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,
389 overlapping_marker_traits,
393 panic_implementation,
406 poll_with_tls_context,
407 powerpc_target_feature,
408 precise_pointer_size_matching,
412 proc_dash_macro: "proc-macro",
414 proc_macro_attribute,
420 proc_macro_non_items,
421 proc_macro_path_invoc,
425 quad_precision_float,
438 reexport_test_harness_main,
448 re_rebalance_coherence,
458 rustc_allocator_nounwind,
459 rustc_allow_const_fn_ptr,
460 rustc_args_required_const,
463 rustc_const_unstable,
464 rustc_conversion_suggestion,
465 rustc_copy_clone_marker,
468 rustc_diagnostic_macros,
470 rustc_doc_only_macro,
471 rustc_dump_env_program_clauses,
472 rustc_dump_program_clauses,
473 rustc_dump_user_substs,
475 rustc_expected_cgu_reuse,
476 rustc_if_this_changed,
477 rustc_inherit_overflow_checks,
479 rustc_layout_scalar_valid_range_end,
480 rustc_layout_scalar_valid_range_start,
482 rustc_object_lifetime_default,
483 rustc_on_unimplemented,
486 rustc_partition_codegened,
487 rustc_partition_reused,
489 rustc_peek_definite_init,
490 rustc_peek_maybe_init,
491 rustc_peek_maybe_uninit,
493 rustc_proc_macro_decls,
497 rustc_std_internal_symbol,
501 rustc_then_this_would_need,
502 rustc_transparent_macro,
506 rust_eh_unwind_resume,
508 __rust_unstable_column,
509 rvalue_static_promotion,
525 sse4a_target_feature,
534 stmt_expr_attributes,
536 struct_field_attributes,
547 termination_trait_test,
550 test_accepted_feature,
551 test_removed_feature,
565 type_alias_enum_variants,
575 underscore_const_names,
577 underscore_lifetimes,
579 universal_impl_trait,
581 unrestricted_attribute_tokens,
582 unsafe_destructor_blind_to_params,
585 unsized_tuple_coercion,
596 visible_private_types,
599 warn_directory_ownership,
609 #[derive(Copy, Clone, Eq)]
617 pub const fn new(name: Symbol, span: Span) -> Ident {
622 pub const fn with_empty_ctxt(name: Symbol) -> Ident {
623 Ident::new(name, DUMMY_SP)
626 /// Maps an interned string to an identifier with an empty syntax context.
627 pub fn from_interned_str(string: InternedString) -> Ident {
628 Ident::with_empty_ctxt(string.as_symbol())
631 /// Maps a string to an identifier with an empty syntax context.
632 pub fn from_str(string: &str) -> Ident {
633 Ident::with_empty_ctxt(Symbol::intern(string))
636 /// Replaces `lo` and `hi` with those from `span`, but keep hygiene context.
637 pub fn with_span_pos(self, span: Span) -> Ident {
638 Ident::new(self.name, span.with_ctxt(self.span.ctxt()))
641 pub fn without_first_quote(self) -> Ident {
642 Ident::new(Symbol::intern(self.as_str().trim_start_matches('\'')), self.span)
645 /// "Normalize" ident for use in comparisons using "item hygiene".
646 /// Identifiers with same string value become same if they came from the same "modern" macro
647 /// (e.g., `macro` item, but not `macro_rules` item) and stay different if they came from
648 /// different "modern" macros.
649 /// Technically, this operation strips all non-opaque marks from ident's syntactic context.
650 pub fn modern(self) -> Ident {
651 Ident::new(self.name, self.span.modern())
654 /// "Normalize" ident for use in comparisons using "local variable hygiene".
655 /// Identifiers with same string value become same if they came from the same non-transparent
656 /// macro (e.g., `macro` or `macro_rules!` items) and stay different if they came from different
657 /// non-transparent macros.
658 /// Technically, this operation strips all transparent marks from ident's syntactic context.
659 pub fn modern_and_legacy(self) -> Ident {
660 Ident::new(self.name, self.span.modern_and_legacy())
663 pub fn gensym(self) -> Ident {
664 Ident::new(self.name.gensymed(), self.span)
667 pub fn gensym_if_underscore(self) -> Ident {
668 if self.name == keywords::Underscore.name() { self.gensym() } else { self }
671 pub fn as_str(self) -> LocalInternedString {
675 pub fn as_interned_str(self) -> InternedString {
676 self.name.as_interned_str()
680 impl PartialEq for Ident {
681 fn eq(&self, rhs: &Self) -> bool {
682 self.name == rhs.name && self.span.ctxt() == rhs.span.ctxt()
686 impl Hash for Ident {
687 fn hash<H: Hasher>(&self, state: &mut H) {
688 self.name.hash(state);
689 self.span.ctxt().hash(state);
693 impl fmt::Debug for Ident {
694 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
695 write!(f, "{}{:?}", self.name, self.span.ctxt())
699 impl fmt::Display for Ident {
700 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
701 fmt::Display::fmt(&self.name, f)
705 impl Encodable for Ident {
706 fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
707 if self.span.ctxt().modern() == SyntaxContext::empty() {
708 s.emit_str(&self.as_str())
709 } else { // FIXME(jseyfried): intercrate hygiene
710 let mut string = "#".to_owned();
711 string.push_str(&self.as_str());
717 impl Decodable for Ident {
718 fn decode<D: Decoder>(d: &mut D) -> Result<Ident, D::Error> {
719 let string = d.read_str()?;
720 Ok(if !string.starts_with('#') {
721 Ident::from_str(&string)
722 } else { // FIXME(jseyfried): intercrate hygiene
723 Ident::with_empty_ctxt(Symbol::gensym(&string[1..]))
728 /// A symbol is an interned or gensymed string. A gensym is a symbol that is
729 /// never equal to any other symbol. E.g.:
731 /// assert_eq!(Symbol::intern("x"), Symbol::intern("x"))
732 /// assert_ne!(Symbol::gensym("x"), Symbol::intern("x"))
733 /// assert_ne!(Symbol::gensym("x"), Symbol::gensym("x"))
735 /// Conceptually, a gensym can be thought of as a normal symbol with an
736 /// invisible unique suffix. Gensyms are useful when creating new identifiers
737 /// that must not match any existing identifiers, e.g. during macro expansion
738 /// and syntax desugaring.
740 /// Internally, a Symbol is implemented as an index, and all operations
741 /// (including hashing, equality, and ordering) operate on that index. The use
742 /// of `newtype_index!` means that `Option<Symbol>` only takes up 4 bytes,
743 /// because `newtype_index!` reserves the last 256 values for tagging purposes.
745 /// Note that `Symbol` cannot directly be a `newtype_index!` because it implements
746 /// `fmt::Debug`, `Encodable`, and `Decodable` in special ways.
747 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
748 pub struct Symbol(SymbolIndex);
751 pub struct SymbolIndex { .. }
755 const fn new(n: u32) -> Self {
756 Symbol(SymbolIndex::from_u32_const(n))
759 /// Maps a string to its interned representation.
760 pub fn intern(string: &str) -> Self {
761 with_interner(|interner| interner.intern(string))
764 /// Gensyms a new `usize`, using the current interner.
765 pub fn gensym(string: &str) -> Self {
766 with_interner(|interner| interner.gensym(string))
769 pub fn gensymed(self) -> Self {
770 with_interner(|interner| interner.gensymed(self))
773 // WARNING: this function is deprecated and will be removed in the future.
774 pub fn is_gensymed(self) -> bool {
775 with_interner(|interner| interner.is_gensymed(self))
778 pub fn as_str(self) -> LocalInternedString {
779 with_interner(|interner| unsafe {
780 LocalInternedString {
781 string: std::mem::transmute::<&str, &str>(interner.get(self))
786 pub fn as_interned_str(self) -> InternedString {
787 with_interner(|interner| InternedString {
788 symbol: interner.interned(self)
792 pub fn as_u32(self) -> u32 {
797 impl fmt::Debug for Symbol {
798 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
799 let is_gensymed = with_interner(|interner| interner.is_gensymed(*self));
801 write!(f, "{}({:?})", self, self.0)
803 write!(f, "{}", self)
808 impl fmt::Display for Symbol {
809 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
810 fmt::Display::fmt(&self.as_str(), f)
814 impl Encodable for Symbol {
815 fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
816 s.emit_str(&self.as_str())
820 impl Decodable for Symbol {
821 fn decode<D: Decoder>(d: &mut D) -> Result<Symbol, D::Error> {
822 Ok(Symbol::intern(&d.read_str()?))
826 // The `&'static str`s in this type actually point into the arena.
828 // Note that normal symbols are indexed upward from 0, and gensyms are indexed
829 // downward from SymbolIndex::MAX_AS_U32.
831 pub struct Interner {
832 arena: DroplessArena,
833 names: FxHashMap<&'static str, Symbol>,
834 strings: Vec<&'static str>,
835 gensyms: Vec<Symbol>,
839 fn prefill(init: &[&str]) -> Self {
840 let mut this = Interner::default();
841 this.names.reserve(init.len());
842 this.strings.reserve(init.len());
844 // We can't allocate empty strings in the arena, so handle this here.
845 assert!(keywords::Invalid.name().as_u32() == 0 && init[0].is_empty());
846 this.names.insert("", keywords::Invalid.name());
847 this.strings.push("");
849 for string in &init[1..] {
855 pub fn intern(&mut self, string: &str) -> Symbol {
856 if let Some(&name) = self.names.get(string) {
860 let name = Symbol::new(self.strings.len() as u32);
862 // `from_utf8_unchecked` is safe since we just allocated a `&str` which is known to be
864 let string: &str = unsafe {
865 str::from_utf8_unchecked(self.arena.alloc_slice(string.as_bytes()))
867 // It is safe to extend the arena allocation to `'static` because we only access
868 // these while the arena is still alive.
869 let string: &'static str = unsafe {
870 &*(string as *const str)
872 self.strings.push(string);
873 self.names.insert(string, name);
877 fn interned(&self, symbol: Symbol) -> Symbol {
878 if (symbol.0.as_usize()) < self.strings.len() {
881 self.gensyms[(SymbolIndex::MAX_AS_U32 - symbol.0.as_u32()) as usize]
885 fn gensym(&mut self, string: &str) -> Symbol {
886 let symbol = self.intern(string);
887 self.gensymed(symbol)
890 fn gensymed(&mut self, symbol: Symbol) -> Symbol {
891 self.gensyms.push(symbol);
892 Symbol::new(SymbolIndex::MAX_AS_U32 - self.gensyms.len() as u32 + 1)
895 fn is_gensymed(&mut self, symbol: Symbol) -> bool {
896 symbol.0.as_usize() >= self.strings.len()
899 // Get the symbol as a string. `Symbol::as_str()` should be used in
900 // preference to this function.
901 pub fn get(&self, symbol: Symbol) -> &str {
902 match self.strings.get(symbol.0.as_usize()) {
903 Some(string) => string,
905 let symbol = self.gensyms[(SymbolIndex::MAX_AS_U32 - symbol.0.as_u32()) as usize];
906 self.strings[symbol.0.as_usize()]
913 use super::{Symbol, Ident};
915 #[derive(Clone, Copy, PartialEq, Eq)]
922 pub fn ident(self) -> Ident {
927 pub fn name(self) -> Symbol {
935 // This module has a very short name because it's used a lot.
942 fn is_used_keyword_2018(self) -> bool {
943 self == keywords::Dyn.name()
946 fn is_unused_keyword_2018(self) -> bool {
947 self >= keywords::Async.name() && self <= keywords::Try.name()
952 // Returns `true` for reserved identifiers used internally for elided lifetimes,
953 // unnamed method parameters, crate root module, error recovery etc.
954 pub fn is_special(self) -> bool {
955 self.name <= keywords::Underscore.name()
958 /// Returns `true` if the token is a keyword used in the language.
959 pub fn is_used_keyword(self) -> bool {
960 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
961 self.name >= keywords::As.name() && self.name <= keywords::While.name() ||
962 self.name.is_used_keyword_2018() && self.span.rust_2018()
965 /// Returns `true` if the token is a keyword reserved for possible future use.
966 pub fn is_unused_keyword(self) -> bool {
967 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
968 self.name >= keywords::Abstract.name() && self.name <= keywords::Yield.name() ||
969 self.name.is_unused_keyword_2018() && self.span.rust_2018()
972 /// Returns `true` if the token is either a special identifier or a keyword.
973 pub fn is_reserved(self) -> bool {
974 self.is_special() || self.is_used_keyword() || self.is_unused_keyword()
977 /// A keyword or reserved identifier that can be used as a path segment.
978 pub fn is_path_segment_keyword(self) -> bool {
979 self.name == keywords::Super.name() ||
980 self.name == keywords::SelfLower.name() ||
981 self.name == keywords::SelfUpper.name() ||
982 self.name == keywords::Crate.name() ||
983 self.name == keywords::PathRoot.name() ||
984 self.name == keywords::DollarCrate.name()
987 /// This identifier can be a raw identifier.
988 pub fn can_be_raw(self) -> bool {
989 self.name != keywords::Invalid.name() && self.name != keywords::Underscore.name() &&
990 !self.is_path_segment_keyword()
993 /// We see this identifier in a normal identifier position, like variable name or a type.
994 /// How was it written originally? Did it use the raw form? Let's try to guess.
995 pub fn is_raw_guess(self) -> bool {
996 self.can_be_raw() && self.is_reserved()
1000 // If an interner exists, return it. Otherwise, prepare a fresh one.
1002 fn with_interner<T, F: FnOnce(&mut Interner) -> T>(f: F) -> T {
1003 GLOBALS.with(|globals| f(&mut *globals.symbol_interner.lock()))
1006 /// An alternative to `Symbol` and `InternedString`, useful when the chars
1007 /// within the symbol need to be accessed. It is best used for temporary
1010 /// Because the interner outlives any thread which uses this type, we can
1011 /// safely treat `string` which points to interner data, as an immortal string,
1012 /// as long as this type never crosses between threads.
1014 // FIXME: ensure that the interner outlives any thread which uses
1015 // `LocalInternedString`, by creating a new thread right after constructing the
1017 #[derive(Clone, Copy, Hash, PartialOrd, Eq, Ord)]
1018 pub struct LocalInternedString {
1019 string: &'static str,
1022 impl LocalInternedString {
1023 pub fn as_interned_str(self) -> InternedString {
1025 symbol: Symbol::intern(self.string)
1029 pub fn get(&self) -> &str {
1030 // This returns a valid string since we ensure that `self` outlives the interner
1031 // by creating the interner on a thread which outlives threads which can access it.
1032 // This type cannot move to a thread which outlives the interner since it does
1033 // not implement Send.
1038 impl<U: ?Sized> std::convert::AsRef<U> for LocalInternedString
1040 str: std::convert::AsRef<U>
1042 fn as_ref(&self) -> &U {
1043 self.string.as_ref()
1047 impl<T: std::ops::Deref<Target = str>> std::cmp::PartialEq<T> for LocalInternedString {
1048 fn eq(&self, other: &T) -> bool {
1049 self.string == other.deref()
1053 impl std::cmp::PartialEq<LocalInternedString> for str {
1054 fn eq(&self, other: &LocalInternedString) -> bool {
1055 self == other.string
1059 impl<'a> std::cmp::PartialEq<LocalInternedString> for &'a str {
1060 fn eq(&self, other: &LocalInternedString) -> bool {
1061 *self == other.string
1065 impl std::cmp::PartialEq<LocalInternedString> for String {
1066 fn eq(&self, other: &LocalInternedString) -> bool {
1067 self == other.string
1071 impl<'a> std::cmp::PartialEq<LocalInternedString> for &'a String {
1072 fn eq(&self, other: &LocalInternedString) -> bool {
1073 *self == other.string
1077 impl !Send for LocalInternedString {}
1078 impl !Sync for LocalInternedString {}
1080 impl std::ops::Deref for LocalInternedString {
1082 fn deref(&self) -> &str { self.string }
1085 impl fmt::Debug for LocalInternedString {
1086 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1087 fmt::Debug::fmt(self.string, f)
1091 impl fmt::Display for LocalInternedString {
1092 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1093 fmt::Display::fmt(self.string, f)
1097 impl Decodable for LocalInternedString {
1098 fn decode<D: Decoder>(d: &mut D) -> Result<LocalInternedString, D::Error> {
1099 Ok(Symbol::intern(&d.read_str()?).as_str())
1103 impl Encodable for LocalInternedString {
1104 fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
1105 s.emit_str(self.string)
1109 /// An alternative to `Symbol` that is focused on string contents. It has two
1110 /// main differences to `Symbol`.
1112 /// First, its implementations of `Hash`, `PartialOrd` and `Ord` work with the
1113 /// string chars rather than the symbol integer. This is useful when hash
1114 /// stability is required across compile sessions, or a guaranteed sort
1115 /// ordering is required.
1117 /// Second, gensym-ness is irrelevant. E.g.:
1119 /// assert_ne!(Symbol::gensym("x"), Symbol::gensym("x"))
1120 /// assert_eq!(Symbol::gensym("x").as_interned_str(), Symbol::gensym("x").as_interned_str())
1122 #[derive(Clone, Copy, Eq)]
1123 pub struct InternedString {
1127 impl InternedString {
1128 pub fn with<F: FnOnce(&str) -> R, R>(self, f: F) -> R {
1129 let str = with_interner(|interner| {
1130 interner.get(self.symbol) as *const str
1132 // This is safe because the interner keeps string alive until it is dropped.
1133 // We can access it because we know the interner is still alive since we use a
1134 // scoped thread local to access it, and it was alive at the beginning of this scope
1138 fn with2<F: FnOnce(&str, &str) -> R, R>(self, other: &InternedString, f: F) -> R {
1139 let (self_str, other_str) = with_interner(|interner| {
1140 (interner.get(self.symbol) as *const str,
1141 interner.get(other.symbol) as *const str)
1143 // This is safe for the same reason that `with` is safe.
1144 unsafe { f(&*self_str, &*other_str) }
1147 pub fn as_symbol(self) -> Symbol {
1151 pub fn as_str(self) -> LocalInternedString {
1152 self.symbol.as_str()
1156 impl Hash for InternedString {
1157 fn hash<H: Hasher>(&self, state: &mut H) {
1158 self.with(|str| str.hash(state))
1162 impl PartialOrd<InternedString> for InternedString {
1163 fn partial_cmp(&self, other: &InternedString) -> Option<Ordering> {
1164 if self.symbol == other.symbol {
1165 return Some(Ordering::Equal);
1167 self.with2(other, |self_str, other_str| self_str.partial_cmp(other_str))
1171 impl Ord for InternedString {
1172 fn cmp(&self, other: &InternedString) -> Ordering {
1173 if self.symbol == other.symbol {
1174 return Ordering::Equal;
1176 self.with2(other, |self_str, other_str| self_str.cmp(other_str))
1180 impl<T: std::ops::Deref<Target = str>> PartialEq<T> for InternedString {
1181 fn eq(&self, other: &T) -> bool {
1182 self.with(|string| string == other.deref())
1186 impl PartialEq<InternedString> for InternedString {
1187 fn eq(&self, other: &InternedString) -> bool {
1188 self.symbol == other.symbol
1192 impl PartialEq<InternedString> for str {
1193 fn eq(&self, other: &InternedString) -> bool {
1194 other.with(|string| self == string)
1198 impl<'a> PartialEq<InternedString> for &'a str {
1199 fn eq(&self, other: &InternedString) -> bool {
1200 other.with(|string| *self == string)
1204 impl PartialEq<InternedString> for String {
1205 fn eq(&self, other: &InternedString) -> bool {
1206 other.with(|string| self == string)
1210 impl<'a> PartialEq<InternedString> for &'a String {
1211 fn eq(&self, other: &InternedString) -> bool {
1212 other.with(|string| *self == string)
1216 impl fmt::Debug for InternedString {
1217 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1218 self.with(|str| fmt::Debug::fmt(&str, f))
1222 impl fmt::Display for InternedString {
1223 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1224 self.with(|str| fmt::Display::fmt(&str, f))
1228 impl Decodable for InternedString {
1229 fn decode<D: Decoder>(d: &mut D) -> Result<InternedString, D::Error> {
1230 Ok(Symbol::intern(&d.read_str()?).as_interned_str())
1234 impl Encodable for InternedString {
1235 fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
1236 self.with(|string| s.emit_str(string))
1246 fn interner_tests() {
1247 let mut i: Interner = Interner::default();
1248 // first one is zero:
1249 assert_eq!(i.intern("dog"), Symbol::new(0));
1250 // re-use gets the same entry:
1251 assert_eq!(i.intern("dog"), Symbol::new(0));
1252 // different string gets a different #:
1253 assert_eq!(i.intern("cat"), Symbol::new(1));
1254 assert_eq!(i.intern("cat"), Symbol::new(1));
1255 // dog is still at zero
1256 assert_eq!(i.intern("dog"), Symbol::new(0));
1257 assert_eq!(i.gensym("zebra"), Symbol::new(SymbolIndex::MAX_AS_U32));
1258 // gensym of same string gets new number:
1259 assert_eq!(i.gensym("zebra"), Symbol::new(SymbolIndex::MAX_AS_U32 - 1));
1260 // gensym of *existing* string gets new number:
1261 assert_eq!(i.gensym("dog"), Symbol::new(SymbolIndex::MAX_AS_U32 - 2));
1265 fn without_first_quote_test() {
1266 GLOBALS.set(&Globals::new(), || {
1267 let i = Ident::from_str("'break");
1268 assert_eq!(i.without_first_quote().name, keywords::Break.name());