diff --git a/src/libsyntax_pos/symbol.rs b/src/libsyntax_pos/symbol.rs index 2b005c3fc42..d17e909c4d5 100644 --- a/src/libsyntax_pos/symbol.rs +++ b/src/libsyntax_pos/symbol.rs @@ -807,25 +807,13 @@ impl Ident { Ident::new(self.name, self.span.modern_and_legacy()) } - /// Transforms an underscore identifier into one with the same name, but - /// gensymed. Leaves non-underscore identifiers unchanged. - pub fn gensym_if_underscore(self) -> Ident { - if self.name == kw::Underscore { - let name = with_interner(|interner| interner.gensymed(self.name)); - Ident::new(name, self.span) - } else { - self - } - } - /// Convert the name to a `LocalInternedString`. This is a slowish /// operation because it requires locking the symbol interner. pub fn as_str(self) -> LocalInternedString { self.name.as_str() } - /// Convert the name to an `InternedString`. This is a slowish operation - /// because it requires locking the symbol interner. + /// Convert the name to an `InternedString`. pub fn as_interned_str(self) -> InternedString { self.name.as_interned_str() } @@ -880,26 +868,9 @@ impl UseSpecializedDecodable for Ident { } } -/// A symbol is an interned or gensymed string. A gensym is a symbol that is -/// never equal to any other symbol. +/// An interned string. /// -/// Conceptually, a gensym can be thought of as a normal symbol with an -/// invisible unique suffix. Gensyms are useful when creating new identifiers -/// that must not match any existing identifiers, e.g. during macro expansion -/// and syntax desugaring. Because gensyms should always be identifiers, all -/// gensym operations are on `Ident` rather than `Symbol`. (Indeed, in the -/// future the gensym-ness may be moved from `Symbol` to hygiene data.) -/// -/// Examples: -/// ``` -/// assert_eq!(Ident::from_str("_"), Ident::from_str("_")) -/// assert_ne!(Ident::from_str("_").gensym_if_underscore(), Ident::from_str("_")) -/// assert_ne!( -/// Ident::from_str("_").gensym_if_underscore(), -/// Ident::from_str("_").gensym_if_underscore(), -/// ) -/// ``` -/// Internally, a symbol is implemented as an index, and all operations +/// Internally, a `Symbol` is implemented as an index, and all operations /// (including hashing, equality, and ordering) operate on that index. The use /// of `rustc_index::newtype_index!` means that `Option` only takes up 4 bytes, /// because `rustc_index::newtype_index!` reserves the last 256 values for tagging purposes. @@ -950,12 +921,9 @@ impl Symbol { }) } - /// Convert to an `InternedString`. This is a slowish operation because it - /// requires locking the symbol interner. + /// Convert to an `InternedString`. pub fn as_interned_str(self) -> InternedString { - with_interner(|interner| InternedString { - symbol: interner.interned(self) - }) + InternedString { symbol: self } } pub fn as_u32(self) -> u32 { @@ -965,12 +933,7 @@ impl Symbol { impl fmt::Debug for Symbol { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - let is_gensymed = with_interner(|interner| interner.is_gensymed(*self)); - if is_gensymed { - write!(f, "{}({:?})", self, self.0) - } else { - write!(f, "{}", self) - } + fmt::Display::fmt(self, f) } } @@ -993,15 +956,11 @@ impl Decodable for Symbol { } // The `&'static str`s in this type actually point into the arena. -// -// Note that normal symbols are indexed upward from 0, and gensyms are indexed -// downward from SymbolIndex::MAX_AS_U32. #[derive(Default)] pub struct Interner { arena: DroplessArena, names: FxHashMap<&'static str, Symbol>, strings: Vec<&'static str>, - gensyms: Vec, } impl Interner { @@ -1034,34 +993,10 @@ impl Interner { self.names.insert(string, name); name } - - fn interned(&self, symbol: Symbol) -> Symbol { - if (symbol.0.as_usize()) < self.strings.len() { - symbol - } else { - self.gensyms[(SymbolIndex::MAX_AS_U32 - symbol.0.as_u32()) as usize] - } - } - - fn gensymed(&mut self, symbol: Symbol) -> Symbol { - self.gensyms.push(symbol); - Symbol::new(SymbolIndex::MAX_AS_U32 - self.gensyms.len() as u32 + 1) - } - - fn is_gensymed(&mut self, symbol: Symbol) -> bool { - symbol.0.as_usize() >= self.strings.len() - } - // Get the symbol as a string. `Symbol::as_str()` should be used in // preference to this function. pub fn get(&self, symbol: Symbol) -> &str { - match self.strings.get(symbol.0.as_usize()) { - Some(string) => string, - None => { - let symbol = self.gensyms[(SymbolIndex::MAX_AS_U32 - symbol.0.as_u32()) as usize]; - self.strings[symbol.0.as_usize()] - } - } + self.strings[symbol.0.as_usize()] } } @@ -1246,19 +1181,12 @@ impl fmt::Display for LocalInternedString { } } -/// An alternative to `Symbol` that is focused on string contents. It has two -/// main differences to `Symbol`. +/// An alternative to `Symbol` that is focused on string contents. /// -/// First, its implementations of `Hash`, `PartialOrd` and `Ord` work with the +/// Its implementations of `Hash`, `PartialOrd` and `Ord` work with the /// string chars rather than the symbol integer. This is useful when hash /// stability is required across compile sessions, or a guaranteed sort /// ordering is required. -/// -/// Second, gensym-ness is irrelevant. E.g.: -/// ``` -/// assert_ne!(Symbol::gensym("x"), Symbol::gensym("x")) -/// assert_eq!(Symbol::gensym("x").as_interned_str(), Symbol::gensym("x").as_interned_str()) -/// ``` #[derive(Clone, Copy, PartialEq, Eq)] pub struct InternedString { symbol: Symbol, diff --git a/src/libsyntax_pos/symbol/tests.rs b/src/libsyntax_pos/symbol/tests.rs index 1b91c9bb845..f74b9a0cd1d 100644 --- a/src/libsyntax_pos/symbol/tests.rs +++ b/src/libsyntax_pos/symbol/tests.rs @@ -14,13 +14,6 @@ fn interner_tests() { assert_eq!(i.intern("cat"), Symbol::new(1)); // dog is still at zero assert_eq!(i.intern("dog"), Symbol::new(0)); - let z = i.intern("zebra"); - assert_eq!(i.gensymed(z), Symbol::new(SymbolIndex::MAX_AS_U32)); - // gensym of same string gets new number: - assert_eq!(i.gensymed(z), Symbol::new(SymbolIndex::MAX_AS_U32 - 1)); - // gensym of *existing* string gets new number: - let d = i.intern("dog"); - assert_eq!(i.gensymed(d), Symbol::new(SymbolIndex::MAX_AS_U32 - 2)); } #[test]