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,
253 field_init_shorthand,
268 generic_associated_types,
273 hexagon_target_feature,
275 homogeneous_aggregate,
289 if_while_or_patterns,
291 impl_header_lifetime_elision,
292 impl_trait_in_bindings,
296 inclusive_range_syntax,
297 infer_outlives_requirements,
298 infer_static_outlives_requirements,
305 irrefutable_let_patterns,
308 issue_5723_bootstrap,
309 issue_tracker_base_url,
324 link_llvm_intrinsics,
331 macro_at_most_once_rep,
334 macro_lifetime_matcher,
335 macro_literal_matcher,
346 match_beginning_vert,
347 match_default_bindings,
357 movbe_target_feature,
390 omit_gdb_pretty_printer_section,
397 optin_builtin_traits,
402 overlapping_marker_traits,
406 panic_implementation,
420 poll_with_tls_context,
421 powerpc_target_feature,
422 precise_pointer_size_matching,
426 proc_dash_macro: "proc-macro",
428 proc_macro_attribute,
434 proc_macro_non_items,
435 proc_macro_path_invoc,
439 quad_precision_float,
452 reexport_test_harness_main,
462 re_rebalance_coherence,
472 rustc_allocator_nounwind,
473 rustc_allow_const_fn_ptr,
474 rustc_args_required_const,
477 rustc_const_unstable,
478 rustc_conversion_suggestion,
479 rustc_copy_clone_marker,
482 rustc_diagnostic_macros,
484 rustc_doc_only_macro,
485 rustc_dump_env_program_clauses,
486 rustc_dump_program_clauses,
487 rustc_dump_user_substs,
489 rustc_expected_cgu_reuse,
490 rustc_if_this_changed,
491 rustc_inherit_overflow_checks,
493 rustc_layout_scalar_valid_range_end,
494 rustc_layout_scalar_valid_range_start,
496 rustc_nonnull_optimization_guaranteed,
497 rustc_object_lifetime_default,
498 rustc_on_unimplemented,
501 rustc_partition_codegened,
502 rustc_partition_reused,
504 rustc_peek_definite_init,
505 rustc_peek_maybe_init,
506 rustc_peek_maybe_uninit,
508 rustc_proc_macro_decls,
512 rustc_std_internal_symbol,
516 rustc_then_this_would_need,
517 rustc_transparent_macro,
521 rust_eh_unwind_resume,
523 __rust_unstable_column,
524 rvalue_static_promotion,
540 sse4a_target_feature,
550 stmt_expr_attributes,
552 struct_field_attributes,
563 termination_trait_test,
566 test_accepted_feature,
567 test_removed_feature,
582 type_alias_enum_variants,
592 underscore_const_names,
594 underscore_lifetimes,
596 universal_impl_trait,
599 unrestricted_attribute_tokens,
600 unsafe_destructor_blind_to_params,
603 unsized_tuple_coercion,
615 visible_private_types,
618 warn_directory_ownership,
628 #[derive(Copy, Clone, Eq)]
636 /// Constructs a new identifier from a symbol and a span.
637 pub const fn new(name: Symbol, span: Span) -> Ident {
641 /// Constructs a new identifier with an empty syntax context.
643 pub const fn with_empty_ctxt(name: Symbol) -> Ident {
644 Ident::new(name, DUMMY_SP)
648 pub fn invalid() -> Ident {
649 Ident::with_empty_ctxt(kw::Invalid)
652 /// Maps an interned string to an identifier with an empty syntax context.
653 pub fn from_interned_str(string: InternedString) -> Ident {
654 Ident::with_empty_ctxt(string.as_symbol())
657 /// Maps a string to an identifier with an empty span.
658 pub fn from_str(string: &str) -> Ident {
659 Ident::with_empty_ctxt(Symbol::intern(string))
662 /// Maps a string and a span to an identifier.
663 pub fn from_str_and_span(string: &str, span: Span) -> Ident {
664 Ident::new(Symbol::intern(string), span)
667 /// Replaces `lo` and `hi` with those from `span`, but keep hygiene context.
668 pub fn with_span_pos(self, span: Span) -> Ident {
669 Ident::new(self.name, span.with_ctxt(self.span.ctxt()))
672 pub fn without_first_quote(self) -> Ident {
673 Ident::new(Symbol::intern(self.as_str().trim_start_matches('\'')), self.span)
676 /// "Normalize" ident for use in comparisons using "item hygiene".
677 /// Identifiers with same string value become same if they came from the same "modern" macro
678 /// (e.g., `macro` item, but not `macro_rules` item) and stay different if they came from
679 /// different "modern" macros.
680 /// Technically, this operation strips all non-opaque marks from ident's syntactic context.
681 pub fn modern(self) -> Ident {
682 Ident::new(self.name, self.span.modern())
685 /// "Normalize" ident for use in comparisons using "local variable hygiene".
686 /// Identifiers with same string value become same if they came from the same non-transparent
687 /// macro (e.g., `macro` or `macro_rules!` items) and stay different if they came from different
688 /// non-transparent macros.
689 /// Technically, this operation strips all transparent marks from ident's syntactic context.
690 pub fn modern_and_legacy(self) -> Ident {
691 Ident::new(self.name, self.span.modern_and_legacy())
694 /// Transforms an identifier into one with the same name, but gensymed.
695 pub fn gensym(self) -> Ident {
696 let name = with_interner(|interner| interner.gensymed(self.name));
697 Ident::new(name, self.span)
700 /// Transforms an underscore identifier into one with the same name, but
701 /// gensymed. Leaves non-underscore identifiers unchanged.
702 pub fn gensym_if_underscore(self) -> Ident {
703 if self.name == kw::Underscore { self.gensym() } else { self }
706 // WARNING: this function is deprecated and will be removed in the future.
707 pub fn is_gensymed(self) -> bool {
708 with_interner(|interner| interner.is_gensymed(self.name))
711 pub fn as_str(self) -> LocalInternedString {
715 pub fn as_interned_str(self) -> InternedString {
716 self.name.as_interned_str()
720 impl PartialEq for Ident {
721 fn eq(&self, rhs: &Self) -> bool {
722 self.name == rhs.name && self.span.ctxt() == rhs.span.ctxt()
726 impl Hash for Ident {
727 fn hash<H: Hasher>(&self, state: &mut H) {
728 self.name.hash(state);
729 self.span.ctxt().hash(state);
733 impl fmt::Debug for Ident {
734 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
735 write!(f, "{}{:?}", self.name, self.span.ctxt())
739 impl fmt::Display for Ident {
740 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
741 fmt::Display::fmt(&self.name, f)
745 impl Encodable for Ident {
746 fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
747 if self.span.ctxt().modern() == SyntaxContext::empty() {
748 s.emit_str(&self.as_str())
749 } else { // FIXME(jseyfried): intercrate hygiene
750 let mut string = "#".to_owned();
751 string.push_str(&self.as_str());
757 impl Decodable for Ident {
758 fn decode<D: Decoder>(d: &mut D) -> Result<Ident, D::Error> {
759 let string = d.read_str()?;
760 Ok(if !string.starts_with('#') {
761 Ident::from_str(&string)
762 } else { // FIXME(jseyfried): intercrate hygiene
763 Ident::from_str(&string[1..]).gensym()
768 /// A symbol is an interned or gensymed string. A gensym is a symbol that is
769 /// never equal to any other symbol.
771 /// Conceptually, a gensym can be thought of as a normal symbol with an
772 /// invisible unique suffix. Gensyms are useful when creating new identifiers
773 /// that must not match any existing identifiers, e.g. during macro expansion
774 /// and syntax desugaring. Because gensyms should always be identifiers, all
775 /// gensym operations are on `Ident` rather than `Symbol`. (Indeed, in the
776 /// future the gensym-ness may be moved from `Symbol` to hygiene data.)
780 /// assert_eq!(Ident::from_str("x"), Ident::from_str("x"))
781 /// assert_ne!(Ident::from_str("x").gensym(), Ident::from_str("x"))
782 /// assert_ne!(Ident::from_str("x").gensym(), Ident::from_str("x").gensym())
784 /// Internally, a symbol is implemented as an index, and all operations
785 /// (including hashing, equality, and ordering) operate on that index. The use
786 /// of `newtype_index!` means that `Option<Symbol>` only takes up 4 bytes,
787 /// because `newtype_index!` reserves the last 256 values for tagging purposes.
789 /// Note that `Symbol` cannot directly be a `newtype_index!` because it
790 /// implements `fmt::Debug`, `Encodable`, and `Decodable` in special ways.
791 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
792 pub struct Symbol(SymbolIndex);
795 pub struct SymbolIndex { .. }
799 const fn new(n: u32) -> Self {
800 Symbol(SymbolIndex::from_u32_const(n))
803 /// Maps a string to its interned representation.
804 pub fn intern(string: &str) -> Self {
805 with_interner(|interner| interner.intern(string))
808 pub fn as_str(self) -> LocalInternedString {
809 with_interner(|interner| unsafe {
810 LocalInternedString {
811 string: std::mem::transmute::<&str, &str>(interner.get(self))
816 pub fn as_interned_str(self) -> InternedString {
817 with_interner(|interner| InternedString {
818 symbol: interner.interned(self)
822 pub fn as_u32(self) -> u32 {
827 impl fmt::Debug for Symbol {
828 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
829 let is_gensymed = with_interner(|interner| interner.is_gensymed(*self));
831 write!(f, "{}({:?})", self, self.0)
833 write!(f, "{}", self)
838 impl fmt::Display for Symbol {
839 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
840 fmt::Display::fmt(&self.as_str(), f)
844 impl Encodable for Symbol {
845 fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
846 s.emit_str(&self.as_str())
850 impl Decodable for Symbol {
851 fn decode<D: Decoder>(d: &mut D) -> Result<Symbol, D::Error> {
852 Ok(Symbol::intern(&d.read_str()?))
856 // The `&'static str`s in this type actually point into the arena.
858 // Note that normal symbols are indexed upward from 0, and gensyms are indexed
859 // downward from SymbolIndex::MAX_AS_U32.
861 pub struct Interner {
862 arena: DroplessArena,
863 names: FxHashMap<&'static str, Symbol>,
864 strings: Vec<&'static str>,
865 gensyms: Vec<Symbol>,
869 fn prefill(init: &[&'static str]) -> Self {
870 let symbols = (0 .. init.len() as u32).map(Symbol::new);
872 strings: init.to_vec(),
873 names: init.iter().copied().zip(symbols).collect(),
878 pub fn intern(&mut self, string: &str) -> Symbol {
879 if let Some(&name) = self.names.get(string) {
883 let name = Symbol::new(self.strings.len() as u32);
885 // `from_utf8_unchecked` is safe since we just allocated a `&str` which is known to be
887 let string: &str = unsafe {
888 str::from_utf8_unchecked(self.arena.alloc_slice(string.as_bytes()))
890 // It is safe to extend the arena allocation to `'static` because we only access
891 // these while the arena is still alive.
892 let string: &'static str = unsafe {
893 &*(string as *const str)
895 self.strings.push(string);
896 self.names.insert(string, name);
900 fn interned(&self, symbol: Symbol) -> Symbol {
901 if (symbol.0.as_usize()) < self.strings.len() {
904 self.gensyms[(SymbolIndex::MAX_AS_U32 - symbol.0.as_u32()) as usize]
908 fn gensymed(&mut self, symbol: Symbol) -> Symbol {
909 self.gensyms.push(symbol);
910 Symbol::new(SymbolIndex::MAX_AS_U32 - self.gensyms.len() as u32 + 1)
913 fn is_gensymed(&mut self, symbol: Symbol) -> bool {
914 symbol.0.as_usize() >= self.strings.len()
917 // Get the symbol as a string. `Symbol::as_str()` should be used in
918 // preference to this function.
919 pub fn get(&self, symbol: Symbol) -> &str {
920 match self.strings.get(symbol.0.as_usize()) {
921 Some(string) => string,
923 let symbol = self.gensyms[(SymbolIndex::MAX_AS_U32 - symbol.0.as_u32()) as usize];
924 self.strings[symbol.0.as_usize()]
930 // This module has a very short name because it's used a lot.
936 // This module has a very short name because it's used a lot.
943 fn is_used_keyword_2018(self) -> bool {
947 fn is_unused_keyword_2018(self) -> bool {
948 self >= kw::Async && self <= kw::Try
951 /// Used for sanity checking rustdoc keyword sections.
952 pub fn is_doc_keyword(self) -> bool {
958 // Returns `true` for reserved identifiers used internally for elided lifetimes,
959 // unnamed method parameters, crate root module, error recovery etc.
960 pub fn is_special(self) -> bool {
961 self.name <= kw::Underscore
964 /// Returns `true` if the token is a keyword used in the language.
965 pub fn is_used_keyword(self) -> bool {
966 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
967 self.name >= kw::As && self.name <= kw::While ||
968 self.name.is_used_keyword_2018() && self.span.rust_2018()
971 /// Returns `true` if the token is a keyword reserved for possible future use.
972 pub fn is_unused_keyword(self) -> bool {
973 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
974 self.name >= kw::Abstract && self.name <= kw::Yield ||
975 self.name.is_unused_keyword_2018() && self.span.rust_2018()
978 /// Returns `true` if the token is either a special identifier or a keyword.
979 pub fn is_reserved(self) -> bool {
980 self.is_special() || self.is_used_keyword() || self.is_unused_keyword()
983 /// A keyword or reserved identifier that can be used as a path segment.
984 pub fn is_path_segment_keyword(self) -> bool {
985 self.name == kw::Super ||
986 self.name == kw::SelfLower ||
987 self.name == kw::SelfUpper ||
988 self.name == kw::Crate ||
989 self.name == kw::PathRoot ||
990 self.name == kw::DollarCrate
993 /// This identifier can be a raw identifier.
994 pub fn can_be_raw(self) -> bool {
995 self.name != kw::Invalid && self.name != kw::Underscore &&
996 !self.is_path_segment_keyword()
999 /// We see this identifier in a normal identifier position, like variable name or a type.
1000 /// How was it written originally? Did it use the raw form? Let's try to guess.
1001 pub fn is_raw_guess(self) -> bool {
1002 self.can_be_raw() && self.is_reserved()
1006 // If an interner exists, return it. Otherwise, prepare a fresh one.
1008 fn with_interner<T, F: FnOnce(&mut Interner) -> T>(f: F) -> T {
1009 GLOBALS.with(|globals| f(&mut *globals.symbol_interner.lock()))
1012 /// An alternative to `Symbol` and `InternedString`, useful when the chars
1013 /// within the symbol need to be accessed. It is best used for temporary
1016 /// Because the interner outlives any thread which uses this type, we can
1017 /// safely treat `string` which points to interner data, as an immortal string,
1018 /// as long as this type never crosses between threads.
1020 // FIXME: ensure that the interner outlives any thread which uses
1021 // `LocalInternedString`, by creating a new thread right after constructing the
1023 #[derive(Clone, Copy, Hash, PartialOrd, Eq, Ord)]
1024 pub struct LocalInternedString {
1025 string: &'static str,
1028 impl LocalInternedString {
1029 /// Maps a string to its interned representation.
1030 pub fn intern(string: &str) -> Self {
1031 let string = with_interner(|interner| {
1032 let symbol = interner.intern(string);
1033 interner.strings[symbol.0.as_usize()]
1035 LocalInternedString {
1036 string: unsafe { std::mem::transmute::<&str, &str>(string) }
1040 pub fn as_interned_str(self) -> InternedString {
1042 symbol: Symbol::intern(self.string)
1046 pub fn get(&self) -> &str {
1047 // This returns a valid string since we ensure that `self` outlives the interner
1048 // by creating the interner on a thread which outlives threads which can access it.
1049 // This type cannot move to a thread which outlives the interner since it does
1050 // not implement Send.
1055 impl<U: ?Sized> std::convert::AsRef<U> for LocalInternedString
1057 str: std::convert::AsRef<U>
1059 fn as_ref(&self) -> &U {
1060 self.string.as_ref()
1064 impl<T: std::ops::Deref<Target = str>> std::cmp::PartialEq<T> for LocalInternedString {
1065 fn eq(&self, other: &T) -> bool {
1066 self.string == other.deref()
1070 impl std::cmp::PartialEq<LocalInternedString> for str {
1071 fn eq(&self, other: &LocalInternedString) -> bool {
1072 self == other.string
1076 impl<'a> std::cmp::PartialEq<LocalInternedString> for &'a str {
1077 fn eq(&self, other: &LocalInternedString) -> bool {
1078 *self == other.string
1082 impl std::cmp::PartialEq<LocalInternedString> for String {
1083 fn eq(&self, other: &LocalInternedString) -> bool {
1084 self == other.string
1088 impl<'a> std::cmp::PartialEq<LocalInternedString> for &'a String {
1089 fn eq(&self, other: &LocalInternedString) -> bool {
1090 *self == other.string
1094 impl !Send for LocalInternedString {}
1095 impl !Sync for LocalInternedString {}
1097 impl std::ops::Deref for LocalInternedString {
1099 fn deref(&self) -> &str { self.string }
1102 impl fmt::Debug for LocalInternedString {
1103 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1104 fmt::Debug::fmt(self.string, f)
1108 impl fmt::Display for LocalInternedString {
1109 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1110 fmt::Display::fmt(self.string, f)
1114 impl Decodable for LocalInternedString {
1115 fn decode<D: Decoder>(d: &mut D) -> Result<LocalInternedString, D::Error> {
1116 Ok(LocalInternedString::intern(&d.read_str()?))
1120 impl Encodable for LocalInternedString {
1121 fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
1122 s.emit_str(self.string)
1126 /// An alternative to `Symbol` that is focused on string contents. It has two
1127 /// main differences to `Symbol`.
1129 /// First, its implementations of `Hash`, `PartialOrd` and `Ord` work with the
1130 /// string chars rather than the symbol integer. This is useful when hash
1131 /// stability is required across compile sessions, or a guaranteed sort
1132 /// ordering is required.
1134 /// Second, gensym-ness is irrelevant. E.g.:
1136 /// assert_ne!(Symbol::gensym("x"), Symbol::gensym("x"))
1137 /// assert_eq!(Symbol::gensym("x").as_interned_str(), Symbol::gensym("x").as_interned_str())
1139 #[derive(Clone, Copy, PartialEq, Eq)]
1140 pub struct InternedString {
1144 impl InternedString {
1145 /// Maps a string to its interned representation.
1146 pub fn intern(string: &str) -> Self {
1148 symbol: Symbol::intern(string)
1152 pub fn with<F: FnOnce(&str) -> R, R>(self, f: F) -> R {
1153 let str = with_interner(|interner| {
1154 interner.get(self.symbol) as *const str
1156 // This is safe because the interner keeps string alive until it is dropped.
1157 // We can access it because we know the interner is still alive since we use a
1158 // scoped thread local to access it, and it was alive at the beginning of this scope
1162 fn with2<F: FnOnce(&str, &str) -> R, R>(self, other: &InternedString, f: F) -> R {
1163 let (self_str, other_str) = with_interner(|interner| {
1164 (interner.get(self.symbol) as *const str,
1165 interner.get(other.symbol) as *const str)
1167 // This is safe for the same reason that `with` is safe.
1168 unsafe { f(&*self_str, &*other_str) }
1171 pub fn as_symbol(self) -> Symbol {
1175 pub fn as_str(self) -> LocalInternedString {
1176 self.symbol.as_str()
1180 impl Hash for InternedString {
1181 fn hash<H: Hasher>(&self, state: &mut H) {
1182 self.with(|str| str.hash(state))
1186 impl PartialOrd<InternedString> for InternedString {
1187 fn partial_cmp(&self, other: &InternedString) -> Option<Ordering> {
1188 if self.symbol == other.symbol {
1189 return Some(Ordering::Equal);
1191 self.with2(other, |self_str, other_str| self_str.partial_cmp(other_str))
1195 impl Ord for InternedString {
1196 fn cmp(&self, other: &InternedString) -> Ordering {
1197 if self.symbol == other.symbol {
1198 return Ordering::Equal;
1200 self.with2(other, |self_str, other_str| self_str.cmp(other_str))
1204 impl fmt::Debug for InternedString {
1205 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1206 self.with(|str| fmt::Debug::fmt(&str, f))
1210 impl fmt::Display for InternedString {
1211 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1212 self.with(|str| fmt::Display::fmt(&str, f))
1216 impl Decodable for InternedString {
1217 fn decode<D: Decoder>(d: &mut D) -> Result<InternedString, D::Error> {
1218 Ok(InternedString::intern(&d.read_str()?))
1222 impl Encodable for InternedString {
1223 fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
1224 self.with(|string| s.emit_str(string))
1235 fn interner_tests() {
1236 let mut i: Interner = Interner::default();
1237 // first one is zero:
1238 assert_eq!(i.intern("dog"), Symbol::new(0));
1239 // re-use gets the same entry:
1240 assert_eq!(i.intern("dog"), Symbol::new(0));
1241 // different string gets a different #:
1242 assert_eq!(i.intern("cat"), Symbol::new(1));
1243 assert_eq!(i.intern("cat"), Symbol::new(1));
1244 // dog is still at zero
1245 assert_eq!(i.intern("dog"), Symbol::new(0));
1246 let z = i.intern("zebra");
1247 assert_eq!(i.gensymed(z), Symbol::new(SymbolIndex::MAX_AS_U32));
1248 // gensym of same string gets new number:
1249 assert_eq!(i.gensymed(z), Symbol::new(SymbolIndex::MAX_AS_U32 - 1));
1250 // gensym of *existing* string gets new number:
1251 let d = i.intern("dog");
1252 assert_eq!(i.gensymed(d), Symbol::new(SymbolIndex::MAX_AS_U32 - 2));
1256 fn without_first_quote_test() {
1257 GLOBALS.set(&Globals::new(edition::DEFAULT_EDITION), || {
1258 let i = Ident::from_str("'break");
1259 assert_eq!(i.without_first_quote().name, kw::Break);