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,
218 dropck_parametricity,
227 exclusive_range_pattern,
228 exhaustive_integer_patterns,
233 extern_absolute_paths,
235 extern_crate_item_prelude,
243 field_init_shorthand,
257 generic_associated_types,
262 hexagon_target_feature,
264 homogeneous_aggregate,
278 if_while_or_patterns,
280 impl_header_lifetime_elision,
281 impl_trait_in_bindings,
285 inclusive_range_syntax,
286 infer_outlives_requirements,
287 infer_static_outlives_requirements,
294 irrefutable_let_patterns,
297 issue_5723_bootstrap,
298 issue_tracker_base_url,
313 link_llvm_intrinsics,
320 macro_at_most_once_rep,
323 macro_lifetime_matcher,
324 macro_literal_matcher,
335 match_beginning_vert,
336 match_default_bindings,
345 movbe_target_feature,
377 omit_gdb_pretty_printer_section,
384 optin_builtin_traits,
388 overlapping_marker_traits,
392 panic_implementation,
405 poll_with_tls_context,
406 powerpc_target_feature,
407 precise_pointer_size_matching,
411 proc_dash_macro: "proc-macro",
413 proc_macro_attribute,
419 proc_macro_non_items,
420 proc_macro_path_invoc,
424 quad_precision_float,
437 reexport_test_harness_main,
447 re_rebalance_coherence,
457 rustc_allocator_nounwind,
458 rustc_allow_const_fn_ptr,
459 rustc_args_required_const,
462 rustc_const_unstable,
463 rustc_conversion_suggestion,
464 rustc_copy_clone_marker,
467 rustc_diagnostic_macros,
469 rustc_doc_only_macro,
470 rustc_dump_env_program_clauses,
471 rustc_dump_program_clauses,
472 rustc_dump_user_substs,
474 rustc_expected_cgu_reuse,
475 rustc_if_this_changed,
476 rustc_inherit_overflow_checks,
478 rustc_layout_scalar_valid_range_end,
479 rustc_layout_scalar_valid_range_start,
481 rustc_object_lifetime_default,
482 rustc_on_unimplemented,
485 rustc_partition_codegened,
486 rustc_partition_reused,
488 rustc_peek_definite_init,
489 rustc_peek_maybe_init,
490 rustc_peek_maybe_uninit,
492 rustc_proc_macro_decls,
496 rustc_std_internal_symbol,
500 rustc_then_this_would_need,
501 rustc_transparent_macro,
505 rust_eh_unwind_resume,
507 __rust_unstable_column,
508 rvalue_static_promotion,
524 sse4a_target_feature,
533 stmt_expr_attributes,
535 struct_field_attributes,
546 termination_trait_test,
549 test_accepted_feature,
550 test_removed_feature,
564 type_alias_enum_variants,
574 underscore_const_names,
576 underscore_lifetimes,
578 universal_impl_trait,
580 unrestricted_attribute_tokens,
581 unsafe_destructor_blind_to_params,
584 unsized_tuple_coercion,
595 visible_private_types,
598 warn_directory_ownership,
608 #[derive(Copy, Clone, Eq)]
616 pub const fn new(name: Symbol, span: Span) -> Ident {
621 pub const fn with_empty_ctxt(name: Symbol) -> Ident {
622 Ident::new(name, DUMMY_SP)
625 /// Maps an interned string to an identifier with an empty syntax context.
626 pub fn from_interned_str(string: InternedString) -> Ident {
627 Ident::with_empty_ctxt(string.as_symbol())
630 /// Maps a string to an identifier with an empty syntax context.
631 pub fn from_str(string: &str) -> Ident {
632 Ident::with_empty_ctxt(Symbol::intern(string))
635 /// Replaces `lo` and `hi` with those from `span`, but keep hygiene context.
636 pub fn with_span_pos(self, span: Span) -> Ident {
637 Ident::new(self.name, span.with_ctxt(self.span.ctxt()))
640 pub fn without_first_quote(self) -> Ident {
641 Ident::new(Symbol::intern(self.as_str().trim_start_matches('\'')), self.span)
644 /// "Normalize" ident for use in comparisons using "item hygiene".
645 /// Identifiers with same string value become same if they came from the same "modern" macro
646 /// (e.g., `macro` item, but not `macro_rules` item) and stay different if they came from
647 /// different "modern" macros.
648 /// Technically, this operation strips all non-opaque marks from ident's syntactic context.
649 pub fn modern(self) -> Ident {
650 Ident::new(self.name, self.span.modern())
653 /// "Normalize" ident for use in comparisons using "local variable hygiene".
654 /// Identifiers with same string value become same if they came from the same non-transparent
655 /// macro (e.g., `macro` or `macro_rules!` items) and stay different if they came from different
656 /// non-transparent macros.
657 /// Technically, this operation strips all transparent marks from ident's syntactic context.
658 pub fn modern_and_legacy(self) -> Ident {
659 Ident::new(self.name, self.span.modern_and_legacy())
662 pub fn gensym(self) -> Ident {
663 Ident::new(self.name.gensymed(), self.span)
666 pub fn gensym_if_underscore(self) -> Ident {
667 if self.name == keywords::Underscore.name() { self.gensym() } else { self }
670 pub fn as_str(self) -> LocalInternedString {
674 pub fn as_interned_str(self) -> InternedString {
675 self.name.as_interned_str()
679 impl PartialEq for Ident {
680 fn eq(&self, rhs: &Self) -> bool {
681 self.name == rhs.name && self.span.ctxt() == rhs.span.ctxt()
685 impl Hash for Ident {
686 fn hash<H: Hasher>(&self, state: &mut H) {
687 self.name.hash(state);
688 self.span.ctxt().hash(state);
692 impl fmt::Debug for Ident {
693 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
694 write!(f, "{}{:?}", self.name, self.span.ctxt())
698 impl fmt::Display for Ident {
699 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
700 fmt::Display::fmt(&self.name, f)
704 impl Encodable for Ident {
705 fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
706 if self.span.ctxt().modern() == SyntaxContext::empty() {
707 s.emit_str(&self.as_str())
708 } else { // FIXME(jseyfried): intercrate hygiene
709 let mut string = "#".to_owned();
710 string.push_str(&self.as_str());
716 impl Decodable for Ident {
717 fn decode<D: Decoder>(d: &mut D) -> Result<Ident, D::Error> {
718 let string = d.read_str()?;
719 Ok(if !string.starts_with('#') {
720 Ident::from_str(&string)
721 } else { // FIXME(jseyfried): intercrate hygiene
722 Ident::with_empty_ctxt(Symbol::gensym(&string[1..]))
727 /// A symbol is an interned or gensymed string. A gensym is a symbol that is
728 /// never equal to any other symbol. E.g.:
730 /// assert_eq!(Symbol::intern("x"), Symbol::intern("x"))
731 /// assert_ne!(Symbol::gensym("x"), Symbol::intern("x"))
732 /// assert_ne!(Symbol::gensym("x"), Symbol::gensym("x"))
734 /// Conceptually, a gensym can be thought of as a normal symbol with an
735 /// invisible unique suffix. Gensyms are useful when creating new identifiers
736 /// that must not match any existing identifiers, e.g. during macro expansion
737 /// and syntax desugaring.
739 /// Internally, a Symbol is implemented as an index, and all operations
740 /// (including hashing, equality, and ordering) operate on that index. The use
741 /// of `newtype_index!` means that `Option<Symbol>` only takes up 4 bytes,
742 /// because `newtype_index!` reserves the last 256 values for tagging purposes.
744 /// Note that `Symbol` cannot directly be a `newtype_index!` because it implements
745 /// `fmt::Debug`, `Encodable`, and `Decodable` in special ways.
746 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
747 pub struct Symbol(SymbolIndex);
750 pub struct SymbolIndex { .. }
754 const fn new(n: u32) -> Self {
755 Symbol(SymbolIndex::from_u32_const(n))
758 /// Maps a string to its interned representation.
759 pub fn intern(string: &str) -> Self {
760 with_interner(|interner| interner.intern(string))
763 /// Gensyms a new `usize`, using the current interner.
764 pub fn gensym(string: &str) -> Self {
765 with_interner(|interner| interner.gensym(string))
768 pub fn gensymed(self) -> Self {
769 with_interner(|interner| interner.gensymed(self))
772 // WARNING: this function is deprecated and will be removed in the future.
773 pub fn is_gensymed(self) -> bool {
774 with_interner(|interner| interner.is_gensymed(self))
777 pub fn as_str(self) -> LocalInternedString {
778 with_interner(|interner| unsafe {
779 LocalInternedString {
780 string: std::mem::transmute::<&str, &str>(interner.get(self))
785 pub fn as_interned_str(self) -> InternedString {
786 with_interner(|interner| InternedString {
787 symbol: interner.interned(self)
791 pub fn as_u32(self) -> u32 {
796 impl fmt::Debug for Symbol {
797 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
798 let is_gensymed = with_interner(|interner| interner.is_gensymed(*self));
800 write!(f, "{}({:?})", self, self.0)
802 write!(f, "{}", self)
807 impl fmt::Display for Symbol {
808 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
809 fmt::Display::fmt(&self.as_str(), f)
813 impl Encodable for Symbol {
814 fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
815 s.emit_str(&self.as_str())
819 impl Decodable for Symbol {
820 fn decode<D: Decoder>(d: &mut D) -> Result<Symbol, D::Error> {
821 Ok(Symbol::intern(&d.read_str()?))
825 // The `&'static str`s in this type actually point into the arena.
827 // Note that normal symbols are indexed upward from 0, and gensyms are indexed
828 // downward from SymbolIndex::MAX_AS_U32.
830 pub struct Interner {
831 arena: DroplessArena,
832 names: FxHashMap<&'static str, Symbol>,
833 strings: Vec<&'static str>,
834 gensyms: Vec<Symbol>,
838 fn prefill(init: &[&str]) -> Self {
839 let mut this = Interner::default();
840 this.names.reserve(init.len());
841 this.strings.reserve(init.len());
843 // We can't allocate empty strings in the arena, so handle this here.
844 assert!(keywords::Invalid.name().as_u32() == 0 && init[0].is_empty());
845 this.names.insert("", keywords::Invalid.name());
846 this.strings.push("");
848 for string in &init[1..] {
854 pub fn intern(&mut self, string: &str) -> Symbol {
855 if let Some(&name) = self.names.get(string) {
859 let name = Symbol::new(self.strings.len() as u32);
861 // `from_utf8_unchecked` is safe since we just allocated a `&str` which is known to be
863 let string: &str = unsafe {
864 str::from_utf8_unchecked(self.arena.alloc_slice(string.as_bytes()))
866 // It is safe to extend the arena allocation to `'static` because we only access
867 // these while the arena is still alive.
868 let string: &'static str = unsafe {
869 &*(string as *const str)
871 self.strings.push(string);
872 self.names.insert(string, name);
876 fn interned(&self, symbol: Symbol) -> Symbol {
877 if (symbol.0.as_usize()) < self.strings.len() {
880 self.gensyms[(SymbolIndex::MAX_AS_U32 - symbol.0.as_u32()) as usize]
884 fn gensym(&mut self, string: &str) -> Symbol {
885 let symbol = self.intern(string);
886 self.gensymed(symbol)
889 fn gensymed(&mut self, symbol: Symbol) -> Symbol {
890 self.gensyms.push(symbol);
891 Symbol::new(SymbolIndex::MAX_AS_U32 - self.gensyms.len() as u32 + 1)
894 fn is_gensymed(&mut self, symbol: Symbol) -> bool {
895 symbol.0.as_usize() >= self.strings.len()
898 // Get the symbol as a string. `Symbol::as_str()` should be used in
899 // preference to this function.
900 pub fn get(&self, symbol: Symbol) -> &str {
901 match self.strings.get(symbol.0.as_usize()) {
902 Some(string) => string,
904 let symbol = self.gensyms[(SymbolIndex::MAX_AS_U32 - symbol.0.as_u32()) as usize];
905 self.strings[symbol.0.as_usize()]
912 use super::{Symbol, Ident};
914 #[derive(Clone, Copy, PartialEq, Eq)]
921 pub fn ident(self) -> Ident {
926 pub fn name(self) -> Symbol {
934 // This module has a very short name because it's used a lot.
941 fn is_used_keyword_2018(self) -> bool {
942 self == keywords::Dyn.name()
945 fn is_unused_keyword_2018(self) -> bool {
946 self >= keywords::Async.name() && self <= keywords::Try.name()
951 // Returns `true` for reserved identifiers used internally for elided lifetimes,
952 // unnamed method parameters, crate root module, error recovery etc.
953 pub fn is_special(self) -> bool {
954 self.name <= keywords::Underscore.name()
957 /// Returns `true` if the token is a keyword used in the language.
958 pub fn is_used_keyword(self) -> bool {
959 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
960 self.name >= keywords::As.name() && self.name <= keywords::While.name() ||
961 self.name.is_used_keyword_2018() && self.span.rust_2018()
964 /// Returns `true` if the token is a keyword reserved for possible future use.
965 pub fn is_unused_keyword(self) -> bool {
966 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
967 self.name >= keywords::Abstract.name() && self.name <= keywords::Yield.name() ||
968 self.name.is_unused_keyword_2018() && self.span.rust_2018()
971 /// Returns `true` if the token is either a special identifier or a keyword.
972 pub fn is_reserved(self) -> bool {
973 self.is_special() || self.is_used_keyword() || self.is_unused_keyword()
976 /// A keyword or reserved identifier that can be used as a path segment.
977 pub fn is_path_segment_keyword(self) -> bool {
978 self.name == keywords::Super.name() ||
979 self.name == keywords::SelfLower.name() ||
980 self.name == keywords::SelfUpper.name() ||
981 self.name == keywords::Crate.name() ||
982 self.name == keywords::PathRoot.name() ||
983 self.name == keywords::DollarCrate.name()
986 /// This identifier can be a raw identifier.
987 pub fn can_be_raw(self) -> bool {
988 self.name != keywords::Invalid.name() && self.name != keywords::Underscore.name() &&
989 !self.is_path_segment_keyword()
992 /// We see this identifier in a normal identifier position, like variable name or a type.
993 /// How was it written originally? Did it use the raw form? Let's try to guess.
994 pub fn is_raw_guess(self) -> bool {
995 self.can_be_raw() && self.is_reserved()
999 // If an interner exists, return it. Otherwise, prepare a fresh one.
1001 fn with_interner<T, F: FnOnce(&mut Interner) -> T>(f: F) -> T {
1002 GLOBALS.with(|globals| f(&mut *globals.symbol_interner.lock()))
1005 /// An alternative to `Symbol` and `InternedString`, useful when the chars
1006 /// within the symbol need to be accessed. It is best used for temporary
1009 /// Because the interner outlives any thread which uses this type, we can
1010 /// safely treat `string` which points to interner data, as an immortal string,
1011 /// as long as this type never crosses between threads.
1013 // FIXME: ensure that the interner outlives any thread which uses
1014 // `LocalInternedString`, by creating a new thread right after constructing the
1016 #[derive(Clone, Copy, Hash, PartialOrd, Eq, Ord)]
1017 pub struct LocalInternedString {
1018 string: &'static str,
1021 impl LocalInternedString {
1022 pub fn as_interned_str(self) -> InternedString {
1024 symbol: Symbol::intern(self.string)
1028 pub fn get(&self) -> &str {
1029 // This returns a valid string since we ensure that `self` outlives the interner
1030 // by creating the interner on a thread which outlives threads which can access it.
1031 // This type cannot move to a thread which outlives the interner since it does
1032 // not implement Send.
1037 impl<U: ?Sized> std::convert::AsRef<U> for LocalInternedString
1039 str: std::convert::AsRef<U>
1041 fn as_ref(&self) -> &U {
1042 self.string.as_ref()
1046 impl<T: std::ops::Deref<Target = str>> std::cmp::PartialEq<T> for LocalInternedString {
1047 fn eq(&self, other: &T) -> bool {
1048 self.string == other.deref()
1052 impl std::cmp::PartialEq<LocalInternedString> for str {
1053 fn eq(&self, other: &LocalInternedString) -> bool {
1054 self == other.string
1058 impl<'a> std::cmp::PartialEq<LocalInternedString> for &'a str {
1059 fn eq(&self, other: &LocalInternedString) -> bool {
1060 *self == other.string
1064 impl std::cmp::PartialEq<LocalInternedString> for String {
1065 fn eq(&self, other: &LocalInternedString) -> bool {
1066 self == other.string
1070 impl<'a> std::cmp::PartialEq<LocalInternedString> for &'a String {
1071 fn eq(&self, other: &LocalInternedString) -> bool {
1072 *self == other.string
1076 impl !Send for LocalInternedString {}
1077 impl !Sync for LocalInternedString {}
1079 impl std::ops::Deref for LocalInternedString {
1081 fn deref(&self) -> &str { self.string }
1084 impl fmt::Debug for LocalInternedString {
1085 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1086 fmt::Debug::fmt(self.string, f)
1090 impl fmt::Display for LocalInternedString {
1091 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1092 fmt::Display::fmt(self.string, f)
1096 impl Decodable for LocalInternedString {
1097 fn decode<D: Decoder>(d: &mut D) -> Result<LocalInternedString, D::Error> {
1098 Ok(Symbol::intern(&d.read_str()?).as_str())
1102 impl Encodable for LocalInternedString {
1103 fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
1104 s.emit_str(self.string)
1108 /// An alternative to `Symbol` that is focused on string contents. It has two
1109 /// main differences to `Symbol`.
1111 /// First, its implementations of `Hash`, `PartialOrd` and `Ord` work with the
1112 /// string chars rather than the symbol integer. This is useful when hash
1113 /// stability is required across compile sessions, or a guaranteed sort
1114 /// ordering is required.
1116 /// Second, gensym-ness is irrelevant. E.g.:
1118 /// assert_ne!(Symbol::gensym("x"), Symbol::gensym("x"))
1119 /// assert_eq!(Symbol::gensym("x").as_interned_str(), Symbol::gensym("x").as_interned_str())
1121 #[derive(Clone, Copy, Eq)]
1122 pub struct InternedString {
1126 impl InternedString {
1127 pub fn with<F: FnOnce(&str) -> R, R>(self, f: F) -> R {
1128 let str = with_interner(|interner| {
1129 interner.get(self.symbol) as *const str
1131 // This is safe because the interner keeps string alive until it is dropped.
1132 // We can access it because we know the interner is still alive since we use a
1133 // scoped thread local to access it, and it was alive at the beginning of this scope
1137 fn with2<F: FnOnce(&str, &str) -> R, R>(self, other: &InternedString, f: F) -> R {
1138 let (self_str, other_str) = with_interner(|interner| {
1139 (interner.get(self.symbol) as *const str,
1140 interner.get(other.symbol) as *const str)
1142 // This is safe for the same reason that `with` is safe.
1143 unsafe { f(&*self_str, &*other_str) }
1146 pub fn as_symbol(self) -> Symbol {
1150 pub fn as_str(self) -> LocalInternedString {
1151 self.symbol.as_str()
1155 impl Hash for InternedString {
1156 fn hash<H: Hasher>(&self, state: &mut H) {
1157 self.with(|str| str.hash(state))
1161 impl PartialOrd<InternedString> for InternedString {
1162 fn partial_cmp(&self, other: &InternedString) -> Option<Ordering> {
1163 if self.symbol == other.symbol {
1164 return Some(Ordering::Equal);
1166 self.with2(other, |self_str, other_str| self_str.partial_cmp(other_str))
1170 impl Ord for InternedString {
1171 fn cmp(&self, other: &InternedString) -> Ordering {
1172 if self.symbol == other.symbol {
1173 return Ordering::Equal;
1175 self.with2(other, |self_str, other_str| self_str.cmp(other_str))
1179 impl<T: std::ops::Deref<Target = str>> PartialEq<T> for InternedString {
1180 fn eq(&self, other: &T) -> bool {
1181 self.with(|string| string == other.deref())
1185 impl PartialEq<InternedString> for InternedString {
1186 fn eq(&self, other: &InternedString) -> bool {
1187 self.symbol == other.symbol
1191 impl PartialEq<InternedString> for str {
1192 fn eq(&self, other: &InternedString) -> bool {
1193 other.with(|string| self == string)
1197 impl<'a> PartialEq<InternedString> for &'a str {
1198 fn eq(&self, other: &InternedString) -> bool {
1199 other.with(|string| *self == string)
1203 impl PartialEq<InternedString> for String {
1204 fn eq(&self, other: &InternedString) -> bool {
1205 other.with(|string| self == string)
1209 impl<'a> PartialEq<InternedString> for &'a String {
1210 fn eq(&self, other: &InternedString) -> bool {
1211 other.with(|string| *self == string)
1215 impl fmt::Debug for InternedString {
1216 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1217 self.with(|str| fmt::Debug::fmt(&str, f))
1221 impl fmt::Display for InternedString {
1222 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1223 self.with(|str| fmt::Display::fmt(&str, f))
1227 impl Decodable for InternedString {
1228 fn decode<D: Decoder>(d: &mut D) -> Result<InternedString, D::Error> {
1229 Ok(Symbol::intern(&d.read_str()?).as_interned_str())
1233 impl Encodable for InternedString {
1234 fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
1235 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 assert_eq!(i.gensym("zebra"), Symbol::new(SymbolIndex::MAX_AS_U32));
1257 // gensym of same string gets new number:
1258 assert_eq!(i.gensym("zebra"), Symbol::new(SymbolIndex::MAX_AS_U32 - 1));
1259 // gensym of *existing* string gets new number:
1260 assert_eq!(i.gensym("dog"), Symbol::new(SymbolIndex::MAX_AS_U32 - 2));
1264 fn without_first_quote_test() {
1265 GLOBALS.set(&Globals::new(), || {
1266 let i = Ident::from_str("'break");
1267 assert_eq!(i.without_first_quote().name, keywords::Break.name());