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_object_lifetime_default,
495 rustc_on_unimplemented,
498 rustc_partition_codegened,
499 rustc_partition_reused,
501 rustc_peek_definite_init,
502 rustc_peek_maybe_init,
503 rustc_peek_maybe_uninit,
505 rustc_proc_macro_decls,
509 rustc_std_internal_symbol,
513 rustc_then_this_would_need,
514 rustc_transparent_macro,
518 rust_eh_unwind_resume,
520 __rust_unstable_column,
521 rvalue_static_promotion,
537 sse4a_target_feature,
547 stmt_expr_attributes,
549 struct_field_attributes,
560 termination_trait_test,
563 test_accepted_feature,
564 test_removed_feature,
579 type_alias_enum_variants,
589 underscore_const_names,
591 underscore_lifetimes,
593 universal_impl_trait,
596 unrestricted_attribute_tokens,
597 unsafe_destructor_blind_to_params,
600 unsized_tuple_coercion,
612 visible_private_types,
615 warn_directory_ownership,
625 #[derive(Copy, Clone, Eq)]
633 pub const fn new(name: Symbol, span: Span) -> Ident {
638 pub const fn with_empty_ctxt(name: Symbol) -> Ident {
639 Ident::new(name, DUMMY_SP)
642 /// Maps an interned string to an identifier with an empty syntax context.
643 pub fn from_interned_str(string: InternedString) -> Ident {
644 Ident::with_empty_ctxt(string.as_symbol())
647 /// Maps a string to an identifier with an empty syntax context.
648 pub fn from_str(string: &str) -> Ident {
649 Ident::with_empty_ctxt(Symbol::intern(string))
652 /// Replaces `lo` and `hi` with those from `span`, but keep hygiene context.
653 pub fn with_span_pos(self, span: Span) -> Ident {
654 Ident::new(self.name, span.with_ctxt(self.span.ctxt()))
657 pub fn without_first_quote(self) -> Ident {
658 Ident::new(Symbol::intern(self.as_str().trim_start_matches('\'')), self.span)
661 /// "Normalize" ident for use in comparisons using "item hygiene".
662 /// Identifiers with same string value become same if they came from the same "modern" macro
663 /// (e.g., `macro` item, but not `macro_rules` item) and stay different if they came from
664 /// different "modern" macros.
665 /// Technically, this operation strips all non-opaque marks from ident's syntactic context.
666 pub fn modern(self) -> Ident {
667 Ident::new(self.name, self.span.modern())
670 /// "Normalize" ident for use in comparisons using "local variable hygiene".
671 /// Identifiers with same string value become same if they came from the same non-transparent
672 /// macro (e.g., `macro` or `macro_rules!` items) and stay different if they came from different
673 /// non-transparent macros.
674 /// Technically, this operation strips all transparent marks from ident's syntactic context.
675 pub fn modern_and_legacy(self) -> Ident {
676 Ident::new(self.name, self.span.modern_and_legacy())
679 pub fn gensym(self) -> Ident {
680 let name = with_interner(|interner| interner.gensymed(self.name));
681 Ident::new(name, self.span)
684 pub fn gensym_if_underscore(self) -> Ident {
685 if self.name == keywords::Underscore.name() { self.gensym() } else { self }
688 // WARNING: this function is deprecated and will be removed in the future.
689 pub fn is_gensymed(self) -> bool {
690 with_interner(|interner| interner.is_gensymed(self.name))
693 pub fn as_str(self) -> LocalInternedString {
697 pub fn as_interned_str(self) -> InternedString {
698 self.name.as_interned_str()
702 impl PartialEq for Ident {
703 fn eq(&self, rhs: &Self) -> bool {
704 self.name == rhs.name && self.span.ctxt() == rhs.span.ctxt()
708 impl Hash for Ident {
709 fn hash<H: Hasher>(&self, state: &mut H) {
710 self.name.hash(state);
711 self.span.ctxt().hash(state);
715 impl fmt::Debug for Ident {
716 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
717 write!(f, "{}{:?}", self.name, self.span.ctxt())
721 impl fmt::Display for Ident {
722 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
723 fmt::Display::fmt(&self.name, f)
727 impl Encodable for Ident {
728 fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
729 if self.span.ctxt().modern() == SyntaxContext::empty() {
730 s.emit_str(&self.as_str())
731 } else { // FIXME(jseyfried): intercrate hygiene
732 let mut string = "#".to_owned();
733 string.push_str(&self.as_str());
739 impl Decodable for Ident {
740 fn decode<D: Decoder>(d: &mut D) -> Result<Ident, D::Error> {
741 let string = d.read_str()?;
742 Ok(if !string.starts_with('#') {
743 Ident::from_str(&string)
744 } else { // FIXME(jseyfried): intercrate hygiene
745 Ident::with_empty_ctxt(Symbol::gensym(&string[1..]))
750 /// A symbol is an interned or gensymed string. A gensym is a symbol that is
751 /// never equal to any other symbol. E.g.:
753 /// assert_eq!(Symbol::intern("x"), Symbol::intern("x"))
754 /// assert_ne!(Symbol::gensym("x"), Symbol::intern("x"))
755 /// assert_ne!(Symbol::gensym("x"), Symbol::gensym("x"))
757 /// Conceptually, a gensym can be thought of as a normal symbol with an
758 /// invisible unique suffix. Gensyms are useful when creating new identifiers
759 /// that must not match any existing identifiers, e.g. during macro expansion
760 /// and syntax desugaring.
762 /// Internally, a Symbol is implemented as an index, and all operations
763 /// (including hashing, equality, and ordering) operate on that index. The use
764 /// of `newtype_index!` means that `Option<Symbol>` only takes up 4 bytes,
765 /// because `newtype_index!` reserves the last 256 values for tagging purposes.
767 /// Note that `Symbol` cannot directly be a `newtype_index!` because it implements
768 /// `fmt::Debug`, `Encodable`, and `Decodable` in special ways.
769 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
770 pub struct Symbol(SymbolIndex);
773 pub struct SymbolIndex { .. }
777 const fn new(n: u32) -> Self {
778 Symbol(SymbolIndex::from_u32_const(n))
781 /// Maps a string to its interned representation.
782 pub fn intern(string: &str) -> Self {
783 with_interner(|interner| interner.intern(string))
786 /// Gensyms a new `usize`, using the current interner.
787 pub fn gensym(string: &str) -> Self {
788 with_interner(|interner| interner.gensym(string))
791 pub fn as_str(self) -> LocalInternedString {
792 with_interner(|interner| unsafe {
793 LocalInternedString {
794 string: std::mem::transmute::<&str, &str>(interner.get(self))
799 pub fn as_interned_str(self) -> InternedString {
800 with_interner(|interner| InternedString {
801 symbol: interner.interned(self)
805 pub fn as_u32(self) -> u32 {
810 impl fmt::Debug for Symbol {
811 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
812 let is_gensymed = with_interner(|interner| interner.is_gensymed(*self));
814 write!(f, "{}({:?})", self, self.0)
816 write!(f, "{}", self)
821 impl fmt::Display for Symbol {
822 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
823 fmt::Display::fmt(&self.as_str(), f)
827 impl Encodable for Symbol {
828 fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
829 s.emit_str(&self.as_str())
833 impl Decodable for Symbol {
834 fn decode<D: Decoder>(d: &mut D) -> Result<Symbol, D::Error> {
835 Ok(Symbol::intern(&d.read_str()?))
839 // The `&'static str`s in this type actually point into the arena.
841 // Note that normal symbols are indexed upward from 0, and gensyms are indexed
842 // downward from SymbolIndex::MAX_AS_U32.
844 pub struct Interner {
845 arena: DroplessArena,
846 names: FxHashMap<&'static str, Symbol>,
847 strings: Vec<&'static str>,
848 gensyms: Vec<Symbol>,
852 fn prefill(init: &[&str]) -> Self {
853 let mut this = Interner::default();
854 this.names.reserve(init.len());
855 this.strings.reserve(init.len());
857 // We can't allocate empty strings in the arena, so handle this here.
858 assert!(keywords::Invalid.name().as_u32() == 0 && init[0].is_empty());
859 this.names.insert("", keywords::Invalid.name());
860 this.strings.push("");
862 for string in &init[1..] {
868 pub fn intern(&mut self, string: &str) -> Symbol {
869 if let Some(&name) = self.names.get(string) {
873 let name = Symbol::new(self.strings.len() as u32);
875 // `from_utf8_unchecked` is safe since we just allocated a `&str` which is known to be
877 let string: &str = unsafe {
878 str::from_utf8_unchecked(self.arena.alloc_slice(string.as_bytes()))
880 // It is safe to extend the arena allocation to `'static` because we only access
881 // these while the arena is still alive.
882 let string: &'static str = unsafe {
883 &*(string as *const str)
885 self.strings.push(string);
886 self.names.insert(string, name);
890 fn interned(&self, symbol: Symbol) -> Symbol {
891 if (symbol.0.as_usize()) < self.strings.len() {
894 self.gensyms[(SymbolIndex::MAX_AS_U32 - symbol.0.as_u32()) as usize]
898 fn gensym(&mut self, string: &str) -> Symbol {
899 let symbol = self.intern(string);
900 self.gensymed(symbol)
903 fn gensymed(&mut self, symbol: Symbol) -> Symbol {
904 self.gensyms.push(symbol);
905 Symbol::new(SymbolIndex::MAX_AS_U32 - self.gensyms.len() as u32 + 1)
908 fn is_gensymed(&mut self, symbol: Symbol) -> bool {
909 symbol.0.as_usize() >= self.strings.len()
912 // Get the symbol as a string. `Symbol::as_str()` should be used in
913 // preference to this function.
914 pub fn get(&self, symbol: Symbol) -> &str {
915 match self.strings.get(symbol.0.as_usize()) {
916 Some(string) => string,
918 let symbol = self.gensyms[(SymbolIndex::MAX_AS_U32 - symbol.0.as_u32()) as usize];
919 self.strings[symbol.0.as_usize()]
926 use super::{Symbol, Ident};
928 #[derive(Clone, Copy, PartialEq, Eq)]
935 pub fn ident(self) -> Ident {
940 pub fn name(self) -> Symbol {
948 // This module has a very short name because it's used a lot.
955 fn is_used_keyword_2018(self) -> bool {
956 self == keywords::Dyn.name()
959 fn is_unused_keyword_2018(self) -> bool {
960 self >= keywords::Async.name() && self <= keywords::Try.name()
965 // Returns `true` for reserved identifiers used internally for elided lifetimes,
966 // unnamed method parameters, crate root module, error recovery etc.
967 pub fn is_special(self) -> bool {
968 self.name <= keywords::Underscore.name()
971 /// Returns `true` if the token is a keyword used in the language.
972 pub fn is_used_keyword(self) -> bool {
973 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
974 self.name >= keywords::As.name() && self.name <= keywords::While.name() ||
975 self.name.is_used_keyword_2018() && self.span.rust_2018()
978 /// Returns `true` if the token is a keyword reserved for possible future use.
979 pub fn is_unused_keyword(self) -> bool {
980 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
981 self.name >= keywords::Abstract.name() && self.name <= keywords::Yield.name() ||
982 self.name.is_unused_keyword_2018() && self.span.rust_2018()
985 /// Returns `true` if the token is either a special identifier or a keyword.
986 pub fn is_reserved(self) -> bool {
987 self.is_special() || self.is_used_keyword() || self.is_unused_keyword()
990 /// A keyword or reserved identifier that can be used as a path segment.
991 pub fn is_path_segment_keyword(self) -> bool {
992 self.name == keywords::Super.name() ||
993 self.name == keywords::SelfLower.name() ||
994 self.name == keywords::SelfUpper.name() ||
995 self.name == keywords::Crate.name() ||
996 self.name == keywords::PathRoot.name() ||
997 self.name == keywords::DollarCrate.name()
1000 /// This identifier can be a raw identifier.
1001 pub fn can_be_raw(self) -> bool {
1002 self.name != keywords::Invalid.name() && self.name != keywords::Underscore.name() &&
1003 !self.is_path_segment_keyword()
1006 /// We see this identifier in a normal identifier position, like variable name or a type.
1007 /// How was it written originally? Did it use the raw form? Let's try to guess.
1008 pub fn is_raw_guess(self) -> bool {
1009 self.can_be_raw() && self.is_reserved()
1013 // If an interner exists, return it. Otherwise, prepare a fresh one.
1015 fn with_interner<T, F: FnOnce(&mut Interner) -> T>(f: F) -> T {
1016 GLOBALS.with(|globals| f(&mut *globals.symbol_interner.lock()))
1019 /// An alternative to `Symbol` and `InternedString`, useful when the chars
1020 /// within the symbol need to be accessed. It is best used for temporary
1023 /// Because the interner outlives any thread which uses this type, we can
1024 /// safely treat `string` which points to interner data, as an immortal string,
1025 /// as long as this type never crosses between threads.
1027 // FIXME: ensure that the interner outlives any thread which uses
1028 // `LocalInternedString`, by creating a new thread right after constructing the
1030 #[derive(Clone, Copy, Hash, PartialOrd, Eq, Ord)]
1031 pub struct LocalInternedString {
1032 string: &'static str,
1035 impl LocalInternedString {
1036 pub fn as_interned_str(self) -> InternedString {
1038 symbol: Symbol::intern(self.string)
1042 pub fn get(&self) -> &str {
1043 // This returns a valid string since we ensure that `self` outlives the interner
1044 // by creating the interner on a thread which outlives threads which can access it.
1045 // This type cannot move to a thread which outlives the interner since it does
1046 // not implement Send.
1051 impl<U: ?Sized> std::convert::AsRef<U> for LocalInternedString
1053 str: std::convert::AsRef<U>
1055 fn as_ref(&self) -> &U {
1056 self.string.as_ref()
1060 impl<T: std::ops::Deref<Target = str>> std::cmp::PartialEq<T> for LocalInternedString {
1061 fn eq(&self, other: &T) -> bool {
1062 self.string == other.deref()
1066 impl std::cmp::PartialEq<LocalInternedString> for str {
1067 fn eq(&self, other: &LocalInternedString) -> bool {
1068 self == other.string
1072 impl<'a> std::cmp::PartialEq<LocalInternedString> for &'a str {
1073 fn eq(&self, other: &LocalInternedString) -> bool {
1074 *self == other.string
1078 impl std::cmp::PartialEq<LocalInternedString> for String {
1079 fn eq(&self, other: &LocalInternedString) -> bool {
1080 self == other.string
1084 impl<'a> std::cmp::PartialEq<LocalInternedString> for &'a String {
1085 fn eq(&self, other: &LocalInternedString) -> bool {
1086 *self == other.string
1090 impl !Send for LocalInternedString {}
1091 impl !Sync for LocalInternedString {}
1093 impl std::ops::Deref for LocalInternedString {
1095 fn deref(&self) -> &str { self.string }
1098 impl fmt::Debug for LocalInternedString {
1099 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1100 fmt::Debug::fmt(self.string, f)
1104 impl fmt::Display for LocalInternedString {
1105 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1106 fmt::Display::fmt(self.string, f)
1110 impl Decodable for LocalInternedString {
1111 fn decode<D: Decoder>(d: &mut D) -> Result<LocalInternedString, D::Error> {
1112 Ok(Symbol::intern(&d.read_str()?).as_str())
1116 impl Encodable for LocalInternedString {
1117 fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
1118 s.emit_str(self.string)
1122 /// An alternative to `Symbol` that is focused on string contents. It has two
1123 /// main differences to `Symbol`.
1125 /// First, its implementations of `Hash`, `PartialOrd` and `Ord` work with the
1126 /// string chars rather than the symbol integer. This is useful when hash
1127 /// stability is required across compile sessions, or a guaranteed sort
1128 /// ordering is required.
1130 /// Second, gensym-ness is irrelevant. E.g.:
1132 /// assert_ne!(Symbol::gensym("x"), Symbol::gensym("x"))
1133 /// assert_eq!(Symbol::gensym("x").as_interned_str(), Symbol::gensym("x").as_interned_str())
1135 #[derive(Clone, Copy, Eq)]
1136 pub struct InternedString {
1140 impl InternedString {
1141 pub fn with<F: FnOnce(&str) -> R, R>(self, f: F) -> R {
1142 let str = with_interner(|interner| {
1143 interner.get(self.symbol) as *const str
1145 // This is safe because the interner keeps string alive until it is dropped.
1146 // We can access it because we know the interner is still alive since we use a
1147 // scoped thread local to access it, and it was alive at the beginning of this scope
1151 fn with2<F: FnOnce(&str, &str) -> R, R>(self, other: &InternedString, f: F) -> R {
1152 let (self_str, other_str) = with_interner(|interner| {
1153 (interner.get(self.symbol) as *const str,
1154 interner.get(other.symbol) as *const str)
1156 // This is safe for the same reason that `with` is safe.
1157 unsafe { f(&*self_str, &*other_str) }
1160 pub fn as_symbol(self) -> Symbol {
1164 pub fn as_str(self) -> LocalInternedString {
1165 self.symbol.as_str()
1169 impl Hash for InternedString {
1170 fn hash<H: Hasher>(&self, state: &mut H) {
1171 self.with(|str| str.hash(state))
1175 impl PartialOrd<InternedString> for InternedString {
1176 fn partial_cmp(&self, other: &InternedString) -> Option<Ordering> {
1177 if self.symbol == other.symbol {
1178 return Some(Ordering::Equal);
1180 self.with2(other, |self_str, other_str| self_str.partial_cmp(other_str))
1184 impl Ord for InternedString {
1185 fn cmp(&self, other: &InternedString) -> Ordering {
1186 if self.symbol == other.symbol {
1187 return Ordering::Equal;
1189 self.with2(other, |self_str, other_str| self_str.cmp(other_str))
1193 impl<T: std::ops::Deref<Target = str>> PartialEq<T> for InternedString {
1194 fn eq(&self, other: &T) -> bool {
1195 self.with(|string| string == other.deref())
1199 impl PartialEq<InternedString> for InternedString {
1200 fn eq(&self, other: &InternedString) -> bool {
1201 self.symbol == other.symbol
1205 impl PartialEq<InternedString> for str {
1206 fn eq(&self, other: &InternedString) -> bool {
1207 other.with(|string| self == string)
1211 impl<'a> PartialEq<InternedString> for &'a str {
1212 fn eq(&self, other: &InternedString) -> bool {
1213 other.with(|string| *self == string)
1217 impl PartialEq<InternedString> for String {
1218 fn eq(&self, other: &InternedString) -> bool {
1219 other.with(|string| self == string)
1223 impl<'a> PartialEq<InternedString> for &'a String {
1224 fn eq(&self, other: &InternedString) -> bool {
1225 other.with(|string| *self == string)
1229 impl fmt::Debug for InternedString {
1230 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1231 self.with(|str| fmt::Debug::fmt(&str, f))
1235 impl fmt::Display for InternedString {
1236 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1237 self.with(|str| fmt::Display::fmt(&str, f))
1241 impl Decodable for InternedString {
1242 fn decode<D: Decoder>(d: &mut D) -> Result<InternedString, D::Error> {
1243 Ok(Symbol::intern(&d.read_str()?).as_interned_str())
1247 impl Encodable for InternedString {
1248 fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
1249 self.with(|string| s.emit_str(string))
1259 fn interner_tests() {
1260 let mut i: Interner = Interner::default();
1261 // first one is zero:
1262 assert_eq!(i.intern("dog"), Symbol::new(0));
1263 // re-use gets the same entry:
1264 assert_eq!(i.intern("dog"), Symbol::new(0));
1265 // different string gets a different #:
1266 assert_eq!(i.intern("cat"), Symbol::new(1));
1267 assert_eq!(i.intern("cat"), Symbol::new(1));
1268 // dog is still at zero
1269 assert_eq!(i.intern("dog"), Symbol::new(0));
1270 assert_eq!(i.gensym("zebra"), Symbol::new(SymbolIndex::MAX_AS_U32));
1271 // gensym of same string gets new number:
1272 assert_eq!(i.gensym("zebra"), Symbol::new(SymbolIndex::MAX_AS_U32 - 1));
1273 // gensym of *existing* string gets new number:
1274 assert_eq!(i.gensym("dog"), Symbol::new(SymbolIndex::MAX_AS_U32 - 2));
1278 fn without_first_quote_test() {
1279 GLOBALS.set(&Globals::new(), || {
1280 let i = Ident::from_str("'break");
1281 assert_eq!(i.without_first_quote().name, keywords::Break.name());