200                           did: DefId) -> clean::Struct {
 201     let t = tcx.lookup_item_type(did);
 202     let predicates = tcx.lookup_predicates(did);
 203     let variant = tcx.lookup_adt_def(did).struct_variant();
 204
 205     clean::Struct {
 206         struct_type: match &variant.fields[..] {
 207             &[] => doctree::Unit,
 208             &[_] if variant.kind == ty::VariantKind::Tuple => doctree::Newtype,
 209             &[..] if variant.kind == ty::VariantKind::Tuple => doctree::Tuple,
 210             _ => doctree::Plain,
 211         },
 212         generics: (&t.generics, &predicates, subst::TypeSpace).clean(cx),
 213         fields: variant.fields.clean(cx),
 214         fields_stripped: false,
 215     }
 216 }
 217
 218 fn build_type<'a, 'tcx>(cx: &DocContext, tcx: TyCtxt<'a, 'tcx, 'tcx>,
 219                         did: DefId) -> clean::ItemEnum {
 220     let t = tcx.lookup_item_type(did);
 221     let predicates = tcx.lookup_predicates(did);
 222     match t.ty.sty {
 223         ty::TyEnum(edef, _) if !tcx.sess.cstore.is_typedef(did) => {
 224             return clean::EnumItem(clean::Enum {
 225                 generics: (&t.generics, &predicates, subst::TypeSpace).clean(cx),
 226                 variants_stripped: false,
 227                 variants: edef.variants.clean(cx),
 228             })
 229         }
 230         _ => {}
 231     }
 232
 233     clean::TypedefItem(clean::Typedef {
 234         type_: t.ty.clean(cx),
 235         generics: (&t.generics, &predicates, subst::TypeSpace).clean(cx),
 236     }, false)
 237 }
 238
 239 pub fn build_impls<'a, 'tcx>(cx: &DocContext,
 240                              tcx: TyCtxt<'a, 'tcx, 'tcx>,
 241                              did: DefId) -> Vec<clean::Item> {
 242     tcx.populate_inherent_implementations_for_type_if_necessary(did);
 243     let mut impls = Vec::new();
 244
 245     if let Some(i) = tcx.inherent_impls.borrow().get(&did) {
 246         for &did in i.iter() {
 247             build_impl(cx, tcx, did, &mut impls);
 248         }
 249     }
 250
 251     // If this is the first time we've inlined something from this crate, then
 252     // we inline *all* impls from the crate into this crate. Note that there's
 253     // currently no way for us to filter this based on type, and we likely need
 254     // many impls for a variety of reasons.
 255     //
 256     // Primarily, the impls will be used to populate the documentation for this
 257     // type being inlined, but impls can also be used when generating
 258     // documentation for primitives (no way to find those specifically).
 259     if cx.populated_crate_impls.borrow_mut().insert(did.krate) {
 260         for item in tcx.sess.cstore.crate_top_level_items(did.krate) {
 261             populate_impls(cx, tcx, item.def, &mut impls);
 262         }
 263
 264         fn populate_impls<'a, 'tcx>(cx: &DocContext, tcx: TyCtxt<'a, 'tcx, 'tcx>,
 265                                     def: cstore::DefLike,
 266                                     impls: &mut Vec<clean::Item>) {
 267             match def {
 268                 cstore::DlImpl(did) => build_impl(cx, tcx, did, impls),
 269                 cstore::DlDef(Def::Mod(did)) => {
 270                     for item in tcx.sess.cstore.item_children(did) {
 271                         populate_impls(cx, tcx, item.def, impls)
 272                     }
 273                 }
 274                 _ => {}
 275             }
 276         }
 277     }
 278
 279     impls
 280 }
 281
 282 pub fn build_impl<'a, 'tcx>(cx: &DocContext,
 283                             tcx: TyCtxt<'a, 'tcx, 'tcx>,
 284                             did: DefId,
 285                             ret: &mut Vec<clean::Item>) {
 286     if !cx.renderinfo.borrow_mut().inlined.insert(did) {
 287         return
 288     }
 289
 290     let attrs = load_attrs(cx, tcx, did);
 291     let associated_trait = tcx.impl_trait_ref(did);
 292
 293     // Only inline impl if the implemented trait is
 294     // reachable in rustdoc generated documentation
 295     if let Some(traitref) = associated_trait {
 296         if !cx.access_levels.borrow().is_doc_reachable(traitref.def_id) {
 297             return
 298         }
 299     }
 300
 301     // If this is a defaulted impl, then bail out early here
 302     if tcx.sess.cstore.is_default_impl(did) {
 303         return ret.push(clean::Item {
 304             inner: clean::DefaultImplItem(clean::DefaultImpl {
 305                 // FIXME: this should be decoded
 306                 unsafety: hir::Unsafety::Normal,
 307                 trait_: match associated_trait.as_ref().unwrap().clean(cx) {
 308                     clean::TraitBound(polyt, _) => polyt.trait_,
 309                     clean::RegionBound(..) => unreachable!(),
 310                 },
 311             }),
 312             source: clean::Span::empty(),
 313             name: None,
 314             attrs: attrs,
 315             visibility: Some(clean::Inherited),
 316             stability: tcx.lookup_stability(did).clean(cx),
 317             deprecation: tcx.lookup_deprecation(did).clean(cx),
 318             def_id: did,
 319         });
 320     }
 321
 322     let ty = tcx.lookup_item_type(did);
 323     let for_ = ty.ty.clean(cx);
 324
 325     // Only inline impl if the implementing type is
 326     // reachable in rustdoc generated documentation
 327     if let Some(did) = for_.def_id() {
 328         if !cx.access_levels.borrow().is_doc_reachable(did) {
 329             return
 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(pprust::expr_to_string(
 345                         lookup_const_by_id(tcx, did, None).unwrap().0))
 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: tcx.lookup_stability(did).clean(cx),
 359                     deprecation: tcx.lookup_deprecation(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, 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                             generics: generics,
 383                             abi: abi
 384                         })
 385                     }
 386                     _ => panic!("not a tymethod"),
 387                 };
 388                 Some(item)
 389             }
 390             ty::TypeTraitItem(ref assoc_ty) => {
 391                 let did = assoc_ty.def_id;
 392                 let type_scheme = ty::TypeScheme {
 393                     ty: assoc_ty.ty.unwrap(),
 394                     generics: ty::Generics::empty()
 395                 };
 396                 // Not sure the choice of ParamSpace actually matters here,
 397                 // because an associated type won't have generics on the LHS
 398                 let typedef = (type_scheme, ty::GenericPredicates::empty(),
 399                                subst::ParamSpace::TypeSpace).clean(cx);
 400                 Some(clean::Item {
 401                     name: Some(assoc_ty.name.clean(cx)),
 402                     inner: clean::TypedefItem(typedef, true),
 403                     source: clean::Span::empty(),
 404                     attrs: vec![],
 405                     visibility: None,
 406                     stability: tcx.lookup_stability(did).clean(cx),
 407                     deprecation: tcx.lookup_deprecation(did).clean(cx),
 408                     def_id: did
 409                 })
 410             }
 411         }
 412     }).collect::<Vec<_>>();
 413     let polarity = tcx.trait_impl_polarity(did);
 414     let trait_ = associated_trait.clean(cx).map(|bound| {
 415         match bound {
 416             clean::TraitBound(polyt, _) => polyt.trait_,
 417             clean::RegionBound(..) => unreachable!(),
 418         }
 419     });
 420     if trait_.def_id() == cx.deref_trait_did.get() {
 421         super::build_deref_target_impls(cx, &trait_items, ret);
 422     }
 423
 424     let provided = trait_.def_id().map(|did| {
 425         cx.tcx().provided_trait_methods(did)
 426                 .into_iter()
 427                 .map(|meth| meth.name.to_string())
 428                 .collect()
 429     }).unwrap_or(HashSet::new());
 430
 431     ret.push(clean::Item {
 432         inner: clean::ImplItem(clean::Impl {
 433             unsafety: hir::Unsafety::Normal, // FIXME: this should be decoded
 434             provided_trait_methods: provided,
 435             trait_: trait_,
 436             for_: for_,
 437             generics: (&ty.generics, &predicates, subst::TypeSpace).clean(cx),
 438             items: trait_items,
 439             polarity: polarity.map(|p| { p.clean(cx) }),
 440         }),
 441         source: clean::Span::empty(),
 442         name: None,
 443         attrs: attrs,
 444         visibility: Some(clean::Inherited),
 445         stability: tcx.lookup_stability(did).clean(cx),
 446         deprecation: tcx.lookup_deprecation(did).clean(cx),
 447         def_id: did,
 448     });
 449 }
 450
 451 fn build_module<'a, 'tcx>(cx: &DocContext, tcx: TyCtxt<'a, 'tcx, 'tcx>,
 452                           did: DefId) -> clean::Module {
 453     let mut items = Vec::new();
 454     fill_in(cx, tcx, did, &mut items);
 455     return clean::Module {
 456         items: items,
 457         is_crate: false,
 458     };
 459
 460     fn fill_in<'a, 'tcx>(cx: &DocContext, tcx: TyCtxt<'a, 'tcx, 'tcx>,
 461                          did: DefId, items: &mut Vec<clean::Item>) {
 462         // If we're reexporting a reexport it may actually reexport something in
 463         // two namespaces, so the target may be listed twice. Make sure we only
 464         // visit each node at most once.
 465         let mut visited = HashSet::new();
 466         for item in tcx.sess.cstore.item_children(did) {
 467             match item.def {
 468                 cstore::DlDef(Def::ForeignMod(did)) => {
 469                     fill_in(cx, tcx, did, items);
 470                 }
 471                 cstore::DlDef(def) if item.vis == ty::Visibility::Public => {
 472                     if !visited.insert(def) { continue }
 473                     if let Some(i) = try_inline_def(cx, tcx, def) {
 474                         items.extend(i)
 475                     }
 476                 }
 477                 cstore::DlDef(..) => {}
 478                 // All impls were inlined above
 479                 cstore::DlImpl(..) => {}
 480                 cstore::DlField => panic!("unimplemented field"),
 481             }
 482         }
 483     }
 484 }
 485
 486 fn build_const<'a, 'tcx>(cx: &DocContext, tcx: TyCtxt<'a, 'tcx, 'tcx>,
 487                          did: DefId) -> clean::Constant {
 488     let (expr, ty) = lookup_const_by_id(tcx, did, None).unwrap_or_else(|| {
 489         panic!("expected lookup_const_by_id to succeed for {:?}", did);
 490     });
 491     debug!("converting constant expr {:?} to snippet", expr);
 492     let sn = pprust::expr_to_string(expr);
 493     debug!("got snippet {}", sn);
 494
 495     clean::Constant {
 496         type_: ty.map(|t| t.clean(cx)).unwrap_or_else(|| tcx.lookup_item_type(did).ty.clean(cx)),
 497         expr: sn
 498     }
 499 }
 500
 501 fn build_static<'a, 'tcx>(cx: &DocContext, tcx: TyCtxt<'a, 'tcx, 'tcx>,
 502                           did: DefId,
 503                           mutable: bool) -> clean::Static {
 504     clean::Static {
 505         type_: tcx.lookup_item_type(did).ty.clean(cx),
 506         mutability: if mutable {clean::Mutable} else {clean::Immutable},
 507         expr: "\n\n\n".to_string(), // trigger the "[definition]" links
 508     }
 509 }
 510
 511 /// A trait's generics clause actually contains all of the predicates for all of
 512 /// its associated types as well. We specifically move these clauses to the
 513 /// associated types instead when displaying, so when we're genering the
 514 /// generics for the trait itself we need to be sure to remove them.
 515 ///
 516 /// The inverse of this filtering logic can be found in the `Clean`
 517 /// implementation for `AssociatedType`
 518 fn filter_non_trait_generics(trait_did: DefId, mut g: clean::Generics)
 519                              -> clean::Generics {
 520     g.where_predicates.retain(|pred| {
 521         match *pred {
 522             clean::WherePredicate::BoundPredicate {
 523                 ty: clean::QPath {
 524                     self_type: box clean::Generic(ref s),
 525                     trait_: box clean::ResolvedPath { did, .. },
 526                     name: ref _name,
 527                 }, ..
 528             } => *s != "Self" || did != trait_did,
 529             _ => true,
 530         }
 531     });
 532     return g;
 533 }
 534
 535 /// Supertrait bounds for a trait are also listed in the generics coming from
 536 /// the metadata for a crate, so we want to separate those out and create a new
 537 /// list of explicit supertrait bounds to render nicely.
 538 fn separate_supertrait_bounds(mut g: clean::Generics)
 539                               -> (clean::Generics, Vec<clean::TyParamBound>) {
 540     let mut ty_bounds = Vec::new();
 541     g.where_predicates.retain(|pred| {
 542         match *pred {
 543             clean::WherePredicate::BoundPredicate {
 544                 ty: clean::Generic(ref s),
 545                 ref bounds
 546             } if *s == "Self" => {
 547                 ty_bounds.extend(bounds.iter().cloned());
 548                 false
 549             }
 550             _ => true,
 551         }
 552     });
 553     (g, ty_bounds)
 554 }