js/src/jsatom.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
   2  * vim: set ts=8 sts=4 et sw=4 tw=99:
   3  * This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef jsatom_h
   8 #define jsatom_h
   9
  10 #include "mozilla/HashFunctions.h"
  11
  12 #include "jsalloc.h"
  13
  14 #include "gc/Barrier.h"
  15 #include "gc/Rooting.h"
  16 #include "js/GCAPI.h"
  17 #include "vm/CommonPropertyNames.h"
  18
  19 class JSAtom;
  20 class JSAutoByteString;
  21
  22 struct JSIdArray {
  23     int length;
  24     js::HeapId vector[1];    /* actually, length jsid words */
  25 };
  26
  27 namespace js {
  28
  29 JS_STATIC_ASSERT(sizeof(HashNumber) == 4);
  30
  31 static MOZ_ALWAYS_INLINE js::HashNumber
  32 HashId(jsid id)
  33 {
  34     return mozilla::HashGeneric(JSID_BITS(id));
  35 }
  36
  37 struct JsidHasher
  38 {
  39     typedef jsid Lookup;
  40     static HashNumber hash(const Lookup& l) {
  41         return HashNumber(JSID_BITS(l));
  42     }
  43     static bool match(const jsid& id, const Lookup& l) {
  44         return id == l;
  45     }
  46 };
  47
  48 /*
  49  * Return a printable, lossless char[] representation of a string-type atom.
  50  * The lifetime of the result matches the lifetime of bytes.
  51  */
  52 extern const char*
  53 AtomToPrintableString(ExclusiveContext* cx, JSAtom* atom, JSAutoByteString* bytes);
  54
  55 class AtomStateEntry
  56 {
  57     uintptr_t bits;
  58
  59     static const uintptr_t NO_TAG_MASK = uintptr_t(-1) - 1;
  60
  61   public:
  62     AtomStateEntry() : bits(0) {}
  63     AtomStateEntry(const AtomStateEntry& other) : bits(other.bits) {}
  64     AtomStateEntry(JSAtom* ptr, bool tagged)
  65       : bits(uintptr_t(ptr) | uintptr_t(tagged))
  66     {
  67         MOZ_ASSERT((uintptr_t(ptr) & 0x1) == 0);
  68     }
  69
  70     bool isTagged() const {
  71         return bits & 0x1;
  72     }
  73
  74     /*
  75      * Non-branching code sequence. Note that the const_cast is safe because
  76      * the hash function doesn't consider the tag to be a portion of the key.
  77      */
  78     void setTagged(bool enabled) const {
  79         const_cast<AtomStateEntry*>(this)->bits |= uintptr_t(enabled);
  80     }
  81
  82     JSAtom* asPtr() const;
  83 };
  84
  85 struct AtomHasher
  86 {
  87     struct Lookup
  88     {
  89         union {
  90             const JS::Latin1Char* latin1Chars;
  91             const char16_t* twoByteChars;
  92         };
  93         bool isLatin1;
  94         size_t length;
  95         const JSAtom* atom; /* Optional. */
  96         JS::AutoCheckCannotGC nogc;
  97
  98         HashNumber hash;
  99
 100         Lookup(const char16_t* chars, size_t length)
 101           : twoByteChars(chars), isLatin1(false), length(length), atom(nullptr)
 102         {
 103             hash = mozilla::HashString(chars, length);
 104         }
 105         Lookup(const JS::Latin1Char* chars, size_t length)
 106           : latin1Chars(chars), isLatin1(true), length(length), atom(nullptr)
 107         {
 108             hash = mozilla::HashString(chars, length);
 109         }
 110         inline explicit Lookup(const JSAtom* atom);
 111     };
 112
 113     static HashNumber hash(const Lookup& l) { return l.hash; }
 114     static inline bool match(const AtomStateEntry& entry, const Lookup& lookup);
 115     static void rekey(AtomStateEntry& k, const AtomStateEntry& newKey) { k = newKey; }
 116 };
 117
 118 typedef HashSet<AtomStateEntry, AtomHasher, SystemAllocPolicy> AtomSet;
 119
 120 class PropertyName;
 121
 122 }  /* namespace js */
 123
 124 extern bool
 125 AtomIsInterned(JSContext* cx, JSAtom* atom);
 126
 127 /* Well-known predefined C strings. */
 128 #define DECLARE_PROTO_STR(name,code,init,clasp) extern const char js_##name##_str[];
 129 JS_FOR_EACH_PROTOTYPE(DECLARE_PROTO_STR)
 130 #undef DECLARE_PROTO_STR
 131
 132 #define DECLARE_CONST_CHAR_STR(idpart, id, text)  extern const char js_##idpart##_str[];
 133 FOR_EACH_COMMON_PROPERTYNAME(DECLARE_CONST_CHAR_STR)
 134 #undef DECLARE_CONST_CHAR_STR
 135
 136 /* Constant strings that are not atomized. */
 137 extern const char js_break_str[];
 138 extern const char js_case_str[];
 139 extern const char js_catch_str[];
 140 extern const char js_class_str[];
 141 extern const char js_close_str[];
 142 extern const char js_const_str[];
 143 extern const char js_continue_str[];
 144 extern const char js_debugger_str[];
 145 extern const char js_default_str[];
 146 extern const char js_do_str[];
 147 extern const char js_else_str[];
 148 extern const char js_enum_str[];
 149 extern const char js_export_str[];
 150 extern const char js_extends_str[];
 151 extern const char js_finally_str[];
 152 extern const char js_for_str[];
 153 extern const char js_getter_str[];
 154 extern const char js_if_str[];
 155 extern const char js_implements_str[];
 156 extern const char js_import_str[];
 157 extern const char js_in_str[];
 158 extern const char js_instanceof_str[];
 159 extern const char js_interface_str[];
 160 extern const char js_new_str[];
 161 extern const char js_package_str[];
 162 extern const char js_private_str[];
 163 extern const char js_protected_str[];
 164 extern const char js_public_str[];
 165 extern const char js_send_str[];
 166 extern const char js_setter_str[];
 167 extern const char js_static_str[];
 168 extern const char js_super_str[];
 169 extern const char js_switch_str[];
 170 extern const char js_this_str[];
 171 extern const char js_try_str[];
 172 extern const char js_typeof_str[];
 173 extern const char js_void_str[];
 174 extern const char js_while_str[];
 175 extern const char js_with_str[];
 176
 177 namespace js {
 178
 179 /*
 180  * Atom tracing and garbage collection hooks.
 181  */
 182 void
 183 MarkAtoms(JSTracer* trc);
 184
 185 void
 186 MarkPermanentAtoms(JSTracer* trc);
 187
 188 void
 189 MarkWellKnownSymbols(JSTracer* trc);
 190
 191 /* N.B. must correspond to boolean tagging behavior. */
 192 enum InternBehavior
 193 {
 194     DoNotInternAtom = false,
 195     InternAtom = true
 196 };
 197
 198 extern JSAtom*
 199 Atomize(ExclusiveContext* cx, const char* bytes, size_t length,
 200         js::InternBehavior ib = js::DoNotInternAtom);
 201
 202 template <typename CharT>
 203 extern JSAtom*
 204 AtomizeChars(ExclusiveContext* cx, const CharT* chars, size_t length,
 205              js::InternBehavior ib = js::DoNotInternAtom);
 206
 207 extern JSAtom*
 208 AtomizeString(ExclusiveContext* cx, JSString* str, js::InternBehavior ib = js::DoNotInternAtom);
 209
 210 template <AllowGC allowGC>
 211 extern JSAtom*
 212 ToAtom(ExclusiveContext* cx, typename MaybeRooted<Value, allowGC>::HandleType v);
 213
 214 enum XDRMode {
 215     XDR_ENCODE,
 216     XDR_DECODE
 217 };
 218
 219 template <XDRMode mode>
 220 class XDRState;
 221
 222 template<XDRMode mode>
 223 bool
 224 XDRAtom(XDRState<mode>* xdr, js::MutableHandleAtom atomp);
 225
 226 } /* namespace js */
 227
 228 #endif /* jsatom_h */