1 //! An "interner" is a data structure that associates values with usize tags and
2 //! allows bidirectional lookup; i.e., given a value, one can easily find the
3 //! type, and vice versa.
5 use rustc_arena::DroplessArena;
6 use rustc_data_structures::fx::FxHashMap;
7 use rustc_data_structures::stable_hasher::{HashStable, StableHasher, ToStableHashKey};
8 use rustc_macros::HashStable_Generic;
9 use rustc_serialize::{Decodable, Decoder, Encodable, Encoder};
11 use std::cmp::{Ord, PartialEq, PartialOrd};
13 use std::hash::{Hash, Hasher};
16 use crate::{Edition, Span, DUMMY_SP, SESSION_GLOBALS};
21 // The proc macro code for this is in `src/librustc_macros/src/symbols.rs`.
23 // After modifying this list adjust `is_special`, `is_used_keyword`/`is_unused_keyword`,
24 // this should be rarely necessary though if the keywords are kept in alphabetic order.
26 // Special reserved identifiers used internally for elided lifetimes,
27 // unnamed method parameters, crate root module, error recovery etc.
30 DollarCrate: "$crate",
33 // Keywords that are used in stable Rust.
70 // Keywords that are used in unstable Rust or reserved for future use.
84 // Edition-specific keywords that are used in stable Rust.
85 Async: "async", // >= 2018 Edition only
86 Await: "await", // >= 2018 Edition only
87 Dyn: "dyn", // >= 2018 Edition only
89 // Edition-specific keywords that are used in unstable Rust or reserved for future use.
90 Try: "try", // >= 2018 Edition only
92 // Special lifetime names
93 UnderscoreLifetime: "'_",
94 StaticLifetime: "'static",
96 // Weak keywords, have special meaning only in specific contexts.
100 MacroRules: "macro_rules",
105 // Pre-interned symbols that can be referred to with `rustc_span::sym::*`.
107 // The symbol is the stringified identifier unless otherwise specified, in
108 // which case the name should mention the non-identifier punctuation.
109 // E.g. `sym::proc_dash_macro` represents "proc-macro", and it shouldn't be
110 // called `sym::proc_macro` because then it's easy to mistakenly think it
111 // represents "proc_macro".
113 // As well as the symbols listed, there are symbols for the strings
114 // "0", "1", ..., "9", which are accessible via `sym::integer`.
116 // The proc macro will abort if symbols are not in alphabetical order (as
117 // defined by `impl Ord for str`) or if any symbols are duplicated. Vim
118 // users can sort the list by selecting it and executing the command
119 // `:'<,'>!LC_ALL=C sort`.
121 // There is currently no checking that all symbols are used; that would be
189 ProceduralMasqueradeDummyType,
230 aarch64_target_feature,
234 abi_c_cmse_nonsecure_call,
236 abi_msp430_interrupt,
249 advanced_slice_patterns,
264 allow_internal_unsafe,
265 allow_internal_unstable,
271 arbitrary_enum_discriminant,
272 arbitrary_self_types,
284 assert_receiver_is_total_eq,
288 associated_type_bounds,
289 associated_type_defaults,
300 augmented_assignments,
302 automatically_derived,
303 avx512_target_feature,
309 bind_by_move_pattern_guards,
320 borrowck_graphviz_format,
321 borrowck_graphviz_postflow,
322 borrowck_graphviz_preflow,
326 braced_empty_structs,
336 capture_disjoint_fields,
348 cfg_target_has_atomic,
349 cfg_target_thread_local,
359 closure_to_fn_coercion,
361 cmpxchg16b_target_feature,
362 cmse_nonsecure_entry,
370 conservative_impl_trait,
373 const_compare_raw_pointers,
376 const_evaluatable_checked,
379 const_fn_floating_point_arithmetic,
380 const_fn_fn_ptr_basics,
384 const_generics_defaults,
387 const_in_array_repeat_expressions,
393 const_precise_live_drops,
396 const_raw_ptr_to_usize_cast,
399 const_trait_bound_opt_out,
415 core_panic_2015_macro,
424 crate_visibility_modifier,
425 crt_dash_static: "crt-static",
434 custom_inner_attributes,
435 custom_test_frameworks,
449 default_alloc_error_handler,
450 default_lib_allocator,
451 default_type_parameter_fallback,
453 delay_span_bug_from_inside_query,
461 destructuring_assignment,
477 document_private_items,
478 dotdot_in_tuple_patterns,
479 dotdoteq_in_patterns,
487 dropck_parametricity,
496 emit_enum_variant_arg,
504 ermsb_target_feature,
509 exclusive_range_pattern,
510 exhaustive_integer_patterns,
521 extended_key_value_attributes,
522 extern_absolute_paths,
523 extern_crate_item_prelude,
545 field_init_shorthand,
550 float_to_int_unchecked,
578 from_size_align_unchecked,
591 generic_associated_types,
598 half_open_range_patterns,
602 hexagon_target_feature,
604 homogeneous_aggregate,
621 if_while_or_patterns,
623 impl_header_lifetime_elision,
626 impl_trait_in_bindings,
632 inclusive_range_syntax,
635 infer_outlives_requirements,
636 infer_static_outlives_requirements,
648 irrefutable_let_patterns,
652 issue_5723_bootstrap,
653 issue_tracker_base_url,
665 lazy_normalization_consts,
677 link_llvm_intrinsics,
696 macro_at_most_once_rep,
697 macro_attributes_in_derive_output,
700 macro_lifetime_matcher,
701 macro_literal_matcher,
713 match_beginning_vert,
714 match_default_bindings,
741 movbe_target_feature,
790 nontrapping_dash_fptoint: "nontrapping-fptoint",
795 object_safe_for_dispatch,
798 omit_gdb_pretty_printer_section,
807 optin_builtin_traits,
816 overlapping_marker_traits,
826 panic_implementation,
856 post_dash_lto: "post-lto",
857 powerpc_target_feature,
862 pre_dash_lto: "pre-lto",
863 precise_pointer_size_matching,
867 prefetch_read_instruction,
869 prefetch_write_instruction,
874 proc_dash_macro: "proc-macro",
876 proc_macro_attribute,
882 proc_macro_internals,
884 proc_macro_non_items,
885 proc_macro_path_invoc,
898 quad_precision_float,
905 re_rebalance_coherence,
908 read_enum_variant_arg,
916 reexport_test_harness_main,
929 relaxed_struct_unsize,
945 riscv_target_feature,
958 rust_eh_catch_typeinfo,
960 rust_eh_register_frames,
961 rust_eh_unregister_frames,
965 rustc_allocator_nounwind,
966 rustc_allow_const_fn_unstable,
967 rustc_args_required_const,
970 rustc_capture_analysis,
973 rustc_const_unstable,
974 rustc_conversion_suggestion,
977 rustc_diagnostic_item,
978 rustc_diagnostic_macros,
981 rustc_dump_env_program_clauses,
982 rustc_dump_program_clauses,
983 rustc_dump_user_substs,
985 rustc_expected_cgu_reuse,
986 rustc_if_this_changed,
987 rustc_inherit_overflow_checks,
989 rustc_layout_scalar_valid_range_end,
990 rustc_layout_scalar_valid_range_start,
991 rustc_legacy_const_generics,
992 rustc_macro_transparency,
994 rustc_nonnull_optimization_guaranteed,
995 rustc_object_lifetime_default,
996 rustc_on_unimplemented,
999 rustc_partition_codegened,
1000 rustc_partition_reused,
1002 rustc_peek_definite_init,
1003 rustc_peek_indirectly_mutable,
1004 rustc_peek_liveness,
1005 rustc_peek_maybe_init,
1006 rustc_peek_maybe_uninit,
1007 rustc_polymorphize_error,
1009 rustc_proc_macro_decls,
1012 rustc_reservation_impl,
1014 rustc_specialization_trait,
1016 rustc_std_internal_symbol,
1020 rustc_then_this_would_need,
1021 rustc_unsafe_specialization_marker,
1024 rvalue_static_promotion,
1072 simd_reduce_add_ordered,
1073 simd_reduce_add_unordered,
1078 simd_reduce_max_nanless,
1080 simd_reduce_min_nanless,
1081 simd_reduce_mul_ordered,
1082 simd_reduce_mul_unordered,
1086 simd_saturating_add,
1087 simd_saturating_sub,
1090 simd_select_bitmask,
1116 sse4a_target_feature,
1128 std_panic_2015_macro,
1131 stmt_expr_attributes,
1132 stop_after_dataflow,
1137 struct_field_attributes,
1159 target_has_atomic_equal_alignment,
1160 target_has_atomic_load_store,
1162 target_pointer_width,
1163 target_target_vendor,
1164 target_thread_local,
1170 termination_trait_test,
1173 test_accepted_feature,
1175 test_removed_feature,
1202 type_alias_enum_variants,
1203 type_alias_impl_trait,
1214 unaligned_volatile_load,
1215 unaligned_volatile_store,
1224 underscore_const_names,
1226 underscore_lifetimes,
1229 universal_impl_trait,
1236 unrestricted_attribute_tokens,
1237 unsafe_block_in_unsafe_fn,
1239 unsafe_no_drop_flag,
1243 unsized_tuple_coercion,
1246 unused_qualifications,
1269 visible_private_types,
1271 volatile_copy_memory,
1272 volatile_copy_nonoverlapping_memory,
1274 volatile_set_memory,
1280 wasm_target_feature,
1295 #[derive(Copy, Clone, Eq, HashStable_Generic, Encodable, Decodable)]
1303 /// Constructs a new identifier from a symbol and a span.
1304 pub const fn new(name: Symbol, span: Span) -> Ident {
1305 Ident { name, span }
1308 /// Constructs a new identifier with a dummy span.
1310 pub const fn with_dummy_span(name: Symbol) -> Ident {
1311 Ident::new(name, DUMMY_SP)
1315 pub fn invalid() -> Ident {
1316 Ident::with_dummy_span(kw::Empty)
1319 /// Maps a string to an identifier with a dummy span.
1320 pub fn from_str(string: &str) -> Ident {
1321 Ident::with_dummy_span(Symbol::intern(string))
1324 /// Maps a string and a span to an identifier.
1325 pub fn from_str_and_span(string: &str, span: Span) -> Ident {
1326 Ident::new(Symbol::intern(string), span)
1329 /// Replaces `lo` and `hi` with those from `span`, but keep hygiene context.
1330 pub fn with_span_pos(self, span: Span) -> Ident {
1331 Ident::new(self.name, span.with_ctxt(self.span.ctxt()))
1334 pub fn without_first_quote(self) -> Ident {
1335 Ident::new(Symbol::intern(self.as_str().trim_start_matches('\'')), self.span)
1338 /// "Normalize" ident for use in comparisons using "item hygiene".
1339 /// Identifiers with same string value become same if they came from the same macro 2.0 macro
1340 /// (e.g., `macro` item, but not `macro_rules` item) and stay different if they came from
1341 /// different macro 2.0 macros.
1342 /// Technically, this operation strips all non-opaque marks from ident's syntactic context.
1343 pub fn normalize_to_macros_2_0(self) -> Ident {
1344 Ident::new(self.name, self.span.normalize_to_macros_2_0())
1347 /// "Normalize" ident for use in comparisons using "local variable hygiene".
1348 /// Identifiers with same string value become same if they came from the same non-transparent
1349 /// macro (e.g., `macro` or `macro_rules!` items) and stay different if they came from different
1350 /// non-transparent macros.
1351 /// Technically, this operation strips all transparent marks from ident's syntactic context.
1352 pub fn normalize_to_macro_rules(self) -> Ident {
1353 Ident::new(self.name, self.span.normalize_to_macro_rules())
1356 /// Convert the name to a `SymbolStr`. This is a slowish operation because
1357 /// it requires locking the symbol interner.
1358 pub fn as_str(self) -> SymbolStr {
1363 impl PartialEq for Ident {
1364 fn eq(&self, rhs: &Self) -> bool {
1365 self.name == rhs.name && self.span.ctxt() == rhs.span.ctxt()
1369 impl Hash for Ident {
1370 fn hash<H: Hasher>(&self, state: &mut H) {
1371 self.name.hash(state);
1372 self.span.ctxt().hash(state);
1376 impl fmt::Debug for Ident {
1377 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1378 fmt::Display::fmt(self, f)?;
1379 fmt::Debug::fmt(&self.span.ctxt(), f)
1383 /// This implementation is supposed to be used in error messages, so it's expected to be identical
1384 /// to printing the original identifier token written in source code (`token_to_string`),
1385 /// except that AST identifiers don't keep the rawness flag, so we have to guess it.
1386 impl fmt::Display for Ident {
1387 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1388 fmt::Display::fmt(&IdentPrinter::new(self.name, self.is_raw_guess(), None), f)
1392 /// This is the most general way to print identifiers.
1393 /// AST pretty-printer is used as a fallback for turning AST structures into token streams for
1394 /// proc macros. Additionally, proc macros may stringify their input and expect it survive the
1395 /// stringification (especially true for proc macro derives written between Rust 1.15 and 1.30).
1396 /// So we need to somehow pretty-print `$crate` in a way preserving at least some of its
1397 /// hygiene data, most importantly name of the crate it refers to.
1398 /// As a result we print `$crate` as `crate` if it refers to the local crate
1399 /// and as `::other_crate_name` if it refers to some other crate.
1400 /// Note, that this is only done if the ident token is printed from inside of AST pretty-pringing,
1401 /// but not otherwise. Pretty-printing is the only way for proc macros to discover token contents,
1402 /// so we should not perform this lossy conversion if the top level call to the pretty-printer was
1403 /// done for a token stream or a single token.
1404 pub struct IdentPrinter {
1407 /// Span used for retrieving the crate name to which `$crate` refers to,
1408 /// if this field is `None` then the `$crate` conversion doesn't happen.
1409 convert_dollar_crate: Option<Span>,
1413 /// The most general `IdentPrinter` constructor. Do not use this.
1414 pub fn new(symbol: Symbol, is_raw: bool, convert_dollar_crate: Option<Span>) -> IdentPrinter {
1415 IdentPrinter { symbol, is_raw, convert_dollar_crate }
1418 /// This implementation is supposed to be used when printing identifiers
1419 /// as a part of pretty-printing for larger AST pieces.
1420 /// Do not use this either.
1421 pub fn for_ast_ident(ident: Ident, is_raw: bool) -> IdentPrinter {
1422 IdentPrinter::new(ident.name, is_raw, Some(ident.span))
1426 impl fmt::Display for IdentPrinter {
1427 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1430 } else if self.symbol == kw::DollarCrate {
1431 if let Some(span) = self.convert_dollar_crate {
1432 let converted = span.ctxt().dollar_crate_name();
1433 if !converted.is_path_segment_keyword() {
1436 return fmt::Display::fmt(&converted, f);
1439 fmt::Display::fmt(&self.symbol, f)
1443 /// An newtype around `Ident` that calls [Ident::normalize_to_macro_rules] on
1445 // FIXME(matthewj, petrochenkov) Use this more often, add a similar
1446 // `ModernIdent` struct and use that as well.
1447 #[derive(Copy, Clone, Eq, PartialEq, Hash)]
1448 pub struct MacroRulesNormalizedIdent(Ident);
1450 impl MacroRulesNormalizedIdent {
1451 pub fn new(ident: Ident) -> Self {
1452 Self(ident.normalize_to_macro_rules())
1456 impl fmt::Debug for MacroRulesNormalizedIdent {
1457 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1458 fmt::Debug::fmt(&self.0, f)
1462 impl fmt::Display for MacroRulesNormalizedIdent {
1463 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1464 fmt::Display::fmt(&self.0, f)
1468 /// An interned string.
1470 /// Internally, a `Symbol` is implemented as an index, and all operations
1471 /// (including hashing, equality, and ordering) operate on that index. The use
1472 /// of `rustc_index::newtype_index!` means that `Option<Symbol>` only takes up 4 bytes,
1473 /// because `rustc_index::newtype_index!` reserves the last 256 values for tagging purposes.
1475 /// Note that `Symbol` cannot directly be a `rustc_index::newtype_index!` because it
1476 /// implements `fmt::Debug`, `Encodable`, and `Decodable` in special ways.
1477 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
1478 pub struct Symbol(SymbolIndex);
1480 rustc_index::newtype_index! {
1481 pub struct SymbolIndex { .. }
1485 const fn new(n: u32) -> Self {
1486 Symbol(SymbolIndex::from_u32(n))
1489 /// Maps a string to its interned representation.
1490 pub fn intern(string: &str) -> Self {
1491 with_interner(|interner| interner.intern(string))
1494 /// Convert to a `SymbolStr`. This is a slowish operation because it
1495 /// requires locking the symbol interner.
1496 pub fn as_str(self) -> SymbolStr {
1497 with_interner(|interner| unsafe {
1498 SymbolStr { string: std::mem::transmute::<&str, &str>(interner.get(self)) }
1502 pub fn as_u32(self) -> u32 {
1506 pub fn is_empty(self) -> bool {
1510 /// This method is supposed to be used in error messages, so it's expected to be
1511 /// identical to printing the original identifier token written in source code
1512 /// (`token_to_string`, `Ident::to_string`), except that symbols don't keep the rawness flag
1513 /// or edition, so we have to guess the rawness using the global edition.
1514 pub fn to_ident_string(self) -> String {
1515 Ident::with_dummy_span(self).to_string()
1519 impl fmt::Debug for Symbol {
1520 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1521 fmt::Debug::fmt(&self.as_str(), f)
1525 impl fmt::Display for Symbol {
1526 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1527 fmt::Display::fmt(&self.as_str(), f)
1531 impl<S: Encoder> Encodable<S> for Symbol {
1532 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
1533 s.emit_str(&self.as_str())
1537 impl<D: Decoder> Decodable<D> for Symbol {
1539 fn decode(d: &mut D) -> Result<Symbol, D::Error> {
1540 Ok(Symbol::intern(&d.read_str()?))
1544 impl<CTX> HashStable<CTX> for Symbol {
1546 fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
1547 self.as_str().hash_stable(hcx, hasher);
1551 impl<CTX> ToStableHashKey<CTX> for Symbol {
1552 type KeyType = SymbolStr;
1555 fn to_stable_hash_key(&self, _: &CTX) -> SymbolStr {
1560 // The `&'static str`s in this type actually point into the arena.
1562 // The `FxHashMap`+`Vec` pair could be replaced by `FxIndexSet`, but #75278
1563 // found that to regress performance up to 2% in some cases. This might be
1564 // revisited after further improvements to `indexmap`.
1566 pub struct Interner {
1567 arena: DroplessArena,
1568 names: FxHashMap<&'static str, Symbol>,
1569 strings: Vec<&'static str>,
1573 fn prefill(init: &[&'static str]) -> Self {
1575 strings: init.into(),
1576 names: init.iter().copied().zip((0..).map(Symbol::new)).collect(),
1577 ..Default::default()
1582 pub fn intern(&mut self, string: &str) -> Symbol {
1583 if let Some(&name) = self.names.get(string) {
1587 let name = Symbol::new(self.strings.len() as u32);
1589 // `from_utf8_unchecked` is safe since we just allocated a `&str` which is known to be
1592 unsafe { str::from_utf8_unchecked(self.arena.alloc_slice(string.as_bytes())) };
1593 // It is safe to extend the arena allocation to `'static` because we only access
1594 // these while the arena is still alive.
1595 let string: &'static str = unsafe { &*(string as *const str) };
1596 self.strings.push(string);
1597 self.names.insert(string, name);
1601 // Get the symbol as a string. `Symbol::as_str()` should be used in
1602 // preference to this function.
1603 pub fn get(&self, symbol: Symbol) -> &str {
1604 self.strings[symbol.0.as_usize()]
1608 // This module has a very short name because it's used a lot.
1609 /// This module contains all the defined keyword `Symbol`s.
1611 /// Given that `kw` is imported, use them like `kw::keyword_name`.
1612 /// For example `kw::Loop` or `kw::Break`.
1614 pub use super::kw_generated::*;
1617 // This module has a very short name because it's used a lot.
1618 /// This module contains all the defined non-keyword `Symbol`s.
1620 /// Given that `sym` is imported, use them like `sym::symbol_name`.
1621 /// For example `sym::rustfmt` or `sym::u8`.
1624 use std::convert::TryInto;
1627 pub use super::sym_generated::*;
1629 // Used from a macro in `librustc_feature/accepted.rs`
1630 pub use super::kw::MacroRules as macro_rules;
1632 /// Get the symbol for an integer.
1634 /// The first few non-negative integers each have a static symbol and therefore
1636 pub fn integer<N: TryInto<usize> + Copy + ToString>(n: N) -> Symbol {
1637 if let Result::Ok(idx) = n.try_into() {
1639 return Symbol::new(super::SYMBOL_DIGITS_BASE + idx as u32);
1642 Symbol::intern(&n.to_string())
1647 fn is_special(self) -> bool {
1648 self <= kw::Underscore
1651 fn is_used_keyword_always(self) -> bool {
1652 self >= kw::As && self <= kw::While
1655 fn is_used_keyword_conditional(self, edition: impl FnOnce() -> Edition) -> bool {
1656 (self >= kw::Async && self <= kw::Dyn) && edition() >= Edition::Edition2018
1659 fn is_unused_keyword_always(self) -> bool {
1660 self >= kw::Abstract && self <= kw::Yield
1663 fn is_unused_keyword_conditional(self, edition: impl FnOnce() -> Edition) -> bool {
1664 self == kw::Try && edition() >= Edition::Edition2018
1667 pub fn is_reserved(self, edition: impl Copy + FnOnce() -> Edition) -> bool {
1669 || self.is_used_keyword_always()
1670 || self.is_unused_keyword_always()
1671 || self.is_used_keyword_conditional(edition)
1672 || self.is_unused_keyword_conditional(edition)
1675 /// A keyword or reserved identifier that can be used as a path segment.
1676 pub fn is_path_segment_keyword(self) -> bool {
1678 || self == kw::SelfLower
1679 || self == kw::SelfUpper
1680 || self == kw::Crate
1681 || self == kw::PathRoot
1682 || self == kw::DollarCrate
1685 /// Returns `true` if the symbol is `true` or `false`.
1686 pub fn is_bool_lit(self) -> bool {
1687 self == kw::True || self == kw::False
1690 /// Returns `true` if this symbol can be a raw identifier.
1691 pub fn can_be_raw(self) -> bool {
1692 self != kw::Empty && self != kw::Underscore && !self.is_path_segment_keyword()
1697 // Returns `true` for reserved identifiers used internally for elided lifetimes,
1698 // unnamed method parameters, crate root module, error recovery etc.
1699 pub fn is_special(self) -> bool {
1700 self.name.is_special()
1703 /// Returns `true` if the token is a keyword used in the language.
1704 pub fn is_used_keyword(self) -> bool {
1705 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
1706 self.name.is_used_keyword_always()
1707 || self.name.is_used_keyword_conditional(|| self.span.edition())
1710 /// Returns `true` if the token is a keyword reserved for possible future use.
1711 pub fn is_unused_keyword(self) -> bool {
1712 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
1713 self.name.is_unused_keyword_always()
1714 || self.name.is_unused_keyword_conditional(|| self.span.edition())
1717 /// Returns `true` if the token is either a special identifier or a keyword.
1718 pub fn is_reserved(self) -> bool {
1719 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
1720 self.name.is_reserved(|| self.span.edition())
1723 /// A keyword or reserved identifier that can be used as a path segment.
1724 pub fn is_path_segment_keyword(self) -> bool {
1725 self.name.is_path_segment_keyword()
1728 /// We see this identifier in a normal identifier position, like variable name or a type.
1729 /// How was it written originally? Did it use the raw form? Let's try to guess.
1730 pub fn is_raw_guess(self) -> bool {
1731 self.name.can_be_raw() && self.is_reserved()
1736 fn with_interner<T, F: FnOnce(&mut Interner) -> T>(f: F) -> T {
1737 SESSION_GLOBALS.with(|session_globals| f(&mut *session_globals.symbol_interner.lock()))
1740 /// An alternative to [`Symbol`], useful when the chars within the symbol need to
1741 /// be accessed. It deliberately has limited functionality and should only be
1742 /// used for temporary values.
1744 /// Because the interner outlives any thread which uses this type, we can
1745 /// safely treat `string` which points to interner data, as an immortal string,
1746 /// as long as this type never crosses between threads.
1748 // FIXME: ensure that the interner outlives any thread which uses `SymbolStr`,
1749 // by creating a new thread right after constructing the interner.
1750 #[derive(Clone, Eq, PartialOrd, Ord)]
1751 pub struct SymbolStr {
1752 string: &'static str,
1755 // This impl allows a `SymbolStr` to be directly equated with a `String` or
1757 impl<T: std::ops::Deref<Target = str>> std::cmp::PartialEq<T> for SymbolStr {
1758 fn eq(&self, other: &T) -> bool {
1759 self.string == other.deref()
1763 impl !Send for SymbolStr {}
1764 impl !Sync for SymbolStr {}
1766 /// This impl means that if `ss` is a `SymbolStr`:
1767 /// - `*ss` is a `str`;
1768 /// - `&*ss` is a `&str` (and `match &*ss { ... }` is a common pattern).
1769 /// - `&ss as &str` is a `&str`, which means that `&ss` can be passed to a
1770 /// function expecting a `&str`.
1771 impl std::ops::Deref for SymbolStr {
1774 fn deref(&self) -> &str {
1779 impl fmt::Debug for SymbolStr {
1780 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1781 fmt::Debug::fmt(self.string, f)
1785 impl fmt::Display for SymbolStr {
1786 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1787 fmt::Display::fmt(self.string, f)
1791 impl<CTX> HashStable<CTX> for SymbolStr {
1793 fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
1794 self.string.hash_stable(hcx, hasher)
1798 impl<CTX> ToStableHashKey<CTX> for SymbolStr {
1799 type KeyType = SymbolStr;
1802 fn to_stable_hash_key(&self, _: &CTX) -> SymbolStr {