//! HTML formatting module //! //! This module contains a large number of `fmt::Display` implementations for //! various types in `rustdoc::clean`. //! //! These implementations all emit HTML. As an internal implementation detail, //! some of them support an alternate format that emits text, but that should //! not be used external to this module. use std::borrow::Cow; use std::cell::Cell; use std::fmt::{self, Write}; use std::iter::{self, once}; use rustc_ast as ast; use rustc_attr::{ConstStability, StabilityLevel}; use rustc_data_structures::captures::Captures; use rustc_data_structures::fx::FxHashSet; use rustc_hir as hir; use rustc_hir::def::DefKind; use rustc_hir::def_id::DefId; use rustc_metadata::creader::{CStore, LoadedMacro}; use rustc_middle::ty; use rustc_middle::ty::TyCtxt; use rustc_span::symbol::kw; use rustc_span::{sym, Symbol}; use rustc_target::spec::abi::Abi; use itertools::Itertools; use crate::clean::{ self, types::ExternalLocation, utils::find_nearest_parent_module, ExternalCrate, ItemId, PrimitiveType, }; use crate::formats::item_type::ItemType; use crate::html::escape::Escape; use crate::html::render::Context; use crate::passes::collect_intra_doc_links::UrlFragment; use super::url_parts_builder::estimate_item_path_byte_length; use super::url_parts_builder::UrlPartsBuilder; pub(crate) trait Print { fn print(self, buffer: &mut Buffer); } impl Print for F where F: FnOnce(&mut Buffer), { fn print(self, buffer: &mut Buffer) { (self)(buffer) } } impl Print for String { fn print(self, buffer: &mut Buffer) { buffer.write_str(&self); } } impl Print for &'_ str { fn print(self, buffer: &mut Buffer) { buffer.write_str(self); } } #[derive(Debug, Clone)] pub(crate) struct Buffer { for_html: bool, buffer: String, } impl core::fmt::Write for Buffer { #[inline] fn write_str(&mut self, s: &str) -> fmt::Result { self.buffer.write_str(s) } #[inline] fn write_char(&mut self, c: char) -> fmt::Result { self.buffer.write_char(c) } #[inline] fn write_fmt(&mut self, args: fmt::Arguments<'_>) -> fmt::Result { self.buffer.write_fmt(args) } } impl Buffer { pub(crate) fn empty_from(v: &Buffer) -> Buffer { Buffer { for_html: v.for_html, buffer: String::new() } } pub(crate) fn html() -> Buffer { Buffer { for_html: true, buffer: String::new() } } pub(crate) fn new() -> Buffer { Buffer { for_html: false, buffer: String::new() } } pub(crate) fn is_empty(&self) -> bool { self.buffer.is_empty() } pub(crate) fn into_inner(self) -> String { self.buffer } pub(crate) fn push_str(&mut self, s: &str) { self.buffer.push_str(s); } pub(crate) fn push_buffer(&mut self, other: Buffer) { self.buffer.push_str(&other.buffer); } // Intended for consumption by write! and writeln! (std::fmt) but without // the fmt::Result return type imposed by fmt::Write (and avoiding the trait // import). pub(crate) fn write_str(&mut self, s: &str) { self.buffer.push_str(s); } // Intended for consumption by write! and writeln! (std::fmt) but without // the fmt::Result return type imposed by fmt::Write (and avoiding the trait // import). pub(crate) fn write_fmt(&mut self, v: fmt::Arguments<'_>) { self.buffer.write_fmt(v).unwrap(); } pub(crate) fn to_display(mut self, t: T) -> String { t.print(&mut self); self.into_inner() } pub(crate) fn reserve(&mut self, additional: usize) { self.buffer.reserve(additional) } pub(crate) fn len(&self) -> usize { self.buffer.len() } } pub(crate) fn comma_sep( items: impl Iterator, space_after_comma: bool, ) -> impl fmt::Display { display_fn(move |f| { for (i, item) in items.enumerate() { if i != 0 { write!(f, ",{}", if space_after_comma { " " } else { "" })?; } fmt::Display::fmt(&item, f)?; } Ok(()) }) } pub(crate) fn print_generic_bounds<'a, 'tcx: 'a>( bounds: &'a [clean::GenericBound], cx: &'a Context<'tcx>, ) -> impl fmt::Display + 'a + Captures<'tcx> { display_fn(move |f| { let mut bounds_dup = FxHashSet::default(); for (i, bound) in bounds.iter().filter(|b| bounds_dup.insert(b.clone())).enumerate() { if i > 0 { f.write_str(" + ")?; } fmt::Display::fmt(&bound.print(cx), f)?; } Ok(()) }) } impl clean::GenericParamDef { pub(crate) fn print<'a, 'tcx: 'a>( &'a self, cx: &'a Context<'tcx>, ) -> impl fmt::Display + 'a + Captures<'tcx> { display_fn(move |f| match &self.kind { clean::GenericParamDefKind::Lifetime { outlives } => { write!(f, "{}", self.name)?; if !outlives.is_empty() { f.write_str(": ")?; for (i, lt) in outlives.iter().enumerate() { if i != 0 { f.write_str(" + ")?; } write!(f, "{}", lt.print())?; } } Ok(()) } clean::GenericParamDefKind::Type { bounds, default, .. } => { f.write_str(self.name.as_str())?; if !bounds.is_empty() { if f.alternate() { write!(f, ": {:#}", print_generic_bounds(bounds, cx))?; } else { write!(f, ": {}", print_generic_bounds(bounds, cx))?; } } if let Some(ref ty) = default { if f.alternate() { write!(f, " = {:#}", ty.print(cx))?; } else { write!(f, " = {}", ty.print(cx))?; } } Ok(()) } clean::GenericParamDefKind::Const { ty, default, .. } => { if f.alternate() { write!(f, "const {}: {:#}", self.name, ty.print(cx))?; } else { write!(f, "const {}: {}", self.name, ty.print(cx))?; } if let Some(default) = default { if f.alternate() { write!(f, " = {:#}", default)?; } else { write!(f, " = {}", default)?; } } Ok(()) } }) } } impl clean::Generics { pub(crate) fn print<'a, 'tcx: 'a>( &'a self, cx: &'a Context<'tcx>, ) -> impl fmt::Display + 'a + Captures<'tcx> { display_fn(move |f| { let mut real_params = self.params.iter().filter(|p| !p.is_synthetic_type_param()).peekable(); if real_params.peek().is_none() { return Ok(()); } if f.alternate() { write!(f, "<{:#}>", comma_sep(real_params.map(|g| g.print(cx)), true)) } else { write!(f, "<{}>", comma_sep(real_params.map(|g| g.print(cx)), true)) } }) } } #[derive(Clone, Copy, PartialEq, Eq)] pub(crate) enum Ending { Newline, NoNewline, } /// * The Generics from which to emit a where-clause. /// * The number of spaces to indent each line with. /// * Whether the where-clause needs to add a comma and newline after the last bound. pub(crate) fn print_where_clause<'a, 'tcx: 'a>( gens: &'a clean::Generics, cx: &'a Context<'tcx>, indent: usize, ending: Ending, ) -> impl fmt::Display + 'a + Captures<'tcx> { display_fn(move |f| { let mut where_predicates = gens.where_predicates.iter().filter(|pred| { !matches!(pred, clean::WherePredicate::BoundPredicate { bounds, .. } if bounds.is_empty()) }).map(|pred| { display_fn(move |f| { if f.alternate() { f.write_str(" ")?; } else { f.write_str("\n")?; } match pred { clean::WherePredicate::BoundPredicate { ty, bounds, bound_params } => { let ty_cx = ty.print(cx); let generic_bounds = print_generic_bounds(bounds, cx); if bound_params.is_empty() { if f.alternate() { write!(f, "{ty_cx:#}: {generic_bounds:#}") } else { write!(f, "{ty_cx}: {generic_bounds}") } } else { if f.alternate() { write!( f, "for<{:#}> {ty_cx:#}: {generic_bounds:#}", comma_sep(bound_params.iter().map(|lt| lt.print(cx)), true) ) } else { write!( f, "for<{}> {ty_cx}: {generic_bounds}", comma_sep(bound_params.iter().map(|lt| lt.print(cx)), true) ) } } } clean::WherePredicate::RegionPredicate { lifetime, bounds } => { let mut bounds_display = String::new(); for bound in bounds.iter().map(|b| b.print(cx)) { write!(bounds_display, "{bound} + ")?; } bounds_display.truncate(bounds_display.len() - " + ".len()); write!(f, "{}: {bounds_display}", lifetime.print()) } // FIXME(fmease): Render bound params. clean::WherePredicate::EqPredicate { lhs, rhs, bound_params: _ } => { if f.alternate() { write!(f, "{:#} == {:#}", lhs.print(cx), rhs.print(cx)) } else { write!(f, "{} == {}", lhs.print(cx), rhs.print(cx)) } } } }) }).peekable(); if where_predicates.peek().is_none() { return Ok(()); } let where_preds = comma_sep(where_predicates, false); let clause = if f.alternate() { if ending == Ending::Newline { format!(" where{where_preds},") } else { format!(" where{where_preds}") } } else { let mut br_with_padding = String::with_capacity(6 * indent + 28); br_with_padding.push_str("\n"); let padding_amount = if ending == Ending::Newline { indent + 4 } else { indent + "fn where ".len() }; for _ in 0..padding_amount { br_with_padding.push_str(" "); } let where_preds = where_preds.to_string().replace('\n', &br_with_padding); if ending == Ending::Newline { let mut clause = " ".repeat(indent.saturating_sub(1)); write!(clause, "where{where_preds},")?; clause } else { // insert a newline after a single space but before multiple spaces at the start if indent == 0 { format!("\nwhere{where_preds}") } else { // put the first one on the same line as the 'where' keyword let where_preds = where_preds.replacen(&br_with_padding, " ", 1); let mut clause = br_with_padding; clause.truncate(clause.len() - "where ".len()); write!(clause, "where{where_preds}")?; clause } } }; write!(f, "{clause}") }) } impl clean::Lifetime { pub(crate) fn print(&self) -> impl fmt::Display + '_ { self.0.as_str() } } impl clean::Constant { pub(crate) fn print(&self, tcx: TyCtxt<'_>) -> impl fmt::Display + '_ { let expr = self.expr(tcx); display_fn( move |f| { if f.alternate() { f.write_str(&expr) } else { write!(f, "{}", Escape(&expr)) } }, ) } } impl clean::PolyTrait { fn print<'a, 'tcx: 'a>( &'a self, cx: &'a Context<'tcx>, ) -> impl fmt::Display + 'a + Captures<'tcx> { display_fn(move |f| { if !self.generic_params.is_empty() { if f.alternate() { write!( f, "for<{:#}> ", comma_sep(self.generic_params.iter().map(|g| g.print(cx)), true) )?; } else { write!( f, "for<{}> ", comma_sep(self.generic_params.iter().map(|g| g.print(cx)), true) )?; } } if f.alternate() { write!(f, "{:#}", self.trait_.print(cx)) } else { write!(f, "{}", self.trait_.print(cx)) } }) } } impl clean::GenericBound { pub(crate) fn print<'a, 'tcx: 'a>( &'a self, cx: &'a Context<'tcx>, ) -> impl fmt::Display + 'a + Captures<'tcx> { display_fn(move |f| match self { clean::GenericBound::Outlives(lt) => write!(f, "{}", lt.print()), clean::GenericBound::TraitBound(ty, modifier) => { let modifier_str = match modifier { hir::TraitBoundModifier::None => "", hir::TraitBoundModifier::Maybe => "?", // ~const is experimental; do not display those bounds in rustdoc hir::TraitBoundModifier::MaybeConst => "", }; if f.alternate() { write!(f, "{}{:#}", modifier_str, ty.print(cx)) } else { write!(f, "{}{}", modifier_str, ty.print(cx)) } } }) } } impl clean::GenericArgs { fn print<'a, 'tcx: 'a>( &'a self, cx: &'a Context<'tcx>, ) -> impl fmt::Display + 'a + Captures<'tcx> { display_fn(move |f| { match self { clean::GenericArgs::AngleBracketed { args, bindings } => { if !args.is_empty() || !bindings.is_empty() { if f.alternate() { f.write_str("<")?; } else { f.write_str("<")?; } let mut comma = false; for arg in args.iter() { if comma { f.write_str(", ")?; } comma = true; if f.alternate() { write!(f, "{:#}", arg.print(cx))?; } else { write!(f, "{}", arg.print(cx))?; } } for binding in bindings.iter() { if comma { f.write_str(", ")?; } comma = true; if f.alternate() { write!(f, "{:#}", binding.print(cx))?; } else { write!(f, "{}", binding.print(cx))?; } } if f.alternate() { f.write_str(">")?; } else { f.write_str(">")?; } } } clean::GenericArgs::Parenthesized { inputs, output } => { f.write_str("(")?; let mut comma = false; for ty in inputs.iter() { if comma { f.write_str(", ")?; } comma = true; if f.alternate() { write!(f, "{:#}", ty.print(cx))?; } else { write!(f, "{}", ty.print(cx))?; } } f.write_str(")")?; if let Some(ref ty) = *output { if f.alternate() { write!(f, " -> {:#}", ty.print(cx))?; } else { write!(f, " -> {}", ty.print(cx))?; } } } } Ok(()) }) } } // Possible errors when computing href link source for a `DefId` #[derive(PartialEq, Eq)] pub(crate) enum HrefError { /// This item is known to rustdoc, but from a crate that does not have documentation generated. /// /// This can only happen for non-local items. /// /// # Example /// /// Crate `a` defines a public trait and crate `b` – the target crate that depends on `a` – /// implements it for a local type. /// We document `b` but **not** `a` (we only _build_ the latter – with `rustc`): /// /// ```sh /// rustc a.rs --crate-type=lib /// rustdoc b.rs --crate-type=lib --extern=a=liba.rlib /// ``` /// /// Now, the associated items in the trait impl want to link to the corresponding item in the /// trait declaration (see `html::render::assoc_href_attr`) but it's not available since their /// *documentation (was) not built*. DocumentationNotBuilt, /// This can only happen for non-local items when `--document-private-items` is not passed. Private, // Not in external cache, href link should be in same page NotInExternalCache, } // Panics if `syms` is empty. pub(crate) fn join_with_double_colon(syms: &[Symbol]) -> String { let mut s = String::with_capacity(estimate_item_path_byte_length(syms.len())); s.push_str(syms[0].as_str()); for sym in &syms[1..] { s.push_str("::"); s.push_str(sym.as_str()); } s } /// This function is to get the external macro path because they are not in the cache used in /// `href_with_root_path`. fn generate_macro_def_id_path( def_id: DefId, cx: &Context<'_>, root_path: Option<&str>, ) -> Result<(String, ItemType, Vec), HrefError> { let tcx = cx.shared.tcx; let crate_name = tcx.crate_name(def_id.krate); let cache = cx.cache(); let fqp: Vec = tcx .def_path(def_id) .data .into_iter() .filter_map(|elem| { // extern blocks (and a few others things) have an empty name. match elem.data.get_opt_name() { Some(s) if !s.is_empty() => Some(s), _ => None, } }) .collect(); let mut relative = fqp.iter().copied(); let cstore = CStore::from_tcx(tcx); // We need this to prevent a `panic` when this function is used from intra doc links... if !cstore.has_crate_data(def_id.krate) { debug!("No data for crate {}", crate_name); return Err(HrefError::NotInExternalCache); } // Check to see if it is a macro 2.0 or built-in macro. // More information in . let is_macro_2 = match cstore.load_macro_untracked(def_id, tcx.sess) { LoadedMacro::MacroDef(def, _) => { // If `ast_def.macro_rules` is `true`, then it's not a macro 2.0. matches!(&def.kind, ast::ItemKind::MacroDef(ast_def) if !ast_def.macro_rules) } _ => false, }; let mut path = if is_macro_2 { once(crate_name).chain(relative).collect() } else { vec![crate_name, relative.next_back().unwrap()] }; if path.len() < 2 { // The minimum we can have is the crate name followed by the macro name. If shorter, then // it means that `relative` was empty, which is an error. debug!("macro path cannot be empty!"); return Err(HrefError::NotInExternalCache); } if let Some(last) = path.last_mut() { *last = Symbol::intern(&format!("macro.{}.html", last.as_str())); } let url = match cache.extern_locations[&def_id.krate] { ExternalLocation::Remote(ref s) => { // `ExternalLocation::Remote` always end with a `/`. format!("{}{}", s, path.iter().map(|p| p.as_str()).join("/")) } ExternalLocation::Local => { // `root_path` always end with a `/`. format!( "{}{}/{}", root_path.unwrap_or(""), crate_name, path.iter().map(|p| p.as_str()).join("/") ) } ExternalLocation::Unknown => { debug!("crate {} not in cache when linkifying macros", crate_name); return Err(HrefError::NotInExternalCache); } }; Ok((url, ItemType::Macro, fqp)) } pub(crate) fn href_with_root_path( did: DefId, cx: &Context<'_>, root_path: Option<&str>, ) -> Result<(String, ItemType, Vec), HrefError> { let tcx = cx.tcx(); let def_kind = tcx.def_kind(did); let did = match def_kind { DefKind::AssocTy | DefKind::AssocFn | DefKind::AssocConst | DefKind::Variant => { // documented on their parent's page tcx.parent(did) } _ => did, }; let cache = cx.cache(); let relative_to = &cx.current; fn to_module_fqp(shortty: ItemType, fqp: &[Symbol]) -> &[Symbol] { if shortty == ItemType::Module { fqp } else { &fqp[..fqp.len() - 1] } } if !did.is_local() && !cache.effective_visibilities.is_directly_public(tcx, did) && !cache.document_private && !cache.primitive_locations.values().any(|&id| id == did) { return Err(HrefError::Private); } let mut is_remote = false; let (fqp, shortty, mut url_parts) = match cache.paths.get(&did) { Some(&(ref fqp, shortty)) => (fqp, shortty, { let module_fqp = to_module_fqp(shortty, fqp.as_slice()); debug!(?fqp, ?shortty, ?module_fqp); href_relative_parts(module_fqp, relative_to).collect() }), None => { if let Some(&(ref fqp, shortty)) = cache.external_paths.get(&did) { let module_fqp = to_module_fqp(shortty, fqp); ( fqp, shortty, match cache.extern_locations[&did.krate] { ExternalLocation::Remote(ref s) => { is_remote = true; let s = s.trim_end_matches('/'); let mut builder = UrlPartsBuilder::singleton(s); builder.extend(module_fqp.iter().copied()); builder } ExternalLocation::Local => { href_relative_parts(module_fqp, relative_to).collect() } ExternalLocation::Unknown => return Err(HrefError::DocumentationNotBuilt), }, ) } else if matches!(def_kind, DefKind::Macro(_)) { return generate_macro_def_id_path(did, cx, root_path); } else { return Err(HrefError::NotInExternalCache); } } }; if !is_remote && let Some(root_path) = root_path { let root = root_path.trim_end_matches('/'); url_parts.push_front(root); } debug!(?url_parts); match shortty { ItemType::Module => { url_parts.push("index.html"); } _ => { let prefix = shortty.as_str(); let last = fqp.last().unwrap(); url_parts.push_fmt(format_args!("{}.{}.html", prefix, last)); } } Ok((url_parts.finish(), shortty, fqp.to_vec())) } pub(crate) fn href( did: DefId, cx: &Context<'_>, ) -> Result<(String, ItemType, Vec), HrefError> { href_with_root_path(did, cx, None) } /// Both paths should only be modules. /// This is because modules get their own directories; that is, `std::vec` and `std::vec::Vec` will /// both need `../iter/trait.Iterator.html` to get at the iterator trait. pub(crate) fn href_relative_parts<'fqp>( fqp: &'fqp [Symbol], relative_to_fqp: &[Symbol], ) -> Box + 'fqp> { for (i, (f, r)) in fqp.iter().zip(relative_to_fqp.iter()).enumerate() { // e.g. linking to std::iter from std::vec (`dissimilar_part_count` will be 1) if f != r { let dissimilar_part_count = relative_to_fqp.len() - i; let fqp_module = &fqp[i..fqp.len()]; return Box::new( iter::repeat(sym::dotdot) .take(dissimilar_part_count) .chain(fqp_module.iter().copied()), ); } } // e.g. linking to std::sync::atomic from std::sync if relative_to_fqp.len() < fqp.len() { Box::new(fqp[relative_to_fqp.len()..fqp.len()].iter().copied()) // e.g. linking to std::sync from std::sync::atomic } else if fqp.len() < relative_to_fqp.len() { let dissimilar_part_count = relative_to_fqp.len() - fqp.len(); Box::new(iter::repeat(sym::dotdot).take(dissimilar_part_count)) // linking to the same module } else { Box::new(iter::empty()) } } pub(crate) fn link_tooltip(did: DefId, fragment: &Option, cx: &Context<'_>) -> String { let cache = cx.cache(); let Some((fqp, shortty)) = cache.paths.get(&did) .or_else(|| cache.external_paths.get(&did)) else { return String::new() }; let mut buf = Buffer::new(); let fqp = if *shortty == ItemType::Primitive { // primitives are documented in a crate, but not actually part of it &fqp[fqp.len() - 1..] } else { &fqp }; if let &Some(UrlFragment::Item(id)) = fragment { write!(buf, "{} ", cx.tcx().def_descr(id)); for component in fqp { write!(buf, "{component}::"); } write!(buf, "{}", cx.tcx().item_name(id)); } else if !fqp.is_empty() { let mut fqp_it = fqp.into_iter(); write!(buf, "{shortty} {}", fqp_it.next().unwrap()); for component in fqp_it { write!(buf, "::{component}"); } } buf.into_inner() } /// Used to render a [`clean::Path`]. fn resolved_path<'cx>( w: &mut fmt::Formatter<'_>, did: DefId, path: &clean::Path, print_all: bool, use_absolute: bool, cx: &'cx Context<'_>, ) -> fmt::Result { let last = path.segments.last().unwrap(); if print_all { for seg in &path.segments[..path.segments.len() - 1] { write!(w, "{}::", if seg.name == kw::PathRoot { "" } else { seg.name.as_str() })?; } } if w.alternate() { write!(w, "{}{:#}", &last.name, last.args.print(cx))?; } else { let path = if use_absolute { if let Ok((_, _, fqp)) = href(did, cx) { format!( "{}::{}", join_with_double_colon(&fqp[..fqp.len() - 1]), anchor(did, *fqp.last().unwrap(), cx) ) } else { last.name.to_string() } } else { anchor(did, last.name, cx).to_string() }; write!(w, "{}{}", path, last.args.print(cx))?; } Ok(()) } fn primitive_link( f: &mut fmt::Formatter<'_>, prim: clean::PrimitiveType, name: &str, cx: &Context<'_>, ) -> fmt::Result { primitive_link_fragment(f, prim, name, "", cx) } fn primitive_link_fragment( f: &mut fmt::Formatter<'_>, prim: clean::PrimitiveType, name: &str, fragment: &str, cx: &Context<'_>, ) -> fmt::Result { let m = &cx.cache(); let mut needs_termination = false; if !f.alternate() { match m.primitive_locations.get(&prim) { Some(&def_id) if def_id.is_local() => { let len = cx.current.len(); let len = if len == 0 { 0 } else { len - 1 }; write!( f, "", "../".repeat(len), prim.as_sym() )?; needs_termination = true; } Some(&def_id) => { let loc = match m.extern_locations[&def_id.krate] { ExternalLocation::Remote(ref s) => { let cname_sym = ExternalCrate { crate_num: def_id.krate }.name(cx.tcx()); let builder: UrlPartsBuilder = [s.as_str().trim_end_matches('/'), cname_sym.as_str()] .into_iter() .collect(); Some(builder) } ExternalLocation::Local => { let cname_sym = ExternalCrate { crate_num: def_id.krate }.name(cx.tcx()); Some(if cx.current.first() == Some(&cname_sym) { iter::repeat(sym::dotdot).take(cx.current.len() - 1).collect() } else { iter::repeat(sym::dotdot) .take(cx.current.len()) .chain(iter::once(cname_sym)) .collect() }) } ExternalLocation::Unknown => None, }; if let Some(mut loc) = loc { loc.push_fmt(format_args!("primitive.{}.html", prim.as_sym())); write!(f, "", loc.finish())?; needs_termination = true; } } None => {} } } write!(f, "{}", name)?; if needs_termination { write!(f, "")?; } Ok(()) } /// Helper to render type parameters fn tybounds<'a, 'tcx: 'a>( bounds: &'a [clean::PolyTrait], lt: &'a Option, cx: &'a Context<'tcx>, ) -> impl fmt::Display + 'a + Captures<'tcx> { display_fn(move |f| { for (i, bound) in bounds.iter().enumerate() { if i > 0 { write!(f, " + ")?; } fmt::Display::fmt(&bound.print(cx), f)?; } if let Some(lt) = lt { write!(f, " + ")?; fmt::Display::fmt(<.print(), f)?; } Ok(()) }) } pub(crate) fn anchor<'a, 'cx: 'a>( did: DefId, text: Symbol, cx: &'cx Context<'_>, ) -> impl fmt::Display + 'a { let parts = href(did, cx); display_fn(move |f| { if let Ok((url, short_ty, fqp)) = parts { write!( f, r#"{}"#, short_ty, url, short_ty, join_with_double_colon(&fqp), text.as_str() ) } else { write!(f, "{}", text) } }) } fn fmt_type<'cx>( t: &clean::Type, f: &mut fmt::Formatter<'_>, use_absolute: bool, cx: &'cx Context<'_>, ) -> fmt::Result { trace!("fmt_type(t = {:?})", t); match *t { clean::Generic(name) => write!(f, "{}", name), clean::Type::Path { ref path } => { // Paths like `T::Output` and `Self::Output` should be rendered with all segments. let did = path.def_id(); resolved_path(f, did, path, path.is_assoc_ty(), use_absolute, cx) } clean::DynTrait(ref bounds, ref lt) => { f.write_str("dyn ")?; fmt::Display::fmt(&tybounds(bounds, lt, cx), f) } clean::Infer => write!(f, "_"), clean::Primitive(clean::PrimitiveType::Never) => { primitive_link(f, PrimitiveType::Never, "!", cx) } clean::Primitive(prim) => primitive_link(f, prim, prim.as_sym().as_str(), cx), clean::BareFunction(ref decl) => { if f.alternate() { write!( f, "{:#}{}{:#}fn{:#}", decl.print_hrtb_with_space(cx), decl.unsafety.print_with_space(), print_abi_with_space(decl.abi), decl.decl.print(cx), ) } else { write!( f, "{}{}{}", decl.print_hrtb_with_space(cx), decl.unsafety.print_with_space(), print_abi_with_space(decl.abi) )?; primitive_link(f, PrimitiveType::Fn, "fn", cx)?; write!(f, "{}", decl.decl.print(cx)) } } clean::Tuple(ref typs) => { match &typs[..] { &[] => primitive_link(f, PrimitiveType::Unit, "()", cx), [one] => { if let clean::Generic(name) = one { primitive_link(f, PrimitiveType::Tuple, &format!("({name},)"), cx) } else { write!(f, "(")?; // Carry `f.alternate()` into this display w/o branching manually. fmt::Display::fmt(&one.print(cx), f)?; write!(f, ",)") } } many => { let generic_names: Vec = many .iter() .filter_map(|t| match t { clean::Generic(name) => Some(*name), _ => None, }) .collect(); let is_generic = generic_names.len() == many.len(); if is_generic { primitive_link( f, PrimitiveType::Tuple, &format!("({})", generic_names.iter().map(|s| s.as_str()).join(", ")), cx, ) } else { write!(f, "(")?; for (i, item) in many.iter().enumerate() { if i != 0 { write!(f, ", ")?; } // Carry `f.alternate()` into this display w/o branching manually. fmt::Display::fmt(&item.print(cx), f)?; } write!(f, ")") } } } } clean::Slice(ref t) => match **t { clean::Generic(name) => { primitive_link(f, PrimitiveType::Slice, &format!("[{name}]"), cx) } _ => { write!(f, "[")?; fmt::Display::fmt(&t.print(cx), f)?; write!(f, "]") } }, clean::Array(ref t, ref n) => match **t { clean::Generic(name) if !f.alternate() => primitive_link( f, PrimitiveType::Array, &format!("[{name}; {n}]", n = Escape(n)), cx, ), _ => { write!(f, "[")?; fmt::Display::fmt(&t.print(cx), f)?; if f.alternate() { write!(f, "; {n}")?; } else { write!(f, "; ")?; primitive_link(f, PrimitiveType::Array, &format!("{n}", n = Escape(n)), cx)?; } write!(f, "]") } }, clean::RawPointer(m, ref t) => { let m = match m { hir::Mutability::Mut => "mut", hir::Mutability::Not => "const", }; if matches!(**t, clean::Generic(_)) || t.is_assoc_ty() { let text = if f.alternate() { format!("*{} {:#}", m, t.print(cx)) } else { format!("*{} {}", m, t.print(cx)) }; primitive_link(f, clean::PrimitiveType::RawPointer, &text, cx) } else { primitive_link(f, clean::PrimitiveType::RawPointer, &format!("*{} ", m), cx)?; fmt::Display::fmt(&t.print(cx), f) } } clean::BorrowedRef { lifetime: ref l, mutability, type_: ref ty } => { let lt = match l { Some(l) => format!("{} ", l.print()), _ => String::new(), }; let m = mutability.print_with_space(); let amp = if f.alternate() { "&" } else { "&" }; match **ty { clean::DynTrait(ref bounds, ref trait_lt) if bounds.len() > 1 || trait_lt.is_some() => { write!(f, "{}{}{}(", amp, lt, m)?; fmt_type(ty, f, use_absolute, cx)?; write!(f, ")") } clean::Generic(name) => { primitive_link(f, PrimitiveType::Reference, &format!("{amp}{lt}{m}{name}"), cx) } _ => { write!(f, "{}{}{}", amp, lt, m)?; fmt_type(ty, f, use_absolute, cx) } } } clean::ImplTrait(ref bounds) => { if f.alternate() { write!(f, "impl {:#}", print_generic_bounds(bounds, cx)) } else { write!(f, "impl {}", print_generic_bounds(bounds, cx)) } } clean::QPath(box clean::QPathData { ref assoc, ref self_type, ref trait_, should_show_cast, }) => { if f.alternate() { if should_show_cast { write!(f, "<{:#} as {:#}>::", self_type.print(cx), trait_.print(cx))? } else { write!(f, "{:#}::", self_type.print(cx))? } } else { if should_show_cast { write!(f, "<{} as {}>::", self_type.print(cx), trait_.print(cx))? } else { write!(f, "{}::", self_type.print(cx))? } }; // It's pretty unsightly to look at `::C` in output, and // we've got hyperlinking on our side, so try to avoid longer // notation as much as possible by making `C` a hyperlink to trait // `B` to disambiguate. // // FIXME: this is still a lossy conversion and there should probably // be a better way of representing this in general? Most of // the ugliness comes from inlining across crates where // everything comes in as a fully resolved QPath (hard to // look at). if !f.alternate() && let Ok((url, _, path)) = href(trait_.def_id(), cx) { write!( f, "{name}", shortty = ItemType::AssocType, name = assoc.name, path = join_with_double_colon(&path), ) } else { write!(f, "{}", assoc.name) }?; // Carry `f.alternate()` into this display w/o branching manually. fmt::Display::fmt(&assoc.args.print(cx), f) } } } impl clean::Type { pub(crate) fn print<'b, 'a: 'b, 'tcx: 'a>( &'a self, cx: &'a Context<'tcx>, ) -> impl fmt::Display + 'b + Captures<'tcx> { display_fn(move |f| fmt_type(self, f, false, cx)) } } impl clean::Path { pub(crate) fn print<'b, 'a: 'b, 'tcx: 'a>( &'a self, cx: &'a Context<'tcx>, ) -> impl fmt::Display + 'b + Captures<'tcx> { display_fn(move |f| resolved_path(f, self.def_id(), self, false, false, cx)) } } impl clean::Impl { pub(crate) fn print<'a, 'tcx: 'a>( &'a self, use_absolute: bool, cx: &'a Context<'tcx>, ) -> impl fmt::Display + 'a + Captures<'tcx> { display_fn(move |f| { if f.alternate() { write!(f, "impl{:#} ", self.generics.print(cx))?; } else { write!(f, "impl{} ", self.generics.print(cx))?; } if let Some(ref ty) = self.trait_ { match self.polarity { ty::ImplPolarity::Positive | ty::ImplPolarity::Reservation => {} ty::ImplPolarity::Negative => write!(f, "!")?, } fmt::Display::fmt(&ty.print(cx), f)?; write!(f, " for ")?; } if let clean::Type::Tuple(types) = &self.for_ && let [clean::Type::Generic(name)] = &types[..] && (self.kind.is_fake_variadic() || self.kind.is_auto()) { // Hardcoded anchor library/core/src/primitive_docs.rs // Link should match `# Trait implementations` primitive_link_fragment(f, PrimitiveType::Tuple, &format!("({name}₁, {name}₂, …, {name}ₙ)"), "#trait-implementations-1", cx)?; } else if let clean::BareFunction(bare_fn) = &self.for_ && let [clean::Argument { type_: clean::Type::Generic(name), .. }] = &bare_fn.decl.inputs.values[..] && (self.kind.is_fake_variadic() || self.kind.is_auto()) { // Hardcoded anchor library/core/src/primitive_docs.rs // Link should match `# Trait implementations` let hrtb = bare_fn.print_hrtb_with_space(cx); let unsafety = bare_fn.unsafety.print_with_space(); let abi = print_abi_with_space(bare_fn.abi); if f.alternate() { write!( f, "{hrtb:#}{unsafety}{abi:#}", )?; } else { write!( f, "{hrtb}{unsafety}{abi}", )?; } let ellipsis = if bare_fn.decl.c_variadic { ", ..." } else { "" }; primitive_link_fragment(f, PrimitiveType::Tuple, &format!("fn ({name}₁, {name}₂, …, {name}ₙ{ellipsis})"), "#trait-implementations-1", cx)?; // Write output. if let clean::FnRetTy::Return(ty) = &bare_fn.decl.output { write!(f, " -> ")?; fmt_type(ty, f, use_absolute, cx)?; } } else if let Some(ty) = self.kind.as_blanket_ty() { fmt_type(ty, f, use_absolute, cx)?; } else { fmt_type(&self.for_, f, use_absolute, cx)?; } fmt::Display::fmt(&print_where_clause(&self.generics, cx, 0, Ending::Newline), f)?; Ok(()) }) } } impl clean::Arguments { pub(crate) fn print<'a, 'tcx: 'a>( &'a self, cx: &'a Context<'tcx>, ) -> impl fmt::Display + 'a + Captures<'tcx> { display_fn(move |f| { for (i, input) in self.values.iter().enumerate() { write!(f, "{}: ", input.name)?; if f.alternate() { write!(f, "{:#}", input.type_.print(cx))?; } else { write!(f, "{}", input.type_.print(cx))?; } if i + 1 < self.values.len() { write!(f, ", ")?; } } Ok(()) }) } } impl clean::FnRetTy { pub(crate) fn print<'a, 'tcx: 'a>( &'a self, cx: &'a Context<'tcx>, ) -> impl fmt::Display + 'a + Captures<'tcx> { display_fn(move |f| match self { clean::Return(clean::Tuple(tys)) if tys.is_empty() => Ok(()), clean::Return(ty) if f.alternate() => { write!(f, " -> {:#}", ty.print(cx)) } clean::Return(ty) => write!(f, " -> {}", ty.print(cx)), clean::DefaultReturn => Ok(()), }) } } impl clean::BareFunctionDecl { fn print_hrtb_with_space<'a, 'tcx: 'a>( &'a self, cx: &'a Context<'tcx>, ) -> impl fmt::Display + 'a + Captures<'tcx> { display_fn(move |f| { if !self.generic_params.is_empty() { write!( f, "for<{}> ", comma_sep(self.generic_params.iter().map(|g| g.print(cx)), true) ) } else { Ok(()) } }) } } // Implements Write but only counts the bytes "written". struct WriteCounter(usize); impl std::fmt::Write for WriteCounter { fn write_str(&mut self, s: &str) -> fmt::Result { self.0 += s.len(); Ok(()) } } // Implements Display by emitting the given number of spaces. struct Indent(usize); impl fmt::Display for Indent { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { (0..self.0).for_each(|_| { f.write_char(' ').unwrap(); }); Ok(()) } } impl clean::FnDecl { pub(crate) fn print<'b, 'a: 'b, 'tcx: 'a>( &'a self, cx: &'a Context<'tcx>, ) -> impl fmt::Display + 'b + Captures<'tcx> { display_fn(move |f| { let ellipsis = if self.c_variadic { ", ..." } else { "" }; if f.alternate() { write!( f, "({args:#}{ellipsis}){arrow:#}", args = self.inputs.print(cx), ellipsis = ellipsis, arrow = self.output.print(cx) ) } else { write!( f, "({args}{ellipsis}){arrow}", args = self.inputs.print(cx), ellipsis = ellipsis, arrow = self.output.print(cx) ) } }) } /// * `header_len`: The length of the function header and name. In other words, the number of /// characters in the function declaration up to but not including the parentheses. /// This is expected to go into a `
`/`code-header` block, so indentation and newlines
    ///   are preserved.
    /// * `indent`: The number of spaces to indent each successive line with, if line-wrapping is
    ///   necessary.
    pub(crate) fn full_print<'a, 'tcx: 'a>(
        &'a self,
        header_len: usize,
        indent: usize,
        cx: &'a Context<'tcx>,
    ) -> impl fmt::Display + 'a + Captures<'tcx> {
        display_fn(move |f| {
            // First, generate the text form of the declaration, with no line wrapping, and count the bytes.
            let mut counter = WriteCounter(0);
            write!(&mut counter, "{:#}", display_fn(|f| { self.inner_full_print(None, f, cx) }))
                .unwrap();
            // If the text form was over 80 characters wide, we will line-wrap our output.
            let line_wrapping_indent =
                if header_len + counter.0 > 80 { Some(indent) } else { None };
            // Generate the final output. This happens to accept `{:#}` formatting to get textual
            // output but in practice it is only formatted with `{}` to get HTML output.
            self.inner_full_print(line_wrapping_indent, f, cx)
        })
    }

    fn inner_full_print(
        &self,
        // For None, the declaration will not be line-wrapped. For Some(n),
        // the declaration will be line-wrapped, with an indent of n spaces.
        line_wrapping_indent: Option,
        f: &mut fmt::Formatter<'_>,
        cx: &Context<'_>,
    ) -> fmt::Result {
        let amp = if f.alternate() { "&" } else { "&" };

        write!(f, "(")?;
        if let Some(n) = line_wrapping_indent {
            write!(f, "\n{}", Indent(n + 4))?;
        }
        for (i, input) in self.inputs.values.iter().enumerate() {
            if i > 0 {
                match line_wrapping_indent {
                    None => write!(f, ", ")?,
                    Some(n) => write!(f, ",\n{}", Indent(n + 4))?,
                };
            }
            if let Some(selfty) = input.to_self() {
                match selfty {
                    clean::SelfValue => {
                        write!(f, "self")?;
                    }
                    clean::SelfBorrowed(Some(ref lt), mtbl) => {
                        write!(f, "{}{} {}self", amp, lt.print(), mtbl.print_with_space())?;
                    }
                    clean::SelfBorrowed(None, mtbl) => {
                        write!(f, "{}{}self", amp, mtbl.print_with_space())?;
                    }
                    clean::SelfExplicit(ref typ) => {
                        write!(f, "self: ")?;
                        fmt::Display::fmt(&typ.print(cx), f)?;
                    }
                }
            } else {
                if input.is_const {
                    write!(f, "const ")?;
                }
                write!(f, "{}: ", input.name)?;
                fmt::Display::fmt(&input.type_.print(cx), f)?;
            }
        }

        if self.c_variadic {
            match line_wrapping_indent {
                None => write!(f, ", ...")?,
                Some(n) => write!(f, "\n{}...", Indent(n + 4))?,
            };
        }

        match line_wrapping_indent {
            None => write!(f, ")")?,
            Some(n) => write!(f, "\n{})", Indent(n))?,
        };

        fmt::Display::fmt(&self.output.print(cx), f)?;
        Ok(())
    }
}

pub(crate) fn visibility_print_with_space<'a, 'tcx: 'a>(
    visibility: Option>,
    item_did: ItemId,
    cx: &'a Context<'tcx>,
) -> impl fmt::Display + 'a + Captures<'tcx> {
    use std::fmt::Write as _;

    let to_print: Cow<'static, str> = match visibility {
        None => "".into(),
        Some(ty::Visibility::Public) => "pub ".into(),
        Some(ty::Visibility::Restricted(vis_did)) => {
            // FIXME(camelid): This may not work correctly if `item_did` is a module.
            //                 However, rustdoc currently never displays a module's
            //                 visibility, so it shouldn't matter.
            let parent_module = find_nearest_parent_module(cx.tcx(), item_did.expect_def_id());

            if vis_did.is_crate_root() {
                "pub(crate) ".into()
            } else if parent_module == Some(vis_did) {
                // `pub(in foo)` where `foo` is the parent module
                // is the same as no visibility modifier
                "".into()
            } else if parent_module.and_then(|parent| find_nearest_parent_module(cx.tcx(), parent))
                == Some(vis_did)
            {
                "pub(super) ".into()
            } else {
                let path = cx.tcx().def_path(vis_did);
                debug!("path={:?}", path);
                // modified from `resolved_path()` to work with `DefPathData`
                let last_name = path.data.last().unwrap().data.get_opt_name().unwrap();
                let anchor = anchor(vis_did, last_name, cx);

                let mut s = "pub(in ".to_owned();
                for seg in &path.data[..path.data.len() - 1] {
                    let _ = write!(s, "{}::", seg.data.get_opt_name().unwrap());
                }
                let _ = write!(s, "{}) ", anchor);
                s.into()
            }
        }
    };
    display_fn(move |f| write!(f, "{}", to_print))
}

/// This function is the same as print_with_space, except that it renders no links.
/// It's used for macros' rendered source view, which is syntax highlighted and cannot have
/// any HTML in it.
pub(crate) fn visibility_to_src_with_space<'a, 'tcx: 'a>(
    visibility: Option>,
    tcx: TyCtxt<'tcx>,
    item_did: DefId,
) -> impl fmt::Display + 'a + Captures<'tcx> {
    let to_print: Cow<'static, str> = match visibility {
        None => "".into(),
        Some(ty::Visibility::Public) => "pub ".into(),
        Some(ty::Visibility::Restricted(vis_did)) => {
            // FIXME(camelid): This may not work correctly if `item_did` is a module.
            //                 However, rustdoc currently never displays a module's
            //                 visibility, so it shouldn't matter.
            let parent_module = find_nearest_parent_module(tcx, item_did);

            if vis_did.is_crate_root() {
                "pub(crate) ".into()
            } else if parent_module == Some(vis_did) {
                // `pub(in foo)` where `foo` is the parent module
                // is the same as no visibility modifier
                "".into()
            } else if parent_module.and_then(|parent| find_nearest_parent_module(tcx, parent))
                == Some(vis_did)
            {
                "pub(super) ".into()
            } else {
                format!("pub(in {}) ", tcx.def_path_str(vis_did)).into()
            }
        }
    };
    display_fn(move |f| f.write_str(&to_print))
}

pub(crate) trait PrintWithSpace {
    fn print_with_space(&self) -> &str;
}

impl PrintWithSpace for hir::Unsafety {
    fn print_with_space(&self) -> &str {
        match self {
            hir::Unsafety::Unsafe => "unsafe ",
            hir::Unsafety::Normal => "",
        }
    }
}

impl PrintWithSpace for hir::IsAsync {
    fn print_with_space(&self) -> &str {
        match self {
            hir::IsAsync::Async => "async ",
            hir::IsAsync::NotAsync => "",
        }
    }
}

impl PrintWithSpace for hir::Mutability {
    fn print_with_space(&self) -> &str {
        match self {
            hir::Mutability::Not => "",
            hir::Mutability::Mut => "mut ",
        }
    }
}

pub(crate) fn print_constness_with_space(
    c: &hir::Constness,
    s: Option,
) -> &'static str {
    match (c, s) {
        // const stable or when feature(staged_api) is not set
        (
            hir::Constness::Const,
            Some(ConstStability { level: StabilityLevel::Stable { .. }, .. }),
        )
        | (hir::Constness::Const, None) => "const ",
        // const unstable or not const
        _ => "",
    }
}

impl clean::Import {
    pub(crate) fn print<'a, 'tcx: 'a>(
        &'a self,
        cx: &'a Context<'tcx>,
    ) -> impl fmt::Display + 'a + Captures<'tcx> {
        display_fn(move |f| match self.kind {
            clean::ImportKind::Simple(name) => {
                if name == self.source.path.last() {
                    write!(f, "use {};", self.source.print(cx))
                } else {
                    write!(f, "use {} as {};", self.source.print(cx), name)
                }
            }
            clean::ImportKind::Glob => {
                if self.source.path.segments.is_empty() {
                    write!(f, "use *;")
                } else {
                    write!(f, "use {}::*;", self.source.print(cx))
                }
            }
        })
    }
}

impl clean::ImportSource {
    pub(crate) fn print<'a, 'tcx: 'a>(
        &'a self,
        cx: &'a Context<'tcx>,
    ) -> impl fmt::Display + 'a + Captures<'tcx> {
        display_fn(move |f| match self.did {
            Some(did) => resolved_path(f, did, &self.path, true, false, cx),
            _ => {
                for seg in &self.path.segments[..self.path.segments.len() - 1] {
                    write!(f, "{}::", seg.name)?;
                }
                let name = self.path.last();
                if let hir::def::Res::PrimTy(p) = self.path.res {
                    primitive_link(f, PrimitiveType::from(p), name.as_str(), cx)?;
                } else {
                    write!(f, "{}", name)?;
                }
                Ok(())
            }
        })
    }
}

impl clean::TypeBinding {
    pub(crate) fn print<'a, 'tcx: 'a>(
        &'a self,
        cx: &'a Context<'tcx>,
    ) -> impl fmt::Display + 'a + Captures<'tcx> {
        display_fn(move |f| {
            f.write_str(self.assoc.name.as_str())?;
            if f.alternate() {
                write!(f, "{:#}", self.assoc.args.print(cx))?;
            } else {
                write!(f, "{}", self.assoc.args.print(cx))?;
            }
            match self.kind {
                clean::TypeBindingKind::Equality { ref term } => {
                    if f.alternate() {
                        write!(f, " = {:#}", term.print(cx))?;
                    } else {
                        write!(f, " = {}", term.print(cx))?;
                    }
                }
                clean::TypeBindingKind::Constraint { ref bounds } => {
                    if !bounds.is_empty() {
                        if f.alternate() {
                            write!(f, ": {:#}", print_generic_bounds(bounds, cx))?;
                        } else {
                            write!(f, ": {}", print_generic_bounds(bounds, cx))?;
                        }
                    }
                }
            }
            Ok(())
        })
    }
}

pub(crate) fn print_abi_with_space(abi: Abi) -> impl fmt::Display {
    display_fn(move |f| {
        let quot = if f.alternate() { "\"" } else { """ };
        match abi {
            Abi::Rust => Ok(()),
            abi => write!(f, "extern {0}{1}{0} ", quot, abi.name()),
        }
    })
}

pub(crate) fn print_default_space<'a>(v: bool) -> &'a str {
    if v { "default " } else { "" }
}

impl clean::GenericArg {
    pub(crate) fn print<'a, 'tcx: 'a>(
        &'a self,
        cx: &'a Context<'tcx>,
    ) -> impl fmt::Display + 'a + Captures<'tcx> {
        display_fn(move |f| match self {
            clean::GenericArg::Lifetime(lt) => fmt::Display::fmt(<.print(), f),
            clean::GenericArg::Type(ty) => fmt::Display::fmt(&ty.print(cx), f),
            clean::GenericArg::Const(ct) => fmt::Display::fmt(&ct.print(cx.tcx()), f),
            clean::GenericArg::Infer => fmt::Display::fmt("_", f),
        })
    }
}

impl clean::types::Term {
    pub(crate) fn print<'a, 'tcx: 'a>(
        &'a self,
        cx: &'a Context<'tcx>,
    ) -> impl fmt::Display + 'a + Captures<'tcx> {
        display_fn(move |f| match self {
            clean::types::Term::Type(ty) => fmt::Display::fmt(&ty.print(cx), f),
            clean::types::Term::Constant(ct) => fmt::Display::fmt(&ct.print(cx.tcx()), f),
        })
    }
}

pub(crate) fn display_fn(
    f: impl FnOnce(&mut fmt::Formatter<'_>) -> fmt::Result,
) -> impl fmt::Display {
    struct WithFormatter(Cell>);

    impl fmt::Display for WithFormatter
    where
        F: FnOnce(&mut fmt::Formatter<'_>) -> fmt::Result,
    {
        fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
            (self.0.take()).unwrap()(f)
        }
    }

    WithFormatter(Cell::new(Some(f)))
}