diff options
| -rw-r--r-- | src/librustdoc/html/render/mod.rs | 31 | ||||
| -rw-r--r-- | src/librustdoc/html/static/js/search.js | 2 |
2 files changed, 26 insertions, 7 deletions
diff --git a/src/librustdoc/html/render/mod.rs b/src/librustdoc/html/render/mod.rs index 8afeec81d87..bea5ccd7c86 100644 --- a/src/librustdoc/html/render/mod.rs +++ b/src/librustdoc/html/render/mod.rs @@ -131,6 +131,10 @@ pub(crate) struct RenderType { } impl RenderType { + // Types are rendered as lists of lists, because that's pretty compact. + // The contents of the lists are always integers in self-terminating hex + // form, handled by `RenderTypeId::write_to_string`, so no commas are + // needed to separate the items. pub fn write_to_string(&self, string: &mut String) { fn write_optional_id(id: Option<RenderTypeId>, string: &mut String) { // 0 is a sentinel, everything else is one-indexed @@ -139,6 +143,9 @@ impl RenderType { None => string.push('`'), } } + // Either just the type id, or `{type, generics, bindings?}` + // where generics is a list of types, + // and bindings is a list of `{id, typelist}` pairs. if self.generics.is_some() || self.bindings.is_some() { string.push('{'); write_optional_id(self.id, string); @@ -186,10 +193,19 @@ impl RenderTypeId { RenderTypeId::Index(idx) => (true, (-*idx).try_into().unwrap()), _ => panic!("must convert render types to indexes before serializing"), }; - // zig-zag notation + // zig-zag encoding let value: u32 = (id << 1) | (if sign { 1 } else { 0 }); - // encode - // Documented in https://rust-lang.github.io/rustc-dev-guide/rustdoc-internals/search.html + // Self-terminating hex use capital letters for everything but the + // least significant digit, which is lowercase. For example, decimal 17 + // would be `` Aa `` if zig-zag encoding weren't used. + // + // Zig-zag encoding, however, stores the sign bit as the last bit. + // This means, in the last hexit, 1 is actually `c`, -1 is `b` + // (`a` is the imaginary -0), and, because all the bits are shifted + // by one, `` A` `` is actually 8 and `` Aa `` is -8. + // + // https://rust-lang.github.io/rustc-dev-guide/rustdoc-internals/search.html + // describes the encoding in more detail. let mut shift: u32 = 28; let mut mask: u32 = 0xF0_00_00_00; while shift < 32 { @@ -219,8 +235,9 @@ impl IndexItemFunctionType { string: &mut String, backref_queue: &mut VecDeque<&'a IndexItemFunctionType>, ) { - assert!(backref_queue.len() < 16); - // If we couldn't figure out a type, just write `0`. + assert!(backref_queue.len() <= 16); + // If we couldn't figure out a type, just write 0, + // which is encoded as `` ` `` (see RenderTypeId::write_to_string). let has_missing = self .inputs .iter() @@ -229,13 +246,15 @@ impl IndexItemFunctionType { if has_missing { string.push('`'); } else if let Some(idx) = backref_queue.iter().position(|other| *other == self) { + // The backref queue has 16 items, so backrefs use + // a single hexit, disjoint from the ones used for numbers. string.push( char::try_from('0' as u32 + u32::try_from(idx).unwrap()) .expect("last possible value is '?'"), ); } else { backref_queue.push_front(self); - if backref_queue.len() >= 16 { + if backref_queue.len() > 16 { backref_queue.pop_back(); } string.push('{'); diff --git a/src/librustdoc/html/static/js/search.js b/src/librustdoc/html/static/js/search.js index 6fb92d8fbb1..e0708485fc0 100644 --- a/src/librustdoc/html/static/js/search.js +++ b/src/librustdoc/html/static/js/search.js @@ -2858,7 +2858,7 @@ ${item.displayPath}<span class="${type}">${name}</span>\ inputs, output, where_clause, }; itemFunctionDecoder.backrefQueue.unshift(ret); - if (itemFunctionDecoder.backrefQueue.length >= 16) { + if (itemFunctionDecoder.backrefQueue.length > 16) { itemFunctionDecoder.backrefQueue.pop(); } return ret; |