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 arena::DroplessArena;
6 use rustc_data_structures::fx::FxHashMap;
7 use rustc_data_structures::indexed_vec::Idx;
8 use rustc_data_structures::newtype_index;
9 use rustc_macros::symbols;
10 use serialize::{Decodable, Decoder, Encodable, Encoder};
14 use std::cmp::{PartialEq, Ordering, PartialOrd, Ord};
15 use std::hash::{Hash, Hasher};
17 use crate::hygiene::SyntaxContext;
18 use crate::{Span, DUMMY_SP, GLOBALS};
21 // After modifying this list adjust `is_special`, `is_used_keyword`/`is_unused_keyword`,
22 // this should be rarely necessary though if the keywords are kept in alphabetic order.
24 // Special reserved identifiers used internally for elided lifetimes,
25 // unnamed method parameters, crate root module, error recovery etc.
28 DollarCrate: "$crate",
31 // Keywords that are used in stable Rust.
68 // Keywords that are used in unstable Rust or reserved for future use.
82 // Edition-specific keywords that are used in stable Rust.
83 Dyn: "dyn", // >= 2018 Edition only
85 // Edition-specific keywords that are used in unstable Rust or reserved for future use.
86 Async: "async", // >= 2018 Edition only
87 Await: "await", // >= 2018 Edition only
88 Try: "try", // >= 2018 Edition only
90 // Special lifetime names
91 UnderscoreLifetime: "'_",
92 StaticLifetime: "'static",
94 // Weak keywords, have special meaning only in specific contexts.
98 Existential: "existential",
102 // Symbols that can be referred to with syntax_pos::sym::*. The symbol is
103 // the stringified identifier unless otherwise specified (e.g.
104 // `proc_dash_macro` represents "proc-macro").
106 aarch64_target_feature,
109 abi_msp430_interrupt,
117 advanced_slice_patterns,
129 allow_internal_unsafe,
130 allow_internal_unstable,
131 allow_internal_unstable_backcompat_hack,
134 arbitrary_self_types,
138 associated_type_defaults,
144 augmented_assignments,
145 automatically_derived,
146 avx512_target_feature,
149 bind_by_move_pattern_guards,
151 borrowck_graphviz_postflow,
152 borrowck_graphviz_preflow,
155 braced_empty_structs,
162 cfg_target_has_atomic,
163 cfg_target_thread_local,
168 closure_to_fn_coercion,
169 cmpxchg16b_target_feature,
174 conservative_impl_trait,
176 const_compare_raw_pointers,
184 const_raw_ptr_to_usize_cast,
195 crate_visibility_modifier,
198 custom_inner_attributes,
199 custom_test_frameworks,
202 default_lib_allocator,
203 default_type_parameter_fallback,
214 document_private_items,
215 dotdoteq_in_patterns,
216 dotdot_in_tuple_patterns,
217 double_braced_crate: "{{crate}}",
218 double_braced_impl: "{{impl}}",
219 double_braced_misc: "{{misc}}",
220 double_braced_closure: "{{closure}}",
221 double_braced_constructor: "{{constructor}}",
222 double_braced_constant: "{{constant}}",
223 double_braced_opaque: "{{opaque}}",
225 dropck_parametricity,
235 exclusive_range_pattern,
236 exhaustive_integer_patterns,
241 extern_absolute_paths,
243 extern_crate_item_prelude,
251 field_init_shorthand,
266 generic_associated_types,
271 hexagon_target_feature,
273 homogeneous_aggregate,
287 if_while_or_patterns,
289 impl_header_lifetime_elision,
290 impl_trait_in_bindings,
294 inclusive_range_syntax,
295 infer_outlives_requirements,
296 infer_static_outlives_requirements,
303 irrefutable_let_patterns,
306 issue_5723_bootstrap,
307 issue_tracker_base_url,
322 link_llvm_intrinsics,
329 macro_at_most_once_rep,
332 macro_lifetime_matcher,
333 macro_literal_matcher,
344 match_beginning_vert,
345 match_default_bindings,
355 movbe_target_feature,
388 omit_gdb_pretty_printer_section,
395 optin_builtin_traits,
400 overlapping_marker_traits,
404 panic_implementation,
418 poll_with_tls_context,
419 powerpc_target_feature,
420 precise_pointer_size_matching,
424 proc_dash_macro: "proc-macro",
426 proc_macro_attribute,
432 proc_macro_non_items,
433 proc_macro_path_invoc,
437 quad_precision_float,
450 reexport_test_harness_main,
460 re_rebalance_coherence,
470 rustc_allocator_nounwind,
471 rustc_allow_const_fn_ptr,
472 rustc_args_required_const,
475 rustc_const_unstable,
476 rustc_conversion_suggestion,
477 rustc_copy_clone_marker,
480 rustc_diagnostic_macros,
482 rustc_doc_only_macro,
483 rustc_dump_env_program_clauses,
484 rustc_dump_program_clauses,
485 rustc_dump_user_substs,
487 rustc_expected_cgu_reuse,
488 rustc_if_this_changed,
489 rustc_inherit_overflow_checks,
491 rustc_layout_scalar_valid_range_end,
492 rustc_layout_scalar_valid_range_start,
494 rustc_nonnull_optimization_guaranteed,
495 rustc_object_lifetime_default,
496 rustc_on_unimplemented,
499 rustc_partition_codegened,
500 rustc_partition_reused,
502 rustc_peek_definite_init,
503 rustc_peek_maybe_init,
504 rustc_peek_maybe_uninit,
506 rustc_proc_macro_decls,
510 rustc_std_internal_symbol,
514 rustc_then_this_would_need,
515 rustc_transparent_macro,
519 rust_eh_unwind_resume,
521 __rust_unstable_column,
522 rvalue_static_promotion,
538 sse4a_target_feature,
548 stmt_expr_attributes,
550 struct_field_attributes,
561 termination_trait_test,
564 test_accepted_feature,
565 test_removed_feature,
580 type_alias_enum_variants,
590 underscore_const_names,
592 underscore_lifetimes,
594 universal_impl_trait,
597 unrestricted_attribute_tokens,
598 unsafe_destructor_blind_to_params,
601 unsized_tuple_coercion,
613 visible_private_types,
616 warn_directory_ownership,
626 #[derive(Copy, Clone, Eq)]
634 /// Constructs a new identifier from a symbol and a span.
635 pub const fn new(name: Symbol, span: Span) -> Ident {
639 /// Constructs a new identifier with an empty syntax context.
641 pub const fn with_empty_ctxt(name: Symbol) -> Ident {
642 Ident::new(name, DUMMY_SP)
646 pub fn invalid() -> Ident {
647 Ident::with_empty_ctxt(kw::Invalid)
650 /// Maps an interned string to an identifier with an empty syntax context.
651 pub fn from_interned_str(string: InternedString) -> Ident {
652 Ident::with_empty_ctxt(string.as_symbol())
655 /// Maps a string to an identifier with an empty span.
656 pub fn from_str(string: &str) -> Ident {
657 Ident::with_empty_ctxt(Symbol::intern(string))
660 /// Maps a string and a span to an identifier.
661 pub fn from_str_and_span(string: &str, span: Span) -> Ident {
662 Ident::new(Symbol::intern(string), span)
665 /// Replaces `lo` and `hi` with those from `span`, but keep hygiene context.
666 pub fn with_span_pos(self, span: Span) -> Ident {
667 Ident::new(self.name, span.with_ctxt(self.span.ctxt()))
670 pub fn without_first_quote(self) -> Ident {
671 Ident::new(Symbol::intern(self.as_str().trim_start_matches('\'')), self.span)
674 /// "Normalize" ident for use in comparisons using "item hygiene".
675 /// Identifiers with same string value become same if they came from the same "modern" macro
676 /// (e.g., `macro` item, but not `macro_rules` item) and stay different if they came from
677 /// different "modern" macros.
678 /// Technically, this operation strips all non-opaque marks from ident's syntactic context.
679 pub fn modern(self) -> Ident {
680 Ident::new(self.name, self.span.modern())
683 /// "Normalize" ident for use in comparisons using "local variable hygiene".
684 /// Identifiers with same string value become same if they came from the same non-transparent
685 /// macro (e.g., `macro` or `macro_rules!` items) and stay different if they came from different
686 /// non-transparent macros.
687 /// Technically, this operation strips all transparent marks from ident's syntactic context.
688 pub fn modern_and_legacy(self) -> Ident {
689 Ident::new(self.name, self.span.modern_and_legacy())
692 /// Transforms an identifier into one with the same name, but gensymed.
693 pub fn gensym(self) -> Ident {
694 let name = with_interner(|interner| interner.gensymed(self.name));
695 Ident::new(name, self.span)
698 /// Transforms an underscore identifier into one with the same name, but
699 /// gensymed. Leaves non-underscore identifiers unchanged.
700 pub fn gensym_if_underscore(self) -> Ident {
701 if self.name == kw::Underscore { self.gensym() } else { self }
704 // WARNING: this function is deprecated and will be removed in the future.
705 pub fn is_gensymed(self) -> bool {
706 with_interner(|interner| interner.is_gensymed(self.name))
709 pub fn as_str(self) -> LocalInternedString {
713 pub fn as_interned_str(self) -> InternedString {
714 self.name.as_interned_str()
718 impl PartialEq for Ident {
719 fn eq(&self, rhs: &Self) -> bool {
720 self.name == rhs.name && self.span.ctxt() == rhs.span.ctxt()
724 impl Hash for Ident {
725 fn hash<H: Hasher>(&self, state: &mut H) {
726 self.name.hash(state);
727 self.span.ctxt().hash(state);
731 impl fmt::Debug for Ident {
732 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
733 write!(f, "{}{:?}", self.name, self.span.ctxt())
737 impl fmt::Display for Ident {
738 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
739 fmt::Display::fmt(&self.name, f)
743 impl Encodable for Ident {
744 fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
745 if self.span.ctxt().modern() == SyntaxContext::empty() {
746 s.emit_str(&self.as_str())
747 } else { // FIXME(jseyfried): intercrate hygiene
748 let mut string = "#".to_owned();
749 string.push_str(&self.as_str());
755 impl Decodable for Ident {
756 fn decode<D: Decoder>(d: &mut D) -> Result<Ident, D::Error> {
757 let string = d.read_str()?;
758 Ok(if !string.starts_with('#') {
759 Ident::from_str(&string)
760 } else { // FIXME(jseyfried): intercrate hygiene
761 Ident::from_str(&string[1..]).gensym()
766 /// A symbol is an interned or gensymed string. A gensym is a symbol that is
767 /// never equal to any other symbol.
769 /// Conceptually, a gensym can be thought of as a normal symbol with an
770 /// invisible unique suffix. Gensyms are useful when creating new identifiers
771 /// that must not match any existing identifiers, e.g. during macro expansion
772 /// and syntax desugaring. Because gensyms should always be identifiers, all
773 /// gensym operations are on `Ident` rather than `Symbol`. (Indeed, in the
774 /// future the gensym-ness may be moved from `Symbol` to hygiene data.)
778 /// assert_eq!(Ident::from_str("x"), Ident::from_str("x"))
779 /// assert_ne!(Ident::from_str("x").gensym(), Ident::from_str("x"))
780 /// assert_ne!(Ident::from_str("x").gensym(), Ident::from_str("x").gensym())
782 /// Internally, a symbol is implemented as an index, and all operations
783 /// (including hashing, equality, and ordering) operate on that index. The use
784 /// of `newtype_index!` means that `Option<Symbol>` only takes up 4 bytes,
785 /// because `newtype_index!` reserves the last 256 values for tagging purposes.
787 /// Note that `Symbol` cannot directly be a `newtype_index!` because it
788 /// implements `fmt::Debug`, `Encodable`, and `Decodable` in special ways.
789 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
790 pub struct Symbol(SymbolIndex);
793 pub struct SymbolIndex { .. }
797 const fn new(n: u32) -> Self {
798 Symbol(SymbolIndex::from_u32_const(n))
801 /// Maps a string to its interned representation.
802 pub fn intern(string: &str) -> Self {
803 with_interner(|interner| interner.intern(string))
806 pub fn as_str(self) -> LocalInternedString {
807 with_interner(|interner| unsafe {
808 LocalInternedString {
809 string: std::mem::transmute::<&str, &str>(interner.get(self))
814 pub fn as_interned_str(self) -> InternedString {
815 with_interner(|interner| InternedString {
816 symbol: interner.interned(self)
820 pub fn as_u32(self) -> u32 {
825 impl fmt::Debug for Symbol {
826 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
827 let is_gensymed = with_interner(|interner| interner.is_gensymed(*self));
829 write!(f, "{}({:?})", self, self.0)
831 write!(f, "{}", self)
836 impl fmt::Display for Symbol {
837 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
838 fmt::Display::fmt(&self.as_str(), f)
842 impl Encodable for Symbol {
843 fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
844 s.emit_str(&self.as_str())
848 impl Decodable for Symbol {
849 fn decode<D: Decoder>(d: &mut D) -> Result<Symbol, D::Error> {
850 Ok(Symbol::intern(&d.read_str()?))
854 // The `&'static str`s in this type actually point into the arena.
856 // Note that normal symbols are indexed upward from 0, and gensyms are indexed
857 // downward from SymbolIndex::MAX_AS_U32.
859 pub struct Interner {
860 arena: DroplessArena,
861 names: FxHashMap<&'static str, Symbol>,
862 strings: Vec<&'static str>,
863 gensyms: Vec<Symbol>,
867 fn prefill(init: &[&str]) -> Self {
868 let mut this = Interner::default();
869 this.names.reserve(init.len());
870 this.strings.reserve(init.len());
872 // We can't allocate empty strings in the arena, so handle this here.
873 assert!(kw::Invalid.as_u32() == 0 && init[0].is_empty());
874 this.names.insert("", kw::Invalid);
875 this.strings.push("");
877 for string in &init[1..] {
883 pub fn intern(&mut self, string: &str) -> Symbol {
884 if let Some(&name) = self.names.get(string) {
888 let name = Symbol::new(self.strings.len() as u32);
890 // `from_utf8_unchecked` is safe since we just allocated a `&str` which is known to be
892 let string: &str = unsafe {
893 str::from_utf8_unchecked(self.arena.alloc_slice(string.as_bytes()))
895 // It is safe to extend the arena allocation to `'static` because we only access
896 // these while the arena is still alive.
897 let string: &'static str = unsafe {
898 &*(string as *const str)
900 self.strings.push(string);
901 self.names.insert(string, name);
905 fn interned(&self, symbol: Symbol) -> Symbol {
906 if (symbol.0.as_usize()) < self.strings.len() {
909 self.gensyms[(SymbolIndex::MAX_AS_U32 - symbol.0.as_u32()) as usize]
913 fn gensymed(&mut self, symbol: Symbol) -> Symbol {
914 self.gensyms.push(symbol);
915 Symbol::new(SymbolIndex::MAX_AS_U32 - self.gensyms.len() as u32 + 1)
918 fn is_gensymed(&mut self, symbol: Symbol) -> bool {
919 symbol.0.as_usize() >= self.strings.len()
922 // Get the symbol as a string. `Symbol::as_str()` should be used in
923 // preference to this function.
924 pub fn get(&self, symbol: Symbol) -> &str {
925 match self.strings.get(symbol.0.as_usize()) {
926 Some(string) => string,
928 let symbol = self.gensyms[(SymbolIndex::MAX_AS_U32 - symbol.0.as_u32()) as usize];
929 self.strings[symbol.0.as_usize()]
935 // This module has a very short name because it's used a lot.
941 // This module has a very short name because it's used a lot.
948 fn is_used_keyword_2018(self) -> bool {
952 fn is_unused_keyword_2018(self) -> bool {
953 self >= kw::Async && self <= kw::Try
956 /// Used for sanity checking rustdoc keyword sections.
957 pub fn is_doc_keyword(self) -> bool {
963 // Returns `true` for reserved identifiers used internally for elided lifetimes,
964 // unnamed method parameters, crate root module, error recovery etc.
965 pub fn is_special(self) -> bool {
966 self.name <= kw::Underscore
969 /// Returns `true` if the token is a keyword used in the language.
970 pub fn is_used_keyword(self) -> bool {
971 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
972 self.name >= kw::As && self.name <= kw::While ||
973 self.name.is_used_keyword_2018() && self.span.rust_2018()
976 /// Returns `true` if the token is a keyword reserved for possible future use.
977 pub fn is_unused_keyword(self) -> bool {
978 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
979 self.name >= kw::Abstract && self.name <= kw::Yield ||
980 self.name.is_unused_keyword_2018() && self.span.rust_2018()
983 /// Returns `true` if the token is either a special identifier or a keyword.
984 pub fn is_reserved(self) -> bool {
985 self.is_special() || self.is_used_keyword() || self.is_unused_keyword()
988 /// A keyword or reserved identifier that can be used as a path segment.
989 pub fn is_path_segment_keyword(self) -> bool {
990 self.name == kw::Super ||
991 self.name == kw::SelfLower ||
992 self.name == kw::SelfUpper ||
993 self.name == kw::Crate ||
994 self.name == kw::PathRoot ||
995 self.name == kw::DollarCrate
998 /// This identifier can be a raw identifier.
999 pub fn can_be_raw(self) -> bool {
1000 self.name != kw::Invalid && self.name != kw::Underscore &&
1001 !self.is_path_segment_keyword()
1004 /// We see this identifier in a normal identifier position, like variable name or a type.
1005 /// How was it written originally? Did it use the raw form? Let's try to guess.
1006 pub fn is_raw_guess(self) -> bool {
1007 self.can_be_raw() && self.is_reserved()
1011 // If an interner exists, return it. Otherwise, prepare a fresh one.
1013 fn with_interner<T, F: FnOnce(&mut Interner) -> T>(f: F) -> T {
1014 GLOBALS.with(|globals| f(&mut *globals.symbol_interner.lock()))
1017 /// An alternative to `Symbol` and `InternedString`, useful when the chars
1018 /// within the symbol need to be accessed. It is best used for temporary
1021 /// Because the interner outlives any thread which uses this type, we can
1022 /// safely treat `string` which points to interner data, as an immortal string,
1023 /// as long as this type never crosses between threads.
1025 // FIXME: ensure that the interner outlives any thread which uses
1026 // `LocalInternedString`, by creating a new thread right after constructing the
1028 #[derive(Clone, Copy, Hash, PartialOrd, Eq, Ord)]
1029 pub struct LocalInternedString {
1030 string: &'static str,
1033 impl LocalInternedString {
1034 /// Maps a string to its interned representation.
1035 pub fn intern(string: &str) -> Self {
1036 let string = with_interner(|interner| {
1037 let symbol = interner.intern(string);
1038 interner.strings[symbol.0.as_usize()]
1040 LocalInternedString {
1041 string: unsafe { std::mem::transmute::<&str, &str>(string) }
1045 pub fn as_interned_str(self) -> InternedString {
1047 symbol: Symbol::intern(self.string)
1051 pub fn get(&self) -> &str {
1052 // This returns a valid string since we ensure that `self` outlives the interner
1053 // by creating the interner on a thread which outlives threads which can access it.
1054 // This type cannot move to a thread which outlives the interner since it does
1055 // not implement Send.
1060 impl<U: ?Sized> std::convert::AsRef<U> for LocalInternedString
1062 str: std::convert::AsRef<U>
1064 fn as_ref(&self) -> &U {
1065 self.string.as_ref()
1069 impl<T: std::ops::Deref<Target = str>> std::cmp::PartialEq<T> for LocalInternedString {
1070 fn eq(&self, other: &T) -> bool {
1071 self.string == other.deref()
1075 impl std::cmp::PartialEq<LocalInternedString> for str {
1076 fn eq(&self, other: &LocalInternedString) -> bool {
1077 self == other.string
1081 impl<'a> std::cmp::PartialEq<LocalInternedString> for &'a str {
1082 fn eq(&self, other: &LocalInternedString) -> bool {
1083 *self == other.string
1087 impl std::cmp::PartialEq<LocalInternedString> for String {
1088 fn eq(&self, other: &LocalInternedString) -> bool {
1089 self == other.string
1093 impl<'a> std::cmp::PartialEq<LocalInternedString> for &'a String {
1094 fn eq(&self, other: &LocalInternedString) -> bool {
1095 *self == other.string
1099 impl !Send for LocalInternedString {}
1100 impl !Sync for LocalInternedString {}
1102 impl std::ops::Deref for LocalInternedString {
1104 fn deref(&self) -> &str { self.string }
1107 impl fmt::Debug for LocalInternedString {
1108 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1109 fmt::Debug::fmt(self.string, f)
1113 impl fmt::Display for LocalInternedString {
1114 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1115 fmt::Display::fmt(self.string, f)
1119 impl Decodable for LocalInternedString {
1120 fn decode<D: Decoder>(d: &mut D) -> Result<LocalInternedString, D::Error> {
1121 Ok(LocalInternedString::intern(&d.read_str()?))
1125 impl Encodable for LocalInternedString {
1126 fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
1127 s.emit_str(self.string)
1131 /// An alternative to `Symbol` that is focused on string contents. It has two
1132 /// main differences to `Symbol`.
1134 /// First, its implementations of `Hash`, `PartialOrd` and `Ord` work with the
1135 /// string chars rather than the symbol integer. This is useful when hash
1136 /// stability is required across compile sessions, or a guaranteed sort
1137 /// ordering is required.
1139 /// Second, gensym-ness is irrelevant. E.g.:
1141 /// assert_ne!(Symbol::gensym("x"), Symbol::gensym("x"))
1142 /// assert_eq!(Symbol::gensym("x").as_interned_str(), Symbol::gensym("x").as_interned_str())
1144 #[derive(Clone, Copy, PartialEq, Eq)]
1145 pub struct InternedString {
1149 impl InternedString {
1150 /// Maps a string to its interned representation.
1151 pub fn intern(string: &str) -> Self {
1153 symbol: Symbol::intern(string)
1157 pub fn with<F: FnOnce(&str) -> R, R>(self, f: F) -> R {
1158 let str = with_interner(|interner| {
1159 interner.get(self.symbol) as *const str
1161 // This is safe because the interner keeps string alive until it is dropped.
1162 // We can access it because we know the interner is still alive since we use a
1163 // scoped thread local to access it, and it was alive at the beginning of this scope
1167 fn with2<F: FnOnce(&str, &str) -> R, R>(self, other: &InternedString, f: F) -> R {
1168 let (self_str, other_str) = with_interner(|interner| {
1169 (interner.get(self.symbol) as *const str,
1170 interner.get(other.symbol) as *const str)
1172 // This is safe for the same reason that `with` is safe.
1173 unsafe { f(&*self_str, &*other_str) }
1176 pub fn as_symbol(self) -> Symbol {
1180 pub fn as_str(self) -> LocalInternedString {
1181 self.symbol.as_str()
1185 impl Hash for InternedString {
1186 fn hash<H: Hasher>(&self, state: &mut H) {
1187 self.with(|str| str.hash(state))
1191 impl PartialOrd<InternedString> for InternedString {
1192 fn partial_cmp(&self, other: &InternedString) -> Option<Ordering> {
1193 if self.symbol == other.symbol {
1194 return Some(Ordering::Equal);
1196 self.with2(other, |self_str, other_str| self_str.partial_cmp(other_str))
1200 impl Ord for InternedString {
1201 fn cmp(&self, other: &InternedString) -> Ordering {
1202 if self.symbol == other.symbol {
1203 return Ordering::Equal;
1205 self.with2(other, |self_str, other_str| self_str.cmp(other_str))
1209 impl fmt::Debug for InternedString {
1210 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1211 self.with(|str| fmt::Debug::fmt(&str, f))
1215 impl fmt::Display for InternedString {
1216 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1217 self.with(|str| fmt::Display::fmt(&str, f))
1221 impl Decodable for InternedString {
1222 fn decode<D: Decoder>(d: &mut D) -> Result<InternedString, D::Error> {
1223 Ok(InternedString::intern(&d.read_str()?))
1227 impl Encodable for InternedString {
1228 fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
1229 self.with(|string| s.emit_str(string))
1240 fn interner_tests() {
1241 let mut i: Interner = Interner::default();
1242 // first one is zero:
1243 assert_eq!(i.intern("dog"), Symbol::new(0));
1244 // re-use gets the same entry:
1245 assert_eq!(i.intern("dog"), Symbol::new(0));
1246 // different string gets a different #:
1247 assert_eq!(i.intern("cat"), Symbol::new(1));
1248 assert_eq!(i.intern("cat"), Symbol::new(1));
1249 // dog is still at zero
1250 assert_eq!(i.intern("dog"), Symbol::new(0));
1251 let z = i.intern("zebra");
1252 assert_eq!(i.gensymed(z), Symbol::new(SymbolIndex::MAX_AS_U32));
1253 // gensym of same string gets new number:
1254 assert_eq!(i.gensymed(z), Symbol::new(SymbolIndex::MAX_AS_U32 - 1));
1255 // gensym of *existing* string gets new number:
1256 let d = i.intern("dog");
1257 assert_eq!(i.gensymed(d), Symbol::new(SymbolIndex::MAX_AS_U32 - 2));
1261 fn without_first_quote_test() {
1262 GLOBALS.set(&Globals::new(edition::DEFAULT_EDITION), || {
1263 let i = Ident::from_str("'break");
1264 assert_eq!(i.without_first_quote().name, kw::Break);