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_data_structures::sync::Lock;
9 use rustc_macros::HashStable_Generic;
10 use rustc_serialize::{Decodable, Decoder, Encodable, Encoder};
12 use std::cmp::{Ord, PartialEq, PartialOrd};
14 use std::hash::{Hash, Hasher};
17 use crate::{with_session_globals, Edition, Span, DUMMY_SP};
22 // The proc macro code for this is in `compiler/rustc_macros/src/symbols.rs`.
24 // After modifying this list adjust `is_special`, `is_used_keyword`/`is_unused_keyword`,
25 // this should be rarely necessary though if the keywords are kept in alphabetic order.
27 // Special reserved identifiers used internally for elided lifetimes,
28 // unnamed method parameters, crate root module, error recovery etc.
31 DollarCrate: "$crate",
34 // Keywords that are used in stable Rust.
71 // Keywords that are used in unstable Rust or reserved for future use.
85 // Edition-specific keywords that are used in stable Rust.
86 Async: "async", // >= 2018 Edition only
87 Await: "await", // >= 2018 Edition only
88 Dyn: "dyn", // >= 2018 Edition only
90 // Edition-specific keywords that are used in unstable Rust or reserved for future use.
91 Try: "try", // >= 2018 Edition only
93 // Special lifetime names
94 UnderscoreLifetime: "'_",
95 StaticLifetime: "'static",
97 // Weak keywords, have special meaning only in specific contexts.
101 MacroRules: "macro_rules",
107 // Pre-interned symbols that can be referred to with `rustc_span::sym::*`.
109 // The symbol is the stringified identifier unless otherwise specified, in
110 // which case the name should mention the non-identifier punctuation.
111 // E.g. `sym::proc_dash_macro` represents "proc-macro", and it shouldn't be
112 // called `sym::proc_macro` because then it's easy to mistakenly think it
113 // represents "proc_macro".
115 // As well as the symbols listed, there are symbols for the strings
116 // "0", "1", ..., "9", which are accessible via `sym::integer`.
118 // The proc macro will abort if symbols are not in alphabetical order (as
119 // defined by `impl Ord for str`) or if any symbols are duplicated. Vim
120 // users can sort the list by selecting it and executing the command
121 // `:'<,'>!LC_ALL=C sort`.
123 // There is currently no checking that all symbols are used; that would be
255 ProceduralMasqueradeDummyType,
281 SubdiagnosticMessage,
311 aarch64_target_feature,
312 aarch64_ver_target_feature,
316 abi_c_cmse_nonsecure_call,
318 abi_msp430_interrupt,
332 advanced_slice_patterns,
348 allow_internal_unsafe,
349 allow_internal_unstable,
355 anonymous_lifetime_in_impl_trait,
358 arbitrary_enum_discriminant,
359 arbitrary_self_types,
371 asm_experimental_arch,
379 assert_receiver_is_total_eq,
383 associated_const_equality,
385 associated_type_bounds,
386 associated_type_defaults,
399 augmented_assignments,
401 automatically_derived,
403 avx512_target_feature,
411 bind_by_move_pattern_guards,
423 borrowck_graphviz_format,
424 borrowck_graphviz_postflow,
425 borrowck_graphviz_preflow,
430 braced_empty_structs,
442 capture_disjoint_fields,
459 cfg_target_has_atomic,
460 cfg_target_has_atomic_equal_alignment,
461 cfg_target_has_atomic_load_store,
462 cfg_target_thread_local,
474 closure_lifetime_binder,
475 closure_to_fn_coercion,
476 closure_track_caller,
480 cmpxchg16b_target_feature,
481 cmse_nonsecure_entry,
488 compare_exchange_weak,
498 conservative_impl_trait,
502 const_compare_raw_pointers,
507 const_eval_select_ct,
508 const_evaluatable_checked,
511 const_fn_floating_point_arithmetic,
512 const_fn_fn_ptr_basics,
513 const_fn_trait_bound,
519 const_generic_defaults,
521 const_generics_defaults,
524 const_in_array_repeat_expressions,
531 const_precise_live_drops,
533 const_raw_ptr_to_usize_cast,
536 const_trait_bound_opt_out,
553 core_panic_2015_macro,
564 crate_visibility_modifier,
565 crt_dash_static: "crt-static",
574 custom_inner_attributes,
575 custom_test_frameworks,
582 debug_assert_eq_macro,
584 debug_assert_ne_macro,
587 debug_struct_fields_finish,
590 debug_tuple_fields_finish,
595 default_alloc_error_handler,
596 default_lib_allocator,
597 default_method_body_is_const,
598 default_type_parameter_fallback,
600 delay_span_bug_from_inside_query,
604 deprecated_suggestion,
612 destructuring_assignment,
633 document_private_items,
635 dotdot_in_tuple_patterns,
636 dotdoteq_in_patterns,
644 dropck_parametricity,
655 emit_enum_variant_arg,
667 ermsb_target_feature,
671 exclusive_range_pattern,
672 exhaustive_integer_patterns,
681 explicit_generic_args_with_impl_trait,
684 extended_key_value_attributes,
685 extern_absolute_paths,
686 extern_crate_item_prelude,
710 field_init_shorthand,
717 float_to_int_unchecked,
750 from_size_align_unchecked,
767 generic_associated_types,
768 generic_associated_types_extended,
776 half_open_range_patterns,
778 hexagon_target_feature,
780 homogeneous_aggregate,
797 if_while_or_patterns,
799 impl_header_lifetime_elision,
802 impl_trait_in_bindings,
814 inclusive_range_syntax,
817 infer_outlives_requirements,
818 infer_static_outlives_requirements,
819 inherent_associated_types,
833 irrefutable_let_patterns,
837 issue_5723_bootstrap,
838 issue_tracker_base_url,
853 lazy_normalization_consts,
868 link_llvm_intrinsics,
889 macro_at_most_once_rep,
890 macro_attributes_in_derive_output,
893 macro_lifetime_matcher,
894 macro_literal_matcher,
907 match_beginning_vert,
908 match_default_bindings,
938 min_type_alias_impl_trait,
949 more_qualified_paths,
951 movbe_target_feature,
963 native_link_modifiers,
964 native_link_modifiers_as_needed,
965 native_link_modifiers_bundle,
966 native_link_modifiers_verbatim,
967 native_link_modifiers_whole_archive,
1005 non_exhaustive_omitted_patterns_lint,
1017 object_safe_for_dispatch,
1020 omit_gdb_pretty_printer_section,
1029 optin_builtin_traits,
1038 overlapping_marker_traits,
1050 panic_implementation,
1065 pattern_parentheses,
1068 platform_intrinsics,
1077 post_dash_lto: "post-lto",
1078 powerpc_target_feature,
1083 pre_dash_lto: "pre-lto",
1084 precise_pointer_size_matching,
1088 prefetch_read_instruction,
1089 prefetch_write_data,
1090 prefetch_write_instruction,
1098 proc_dash_macro: "proc-macro",
1100 proc_macro_attribute,
1101 proc_macro_def_site,
1106 proc_macro_internals,
1108 proc_macro_non_items,
1109 proc_macro_path_invoc,
1118 ptr_offset_from_unsigned,
1126 quad_precision_float,
1129 range_inclusive_new,
1134 re_rebalance_coherence,
1137 read_enum_variant_arg,
1145 reexport_test_harness_main,
1146 ref_unwind_safe_trait,
1163 relaxed_struct_unsize,
1178 riscv_target_feature,
1197 rust_eh_catch_typeinfo,
1198 rust_eh_personality,
1199 rust_eh_register_frames,
1200 rust_eh_unregister_frames,
1204 rustc_allocator_nounwind,
1205 rustc_allocator_zeroed,
1206 rustc_allow_const_fn_unstable,
1207 rustc_allow_incoherent_impl,
1208 rustc_allowed_through_unstable_modules,
1211 rustc_builtin_macro,
1212 rustc_capture_analysis,
1214 rustc_coherence_is_core,
1216 rustc_const_unstable,
1217 rustc_conversion_suggestion,
1220 rustc_diagnostic_item,
1221 rustc_diagnostic_macros,
1223 rustc_do_not_const_check,
1225 rustc_dump_env_program_clauses,
1226 rustc_dump_program_clauses,
1227 rustc_dump_user_substs,
1230 rustc_evaluate_where_clauses,
1231 rustc_expected_cgu_reuse,
1232 rustc_has_incoherent_inherent_impls,
1233 rustc_if_this_changed,
1234 rustc_inherit_overflow_checks,
1235 rustc_insignificant_dtor,
1237 rustc_layout_scalar_valid_range_end,
1238 rustc_layout_scalar_valid_range_start,
1239 rustc_legacy_const_generics,
1240 rustc_lint_diagnostics,
1241 rustc_lint_opt_deny_field_access,
1243 rustc_lint_query_instability,
1244 rustc_macro_transparency,
1247 rustc_must_implement_one_of,
1248 rustc_nonnull_optimization_guaranteed,
1249 rustc_object_lifetime_default,
1250 rustc_on_unimplemented,
1253 rustc_partition_codegened,
1254 rustc_partition_reused,
1255 rustc_pass_by_value,
1257 rustc_peek_definite_init,
1258 rustc_peek_liveness,
1259 rustc_peek_maybe_init,
1260 rustc_peek_maybe_uninit,
1261 rustc_polymorphize_error,
1263 rustc_proc_macro_decls,
1267 rustc_reservation_impl,
1269 rustc_skip_array_during_method_dispatch,
1270 rustc_specialization_trait,
1272 rustc_std_internal_symbol,
1273 rustc_strict_coherence,
1276 rustc_then_this_would_need,
1277 rustc_trivial_field_reads,
1278 rustc_unsafe_specialization_marker,
1283 rvalue_static_promotion,
1335 simd_reduce_add_ordered,
1336 simd_reduce_add_unordered,
1341 simd_reduce_max_nanless,
1343 simd_reduce_min_nanless,
1344 simd_reduce_mul_ordered,
1345 simd_reduce_mul_unordered,
1350 simd_saturating_add,
1351 simd_saturating_sub,
1354 simd_select_bitmask,
1382 sse4a_target_feature,
1394 std_panic_2015_macro,
1397 stmt_expr_attributes,
1398 stop_after_dataflow,
1401 str_split_whitespace,
1408 struct_field_attributes,
1431 target_has_atomic_equal_alignment,
1432 target_has_atomic_load_store,
1434 target_pointer_width,
1435 target_target_vendor,
1436 target_thread_local,
1442 termination_trait_test,
1445 test_accepted_feature,
1447 test_removed_feature,
1455 thumb_mode: "thumb-mode",
1484 type_alias_enum_variants,
1485 type_alias_impl_trait,
1487 type_changing_struct_update,
1497 unaligned_volatile_load,
1498 unaligned_volatile_store,
1507 underscore_const_names,
1509 underscore_lifetimes,
1511 unimplemented_macro,
1513 universal_impl_trait,
1520 unreachable_2015_macro,
1522 unreachable_2021_macro,
1524 unreachable_display,
1526 unrestricted_attribute_tokens,
1527 unsafe_block_in_unsafe_fn,
1529 unsafe_no_drop_flag,
1530 unsafe_pin_internals,
1534 unsized_tuple_coercion,
1536 unstable_location_reason_default: "this crate is being loaded from the sysroot, an \
1537 unstable location; did you mean to load this crate \
1538 from crates.io via `Cargo.toml` instead?",
1541 unused_qualifications,
1568 visible_private_types,
1570 volatile_copy_memory,
1571 volatile_copy_nonoverlapping_memory,
1573 volatile_set_memory,
1582 wasm_target_feature,
1587 with_negative_coherence,
1599 yeet_desugar_details,
1606 #[derive(Copy, Clone, Eq, HashStable_Generic, Encodable, Decodable)]
1614 /// Constructs a new identifier from a symbol and a span.
1615 pub const fn new(name: Symbol, span: Span) -> Ident {
1616 Ident { name, span }
1619 /// Constructs a new identifier with a dummy span.
1621 pub const fn with_dummy_span(name: Symbol) -> Ident {
1622 Ident::new(name, DUMMY_SP)
1626 pub fn empty() -> Ident {
1627 Ident::with_dummy_span(kw::Empty)
1630 /// Maps a string to an identifier with a dummy span.
1631 pub fn from_str(string: &str) -> Ident {
1632 Ident::with_dummy_span(Symbol::intern(string))
1635 /// Maps a string and a span to an identifier.
1636 pub fn from_str_and_span(string: &str, span: Span) -> Ident {
1637 Ident::new(Symbol::intern(string), span)
1640 /// Replaces `lo` and `hi` with those from `span`, but keep hygiene context.
1641 pub fn with_span_pos(self, span: Span) -> Ident {
1642 Ident::new(self.name, span.with_ctxt(self.span.ctxt()))
1645 pub fn without_first_quote(self) -> Ident {
1646 Ident::new(Symbol::intern(self.as_str().trim_start_matches('\'')), self.span)
1649 /// "Normalize" ident for use in comparisons using "item hygiene".
1650 /// Identifiers with same string value become same if they came from the same macro 2.0 macro
1651 /// (e.g., `macro` item, but not `macro_rules` item) and stay different if they came from
1652 /// different macro 2.0 macros.
1653 /// Technically, this operation strips all non-opaque marks from ident's syntactic context.
1654 pub fn normalize_to_macros_2_0(self) -> Ident {
1655 Ident::new(self.name, self.span.normalize_to_macros_2_0())
1658 /// "Normalize" ident for use in comparisons using "local variable hygiene".
1659 /// Identifiers with same string value become same if they came from the same non-transparent
1660 /// macro (e.g., `macro` or `macro_rules!` items) and stay different if they came from different
1661 /// non-transparent macros.
1662 /// Technically, this operation strips all transparent marks from ident's syntactic context.
1663 pub fn normalize_to_macro_rules(self) -> Ident {
1664 Ident::new(self.name, self.span.normalize_to_macro_rules())
1667 /// Access the underlying string. This is a slowish operation because it
1668 /// requires locking the symbol interner.
1670 /// Note that the lifetime of the return value is a lie. See
1671 /// `Symbol::as_str()` for details.
1672 pub fn as_str(&self) -> &str {
1677 impl PartialEq for Ident {
1678 fn eq(&self, rhs: &Self) -> bool {
1679 self.name == rhs.name && self.span.eq_ctxt(rhs.span)
1683 impl Hash for Ident {
1684 fn hash<H: Hasher>(&self, state: &mut H) {
1685 self.name.hash(state);
1686 self.span.ctxt().hash(state);
1690 impl fmt::Debug for Ident {
1691 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1692 fmt::Display::fmt(self, f)?;
1693 fmt::Debug::fmt(&self.span.ctxt(), f)
1697 /// This implementation is supposed to be used in error messages, so it's expected to be identical
1698 /// to printing the original identifier token written in source code (`token_to_string`),
1699 /// except that AST identifiers don't keep the rawness flag, so we have to guess it.
1700 impl fmt::Display for Ident {
1701 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1702 fmt::Display::fmt(&IdentPrinter::new(self.name, self.is_raw_guess(), None), f)
1706 /// This is the most general way to print identifiers.
1707 /// AST pretty-printer is used as a fallback for turning AST structures into token streams for
1708 /// proc macros. Additionally, proc macros may stringify their input and expect it survive the
1709 /// stringification (especially true for proc macro derives written between Rust 1.15 and 1.30).
1710 /// So we need to somehow pretty-print `$crate` in a way preserving at least some of its
1711 /// hygiene data, most importantly name of the crate it refers to.
1712 /// As a result we print `$crate` as `crate` if it refers to the local crate
1713 /// and as `::other_crate_name` if it refers to some other crate.
1714 /// Note, that this is only done if the ident token is printed from inside of AST pretty-printing,
1715 /// but not otherwise. Pretty-printing is the only way for proc macros to discover token contents,
1716 /// so we should not perform this lossy conversion if the top level call to the pretty-printer was
1717 /// done for a token stream or a single token.
1718 pub struct IdentPrinter {
1721 /// Span used for retrieving the crate name to which `$crate` refers to,
1722 /// if this field is `None` then the `$crate` conversion doesn't happen.
1723 convert_dollar_crate: Option<Span>,
1727 /// The most general `IdentPrinter` constructor. Do not use this.
1728 pub fn new(symbol: Symbol, is_raw: bool, convert_dollar_crate: Option<Span>) -> IdentPrinter {
1729 IdentPrinter { symbol, is_raw, convert_dollar_crate }
1732 /// This implementation is supposed to be used when printing identifiers
1733 /// as a part of pretty-printing for larger AST pieces.
1734 /// Do not use this either.
1735 pub fn for_ast_ident(ident: Ident, is_raw: bool) -> IdentPrinter {
1736 IdentPrinter::new(ident.name, is_raw, Some(ident.span))
1740 impl fmt::Display for IdentPrinter {
1741 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1744 } else if self.symbol == kw::DollarCrate {
1745 if let Some(span) = self.convert_dollar_crate {
1746 let converted = span.ctxt().dollar_crate_name();
1747 if !converted.is_path_segment_keyword() {
1750 return fmt::Display::fmt(&converted, f);
1753 fmt::Display::fmt(&self.symbol, f)
1757 /// An newtype around `Ident` that calls [Ident::normalize_to_macro_rules] on
1759 // FIXME(matthewj, petrochenkov) Use this more often, add a similar
1760 // `ModernIdent` struct and use that as well.
1761 #[derive(Copy, Clone, Eq, PartialEq, Hash)]
1762 pub struct MacroRulesNormalizedIdent(Ident);
1764 impl MacroRulesNormalizedIdent {
1765 pub fn new(ident: Ident) -> Self {
1766 Self(ident.normalize_to_macro_rules())
1770 impl fmt::Debug for MacroRulesNormalizedIdent {
1771 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1772 fmt::Debug::fmt(&self.0, f)
1776 impl fmt::Display for MacroRulesNormalizedIdent {
1777 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1778 fmt::Display::fmt(&self.0, f)
1782 /// An interned string.
1784 /// Internally, a `Symbol` is implemented as an index, and all operations
1785 /// (including hashing, equality, and ordering) operate on that index. The use
1786 /// of `rustc_index::newtype_index!` means that `Option<Symbol>` only takes up 4 bytes,
1787 /// because `rustc_index::newtype_index!` reserves the last 256 values for tagging purposes.
1789 /// Note that `Symbol` cannot directly be a `rustc_index::newtype_index!` because it
1790 /// implements `fmt::Debug`, `Encodable`, and `Decodable` in special ways.
1791 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
1792 pub struct Symbol(SymbolIndex);
1794 rustc_index::newtype_index! {
1795 struct SymbolIndex { .. }
1799 const fn new(n: u32) -> Self {
1800 Symbol(SymbolIndex::from_u32(n))
1803 /// Maps a string to its interned representation.
1804 pub fn intern(string: &str) -> Self {
1805 with_session_globals(|session_globals| session_globals.symbol_interner.intern(string))
1808 /// Access the underlying string. This is a slowish operation because it
1809 /// requires locking the symbol interner.
1811 /// Note that the lifetime of the return value is a lie. It's not the same
1812 /// as `&self`, but actually tied to the lifetime of the underlying
1813 /// interner. Interners are long-lived, and there are very few of them, and
1814 /// this function is typically used for short-lived things, so in practice
1815 /// it works out ok.
1816 pub fn as_str(&self) -> &str {
1817 with_session_globals(|session_globals| unsafe {
1818 std::mem::transmute::<&str, &str>(session_globals.symbol_interner.get(*self))
1822 pub fn as_u32(self) -> u32 {
1826 pub fn is_empty(self) -> bool {
1830 /// This method is supposed to be used in error messages, so it's expected to be
1831 /// identical to printing the original identifier token written in source code
1832 /// (`token_to_string`, `Ident::to_string`), except that symbols don't keep the rawness flag
1833 /// or edition, so we have to guess the rawness using the global edition.
1834 pub fn to_ident_string(self) -> String {
1835 Ident::with_dummy_span(self).to_string()
1839 impl fmt::Debug for Symbol {
1840 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1841 fmt::Debug::fmt(self.as_str(), f)
1845 impl fmt::Display for Symbol {
1846 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1847 fmt::Display::fmt(self.as_str(), f)
1851 impl<S: Encoder> Encodable<S> for Symbol {
1852 fn encode(&self, s: &mut S) {
1853 s.emit_str(self.as_str());
1857 impl<D: Decoder> Decodable<D> for Symbol {
1859 fn decode(d: &mut D) -> Symbol {
1860 Symbol::intern(&d.read_str())
1864 impl<CTX> HashStable<CTX> for Symbol {
1866 fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
1867 self.as_str().hash_stable(hcx, hasher);
1871 impl<CTX> ToStableHashKey<CTX> for Symbol {
1872 type KeyType = String;
1874 fn to_stable_hash_key(&self, _: &CTX) -> String {
1875 self.as_str().to_string()
1880 pub(crate) struct Interner(Lock<InternerInner>);
1882 // The `&'static str`s in this type actually point into the arena.
1884 // The `FxHashMap`+`Vec` pair could be replaced by `FxIndexSet`, but #75278
1885 // found that to regress performance up to 2% in some cases. This might be
1886 // revisited after further improvements to `indexmap`.
1888 // This type is private to prevent accidentally constructing more than one
1889 // `Interner` on the same thread, which makes it easy to mix up `Symbol`s
1890 // between `Interner`s.
1892 struct InternerInner {
1893 arena: DroplessArena,
1894 names: FxHashMap<&'static str, Symbol>,
1895 strings: Vec<&'static str>,
1899 fn prefill(init: &[&'static str]) -> Self {
1900 Interner(Lock::new(InternerInner {
1901 strings: init.into(),
1902 names: init.iter().copied().zip((0..).map(Symbol::new)).collect(),
1903 ..Default::default()
1908 fn intern(&self, string: &str) -> Symbol {
1909 let mut inner = self.0.lock();
1910 if let Some(&name) = inner.names.get(string) {
1914 let name = Symbol::new(inner.strings.len() as u32);
1916 // SAFETY: we convert from `&str` to `&[u8]`, clone it into the arena,
1917 // and immediately convert the clone back to `&[u8], all because there
1918 // is no `inner.arena.alloc_str()` method. This is clearly safe.
1920 unsafe { str::from_utf8_unchecked(inner.arena.alloc_slice(string.as_bytes())) };
1922 // SAFETY: we can extend the arena allocation to `'static` because we
1923 // only access these while the arena is still alive.
1924 let string: &'static str = unsafe { &*(string as *const str) };
1925 inner.strings.push(string);
1927 // This second hash table lookup can be avoided by using `RawEntryMut`,
1928 // but this code path isn't hot enough for it to be worth it. See
1929 // #91445 for details.
1930 inner.names.insert(string, name);
1934 // Get the symbol as a string. `Symbol::as_str()` should be used in
1935 // preference to this function.
1936 fn get(&self, symbol: Symbol) -> &str {
1937 self.0.lock().strings[symbol.0.as_usize()]
1941 // This module has a very short name because it's used a lot.
1942 /// This module contains all the defined keyword `Symbol`s.
1944 /// Given that `kw` is imported, use them like `kw::keyword_name`.
1945 /// For example `kw::Loop` or `kw::Break`.
1947 pub use super::kw_generated::*;
1950 // This module has a very short name because it's used a lot.
1951 /// This module contains all the defined non-keyword `Symbol`s.
1953 /// Given that `sym` is imported, use them like `sym::symbol_name`.
1954 /// For example `sym::rustfmt` or `sym::u8`.
1957 use std::convert::TryInto;
1960 pub use super::sym_generated::*;
1962 // Used from a macro in `librustc_feature/accepted.rs`
1963 pub use super::kw::MacroRules as macro_rules;
1965 /// Get the symbol for an integer.
1967 /// The first few non-negative integers each have a static symbol and therefore
1969 pub fn integer<N: TryInto<usize> + Copy + ToString>(n: N) -> Symbol {
1970 if let Result::Ok(idx) = n.try_into() {
1972 return Symbol::new(super::SYMBOL_DIGITS_BASE + idx as u32);
1975 Symbol::intern(&n.to_string())
1980 fn is_special(self) -> bool {
1981 self <= kw::Underscore
1984 fn is_used_keyword_always(self) -> bool {
1985 self >= kw::As && self <= kw::While
1988 fn is_used_keyword_conditional(self, edition: impl FnOnce() -> Edition) -> bool {
1989 (self >= kw::Async && self <= kw::Dyn) && edition() >= Edition::Edition2018
1992 fn is_unused_keyword_always(self) -> bool {
1993 self >= kw::Abstract && self <= kw::Yield
1996 fn is_unused_keyword_conditional(self, edition: impl FnOnce() -> Edition) -> bool {
1997 self == kw::Try && edition() >= Edition::Edition2018
2000 pub fn is_reserved(self, edition: impl Copy + FnOnce() -> Edition) -> bool {
2002 || self.is_used_keyword_always()
2003 || self.is_unused_keyword_always()
2004 || self.is_used_keyword_conditional(edition)
2005 || self.is_unused_keyword_conditional(edition)
2008 /// A keyword or reserved identifier that can be used as a path segment.
2009 pub fn is_path_segment_keyword(self) -> bool {
2011 || self == kw::SelfLower
2012 || self == kw::SelfUpper
2013 || self == kw::Crate
2014 || self == kw::PathRoot
2015 || self == kw::DollarCrate
2018 /// Returns `true` if the symbol is `true` or `false`.
2019 pub fn is_bool_lit(self) -> bool {
2020 self == kw::True || self == kw::False
2023 /// Returns `true` if this symbol can be a raw identifier.
2024 pub fn can_be_raw(self) -> bool {
2025 self != kw::Empty && self != kw::Underscore && !self.is_path_segment_keyword()
2030 // Returns `true` for reserved identifiers used internally for elided lifetimes,
2031 // unnamed method parameters, crate root module, error recovery etc.
2032 pub fn is_special(self) -> bool {
2033 self.name.is_special()
2036 /// Returns `true` if the token is a keyword used in the language.
2037 pub fn is_used_keyword(self) -> bool {
2038 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
2039 self.name.is_used_keyword_always()
2040 || self.name.is_used_keyword_conditional(|| self.span.edition())
2043 /// Returns `true` if the token is a keyword reserved for possible future use.
2044 pub fn is_unused_keyword(self) -> bool {
2045 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
2046 self.name.is_unused_keyword_always()
2047 || self.name.is_unused_keyword_conditional(|| self.span.edition())
2050 /// Returns `true` if the token is either a special identifier or a keyword.
2051 pub fn is_reserved(self) -> bool {
2052 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
2053 self.name.is_reserved(|| self.span.edition())
2056 /// A keyword or reserved identifier that can be used as a path segment.
2057 pub fn is_path_segment_keyword(self) -> bool {
2058 self.name.is_path_segment_keyword()
2061 /// We see this identifier in a normal identifier position, like variable name or a type.
2062 /// How was it written originally? Did it use the raw form? Let's try to guess.
2063 pub fn is_raw_guess(self) -> bool {
2064 self.name.can_be_raw() && self.is_reserved()