src/librustdoc/html/render/cache.rs

   1 use crate::clean::{self, AttributesExt, GetDefId};
   2 use crate::fold::DocFolder;
   3 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
   4 use rustc_hir::def_id::{CrateNum, DefId, CRATE_DEF_INDEX};
   5 use rustc_middle::middle::privacy::AccessLevels;
   6 use rustc_span::source_map::FileName;
   7 use rustc_span::symbol::sym;
   8 use std::collections::BTreeMap;
   9 use std::mem;
  10 use std::path::{Path, PathBuf};
  11
  12 use serde::Serialize;
  13
  14 use super::{plain_summary_line, shorten, Impl, IndexItem, IndexItemFunctionType, ItemType};
  15 use super::{Generic, RenderInfo, RenderType, TypeWithKind};
  16
  17 /// Indicates where an external crate can be found.
  18 pub enum ExternalLocation {
  19     /// Remote URL root of the external crate
  20     Remote(String),
  21     /// This external crate can be found in the local doc/ folder
  22     Local,
  23     /// The external crate could not be found.
  24     Unknown,
  25 }
  26
  27 /// This cache is used to store information about the `clean::Crate` being
  28 /// rendered in order to provide more useful documentation. This contains
  29 /// information like all implementors of a trait, all traits a type implements,
  30 /// documentation for all known traits, etc.
  31 ///
  32 /// This structure purposefully does not implement `Clone` because it's intended
  33 /// to be a fairly large and expensive structure to clone. Instead this adheres
  34 /// to `Send` so it may be stored in a `Arc` instance and shared among the various
  35 /// rendering threads.
  36 #[derive(Default)]
  37 crate struct Cache {
  38     /// Maps a type ID to all known implementations for that type. This is only
  39     /// recognized for intra-crate `ResolvedPath` types, and is used to print
  40     /// out extra documentation on the page of an enum/struct.
  41     ///
  42     /// The values of the map are a list of implementations and documentation
  43     /// found on that implementation.
  44     pub impls: FxHashMap<DefId, Vec<Impl>>,
  45
  46     /// Maintains a mapping of local crate `DefId`s to the fully qualified name
  47     /// and "short type description" of that node. This is used when generating
  48     /// URLs when a type is being linked to. External paths are not located in
  49     /// this map because the `External` type itself has all the information
  50     /// necessary.
  51     pub paths: FxHashMap<DefId, (Vec<String>, ItemType)>,
  52
  53     /// Similar to `paths`, but only holds external paths. This is only used for
  54     /// generating explicit hyperlinks to other crates.
  55     pub external_paths: FxHashMap<DefId, (Vec<String>, ItemType)>,
  56
  57     /// Maps local `DefId`s of exported types to fully qualified paths.
  58     /// Unlike 'paths', this mapping ignores any renames that occur
  59     /// due to 'use' statements.
  60     ///
  61     /// This map is used when writing out the special 'implementors'
  62     /// javascript file. By using the exact path that the type
  63     /// is declared with, we ensure that each path will be identical
  64     /// to the path used if the corresponding type is inlined. By
  65     /// doing this, we can detect duplicate impls on a trait page, and only display
  66     /// the impl for the inlined type.
  67     pub exact_paths: FxHashMap<DefId, Vec<String>>,
  68
  69     /// This map contains information about all known traits of this crate.
  70     /// Implementations of a crate should inherit the documentation of the
  71     /// parent trait if no extra documentation is specified, and default methods
  72     /// should show up in documentation about trait implementations.
  73     pub traits: FxHashMap<DefId, clean::Trait>,
  74
  75     /// When rendering traits, it's often useful to be able to list all
  76     /// implementors of the trait, and this mapping is exactly, that: a mapping
  77     /// of trait ids to the list of known implementors of the trait
  78     pub implementors: FxHashMap<DefId, Vec<Impl>>,
  79
  80     /// Cache of where external crate documentation can be found.
  81     pub extern_locations: FxHashMap<CrateNum, (String, PathBuf, ExternalLocation)>,
  82
  83     /// Cache of where documentation for primitives can be found.
  84     pub primitive_locations: FxHashMap<clean::PrimitiveType, DefId>,
  85
  86     // Note that external items for which `doc(hidden)` applies to are shown as
  87     // non-reachable while local items aren't. This is because we're reusing
  88     // the access levels from the privacy check pass.
  89     pub access_levels: AccessLevels<DefId>,
  90
  91     /// The version of the crate being documented, if given from the `--crate-version` flag.
  92     pub crate_version: Option<String>,
  93
  94     // Private fields only used when initially crawling a crate to build a cache
  95     stack: Vec<String>,
  96     parent_stack: Vec<DefId>,
  97     parent_is_trait_impl: bool,
  98     search_index: Vec<IndexItem>,
  99     stripped_mod: bool,
 100     pub deref_trait_did: Option<DefId>,
 101     pub deref_mut_trait_did: Option<DefId>,
 102     pub owned_box_did: Option<DefId>,
 103     masked_crates: FxHashSet<CrateNum>,
 104
 105     // In rare case where a structure is defined in one module but implemented
 106     // in another, if the implementing module is parsed before defining module,
 107     // then the fully qualified name of the structure isn't presented in `paths`
 108     // yet when its implementation methods are being indexed. Caches such methods
 109     // and their parent id here and indexes them at the end of crate parsing.
 110     orphan_impl_items: Vec<(DefId, clean::Item)>,
 111
 112     // Similarly to `orphan_impl_items`, sometimes trait impls are picked up
 113     // even though the trait itself is not exported. This can happen if a trait
 114     // was defined in function/expression scope, since the impl will be picked
 115     // up by `collect-trait-impls` but the trait won't be scraped out in the HIR
 116     // crawl. In order to prevent crashes when looking for spotlight traits or
 117     // when gathering trait documentation on a type, hold impls here while
 118     // folding and add them to the cache later on if we find the trait.
 119     orphan_trait_impls: Vec<(DefId, FxHashSet<DefId>, Impl)>,
 120
 121     /// Aliases added through `#[doc(alias = "...")]`. Since a few items can have the same alias,
 122     /// we need the alias element to have an array of items.
 123     pub(super) aliases: FxHashMap<String, Vec<IndexItem>>,
 124 }
 125
 126 impl Cache {
 127     pub fn from_krate(
 128         renderinfo: RenderInfo,
 129         extern_html_root_urls: &BTreeMap<String, String>,
 130         dst: &Path,
 131         mut krate: clean::Crate,
 132     ) -> (clean::Crate, String, Cache) {
 133         // Crawl the crate to build various caches used for the output
 134         let RenderInfo {
 135             inlined: _,
 136             external_paths,
 137             exact_paths,
 138             access_levels,
 139             deref_trait_did,
 140             deref_mut_trait_did,
 141             owned_box_did,
 142             ..
 143         } = renderinfo;
 144
 145         let external_paths =
 146             external_paths.into_iter().map(|(k, (v, t))| (k, (v, ItemType::from(t)))).collect();
 147
 148         let mut cache = Cache {
 149             impls: Default::default(),
 150             external_paths,
 151             exact_paths,
 152             paths: Default::default(),
 153             implementors: Default::default(),
 154             stack: Vec::new(),
 155             parent_stack: Vec::new(),
 156             search_index: Vec::new(),
 157             parent_is_trait_impl: false,
 158             extern_locations: Default::default(),
 159             primitive_locations: Default::default(),
 160             stripped_mod: false,
 161             access_levels,
 162             crate_version: krate.version.take(),
 163             orphan_impl_items: Vec::new(),
 164             orphan_trait_impls: Vec::new(),
 165             traits: krate.external_traits.replace(Default::default()),
 166             deref_trait_did,
 167             deref_mut_trait_did,
 168             owned_box_did,
 169             masked_crates: mem::take(&mut krate.masked_crates),
 170             aliases: Default::default(),
 171         };
 172
 173         // Cache where all our extern crates are located
 174         for &(n, ref e) in &krate.externs {
 175             let src_root = match e.src {
 176                 FileName::Real(ref p) => match p.local_path().parent() {
 177                     Some(p) => p.to_path_buf(),
 178                     None => PathBuf::new(),
 179                 },
 180                 _ => PathBuf::new(),
 181             };
 182             let extern_url = extern_html_root_urls.get(&e.name).map(|u| &**u);
 183             cache
 184                 .extern_locations
 185                 .insert(n, (e.name.clone(), src_root, extern_location(e, extern_url, &dst)));
 186
 187             let did = DefId { krate: n, index: CRATE_DEF_INDEX };
 188             cache.external_paths.insert(did, (vec![e.name.to_string()], ItemType::Module));
 189         }
 190
 191         // Cache where all known primitives have their documentation located.
 192         //
 193         // Favor linking to as local extern as possible, so iterate all crates in
 194         // reverse topological order.
 195         for &(_, ref e) in krate.externs.iter().rev() {
 196             for &(def_id, prim, _) in &e.primitives {
 197                 cache.primitive_locations.insert(prim, def_id);
 198             }
 199         }
 200         for &(def_id, prim, _) in &krate.primitives {
 201             cache.primitive_locations.insert(prim, def_id);
 202         }
 203
 204         cache.stack.push(krate.name.clone());
 205         krate = cache.fold_crate(krate);
 206
 207         for (trait_did, dids, impl_) in cache.orphan_trait_impls.drain(..) {
 208             if cache.traits.contains_key(&trait_did) {
 209                 for did in dids {
 210                     cache.impls.entry(did).or_insert(vec![]).push(impl_.clone());
 211                 }
 212             }
 213         }
 214
 215         // Build our search index
 216         let index = build_index(&krate, &mut cache);
 217
 218         (krate, index, cache)
 219     }
 220 }
 221
 222 impl DocFolder for Cache {
 223     fn fold_item(&mut self, item: clean::Item) -> Option<clean::Item> {
 224         if item.def_id.is_local() {
 225             debug!("folding {} \"{:?}\", id {:?}", item.type_(), item.name, item.def_id);
 226         }
 227
 228         // If this is a stripped module,
 229         // we don't want it or its children in the search index.
 230         let orig_stripped_mod = match item.inner {
 231             clean::StrippedItem(box clean::ModuleItem(..)) => {
 232                 mem::replace(&mut self.stripped_mod, true)
 233             }
 234             _ => self.stripped_mod,
 235         };
 236
 237         // If the impl is from a masked crate or references something from a
 238         // masked crate then remove it completely.
 239         if let clean::ImplItem(ref i) = item.inner {
 240             if self.masked_crates.contains(&item.def_id.krate)
 241                 || i.trait_.def_id().map_or(false, |d| self.masked_crates.contains(&d.krate))
 242                 || i.for_.def_id().map_or(false, |d| self.masked_crates.contains(&d.krate))
 243             {
 244                 return None;
 245             }
 246         }
 247
 248         // Propagate a trait method's documentation to all implementors of the
 249         // trait.
 250         if let clean::TraitItem(ref t) = item.inner {
 251             self.traits.entry(item.def_id).or_insert_with(|| t.clone());
 252         }
 253
 254         // Collect all the implementors of traits.
 255         if let clean::ImplItem(ref i) = item.inner {
 256             if let Some(did) = i.trait_.def_id() {
 257                 if i.blanket_impl.is_none() {
 258                     self.implementors
 259                         .entry(did)
 260                         .or_default()
 261                         .push(Impl { impl_item: item.clone() });
 262                 }
 263             }
 264         }
 265
 266         // Index this method for searching later on.
 267         if let Some(ref s) = item.name {
 268             let (parent, is_inherent_impl_item) = match item.inner {
 269                 clean::StrippedItem(..) => ((None, None), false),
 270                 clean::AssocConstItem(..) | clean::TypedefItem(_, true)
 271                     if self.parent_is_trait_impl =>
 272                 {
 273                     // skip associated items in trait impls
 274                     ((None, None), false)
 275                 }
 276                 clean::AssocTypeItem(..)
 277                 | clean::TyMethodItem(..)
 278                 | clean::StructFieldItem(..)
 279                 | clean::VariantItem(..) => (
 280                     (
 281                         Some(*self.parent_stack.last().expect("parent_stack is empty")),
 282                         Some(&self.stack[..self.stack.len() - 1]),
 283                     ),
 284                     false,
 285                 ),
 286                 clean::MethodItem(..) | clean::AssocConstItem(..) => {
 287                     if self.parent_stack.is_empty() {
 288                         ((None, None), false)
 289                     } else {
 290                         let last = self.parent_stack.last().expect("parent_stack is empty 2");
 291                         let did = *last;
 292                         let path = match self.paths.get(&did) {
 293                             // The current stack not necessarily has correlation
 294                             // for where the type was defined. On the other
 295                             // hand, `paths` always has the right
 296                             // information if present.
 297                             Some(&(
 298                                 ref fqp,
 299                                 ItemType::Trait
 300                                 | ItemType::Struct
 301                                 | ItemType::Union
 302                                 | ItemType::Enum,
 303                             )) => Some(&fqp[..fqp.len() - 1]),
 304                             Some(..) => Some(&*self.stack),
 305                             None => None,
 306                         };
 307                         ((Some(*last), path), true)
 308                     }
 309                 }
 310                 _ => ((None, Some(&*self.stack)), false),
 311             };
 312
 313             match parent {
 314                 (parent, Some(path)) if is_inherent_impl_item || (!self.stripped_mod) => {
 315                     debug_assert!(!item.is_stripped());
 316
 317                     // A crate has a module at its root, containing all items,
 318                     // which should not be indexed. The crate-item itself is
 319                     // inserted later on when serializing the search-index.
 320                     if item.def_id.index != CRATE_DEF_INDEX {
 321                         self.search_index.push(IndexItem {
 322                             ty: item.type_(),
 323                             name: s.to_string(),
 324                             path: path.join("::"),
 325                             desc: shorten(plain_summary_line(item.doc_value())),
 326                             parent,
 327                             parent_idx: None,
 328                             search_type: get_index_search_type(&item),
 329                         });
 330                     }
 331                 }
 332                 (Some(parent), None) if is_inherent_impl_item => {
 333                     // We have a parent, but we don't know where they're
 334                     // defined yet. Wait for later to index this item.
 335                     self.orphan_impl_items.push((parent, item.clone()));
 336                 }
 337                 _ => {}
 338             }
 339         }
 340
 341         // Keep track of the fully qualified path for this item.
 342         let pushed = match item.name {
 343             Some(ref n) if !n.is_empty() => {
 344                 self.stack.push(n.to_string());
 345                 true
 346             }
 347             _ => false,
 348         };
 349
 350         match item.inner {
 351             clean::StructItem(..)
 352             | clean::EnumItem(..)
 353             | clean::TypedefItem(..)
 354             | clean::TraitItem(..)
 355             | clean::FunctionItem(..)
 356             | clean::ModuleItem(..)
 357             | clean::ForeignFunctionItem(..)
 358             | clean::ForeignStaticItem(..)
 359             | clean::ConstantItem(..)
 360             | clean::StaticItem(..)
 361             | clean::UnionItem(..)
 362             | clean::ForeignTypeItem
 363             | clean::MacroItem(..)
 364             | clean::ProcMacroItem(..)
 365             | clean::VariantItem(..)
 366                 if !self.stripped_mod =>
 367             {
 368                 // Re-exported items mean that the same id can show up twice
 369                 // in the rustdoc ast that we're looking at. We know,
 370                 // however, that a re-exported item doesn't show up in the
 371                 // `public_items` map, so we can skip inserting into the
 372                 // paths map if there was already an entry present and we're
 373                 // not a public item.
 374                 if !self.paths.contains_key(&item.def_id)
 375                     || self.access_levels.is_public(item.def_id)
 376                 {
 377                     self.paths.insert(item.def_id, (self.stack.clone(), item.type_()));
 378                 }
 379                 self.add_aliases(&item);
 380             }
 381
 382             clean::PrimitiveItem(..) => {
 383                 self.add_aliases(&item);
 384                 self.paths.insert(item.def_id, (self.stack.clone(), item.type_()));
 385             }
 386
 387             _ => {}
 388         }
 389
 390         // Maintain the parent stack
 391         let orig_parent_is_trait_impl = self.parent_is_trait_impl;
 392         let parent_pushed = match item.inner {
 393             clean::TraitItem(..)
 394             | clean::EnumItem(..)
 395             | clean::ForeignTypeItem
 396             | clean::StructItem(..)
 397             | clean::UnionItem(..)
 398             | clean::VariantItem(..) => {
 399                 self.parent_stack.push(item.def_id);
 400                 self.parent_is_trait_impl = false;
 401                 true
 402             }
 403             clean::ImplItem(ref i) => {
 404                 self.parent_is_trait_impl = i.trait_.is_some();
 405                 match i.for_ {
 406                     clean::ResolvedPath { did, .. } => {
 407                         self.parent_stack.push(did);
 408                         true
 409                     }
 410                     ref t => {
 411                         let prim_did = t
 412                             .primitive_type()
 413                             .and_then(|t| self.primitive_locations.get(&t).cloned());
 414                         match prim_did {
 415                             Some(did) => {
 416                                 self.parent_stack.push(did);
 417                                 true
 418                             }
 419                             None => false,
 420                         }
 421                     }
 422                 }
 423             }
 424             _ => false,
 425         };
 426
 427         // Once we've recursively found all the generics, hoard off all the
 428         // implementations elsewhere.
 429         let ret = self.fold_item_recur(item).and_then(|item| {
 430             if let clean::Item { inner: clean::ImplItem(_), .. } = item {
 431                 // Figure out the id of this impl. This may map to a
 432                 // primitive rather than always to a struct/enum.
 433                 // Note: matching twice to restrict the lifetime of the `i` borrow.
 434                 let mut dids = FxHashSet::default();
 435                 if let clean::Item { inner: clean::ImplItem(ref i), .. } = item {
 436                     match i.for_ {
 437                         clean::ResolvedPath { did, .. }
 438                         | clean::BorrowedRef {
 439                             type_: box clean::ResolvedPath { did, .. }, ..
 440                         } => {
 441                             dids.insert(did);
 442                         }
 443                         ref t => {
 444                             let did = t
 445                                 .primitive_type()
 446                                 .and_then(|t| self.primitive_locations.get(&t).cloned());
 447
 448                             if let Some(did) = did {
 449                                 dids.insert(did);
 450                             }
 451                         }
 452                     }
 453
 454                     if let Some(generics) = i.trait_.as_ref().and_then(|t| t.generics()) {
 455                         for bound in generics {
 456                             if let Some(did) = bound.def_id() {
 457                                 dids.insert(did);
 458                             }
 459                         }
 460                     }
 461                 } else {
 462                     unreachable!()
 463                 };
 464                 let impl_item = Impl { impl_item: item };
 465                 if impl_item.trait_did().map_or(true, |d| self.traits.contains_key(&d)) {
 466                     for did in dids {
 467                         self.impls.entry(did).or_insert(vec![]).push(impl_item.clone());
 468                     }
 469                 } else {
 470                     let trait_did = impl_item.trait_did().expect("no trait did");
 471                     self.orphan_trait_impls.push((trait_did, dids, impl_item));
 472                 }
 473                 None
 474             } else {
 475                 Some(item)
 476             }
 477         });
 478
 479         if pushed {
 480             self.stack.pop().expect("stack already empty");
 481         }
 482         if parent_pushed {
 483             self.parent_stack.pop().expect("parent stack already empty");
 484         }
 485         self.stripped_mod = orig_stripped_mod;
 486         self.parent_is_trait_impl = orig_parent_is_trait_impl;
 487         ret
 488     }
 489 }
 490
 491 impl Cache {
 492     fn add_aliases(&mut self, item: &clean::Item) {
 493         if item.def_id.index == CRATE_DEF_INDEX {
 494             return;
 495         }
 496         if let Some(ref item_name) = item.name {
 497             let path = self
 498                 .paths
 499                 .get(&item.def_id)
 500                 .map(|p| p.0[..p.0.len() - 1].join("::"))
 501                 .unwrap_or("std".to_owned());
 502             for alias in item
 503                 .attrs
 504                 .lists(sym::doc)
 505                 .filter(|a| a.check_name(sym::alias))
 506                 .filter_map(|a| a.value_str().map(|s| s.to_string().replace("\"", "")))
 507                 .filter(|v| !v.is_empty())
 508                 .collect::<FxHashSet<_>>()
 509                 .into_iter()
 510             {
 511                 self.aliases.entry(alias).or_insert(Vec::with_capacity(1)).push(IndexItem {
 512                     ty: item.type_(),
 513                     name: item_name.to_string(),
 514                     path: path.clone(),
 515                     desc: shorten(plain_summary_line(item.doc_value())),
 516                     parent: None,
 517                     parent_idx: None,
 518                     search_type: get_index_search_type(&item),
 519                 });
 520             }
 521         }
 522     }
 523 }
 524
 525 /// Attempts to find where an external crate is located, given that we're
 526 /// rendering in to the specified source destination.
 527 fn extern_location(
 528     e: &clean::ExternalCrate,
 529     extern_url: Option<&str>,
 530     dst: &Path,
 531 ) -> ExternalLocation {
 532     use ExternalLocation::*;
 533     // See if there's documentation generated into the local directory
 534     let local_location = dst.join(&e.name);
 535     if local_location.is_dir() {
 536         return Local;
 537     }
 538
 539     if let Some(url) = extern_url {
 540         let mut url = url.to_string();
 541         if !url.ends_with('/') {
 542             url.push('/');
 543         }
 544         return Remote(url);
 545     }
 546
 547     // Failing that, see if there's an attribute specifying where to find this
 548     // external crate
 549     e.attrs
 550         .lists(sym::doc)
 551         .filter(|a| a.check_name(sym::html_root_url))
 552         .filter_map(|a| a.value_str())
 553         .map(|url| {
 554             let mut url = url.to_string();
 555             if !url.ends_with('/') {
 556                 url.push('/')
 557             }
 558             Remote(url)
 559         })
 560         .next()
 561         .unwrap_or(Unknown) // Well, at least we tried.
 562 }
 563
 564 /// Builds the search index from the collected metadata
 565 fn build_index(krate: &clean::Crate, cache: &mut Cache) -> String {
 566     let mut defid_to_pathid = FxHashMap::default();
 567     let mut crate_items = Vec::with_capacity(cache.search_index.len());
 568     let mut crate_paths = vec![];
 569
 570     let Cache { ref mut search_index, ref orphan_impl_items, ref paths, .. } = *cache;
 571
 572     // Attach all orphan items to the type's definition if the type
 573     // has since been learned.
 574     for &(did, ref item) in orphan_impl_items {
 575         if let Some(&(ref fqp, _)) = paths.get(&did) {
 576             search_index.push(IndexItem {
 577                 ty: item.type_(),
 578                 name: item.name.clone().unwrap(),
 579                 path: fqp[..fqp.len() - 1].join("::"),
 580                 desc: shorten(plain_summary_line(item.doc_value())),
 581                 parent: Some(did),
 582                 parent_idx: None,
 583                 search_type: get_index_search_type(&item),
 584             });
 585         }
 586     }
 587
 588     // Reduce `DefId` in paths into smaller sequential numbers,
 589     // and prune the paths that do not appear in the index.
 590     let mut lastpath = String::new();
 591     let mut lastpathid = 0usize;
 592
 593     for item in search_index {
 594         item.parent_idx = item.parent.and_then(|defid| {
 595             if defid_to_pathid.contains_key(&defid) {
 596                 defid_to_pathid.get(&defid).copied()
 597             } else {
 598                 let pathid = lastpathid;
 599                 defid_to_pathid.insert(defid, pathid);
 600                 lastpathid += 1;
 601
 602                 if let Some(&(ref fqp, short)) = paths.get(&defid) {
 603                     crate_paths.push((short, fqp.last().unwrap().clone()));
 604                     Some(pathid)
 605                 } else {
 606                     None
 607                 }
 608             }
 609         });
 610
 611         // Omit the parent path if it is same to that of the prior item.
 612         if lastpath == item.path {
 613             item.path.clear();
 614         } else {
 615             lastpath = item.path.clone();
 616         }
 617         crate_items.push(&*item);
 618     }
 619
 620     let crate_doc = krate
 621         .module
 622         .as_ref()
 623         .map(|module| shorten(plain_summary_line(module.doc_value())))
 624         .unwrap_or(String::new());
 625
 626     #[derive(Serialize)]
 627     struct CrateData<'a> {
 628         doc: String,
 629         #[serde(rename = "i")]
 630         items: Vec<&'a IndexItem>,
 631         #[serde(rename = "p")]
 632         paths: Vec<(ItemType, String)>,
 633     }
 634
 635     // Collect the index into a string
 636     format!(
 637         r#""{}":{}"#,
 638         krate.name,
 639         serde_json::to_string(&CrateData {
 640             doc: crate_doc,
 641             items: crate_items,
 642             paths: crate_paths,
 643         })
 644         .expect("failed serde conversion")
 645         // All these `replace` calls are because we have to go through JS string for JSON content.
 646         .replace(r"\", r"\\")
 647         .replace("'", r"\'")
 648         // We need to escape double quotes for the JSON.
 649         .replace("\\\"", "\\\\\"")
 650     )
 651 }
 652
 653 fn get_index_search_type(item: &clean::Item) -> Option<IndexItemFunctionType> {
 654     let (all_types, ret_types) = match item.inner {
 655         clean::FunctionItem(ref f) => (&f.all_types, &f.ret_types),
 656         clean::MethodItem(ref m) => (&m.all_types, &m.ret_types),
 657         clean::TyMethodItem(ref m) => (&m.all_types, &m.ret_types),
 658         _ => return None,
 659     };
 660
 661     let inputs = all_types
 662         .iter()
 663         .map(|(ty, kind)| TypeWithKind::from((get_index_type(&ty), *kind)))
 664         .filter(|a| a.ty.name.is_some())
 665         .collect();
 666     let output = ret_types
 667         .iter()
 668         .map(|(ty, kind)| TypeWithKind::from((get_index_type(&ty), *kind)))
 669         .filter(|a| a.ty.name.is_some())
 670         .collect::<Vec<_>>();
 671     let output = if output.is_empty() { None } else { Some(output) };
 672
 673     Some(IndexItemFunctionType { inputs, output })
 674 }
 675
 676 fn get_index_type(clean_type: &clean::Type) -> RenderType {
 677     RenderType {
 678         ty: clean_type.def_id(),
 679         idx: None,
 680         name: get_index_type_name(clean_type, true).map(|s| s.to_ascii_lowercase()),
 681         generics: get_generics(clean_type),
 682     }
 683 }
 684
 685 fn get_index_type_name(clean_type: &clean::Type, accept_generic: bool) -> Option<String> {
 686     match *clean_type {
 687         clean::ResolvedPath { ref path, .. } => {
 688             let segments = &path.segments;
 689             let path_segment = segments.iter().last().unwrap_or_else(|| panic!(
 690                 "get_index_type_name(clean_type: {:?}, accept_generic: {:?}) had length zero path",
 691                 clean_type, accept_generic
 692             ));
 693             Some(path_segment.name.clone())
 694         }
 695         clean::Generic(ref s) if accept_generic => Some(s.clone()),
 696         clean::Primitive(ref p) => Some(format!("{:?}", p)),
 697         clean::BorrowedRef { ref type_, .. } => get_index_type_name(type_, accept_generic),
 698         // FIXME: add all from clean::Type.
 699         _ => None,
 700     }
 701 }
 702
 703 fn get_generics(clean_type: &clean::Type) -> Option<Vec<Generic>> {
 704     clean_type.generics().and_then(|types| {
 705         let r = types
 706             .iter()
 707             .filter_map(|t| {
 708                 get_index_type_name(t, false).map(|name| Generic {
 709                     name: name.to_ascii_lowercase(),
 710                     defid: t.def_id(),
 711                     idx: None,
 712                 })
 713             })
 714             .collect::<Vec<_>>();
 715         if r.is_empty() { None } else { Some(r) }
 716     })
 717 }