DXR is a code search and navigation tool aimed at making sense of large projects. It supports full-text and regex searches as well as structural queries.

Mercurial (4a108e94d3e2)

VCS Links

Line Code
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 * vim: set ts=8 sts=4 et sw=4 tw=99:
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef js_Id_h
#define js_Id_h

// A jsid is an identifier for a property or method of an object which is
// either a 31-bit signed integer, interned string or object.
//
// Also, there is an additional jsid value, JSID_VOID, which does not occur in
// JS scripts but may be used to indicate the absence of a valid jsid.  A void
// jsid is not a valid id and only arises as an exceptional API return value,
// such as in JS_NextProperty. Embeddings must not pass JSID_VOID into JSAPI
// entry points expecting a jsid and do not need to handle JSID_VOID in hooks
// receiving a jsid except when explicitly noted in the API contract.
//
// A jsid is not implicitly convertible to or from a jsval; JS_ValueToId or
// JS_IdToValue must be used instead.

#include "jstypes.h"

#include "js/HeapAPI.h"
#include "js/RootingAPI.h"
#include "js/TypeDecls.h"
#include "js/Utility.h"

struct jsid
{
    size_t asBits;
    bool operator==(jsid rhs) const { return asBits == rhs.asBits; }
    bool operator!=(jsid rhs) const { return asBits != rhs.asBits; }
};
#define JSID_BITS(id) (id.asBits)

#define JSID_TYPE_STRING                 0x0
#define JSID_TYPE_INT                    0x1
#define JSID_TYPE_VOID                   0x2
#define JSID_TYPE_SYMBOL                 0x4
#define JSID_TYPE_MASK                   0x7

// Avoid using canonical 'id' for jsid parameters since this is a magic word in
// Objective-C++ which, apparently, wants to be able to #include jsapi.h.
#define id iden

static MOZ_ALWAYS_INLINE bool
JSID_IS_STRING(jsid id)
{
    return (JSID_BITS(id) & JSID_TYPE_MASK) == 0;
}

static MOZ_ALWAYS_INLINE JSString*
JSID_TO_STRING(jsid id)
{
    MOZ_ASSERT(JSID_IS_STRING(id));
    return (JSString*)JSID_BITS(id);
}

/*
 * Only JSStrings that have been interned via the JSAPI can be turned into
 * jsids by API clients.
 *
 * N.B. if a jsid is backed by a string which has not been interned, that
 * string must be appropriately rooted to avoid being collected by the GC.
 */
JS_PUBLIC_API(jsid)
INTERNED_STRING_TO_JSID(JSContext* cx, JSString* str);

static MOZ_ALWAYS_INLINE bool
JSID_IS_ZERO(jsid id)
{
    return JSID_BITS(id) == 0;
}

static MOZ_ALWAYS_INLINE bool
JSID_IS_INT(jsid id)
{
    return !!(JSID_BITS(id) & JSID_TYPE_INT);
}

static MOZ_ALWAYS_INLINE int32_t
JSID_TO_INT(jsid id)
{
    MOZ_ASSERT(JSID_IS_INT(id));
    return ((uint32_t)JSID_BITS(id)) >> 1;
}

#define JSID_INT_MIN  0
#define JSID_INT_MAX  INT32_MAX

static MOZ_ALWAYS_INLINE bool
INT_FITS_IN_JSID(int32_t i)
{
    return i >= 0;
}

static MOZ_ALWAYS_INLINE jsid
INT_TO_JSID(int32_t i)
{
    jsid id;
    MOZ_ASSERT(INT_FITS_IN_JSID(i));
    JSID_BITS(id) = ((i << 1) | JSID_TYPE_INT);
    return id;
}

static MOZ_ALWAYS_INLINE bool
JSID_IS_SYMBOL(jsid id)
{
    return (JSID_BITS(id) & JSID_TYPE_MASK) == JSID_TYPE_SYMBOL &&
           JSID_BITS(id) != JSID_TYPE_SYMBOL;
}

static MOZ_ALWAYS_INLINE JS::Symbol*
JSID_TO_SYMBOL(jsid id)
{
    MOZ_ASSERT(JSID_IS_SYMBOL(id));
    return (JS::Symbol*)(JSID_BITS(id) & ~(size_t)JSID_TYPE_MASK);
}

static MOZ_ALWAYS_INLINE jsid
SYMBOL_TO_JSID(JS::Symbol* sym)
{
    jsid id;
    MOZ_ASSERT(sym != nullptr);
    MOZ_ASSERT((size_t(sym) & JSID_TYPE_MASK) == 0);
    MOZ_ASSERT(!js::gc::IsInsideNursery(reinterpret_cast<js::gc::Cell*>(sym)));
    MOZ_ASSERT(!JS::IsPoisonedPtr(sym));
    JSID_BITS(id) = (size_t(sym) | JSID_TYPE_SYMBOL);
    return id;
}

static MOZ_ALWAYS_INLINE bool
JSID_IS_GCTHING(jsid id)
{
    return JSID_IS_STRING(id) || JSID_IS_SYMBOL(id);
}

static MOZ_ALWAYS_INLINE JS::GCCellPtr
JSID_TO_GCTHING(jsid id)
{
    void* thing = (void*)(JSID_BITS(id) & ~(size_t)JSID_TYPE_MASK);
    if (JSID_IS_STRING(id))
        return JS::GCCellPtr(thing, JSTRACE_STRING);
    MOZ_ASSERT(JSID_IS_SYMBOL(id));
    return JS::GCCellPtr(thing, JSTRACE_SYMBOL);
}

static MOZ_ALWAYS_INLINE bool
JSID_IS_VOID(const jsid id)
{
    MOZ_ASSERT_IF(((size_t)JSID_BITS(id) & JSID_TYPE_MASK) == JSID_TYPE_VOID,
                 JSID_BITS(id) == JSID_TYPE_VOID);
    return (size_t)JSID_BITS(id) == JSID_TYPE_VOID;
}

static MOZ_ALWAYS_INLINE bool
JSID_IS_EMPTY(const jsid id)
{
    return (size_t)JSID_BITS(id) == JSID_TYPE_SYMBOL;
}

extern JS_PUBLIC_DATA(const jsid) JSID_VOID;
extern JS_PUBLIC_DATA(const jsid) JSID_EMPTY;

extern JS_PUBLIC_DATA(const JS::HandleId) JSID_VOIDHANDLE;
extern JS_PUBLIC_DATA(const JS::HandleId) JSID_EMPTYHANDLE;

namespace js {

inline bool
IsPoisonedId(jsid id)
{
    if (JSID_IS_STRING(id))
        return JS::IsPoisonedPtr(JSID_TO_STRING(id));
    if (JSID_IS_SYMBOL(id))
        return JS::IsPoisonedPtr(JSID_TO_SYMBOL(id));
    return false;
}

template <> struct GCMethods<jsid>
{
    static jsid initial() { return JSID_VOID; }
    static bool poisoned(jsid id) { return IsPoisonedId(id); }
    static bool needsPostBarrier(jsid id) { return false; }
    static void postBarrier(jsid* idp) {}
    static void relocate(jsid* idp) {}
};

#undef id

}

#endif /* js_Id_h */