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,
150 bind_by_move_pattern_guards,
152 borrowck_graphviz_postflow,
153 borrowck_graphviz_preflow,
156 braced_empty_structs,
163 cfg_target_has_atomic,
164 cfg_target_thread_local,
169 closure_to_fn_coercion,
170 cmpxchg16b_target_feature,
175 conservative_impl_trait,
177 const_compare_raw_pointers,
185 const_raw_ptr_to_usize_cast,
196 crate_visibility_modifier,
199 custom_inner_attributes,
200 custom_test_frameworks,
203 default_lib_allocator,
204 default_type_parameter_fallback,
217 document_private_items,
218 dotdoteq_in_patterns,
219 dotdot_in_tuple_patterns,
220 double_braced_crate: "{{crate}}",
221 double_braced_impl: "{{impl}}",
222 double_braced_misc: "{{misc}}",
223 double_braced_closure: "{{closure}}",
224 double_braced_constructor: "{{constructor}}",
225 double_braced_constant: "{{constant}}",
226 double_braced_opaque: "{{opaque}}",
228 dropck_parametricity,
238 exclusive_range_pattern,
239 exhaustive_integer_patterns,
244 extern_absolute_paths,
246 extern_crate_item_prelude,
257 field_init_shorthand,
273 generic_associated_types,
278 hexagon_target_feature,
280 homogeneous_aggregate,
294 if_while_or_patterns,
296 impl_header_lifetime_elision,
297 impl_trait_in_bindings,
303 inclusive_range_syntax,
304 infer_outlives_requirements,
305 infer_static_outlives_requirements,
312 irrefutable_let_patterns,
315 issue_5723_bootstrap,
316 issue_tracker_base_url,
331 link_llvm_intrinsics,
338 macro_at_most_once_rep,
341 macro_lifetime_matcher,
342 macro_literal_matcher,
353 match_beginning_vert,
354 match_default_bindings,
364 movbe_target_feature,
397 omit_gdb_pretty_printer_section,
404 optin_builtin_traits,
409 overlapping_marker_traits,
414 panic_implementation,
428 poll_with_tls_context,
429 powerpc_target_feature,
430 precise_pointer_size_matching,
434 proc_dash_macro: "proc-macro",
436 proc_macro_attribute,
443 proc_macro_non_items,
444 proc_macro_path_invoc,
448 quad_precision_float,
461 reexport_test_harness_main,
471 re_rebalance_coherence,
481 rustc_allocator_nounwind,
482 rustc_allow_const_fn_ptr,
483 rustc_args_required_const,
486 rustc_const_unstable,
487 rustc_conversion_suggestion,
488 rustc_copy_clone_marker,
491 rustc_diagnostic_macros,
493 rustc_doc_only_macro,
494 rustc_dump_env_program_clauses,
495 rustc_dump_program_clauses,
496 rustc_dump_user_substs,
498 rustc_expected_cgu_reuse,
499 rustc_if_this_changed,
500 rustc_inherit_overflow_checks,
502 rustc_layout_scalar_valid_range_end,
503 rustc_layout_scalar_valid_range_start,
505 rustc_nonnull_optimization_guaranteed,
506 rustc_object_lifetime_default,
507 rustc_on_unimplemented,
510 rustc_partition_codegened,
511 rustc_partition_reused,
513 rustc_peek_definite_init,
514 rustc_peek_maybe_init,
515 rustc_peek_maybe_uninit,
517 rustc_proc_macro_decls,
521 rustc_std_internal_symbol,
525 rustc_then_this_would_need,
526 rustc_transparent_macro,
530 rust_eh_unwind_resume,
532 __rust_unstable_column,
533 rvalue_static_promotion,
549 sse4a_target_feature,
559 stmt_expr_attributes,
561 struct_field_attributes,
572 termination_trait_test,
575 test_accepted_feature,
577 test_removed_feature,
592 type_alias_enum_variants,
602 underscore_const_names,
604 underscore_lifetimes,
606 universal_impl_trait,
609 unrestricted_attribute_tokens,
610 unsafe_destructor_blind_to_params,
613 unsized_tuple_coercion,
625 visible_private_types,
628 warn_directory_ownership,
638 #[derive(Copy, Clone, Eq)]
646 /// Constructs a new identifier from a symbol and a span.
647 pub const fn new(name: Symbol, span: Span) -> Ident {
651 /// Constructs a new identifier with an empty syntax context.
653 pub const fn with_empty_ctxt(name: Symbol) -> Ident {
654 Ident::new(name, DUMMY_SP)
658 pub fn invalid() -> Ident {
659 Ident::with_empty_ctxt(kw::Invalid)
662 /// Maps an interned string to an identifier with an empty syntax context.
663 pub fn from_interned_str(string: InternedString) -> Ident {
664 Ident::with_empty_ctxt(string.as_symbol())
667 /// Maps a string to an identifier with an empty span.
668 pub fn from_str(string: &str) -> Ident {
669 Ident::with_empty_ctxt(Symbol::intern(string))
672 /// Maps a string and a span to an identifier.
673 pub fn from_str_and_span(string: &str, span: Span) -> Ident {
674 Ident::new(Symbol::intern(string), span)
677 /// Replaces `lo` and `hi` with those from `span`, but keep hygiene context.
678 pub fn with_span_pos(self, span: Span) -> Ident {
679 Ident::new(self.name, span.with_ctxt(self.span.ctxt()))
682 pub fn without_first_quote(self) -> Ident {
683 Ident::new(Symbol::intern(self.as_str().trim_start_matches('\'')), self.span)
686 /// "Normalize" ident for use in comparisons using "item hygiene".
687 /// Identifiers with same string value become same if they came from the same "modern" macro
688 /// (e.g., `macro` item, but not `macro_rules` item) and stay different if they came from
689 /// different "modern" macros.
690 /// Technically, this operation strips all non-opaque marks from ident's syntactic context.
691 pub fn modern(self) -> Ident {
692 Ident::new(self.name, self.span.modern())
695 /// "Normalize" ident for use in comparisons using "local variable hygiene".
696 /// Identifiers with same string value become same if they came from the same non-transparent
697 /// macro (e.g., `macro` or `macro_rules!` items) and stay different if they came from different
698 /// non-transparent macros.
699 /// Technically, this operation strips all transparent marks from ident's syntactic context.
700 pub fn modern_and_legacy(self) -> Ident {
701 Ident::new(self.name, self.span.modern_and_legacy())
704 /// Transforms an identifier into one with the same name, but gensymed.
705 pub fn gensym(self) -> Ident {
706 let name = with_interner(|interner| interner.gensymed(self.name));
707 Ident::new(name, self.span)
710 /// Transforms an underscore identifier into one with the same name, but
711 /// gensymed. Leaves non-underscore identifiers unchanged.
712 pub fn gensym_if_underscore(self) -> Ident {
713 if self.name == kw::Underscore { self.gensym() } else { self }
716 // WARNING: this function is deprecated and will be removed in the future.
717 pub fn is_gensymed(self) -> bool {
718 with_interner(|interner| interner.is_gensymed(self.name))
721 pub fn as_str(self) -> LocalInternedString {
725 pub fn as_interned_str(self) -> InternedString {
726 self.name.as_interned_str()
730 impl PartialEq for Ident {
731 fn eq(&self, rhs: &Self) -> bool {
732 self.name == rhs.name && self.span.ctxt() == rhs.span.ctxt()
736 impl Hash for Ident {
737 fn hash<H: Hasher>(&self, state: &mut H) {
738 self.name.hash(state);
739 self.span.ctxt().hash(state);
743 impl fmt::Debug for Ident {
744 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
745 write!(f, "{}{:?}", self.name, self.span.ctxt())
749 impl fmt::Display for Ident {
750 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
751 fmt::Display::fmt(&self.name, f)
755 impl Encodable for Ident {
756 fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
757 if self.span.ctxt().modern() == SyntaxContext::empty() {
758 s.emit_str(&self.as_str())
759 } else { // FIXME(jseyfried): intercrate hygiene
760 let mut string = "#".to_owned();
761 string.push_str(&self.as_str());
767 impl Decodable for Ident {
768 fn decode<D: Decoder>(d: &mut D) -> Result<Ident, D::Error> {
769 let string = d.read_str()?;
770 Ok(if !string.starts_with('#') {
771 Ident::from_str(&string)
772 } else { // FIXME(jseyfried): intercrate hygiene
773 Ident::from_str(&string[1..]).gensym()
778 /// A symbol is an interned or gensymed string. A gensym is a symbol that is
779 /// never equal to any other symbol.
781 /// Conceptually, a gensym can be thought of as a normal symbol with an
782 /// invisible unique suffix. Gensyms are useful when creating new identifiers
783 /// that must not match any existing identifiers, e.g. during macro expansion
784 /// and syntax desugaring. Because gensyms should always be identifiers, all
785 /// gensym operations are on `Ident` rather than `Symbol`. (Indeed, in the
786 /// future the gensym-ness may be moved from `Symbol` to hygiene data.)
790 /// assert_eq!(Ident::from_str("x"), Ident::from_str("x"))
791 /// assert_ne!(Ident::from_str("x").gensym(), Ident::from_str("x"))
792 /// assert_ne!(Ident::from_str("x").gensym(), Ident::from_str("x").gensym())
794 /// Internally, a symbol is implemented as an index, and all operations
795 /// (including hashing, equality, and ordering) operate on that index. The use
796 /// of `newtype_index!` means that `Option<Symbol>` only takes up 4 bytes,
797 /// because `newtype_index!` reserves the last 256 values for tagging purposes.
799 /// Note that `Symbol` cannot directly be a `newtype_index!` because it
800 /// implements `fmt::Debug`, `Encodable`, and `Decodable` in special ways.
801 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
802 pub struct Symbol(SymbolIndex);
805 pub struct SymbolIndex { .. }
809 const fn new(n: u32) -> Self {
810 Symbol(SymbolIndex::from_u32_const(n))
813 /// Maps a string to its interned representation.
814 pub fn intern(string: &str) -> Self {
815 with_interner(|interner| interner.intern(string))
818 pub fn as_str(self) -> LocalInternedString {
819 with_interner(|interner| unsafe {
820 LocalInternedString {
821 string: std::mem::transmute::<&str, &str>(interner.get(self))
826 pub fn as_interned_str(self) -> InternedString {
827 with_interner(|interner| InternedString {
828 symbol: interner.interned(self)
832 pub fn as_u32(self) -> u32 {
837 impl fmt::Debug for Symbol {
838 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
839 let is_gensymed = with_interner(|interner| interner.is_gensymed(*self));
841 write!(f, "{}({:?})", self, self.0)
843 write!(f, "{}", self)
848 impl fmt::Display for Symbol {
849 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
850 fmt::Display::fmt(&self.as_str(), f)
854 impl Encodable for Symbol {
855 fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
856 s.emit_str(&self.as_str())
860 impl Decodable for Symbol {
861 fn decode<D: Decoder>(d: &mut D) -> Result<Symbol, D::Error> {
862 Ok(Symbol::intern(&d.read_str()?))
866 // The `&'static str`s in this type actually point into the arena.
868 // Note that normal symbols are indexed upward from 0, and gensyms are indexed
869 // downward from SymbolIndex::MAX_AS_U32.
871 pub struct Interner {
872 arena: DroplessArena,
873 names: FxHashMap<&'static str, Symbol>,
874 strings: Vec<&'static str>,
875 gensyms: Vec<Symbol>,
879 fn prefill(init: &[&'static str]) -> Self {
880 let symbols = (0 .. init.len() as u32).map(Symbol::new);
882 strings: init.to_vec(),
883 names: init.iter().copied().zip(symbols).collect(),
888 pub fn intern(&mut self, string: &str) -> Symbol {
889 if let Some(&name) = self.names.get(string) {
893 let name = Symbol::new(self.strings.len() as u32);
895 // `from_utf8_unchecked` is safe since we just allocated a `&str` which is known to be
897 let string: &str = unsafe {
898 str::from_utf8_unchecked(self.arena.alloc_slice(string.as_bytes()))
900 // It is safe to extend the arena allocation to `'static` because we only access
901 // these while the arena is still alive.
902 let string: &'static str = unsafe {
903 &*(string as *const str)
905 self.strings.push(string);
906 self.names.insert(string, name);
910 fn interned(&self, symbol: Symbol) -> Symbol {
911 if (symbol.0.as_usize()) < self.strings.len() {
914 self.gensyms[(SymbolIndex::MAX_AS_U32 - symbol.0.as_u32()) as usize]
918 fn gensymed(&mut self, symbol: Symbol) -> Symbol {
919 self.gensyms.push(symbol);
920 Symbol::new(SymbolIndex::MAX_AS_U32 - self.gensyms.len() as u32 + 1)
923 fn is_gensymed(&mut self, symbol: Symbol) -> bool {
924 symbol.0.as_usize() >= self.strings.len()
927 // Get the symbol as a string. `Symbol::as_str()` should be used in
928 // preference to this function.
929 pub fn get(&self, symbol: Symbol) -> &str {
930 match self.strings.get(symbol.0.as_usize()) {
931 Some(string) => string,
933 let symbol = self.gensyms[(SymbolIndex::MAX_AS_U32 - symbol.0.as_u32()) as usize];
934 self.strings[symbol.0.as_usize()]
940 // This module has a very short name because it's used a lot.
946 // This module has a very short name because it's used a lot.
953 fn is_used_keyword_2018(self) -> bool {
957 fn is_unused_keyword_2018(self) -> bool {
958 self >= kw::Async && self <= kw::Try
961 /// Used for sanity checking rustdoc keyword sections.
962 pub fn is_doc_keyword(self) -> bool {
968 // Returns `true` for reserved identifiers used internally for elided lifetimes,
969 // unnamed method parameters, crate root module, error recovery etc.
970 pub fn is_special(self) -> bool {
971 self.name <= kw::Underscore
974 /// Returns `true` if the token is a keyword used in the language.
975 pub fn is_used_keyword(self) -> bool {
976 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
977 self.name >= kw::As && self.name <= kw::While ||
978 self.name.is_used_keyword_2018() && self.span.rust_2018()
981 /// Returns `true` if the token is a keyword reserved for possible future use.
982 pub fn is_unused_keyword(self) -> bool {
983 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
984 self.name >= kw::Abstract && self.name <= kw::Yield ||
985 self.name.is_unused_keyword_2018() && self.span.rust_2018()
988 /// Returns `true` if the token is either a special identifier or a keyword.
989 pub fn is_reserved(self) -> bool {
990 self.is_special() || self.is_used_keyword() || self.is_unused_keyword()
993 /// A keyword or reserved identifier that can be used as a path segment.
994 pub fn is_path_segment_keyword(self) -> bool {
995 self.name == kw::Super ||
996 self.name == kw::SelfLower ||
997 self.name == kw::SelfUpper ||
998 self.name == kw::Crate ||
999 self.name == kw::PathRoot ||
1000 self.name == kw::DollarCrate
1003 /// This identifier can be a raw identifier.
1004 pub fn can_be_raw(self) -> bool {
1005 self.name != kw::Invalid && self.name != kw::Underscore &&
1006 !self.is_path_segment_keyword()
1009 /// We see this identifier in a normal identifier position, like variable name or a type.
1010 /// How was it written originally? Did it use the raw form? Let's try to guess.
1011 pub fn is_raw_guess(self) -> bool {
1012 self.can_be_raw() && self.is_reserved()
1016 // If an interner exists, return it. Otherwise, prepare a fresh one.
1018 fn with_interner<T, F: FnOnce(&mut Interner) -> T>(f: F) -> T {
1019 GLOBALS.with(|globals| f(&mut *globals.symbol_interner.lock()))
1022 /// An alternative to `Symbol` and `InternedString`, useful when the chars
1023 /// within the symbol need to be accessed. It is best used for temporary
1026 /// Because the interner outlives any thread which uses this type, we can
1027 /// safely treat `string` which points to interner data, as an immortal string,
1028 /// as long as this type never crosses between threads.
1030 // FIXME: ensure that the interner outlives any thread which uses
1031 // `LocalInternedString`, by creating a new thread right after constructing the
1033 #[derive(Clone, Copy, Hash, PartialOrd, Eq, Ord)]
1034 pub struct LocalInternedString {
1035 string: &'static str,
1038 impl LocalInternedString {
1039 /// Maps a string to its interned representation.
1040 pub fn intern(string: &str) -> Self {
1041 let string = with_interner(|interner| {
1042 let symbol = interner.intern(string);
1043 interner.strings[symbol.0.as_usize()]
1045 LocalInternedString {
1046 string: unsafe { std::mem::transmute::<&str, &str>(string) }
1050 pub fn as_interned_str(self) -> InternedString {
1052 symbol: Symbol::intern(self.string)
1056 pub fn get(&self) -> &str {
1057 // This returns a valid string since we ensure that `self` outlives the interner
1058 // by creating the interner on a thread which outlives threads which can access it.
1059 // This type cannot move to a thread which outlives the interner since it does
1060 // not implement Send.
1065 impl<U: ?Sized> std::convert::AsRef<U> for LocalInternedString
1067 str: std::convert::AsRef<U>
1069 fn as_ref(&self) -> &U {
1070 self.string.as_ref()
1074 impl<T: std::ops::Deref<Target = str>> std::cmp::PartialEq<T> for LocalInternedString {
1075 fn eq(&self, other: &T) -> bool {
1076 self.string == other.deref()
1080 impl std::cmp::PartialEq<LocalInternedString> for str {
1081 fn eq(&self, other: &LocalInternedString) -> bool {
1082 self == other.string
1086 impl<'a> std::cmp::PartialEq<LocalInternedString> for &'a str {
1087 fn eq(&self, other: &LocalInternedString) -> bool {
1088 *self == other.string
1092 impl std::cmp::PartialEq<LocalInternedString> for String {
1093 fn eq(&self, other: &LocalInternedString) -> bool {
1094 self == other.string
1098 impl<'a> std::cmp::PartialEq<LocalInternedString> for &'a String {
1099 fn eq(&self, other: &LocalInternedString) -> bool {
1100 *self == other.string
1104 impl !Send for LocalInternedString {}
1105 impl !Sync for LocalInternedString {}
1107 impl std::ops::Deref for LocalInternedString {
1109 fn deref(&self) -> &str { self.string }
1112 impl fmt::Debug for LocalInternedString {
1113 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1114 fmt::Debug::fmt(self.string, f)
1118 impl fmt::Display for LocalInternedString {
1119 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1120 fmt::Display::fmt(self.string, f)
1124 impl Decodable for LocalInternedString {
1125 fn decode<D: Decoder>(d: &mut D) -> Result<LocalInternedString, D::Error> {
1126 Ok(LocalInternedString::intern(&d.read_str()?))
1130 impl Encodable for LocalInternedString {
1131 fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
1132 s.emit_str(self.string)
1136 /// An alternative to `Symbol` that is focused on string contents. It has two
1137 /// main differences to `Symbol`.
1139 /// First, its implementations of `Hash`, `PartialOrd` and `Ord` work with the
1140 /// string chars rather than the symbol integer. This is useful when hash
1141 /// stability is required across compile sessions, or a guaranteed sort
1142 /// ordering is required.
1144 /// Second, gensym-ness is irrelevant. E.g.:
1146 /// assert_ne!(Symbol::gensym("x"), Symbol::gensym("x"))
1147 /// assert_eq!(Symbol::gensym("x").as_interned_str(), Symbol::gensym("x").as_interned_str())
1149 #[derive(Clone, Copy, PartialEq, Eq)]
1150 pub struct InternedString {
1154 impl InternedString {
1155 /// Maps a string to its interned representation.
1156 pub fn intern(string: &str) -> Self {
1158 symbol: Symbol::intern(string)
1162 pub fn with<F: FnOnce(&str) -> R, R>(self, f: F) -> R {
1163 let str = with_interner(|interner| {
1164 interner.get(self.symbol) as *const str
1166 // This is safe because the interner keeps string alive until it is dropped.
1167 // We can access it because we know the interner is still alive since we use a
1168 // scoped thread local to access it, and it was alive at the beginning of this scope
1172 fn with2<F: FnOnce(&str, &str) -> R, R>(self, other: &InternedString, f: F) -> R {
1173 let (self_str, other_str) = with_interner(|interner| {
1174 (interner.get(self.symbol) as *const str,
1175 interner.get(other.symbol) as *const str)
1177 // This is safe for the same reason that `with` is safe.
1178 unsafe { f(&*self_str, &*other_str) }
1181 pub fn as_symbol(self) -> Symbol {
1185 pub fn as_str(self) -> LocalInternedString {
1186 self.symbol.as_str()
1190 impl Hash for InternedString {
1191 fn hash<H: Hasher>(&self, state: &mut H) {
1192 self.with(|str| str.hash(state))
1196 impl PartialOrd<InternedString> for InternedString {
1197 fn partial_cmp(&self, other: &InternedString) -> Option<Ordering> {
1198 if self.symbol == other.symbol {
1199 return Some(Ordering::Equal);
1201 self.with2(other, |self_str, other_str| self_str.partial_cmp(other_str))
1205 impl Ord for InternedString {
1206 fn cmp(&self, other: &InternedString) -> Ordering {
1207 if self.symbol == other.symbol {
1208 return Ordering::Equal;
1210 self.with2(other, |self_str, other_str| self_str.cmp(other_str))
1214 impl fmt::Debug for InternedString {
1215 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1216 self.with(|str| fmt::Debug::fmt(&str, f))
1220 impl fmt::Display for InternedString {
1221 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1222 self.with(|str| fmt::Display::fmt(&str, f))
1226 impl Decodable for InternedString {
1227 fn decode<D: Decoder>(d: &mut D) -> Result<InternedString, D::Error> {
1228 Ok(InternedString::intern(&d.read_str()?))
1232 impl Encodable for InternedString {
1233 fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
1234 self.with(|string| s.emit_str(string))
1245 fn interner_tests() {
1246 let mut i: Interner = Interner::default();
1247 // first one is zero:
1248 assert_eq!(i.intern("dog"), Symbol::new(0));
1249 // re-use gets the same entry:
1250 assert_eq!(i.intern("dog"), Symbol::new(0));
1251 // different string gets a different #:
1252 assert_eq!(i.intern("cat"), Symbol::new(1));
1253 assert_eq!(i.intern("cat"), Symbol::new(1));
1254 // dog is still at zero
1255 assert_eq!(i.intern("dog"), Symbol::new(0));
1256 let z = i.intern("zebra");
1257 assert_eq!(i.gensymed(z), Symbol::new(SymbolIndex::MAX_AS_U32));
1258 // gensym of same string gets new number:
1259 assert_eq!(i.gensymed(z), Symbol::new(SymbolIndex::MAX_AS_U32 - 1));
1260 // gensym of *existing* string gets new number:
1261 let d = i.intern("dog");
1262 assert_eq!(i.gensymed(d), Symbol::new(SymbolIndex::MAX_AS_U32 - 2));
1266 fn without_first_quote_test() {
1267 GLOBALS.set(&Globals::new(edition::DEFAULT_EDITION), || {
1268 let i = Ident::from_str("'break");
1269 assert_eq!(i.without_first_quote().name, kw::Break);