gecko-dev/js/src/jsatominlines.h

/* -*- 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 jsatominlines_h
#define jsatominlines_h

#include "jsatom.h"

#include "mozilla/PodOperations.h"
#include "mozilla/RangedPtr.h"

#include "jscntxt.h"
#include "jsnum.h"

#include "vm/String.h"

inline JSAtom *
js::AtomStateEntry::asPtr() const
{
    JS_ASSERT(bits != 0);
    JSAtom *atom = reinterpret_cast<JSAtom *>(bits & NO_TAG_MASK);
    JSString::readBarrier(atom);
    return atom;
}

namespace js {

inline jsid
AtomToId(JSAtom *atom)
{
    JS_STATIC_ASSERT(JSID_INT_MIN == 0);

    uint32_t index;
    if (atom->isIndex(&index) && index <= JSID_INT_MAX)
        return INT_TO_JSID(int32_t(index));

    return JSID_FROM_BITS(size_t(atom));
}

inline bool
ValueToIdPure(const Value &v, jsid *id)
{
    int32_t i;
    if (ValueFitsInInt32(v, &i) && INT_FITS_IN_JSID(i)) {
        *id = INT_TO_JSID(i);
        return true;
    }

    if (!v.isString() || !v.toString()->isAtom())
        return false;

    *id = AtomToId(&v.toString()->asAtom());
    return true;
}

template <AllowGC allowGC>
inline bool
ValueToId(JSContext* cx, typename MaybeRooted<Value, allowGC>::HandleType v,
          typename MaybeRooted<jsid, allowGC>::MutableHandleType idp)
{
    int32_t i;
    if (ValueFitsInInt32(v, &i) && INT_FITS_IN_JSID(i)) {
        idp.set(INT_TO_JSID(i));
        return true;
    }

    JSAtom *atom = ToAtom<allowGC>(cx, v);
    if (!atom)
        return false;

    idp.set(AtomToId(atom));
    return true;
}

/*
 * Write out character representing |index| to the memory just before |end|.
 * Thus |*end| is not touched, but |end[-1]| and earlier are modified as
 * appropriate.  There must be at least js::UINT32_CHAR_BUFFER_LENGTH elements
 * before |end| to avoid buffer underflow.  The start of the characters written
 * is returned and is necessarily before |end|.
 */
template <typename T>
inline mozilla::RangedPtr<T>
BackfillIndexInCharBuffer(uint32_t index, mozilla::RangedPtr<T> end)
{
#ifdef DEBUG
    /*
     * Assert that the buffer we're filling will hold as many characters as we
     * could write out, by dereferencing the index that would hold the most
     * significant digit.
     */
    (void) *(end - UINT32_CHAR_BUFFER_LENGTH);
#endif

    do {
        uint32_t next = index / 10, digit = index % 10;
        *--end = '0' + digit;
        index = next;
    } while (index > 0);

    return end;
}

bool
IndexToIdSlow(ExclusiveContext *cx, uint32_t index, MutableHandleId idp);

inline bool
IndexToId(ExclusiveContext *cx, uint32_t index, MutableHandleId idp)
{
    if (index <= JSID_INT_MAX) {
        idp.set(INT_TO_JSID(index));
        return true;
    }

    return IndexToIdSlow(cx, index, idp);
}

static MOZ_ALWAYS_INLINE JSFlatString *
IdToString(JSContext *cx, jsid id)
{
    if (JSID_IS_STRING(id))
        return JSID_TO_ATOM(id);

    if (MOZ_LIKELY(JSID_IS_INT(id)))
        return Int32ToString<CanGC>(cx, JSID_TO_INT(id));

    RootedValue idv(cx, IdToValue(id));
    JSString *str = ToStringSlow<CanGC>(cx, idv);
    if (!str)
        return nullptr;

    return str->ensureFlat(cx);
}

inline
AtomHasher::Lookup::Lookup(const JSAtom *atom)
  : chars(atom->chars()), length(atom->length()), atom(atom)
{
    hash = mozilla::HashString(chars, length);
}

inline bool
AtomHasher::match(const AtomStateEntry &entry, const Lookup &lookup)
{
    JSAtom *key = entry.asPtr();
    if (lookup.atom)
        return lookup.atom == key;
    if (key->length() != lookup.length)
        return false;
    return mozilla::PodEqual(key->chars(), lookup.chars, lookup.length);
}

inline Handle<PropertyName*>
TypeName(JSType type, const JSAtomState &names)
{
    JS_ASSERT(type < JSTYPE_LIMIT);
    JS_STATIC_ASSERT(offsetof(JSAtomState, undefined) +
                     JSTYPE_LIMIT * sizeof(FixedHeapPtr<PropertyName>) <=
                     sizeof(JSAtomState));
    JS_STATIC_ASSERT(JSTYPE_VOID == 0);
    return (&names.undefined)[type];
}

inline Handle<PropertyName*>
ClassName(JSProtoKey key, JSAtomState &atomState)
{
    JS_ASSERT(key < JSProto_LIMIT);
    JS_STATIC_ASSERT(offsetof(JSAtomState, Null) +
                     JSProto_LIMIT * sizeof(FixedHeapPtr<PropertyName>) <=
                     sizeof(JSAtomState));
    JS_STATIC_ASSERT(JSProto_Null == 0);
    return (&atomState.Null)[key];
}

inline Handle<PropertyName*>
ClassName(JSProtoKey key, JSRuntime *rt)
{
    return ClassName(key, *rt->commonNames);
}

inline Handle<PropertyName*>
ClassName(JSProtoKey key, ExclusiveContext *cx)
{
    return ClassName(key, cx->names());
}

} // namespace js

#endif /* jsatominlines_h */