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,
216 document_private_items,
217 dotdoteq_in_patterns,
218 dotdot_in_tuple_patterns,
219 double_braced_crate: "{{crate}}",
220 double_braced_impl: "{{impl}}",
221 double_braced_misc: "{{misc}}",
222 double_braced_closure: "{{closure}}",
223 double_braced_constructor: "{{constructor}}",
224 double_braced_constant: "{{constant}}",
225 double_braced_opaque: "{{opaque}}",
227 dropck_parametricity,
237 exclusive_range_pattern,
238 exhaustive_integer_patterns,
243 extern_absolute_paths,
245 extern_crate_item_prelude,
255 field_init_shorthand,
270 generic_associated_types,
275 hexagon_target_feature,
277 homogeneous_aggregate,
291 if_while_or_patterns,
293 impl_header_lifetime_elision,
294 impl_trait_in_bindings,
300 inclusive_range_syntax,
301 infer_outlives_requirements,
302 infer_static_outlives_requirements,
309 irrefutable_let_patterns,
312 issue_5723_bootstrap,
313 issue_tracker_base_url,
328 link_llvm_intrinsics,
335 macro_at_most_once_rep,
338 macro_lifetime_matcher,
339 macro_literal_matcher,
350 match_beginning_vert,
351 match_default_bindings,
361 movbe_target_feature,
394 omit_gdb_pretty_printer_section,
401 optin_builtin_traits,
406 overlapping_marker_traits,
410 panic_implementation,
424 poll_with_tls_context,
425 powerpc_target_feature,
426 precise_pointer_size_matching,
430 proc_dash_macro: "proc-macro",
432 proc_macro_attribute,
438 proc_macro_non_items,
439 proc_macro_path_invoc,
443 quad_precision_float,
456 reexport_test_harness_main,
466 re_rebalance_coherence,
476 rustc_allocator_nounwind,
477 rustc_allow_const_fn_ptr,
478 rustc_args_required_const,
481 rustc_const_unstable,
482 rustc_conversion_suggestion,
483 rustc_copy_clone_marker,
486 rustc_diagnostic_macros,
488 rustc_doc_only_macro,
489 rustc_dump_env_program_clauses,
490 rustc_dump_program_clauses,
491 rustc_dump_user_substs,
493 rustc_expected_cgu_reuse,
494 rustc_if_this_changed,
495 rustc_inherit_overflow_checks,
497 rustc_layout_scalar_valid_range_end,
498 rustc_layout_scalar_valid_range_start,
500 rustc_nonnull_optimization_guaranteed,
501 rustc_object_lifetime_default,
502 rustc_on_unimplemented,
505 rustc_partition_codegened,
506 rustc_partition_reused,
508 rustc_peek_definite_init,
509 rustc_peek_maybe_init,
510 rustc_peek_maybe_uninit,
512 rustc_proc_macro_decls,
516 rustc_std_internal_symbol,
520 rustc_then_this_would_need,
521 rustc_transparent_macro,
525 rust_eh_unwind_resume,
527 __rust_unstable_column,
528 rvalue_static_promotion,
544 sse4a_target_feature,
554 stmt_expr_attributes,
556 struct_field_attributes,
567 termination_trait_test,
570 test_accepted_feature,
571 test_removed_feature,
586 type_alias_enum_variants,
596 underscore_const_names,
598 underscore_lifetimes,
600 universal_impl_trait,
603 unrestricted_attribute_tokens,
604 unsafe_destructor_blind_to_params,
607 unsized_tuple_coercion,
619 visible_private_types,
622 warn_directory_ownership,
632 #[derive(Copy, Clone, Eq)]
640 /// Constructs a new identifier from a symbol and a span.
641 pub const fn new(name: Symbol, span: Span) -> Ident {
645 /// Constructs a new identifier with an empty syntax context.
647 pub const fn with_empty_ctxt(name: Symbol) -> Ident {
648 Ident::new(name, DUMMY_SP)
652 pub fn invalid() -> Ident {
653 Ident::with_empty_ctxt(kw::Invalid)
656 /// Maps an interned string to an identifier with an empty syntax context.
657 pub fn from_interned_str(string: InternedString) -> Ident {
658 Ident::with_empty_ctxt(string.as_symbol())
661 /// Maps a string to an identifier with an empty span.
662 pub fn from_str(string: &str) -> Ident {
663 Ident::with_empty_ctxt(Symbol::intern(string))
666 /// Maps a string and a span to an identifier.
667 pub fn from_str_and_span(string: &str, span: Span) -> Ident {
668 Ident::new(Symbol::intern(string), span)
671 /// Replaces `lo` and `hi` with those from `span`, but keep hygiene context.
672 pub fn with_span_pos(self, span: Span) -> Ident {
673 Ident::new(self.name, span.with_ctxt(self.span.ctxt()))
676 pub fn without_first_quote(self) -> Ident {
677 Ident::new(Symbol::intern(self.as_str().trim_start_matches('\'')), self.span)
680 /// "Normalize" ident for use in comparisons using "item hygiene".
681 /// Identifiers with same string value become same if they came from the same "modern" macro
682 /// (e.g., `macro` item, but not `macro_rules` item) and stay different if they came from
683 /// different "modern" macros.
684 /// Technically, this operation strips all non-opaque marks from ident's syntactic context.
685 pub fn modern(self) -> Ident {
686 Ident::new(self.name, self.span.modern())
689 /// "Normalize" ident for use in comparisons using "local variable hygiene".
690 /// Identifiers with same string value become same if they came from the same non-transparent
691 /// macro (e.g., `macro` or `macro_rules!` items) and stay different if they came from different
692 /// non-transparent macros.
693 /// Technically, this operation strips all transparent marks from ident's syntactic context.
694 pub fn modern_and_legacy(self) -> Ident {
695 Ident::new(self.name, self.span.modern_and_legacy())
698 /// Transforms an identifier into one with the same name, but gensymed.
699 pub fn gensym(self) -> Ident {
700 let name = with_interner(|interner| interner.gensymed(self.name));
701 Ident::new(name, self.span)
704 /// Transforms an underscore identifier into one with the same name, but
705 /// gensymed. Leaves non-underscore identifiers unchanged.
706 pub fn gensym_if_underscore(self) -> Ident {
707 if self.name == kw::Underscore { self.gensym() } else { self }
710 // WARNING: this function is deprecated and will be removed in the future.
711 pub fn is_gensymed(self) -> bool {
712 with_interner(|interner| interner.is_gensymed(self.name))
715 pub fn as_str(self) -> LocalInternedString {
719 pub fn as_interned_str(self) -> InternedString {
720 self.name.as_interned_str()
724 impl PartialEq for Ident {
725 fn eq(&self, rhs: &Self) -> bool {
726 self.name == rhs.name && self.span.ctxt() == rhs.span.ctxt()
730 impl Hash for Ident {
731 fn hash<H: Hasher>(&self, state: &mut H) {
732 self.name.hash(state);
733 self.span.ctxt().hash(state);
737 impl fmt::Debug for Ident {
738 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
739 write!(f, "{}{:?}", self.name, self.span.ctxt())
743 impl fmt::Display for Ident {
744 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
745 fmt::Display::fmt(&self.name, f)
749 impl Encodable for Ident {
750 fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
751 if self.span.ctxt().modern() == SyntaxContext::empty() {
752 s.emit_str(&self.as_str())
753 } else { // FIXME(jseyfried): intercrate hygiene
754 let mut string = "#".to_owned();
755 string.push_str(&self.as_str());
761 impl Decodable for Ident {
762 fn decode<D: Decoder>(d: &mut D) -> Result<Ident, D::Error> {
763 let string = d.read_str()?;
764 Ok(if !string.starts_with('#') {
765 Ident::from_str(&string)
766 } else { // FIXME(jseyfried): intercrate hygiene
767 Ident::from_str(&string[1..]).gensym()
772 /// A symbol is an interned or gensymed string. A gensym is a symbol that is
773 /// never equal to any other symbol.
775 /// Conceptually, a gensym can be thought of as a normal symbol with an
776 /// invisible unique suffix. Gensyms are useful when creating new identifiers
777 /// that must not match any existing identifiers, e.g. during macro expansion
778 /// and syntax desugaring. Because gensyms should always be identifiers, all
779 /// gensym operations are on `Ident` rather than `Symbol`. (Indeed, in the
780 /// future the gensym-ness may be moved from `Symbol` to hygiene data.)
784 /// assert_eq!(Ident::from_str("x"), Ident::from_str("x"))
785 /// assert_ne!(Ident::from_str("x").gensym(), Ident::from_str("x"))
786 /// assert_ne!(Ident::from_str("x").gensym(), Ident::from_str("x").gensym())
788 /// Internally, a symbol is implemented as an index, and all operations
789 /// (including hashing, equality, and ordering) operate on that index. The use
790 /// of `newtype_index!` means that `Option<Symbol>` only takes up 4 bytes,
791 /// because `newtype_index!` reserves the last 256 values for tagging purposes.
793 /// Note that `Symbol` cannot directly be a `newtype_index!` because it
794 /// implements `fmt::Debug`, `Encodable`, and `Decodable` in special ways.
795 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
796 pub struct Symbol(SymbolIndex);
799 pub struct SymbolIndex { .. }
803 const fn new(n: u32) -> Self {
804 Symbol(SymbolIndex::from_u32_const(n))
807 /// Maps a string to its interned representation.
808 pub fn intern(string: &str) -> Self {
809 with_interner(|interner| interner.intern(string))
812 pub fn as_str(self) -> LocalInternedString {
813 with_interner(|interner| unsafe {
814 LocalInternedString {
815 string: std::mem::transmute::<&str, &str>(interner.get(self))
820 pub fn as_interned_str(self) -> InternedString {
821 with_interner(|interner| InternedString {
822 symbol: interner.interned(self)
826 pub fn as_u32(self) -> u32 {
831 impl fmt::Debug for Symbol {
832 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
833 let is_gensymed = with_interner(|interner| interner.is_gensymed(*self));
835 write!(f, "{}({:?})", self, self.0)
837 write!(f, "{}", self)
842 impl fmt::Display for Symbol {
843 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
844 fmt::Display::fmt(&self.as_str(), f)
848 impl Encodable for Symbol {
849 fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
850 s.emit_str(&self.as_str())
854 impl Decodable for Symbol {
855 fn decode<D: Decoder>(d: &mut D) -> Result<Symbol, D::Error> {
856 Ok(Symbol::intern(&d.read_str()?))
860 // The `&'static str`s in this type actually point into the arena.
862 // Note that normal symbols are indexed upward from 0, and gensyms are indexed
863 // downward from SymbolIndex::MAX_AS_U32.
865 pub struct Interner {
866 arena: DroplessArena,
867 names: FxHashMap<&'static str, Symbol>,
868 strings: Vec<&'static str>,
869 gensyms: Vec<Symbol>,
873 fn prefill(init: &[&'static str]) -> Self {
874 let symbols = (0 .. init.len() as u32).map(Symbol::new);
876 strings: init.to_vec(),
877 names: init.iter().copied().zip(symbols).collect(),
882 pub fn intern(&mut self, string: &str) -> Symbol {
883 if let Some(&name) = self.names.get(string) {
887 let name = Symbol::new(self.strings.len() as u32);
889 // `from_utf8_unchecked` is safe since we just allocated a `&str` which is known to be
891 let string: &str = unsafe {
892 str::from_utf8_unchecked(self.arena.alloc_slice(string.as_bytes()))
894 // It is safe to extend the arena allocation to `'static` because we only access
895 // these while the arena is still alive.
896 let string: &'static str = unsafe {
897 &*(string as *const str)
899 self.strings.push(string);
900 self.names.insert(string, name);
904 fn interned(&self, symbol: Symbol) -> Symbol {
905 if (symbol.0.as_usize()) < self.strings.len() {
908 self.gensyms[(SymbolIndex::MAX_AS_U32 - symbol.0.as_u32()) as usize]
912 fn gensymed(&mut self, symbol: Symbol) -> Symbol {
913 self.gensyms.push(symbol);
914 Symbol::new(SymbolIndex::MAX_AS_U32 - self.gensyms.len() as u32 + 1)
917 fn is_gensymed(&mut self, symbol: Symbol) -> bool {
918 symbol.0.as_usize() >= self.strings.len()
921 // Get the symbol as a string. `Symbol::as_str()` should be used in
922 // preference to this function.
923 pub fn get(&self, symbol: Symbol) -> &str {
924 match self.strings.get(symbol.0.as_usize()) {
925 Some(string) => string,
927 let symbol = self.gensyms[(SymbolIndex::MAX_AS_U32 - symbol.0.as_u32()) as usize];
928 self.strings[symbol.0.as_usize()]
934 // This module has a very short name because it's used a lot.
940 // This module has a very short name because it's used a lot.
947 fn is_used_keyword_2018(self) -> bool {
951 fn is_unused_keyword_2018(self) -> bool {
952 self >= kw::Async && self <= kw::Try
955 /// Used for sanity checking rustdoc keyword sections.
956 pub fn is_doc_keyword(self) -> bool {
962 // Returns `true` for reserved identifiers used internally for elided lifetimes,
963 // unnamed method parameters, crate root module, error recovery etc.
964 pub fn is_special(self) -> bool {
965 self.name <= kw::Underscore
968 /// Returns `true` if the token is a keyword used in the language.
969 pub fn is_used_keyword(self) -> bool {
970 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
971 self.name >= kw::As && self.name <= kw::While ||
972 self.name.is_used_keyword_2018() && self.span.rust_2018()
975 /// Returns `true` if the token is a keyword reserved for possible future use.
976 pub fn is_unused_keyword(self) -> bool {
977 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
978 self.name >= kw::Abstract && self.name <= kw::Yield ||
979 self.name.is_unused_keyword_2018() && self.span.rust_2018()
982 /// Returns `true` if the token is either a special identifier or a keyword.
983 pub fn is_reserved(self) -> bool {
984 self.is_special() || self.is_used_keyword() || self.is_unused_keyword()
987 /// A keyword or reserved identifier that can be used as a path segment.
988 pub fn is_path_segment_keyword(self) -> bool {
989 self.name == kw::Super ||
990 self.name == kw::SelfLower ||
991 self.name == kw::SelfUpper ||
992 self.name == kw::Crate ||
993 self.name == kw::PathRoot ||
994 self.name == kw::DollarCrate
997 /// This identifier can be a raw identifier.
998 pub fn can_be_raw(self) -> bool {
999 self.name != kw::Invalid && self.name != kw::Underscore &&
1000 !self.is_path_segment_keyword()
1003 /// We see this identifier in a normal identifier position, like variable name or a type.
1004 /// How was it written originally? Did it use the raw form? Let's try to guess.
1005 pub fn is_raw_guess(self) -> bool {
1006 self.can_be_raw() && self.is_reserved()
1010 // If an interner exists, return it. Otherwise, prepare a fresh one.
1012 fn with_interner<T, F: FnOnce(&mut Interner) -> T>(f: F) -> T {
1013 GLOBALS.with(|globals| f(&mut *globals.symbol_interner.lock()))
1016 /// An alternative to `Symbol` and `InternedString`, useful when the chars
1017 /// within the symbol need to be accessed. It is best used for temporary
1020 /// Because the interner outlives any thread which uses this type, we can
1021 /// safely treat `string` which points to interner data, as an immortal string,
1022 /// as long as this type never crosses between threads.
1024 // FIXME: ensure that the interner outlives any thread which uses
1025 // `LocalInternedString`, by creating a new thread right after constructing the
1027 #[derive(Clone, Copy, Hash, PartialOrd, Eq, Ord)]
1028 pub struct LocalInternedString {
1029 string: &'static str,
1032 impl LocalInternedString {
1033 /// Maps a string to its interned representation.
1034 pub fn intern(string: &str) -> Self {
1035 let string = with_interner(|interner| {
1036 let symbol = interner.intern(string);
1037 interner.strings[symbol.0.as_usize()]
1039 LocalInternedString {
1040 string: unsafe { std::mem::transmute::<&str, &str>(string) }
1044 pub fn as_interned_str(self) -> InternedString {
1046 symbol: Symbol::intern(self.string)
1050 pub fn get(&self) -> &str {
1051 // This returns a valid string since we ensure that `self` outlives the interner
1052 // by creating the interner on a thread which outlives threads which can access it.
1053 // This type cannot move to a thread which outlives the interner since it does
1054 // not implement Send.
1059 impl<U: ?Sized> std::convert::AsRef<U> for LocalInternedString
1061 str: std::convert::AsRef<U>
1063 fn as_ref(&self) -> &U {
1064 self.string.as_ref()
1068 impl<T: std::ops::Deref<Target = str>> std::cmp::PartialEq<T> for LocalInternedString {
1069 fn eq(&self, other: &T) -> bool {
1070 self.string == other.deref()
1074 impl std::cmp::PartialEq<LocalInternedString> for str {
1075 fn eq(&self, other: &LocalInternedString) -> bool {
1076 self == other.string
1080 impl<'a> std::cmp::PartialEq<LocalInternedString> for &'a str {
1081 fn eq(&self, other: &LocalInternedString) -> bool {
1082 *self == other.string
1086 impl std::cmp::PartialEq<LocalInternedString> for String {
1087 fn eq(&self, other: &LocalInternedString) -> bool {
1088 self == other.string
1092 impl<'a> std::cmp::PartialEq<LocalInternedString> for &'a String {
1093 fn eq(&self, other: &LocalInternedString) -> bool {
1094 *self == other.string
1098 impl !Send for LocalInternedString {}
1099 impl !Sync for LocalInternedString {}
1101 impl std::ops::Deref for LocalInternedString {
1103 fn deref(&self) -> &str { self.string }
1106 impl fmt::Debug for LocalInternedString {
1107 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1108 fmt::Debug::fmt(self.string, f)
1112 impl fmt::Display for LocalInternedString {
1113 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1114 fmt::Display::fmt(self.string, f)
1118 impl Decodable for LocalInternedString {
1119 fn decode<D: Decoder>(d: &mut D) -> Result<LocalInternedString, D::Error> {
1120 Ok(LocalInternedString::intern(&d.read_str()?))
1124 impl Encodable for LocalInternedString {
1125 fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
1126 s.emit_str(self.string)
1130 /// An alternative to `Symbol` that is focused on string contents. It has two
1131 /// main differences to `Symbol`.
1133 /// First, its implementations of `Hash`, `PartialOrd` and `Ord` work with the
1134 /// string chars rather than the symbol integer. This is useful when hash
1135 /// stability is required across compile sessions, or a guaranteed sort
1136 /// ordering is required.
1138 /// Second, gensym-ness is irrelevant. E.g.:
1140 /// assert_ne!(Symbol::gensym("x"), Symbol::gensym("x"))
1141 /// assert_eq!(Symbol::gensym("x").as_interned_str(), Symbol::gensym("x").as_interned_str())
1143 #[derive(Clone, Copy, PartialEq, Eq)]
1144 pub struct InternedString {
1148 impl InternedString {
1149 /// Maps a string to its interned representation.
1150 pub fn intern(string: &str) -> Self {
1152 symbol: Symbol::intern(string)
1156 pub fn with<F: FnOnce(&str) -> R, R>(self, f: F) -> R {
1157 let str = with_interner(|interner| {
1158 interner.get(self.symbol) as *const str
1160 // This is safe because the interner keeps string alive until it is dropped.
1161 // We can access it because we know the interner is still alive since we use a
1162 // scoped thread local to access it, and it was alive at the beginning of this scope
1166 fn with2<F: FnOnce(&str, &str) -> R, R>(self, other: &InternedString, f: F) -> R {
1167 let (self_str, other_str) = with_interner(|interner| {
1168 (interner.get(self.symbol) as *const str,
1169 interner.get(other.symbol) as *const str)
1171 // This is safe for the same reason that `with` is safe.
1172 unsafe { f(&*self_str, &*other_str) }
1175 pub fn as_symbol(self) -> Symbol {
1179 pub fn as_str(self) -> LocalInternedString {
1180 self.symbol.as_str()
1184 impl Hash for InternedString {
1185 fn hash<H: Hasher>(&self, state: &mut H) {
1186 self.with(|str| str.hash(state))
1190 impl PartialOrd<InternedString> for InternedString {
1191 fn partial_cmp(&self, other: &InternedString) -> Option<Ordering> {
1192 if self.symbol == other.symbol {
1193 return Some(Ordering::Equal);
1195 self.with2(other, |self_str, other_str| self_str.partial_cmp(other_str))
1199 impl Ord for InternedString {
1200 fn cmp(&self, other: &InternedString) -> Ordering {
1201 if self.symbol == other.symbol {
1202 return Ordering::Equal;
1204 self.with2(other, |self_str, other_str| self_str.cmp(other_str))
1208 impl fmt::Debug for InternedString {
1209 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1210 self.with(|str| fmt::Debug::fmt(&str, f))
1214 impl fmt::Display for InternedString {
1215 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1216 self.with(|str| fmt::Display::fmt(&str, f))
1220 impl Decodable for InternedString {
1221 fn decode<D: Decoder>(d: &mut D) -> Result<InternedString, D::Error> {
1222 Ok(InternedString::intern(&d.read_str()?))
1226 impl Encodable for InternedString {
1227 fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
1228 self.with(|string| s.emit_str(string))
1239 fn interner_tests() {
1240 let mut i: Interner = Interner::default();
1241 // first one is zero:
1242 assert_eq!(i.intern("dog"), Symbol::new(0));
1243 // re-use gets the same entry:
1244 assert_eq!(i.intern("dog"), Symbol::new(0));
1245 // different string gets a different #:
1246 assert_eq!(i.intern("cat"), Symbol::new(1));
1247 assert_eq!(i.intern("cat"), Symbol::new(1));
1248 // dog is still at zero
1249 assert_eq!(i.intern("dog"), Symbol::new(0));
1250 let z = i.intern("zebra");
1251 assert_eq!(i.gensymed(z), Symbol::new(SymbolIndex::MAX_AS_U32));
1252 // gensym of same string gets new number:
1253 assert_eq!(i.gensymed(z), Symbol::new(SymbolIndex::MAX_AS_U32 - 1));
1254 // gensym of *existing* string gets new number:
1255 let d = i.intern("dog");
1256 assert_eq!(i.gensymed(d), Symbol::new(SymbolIndex::MAX_AS_U32 - 2));
1260 fn without_first_quote_test() {
1261 GLOBALS.set(&Globals::new(edition::DEFAULT_EDITION), || {
1262 let i = Ident::from_str("'break");
1263 assert_eq!(i.without_first_quote().name, kw::Break);