trunk/js/jsobj.cpp

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 * vim: set ts=8 sw=4 et tw=79:
 *
 * ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Mozilla Communicator client code, released
 * March 31, 1998.
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 1998
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either of the GNU General Public License Version 2 or later (the "GPL"),
 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

/*
 * JS object implementation.
 */
#include <stdlib.h>
#include <string.h>
#include "jstypes.h"
#include "jsstdint.h"
#include "jsarena.h" /* Added by JSIFY */
#include "jsbit.h"
#include "jsutil.h" /* Added by JSIFY */
#include "jshash.h" /* Added by JSIFY */
#include "jsdhash.h"
#include "jsprf.h"
#include "jsapi.h"
#include "jsarray.h"
#include "jsatom.h"
#include "jsbool.h"
#include "jsbuiltins.h"
#include "jscntxt.h"
#include "jsversion.h"
#include "jsemit.h"
#include "jsfun.h"
#include "jsgc.h"
#include "jsinterp.h"
#include "jslock.h"
#include "jsnum.h"
#include "jsobj.h"
#include "jsopcode.h"
#include "jsparse.h"
#include "jsscope.h"
#include "jsscript.h"
#include "jsscriptinlines.h"
#include "jsstaticcheck.h"
#include "jsstr.h"
#include "jstracer.h"
#include "jsdbgapi.h"

#if JS_HAS_GENERATORS
#include "jsiter.h"
#endif

#if JS_HAS_XML_SUPPORT
#include "jsxml.h"
#endif

#if JS_HAS_XDR
#include "jsxdrapi.h"
#endif

#ifdef INCLUDE_MOZILLA_DTRACE
#include "jsdtracef.h"
#endif

#include "jsatominlines.h"
#include "jsobjinlines.h"
#include "jsscriptinlines.h"

#include "jsautooplen.h"

#ifdef JS_THREADSAFE
#define NATIVE_DROP_PROPERTY js_DropProperty

extern void
js_DropProperty(JSContext *cx, JSObject *obj, JSProperty *prop);
#else
#define NATIVE_DROP_PROPERTY NULL
#endif

JS_FRIEND_DATA(JSObjectOps) js_ObjectOps = {
    NULL,
    js_LookupProperty,      js_DefineProperty,
    js_GetProperty,         js_SetProperty,
    js_GetAttributes,       js_SetAttributes,
    js_DeleteProperty,      js_DefaultValue,
    js_Enumerate,           js_CheckAccess,
    NULL,                   NATIVE_DROP_PROPERTY,
    js_Call,                js_Construct,
    js_HasInstance,         js_TraceObject,
    js_Clear
};

JSClass js_ObjectClass = {
    js_Object_str,
    JSCLASS_HAS_CACHED_PROTO(JSProto_Object),
    JS_PropertyStub,  JS_PropertyStub,  JS_PropertyStub,  JS_PropertyStub,
    JS_EnumerateStub, JS_ResolveStub,   JS_ConvertStub,   NULL,
    JSCLASS_NO_OPTIONAL_MEMBERS
};

#if JS_HAS_OBJ_PROTO_PROP

static JSBool
obj_getSlot(JSContext *cx, JSObject *obj, jsval id, jsval *vp);

static JSBool
obj_setSlot(JSContext *cx, JSObject *obj, jsval id, jsval *vp);

static JSBool
obj_getCount(JSContext *cx, JSObject *obj, jsval id, jsval *vp);

static JSPropertySpec object_props[] = {
    /* These two must come first; see object_props[slot].name usage below. */
    {js_proto_str, JSSLOT_PROTO, JSPROP_PERMANENT|JSPROP_SHARED,
                                                  obj_getSlot,  obj_setSlot},
    {js_parent_str,JSSLOT_PARENT,JSPROP_READONLY|JSPROP_PERMANENT|JSPROP_SHARED,
                                                  obj_getSlot,  obj_setSlot},
    {js_count_str, 0,            JSPROP_READONLY|JSPROP_PERMANENT|JSPROP_SHARED,
                                                  obj_getCount, NULL},
    {0,0,0,0,0}
};

/* NB: JSSLOT_PROTO and JSSLOT_PARENT are already indexes into object_props. */
#define JSSLOT_COUNT 2

static JSBool
ReportStrictSlot(JSContext *cx, uint32 slot)
{
    if (slot == JSSLOT_PROTO)
        return JS_TRUE;
    return JS_ReportErrorFlagsAndNumber(cx,
                                        JSREPORT_WARNING | JSREPORT_STRICT,
                                        js_GetErrorMessage, NULL,
                                        JSMSG_DEPRECATED_USAGE,
                                        object_props[slot].name);
}

static JSBool
obj_getSlot(JSContext *cx, JSObject *obj, jsval id, jsval *vp)
{
    uint32 slot;
    jsid propid;
    JSAccessMode mode;
    uintN attrs;
    JSObject *pobj;
    JSClass *clasp;

    slot = (uint32) JSVAL_TO_INT(id);
    if (id == INT_TO_JSVAL(JSSLOT_PROTO)) {
        propid = ATOM_TO_JSID(cx->runtime->atomState.protoAtom);
        mode = JSACC_PROTO;
    } else {
        propid = ATOM_TO_JSID(cx->runtime->atomState.parentAtom);
        mode = JSACC_PARENT;
    }

    /* Let obj->checkAccess get the slot's value, based on the access mode. */
    if (!obj->checkAccess(cx, propid, mode, vp, &attrs))
        return JS_FALSE;

    pobj = JSVAL_TO_OBJECT(*vp);
    if (pobj) {
        clasp = OBJ_GET_CLASS(cx, pobj);
        if (clasp == &js_CallClass || clasp == &js_BlockClass) {
            /* Censor activations and lexical scopes per ECMA-262. */
            *vp = JSVAL_NULL;
        } else {
            /*
             * DeclEnv only exists as a parent for a Call object which we
             * censor. So it cannot escape to scripts.
             */
            JS_ASSERT(clasp != &js_DeclEnvClass);
            if (pobj->map->ops->thisObject) {
                pobj = pobj->map->ops->thisObject(cx, pobj);
                if (!pobj)
                    return JS_FALSE;
                *vp = OBJECT_TO_JSVAL(pobj);
            }
        }
    }
    return JS_TRUE;
}

static JSBool
obj_setSlot(JSContext *cx, JSObject *obj, jsval id, jsval *vp)
{
    JSObject *pobj;
    uint32 slot;
    jsid propid;
    uintN attrs;

    if (!JSVAL_IS_OBJECT(*vp))
        return JS_TRUE;
    pobj = JSVAL_TO_OBJECT(*vp);

    if (pobj) {
        /*
         * Innerize pobj here to avoid sticking unwanted properties on the
         * outer object. This ensures that any with statements only grant
         * access to the inner object.
         */
        OBJ_TO_INNER_OBJECT(cx, pobj);
        if (!pobj)
            return JS_FALSE;
    }
    slot = (uint32) JSVAL_TO_INT(id);
    if (JS_HAS_STRICT_OPTION(cx) && !ReportStrictSlot(cx, slot))
        return JS_FALSE;

    /* __parent__ is readonly and permanent, only __proto__ may be set. */
    propid = ATOM_TO_JSID(cx->runtime->atomState.protoAtom);
    if (!obj->checkAccess(cx, propid, (JSAccessMode)(JSACC_PROTO|JSACC_WRITE), vp, &attrs))
        return JS_FALSE;

    return js_SetProtoOrParent(cx, obj, slot, pobj, JS_TRUE);
}

static JSBool
obj_getCount(JSContext *cx, JSObject *obj, jsval id, jsval *vp)
{
    jsval iter_state;
    jsid num_properties;
    JSBool ok;

    if (JS_HAS_STRICT_OPTION(cx) && !ReportStrictSlot(cx, JSSLOT_COUNT))
        return JS_FALSE;

    iter_state = JSVAL_NULL;
    JSAutoEnumStateRooter tvr(cx, obj, &iter_state);

    /* Get the number of properties to enumerate. */
    ok = obj->enumerate(cx, JSENUMERATE_INIT, &iter_state, &num_properties);
    if (!ok)
        goto out;

    if (!JSVAL_IS_INT(num_properties)) {
        JS_ASSERT(0);
        *vp = JSVAL_ZERO;
        goto out;
    }
    *vp = num_properties;

out:
    if (!JSVAL_IS_NULL(iter_state))
        ok &= obj->enumerate(cx, JSENUMERATE_DESTROY, &iter_state, 0);
    return ok;
}

#else  /* !JS_HAS_OBJ_PROTO_PROP */

#define object_props NULL

#endif /* !JS_HAS_OBJ_PROTO_PROP */

JSBool
js_SetProtoOrParent(JSContext *cx, JSObject *obj, uint32 slot, JSObject *pobj,
                    JSBool checkForCycles)
{
    JS_ASSERT(slot == JSSLOT_PARENT || slot == JSSLOT_PROTO);
    JS_ASSERT_IF(!checkForCycles, obj != pobj);

    if (slot == JSSLOT_PROTO) {
        if (OBJ_IS_NATIVE(obj)) {
            JS_LOCK_OBJ(cx, obj);
            bool ok = !!js_GetMutableScope(cx, obj);
            JS_UNLOCK_OBJ(cx, obj);
            if (!ok)
                return JS_FALSE;
        }

        /*
         * Regenerate property cache shape ids for all of the scopes along the
         * old prototype chain to invalidate their property cache entries, in
         * case any entries were filled by looking up through obj.
         */
        JSObject *oldproto = obj;
        while (oldproto && OBJ_IS_NATIVE(oldproto)) {
            JS_LOCK_OBJ(cx, oldproto);
            JSScope *scope = OBJ_SCOPE(oldproto);
            scope->protoShapeChange(cx);
            JSObject *tmp = STOBJ_GET_PROTO(oldproto);
            JS_UNLOCK_OBJ(cx, oldproto);
            oldproto = tmp;
        }
    }

    if (!pobj || !checkForCycles) {
        if (slot == JSSLOT_PROTO)
            obj->setProto(pobj);
        else
            obj->setParent(pobj);
    } else {
        /*
         * Use the GC machinery to serialize access to all objects on the
         * prototype or parent chain.
         */
        JSSetSlotRequest ssr;
        ssr.obj = obj;
        ssr.pobj = pobj;
        ssr.slot = (uint16) slot;
        ssr.cycle = false;

        JSRuntime *rt = cx->runtime;
        JS_LOCK_GC(rt);
        ssr.next = rt->setSlotRequests;
        rt->setSlotRequests = &ssr;
        for (;;) {
            js_GC(cx, GC_SET_SLOT_REQUEST);
            JS_UNLOCK_GC(rt);
            if (!rt->setSlotRequests)
                break;
            JS_LOCK_GC(rt);
        }

        if (ssr.cycle) {
            JS_ReportErrorNumber(cx, js_GetErrorMessage, NULL,
                                 JSMSG_CYCLIC_VALUE,
#if JS_HAS_OBJ_PROTO_PROP
                                 object_props[slot].name
#else
                                 (slot == JSSLOT_PROTO) ? js_proto_str
                                                        : js_parent_str
#endif
                                 );
            return JS_FALSE;
        }
    }
    return JS_TRUE;
}

static JSHashNumber
js_hash_object(const void *key)
{
    return (JSHashNumber)JS_PTR_TO_UINT32(key) >> JSVAL_TAGBITS;
}

static JSHashEntry *
MarkSharpObjects(JSContext *cx, JSObject *obj, JSIdArray **idap)
{
    JSSharpObjectMap *map;
    JSHashTable *table;
    JSHashNumber hash;
    JSHashEntry **hep, *he;
    jsatomid sharpid;
    JSIdArray *ida;
    JSBool ok;
    jsint i, length;
    jsid id;
#if JS_HAS_GETTER_SETTER
    JSObject *obj2;
    JSProperty *prop;
    uintN attrs;
#endif
    jsval val;

    JS_CHECK_RECURSION(cx, return NULL);

    map = &cx->sharpObjectMap;
    JS_ASSERT(map->depth >= 1);
    table = map->table;
    hash = js_hash_object(obj);
    hep = JS_HashTableRawLookup(table, hash, obj);
    he = *hep;
    if (!he) {
        sharpid = 0;
        he = JS_HashTableRawAdd(table, hep, hash, obj,
                                JS_UINT32_TO_PTR(sharpid));
        if (!he) {
            JS_ReportOutOfMemory(cx);
            return NULL;
        }

        ida = JS_Enumerate(cx, obj);
        if (!ida)
            return NULL;

        ok = JS_TRUE;
        for (i = 0, length = ida->length; i < length; i++) {
            id = ida->vector[i];
#if JS_HAS_GETTER_SETTER
            ok = obj->lookupProperty(cx, id, &obj2, &prop);
            if (!ok)
                break;
            if (!prop)
                continue;
            ok = obj2->getAttributes(cx, id, prop, &attrs);
            if (ok) {
                if (OBJ_IS_NATIVE(obj2) &&
                    (attrs & (JSPROP_GETTER | JSPROP_SETTER))) {
                    JSScopeProperty *sprop = (JSScopeProperty *) prop;
                    val = JSVAL_NULL;
                    if (attrs & JSPROP_GETTER)
                        val = js_CastAsObjectJSVal(sprop->getter);
                    if (attrs & JSPROP_SETTER) {
                        if (val != JSVAL_NULL) {
                            /* Mark the getter, then set val to setter. */
                            ok = (MarkSharpObjects(cx, JSVAL_TO_OBJECT(val),
                                                   NULL)
                                  != NULL);
                        }
                        val = js_CastAsObjectJSVal(sprop->setter);
                    }
                } else {
                    ok = obj->getProperty(cx, id, &val);
                }
            }
            obj2->dropProperty(cx, prop);
#else
            ok = obj->getProperty(cx, id, &val);
#endif
            if (!ok)
                break;
            if (!JSVAL_IS_PRIMITIVE(val) &&
                !MarkSharpObjects(cx, JSVAL_TO_OBJECT(val), NULL)) {
                ok = JS_FALSE;
                break;
            }
        }
        if (!ok || !idap)
            JS_DestroyIdArray(cx, ida);
        if (!ok)
            return NULL;
    } else {
        sharpid = JS_PTR_TO_UINT32(he->value);
        if (sharpid == 0) {
            sharpid = ++map->sharpgen << SHARP_ID_SHIFT;
            he->value = JS_UINT32_TO_PTR(sharpid);
        }
        ida = NULL;
    }
    if (idap)
        *idap = ida;
    return he;
}

JSHashEntry *
js_EnterSharpObject(JSContext *cx, JSObject *obj, JSIdArray **idap,
                    jschar **sp)
{
    JSSharpObjectMap *map;
    JSHashTable *table;
    JSIdArray *ida;
    JSHashNumber hash;
    JSHashEntry *he, **hep;
    jsatomid sharpid;
    char buf[20];
    size_t len;

    if (!JS_CHECK_OPERATION_LIMIT(cx))
        return NULL;

    /* Set to null in case we return an early error. */
    *sp = NULL;
    map = &cx->sharpObjectMap;
    table = map->table;
    if (!table) {
        table = JS_NewHashTable(8, js_hash_object, JS_CompareValues,
                                JS_CompareValues, NULL, NULL);
        if (!table) {
            JS_ReportOutOfMemory(cx);
            return NULL;
        }
        map->table = table;
        JS_KEEP_ATOMS(cx->runtime);
    }

    /* From this point the control must flow either through out: or bad:. */
    ida = NULL;
    if (map->depth == 0) {
        /*
         * Although MarkSharpObjects tries to avoid invoking getters,
         * it ends up doing so anyway under some circumstances; for
         * example, if a wrapped object has getters, the wrapper will
         * prevent MarkSharpObjects from recognizing them as such.
         * This could lead to js_LeaveSharpObject being called while
         * MarkSharpObjects is still working.
         *
         * Increment map->depth while we call MarkSharpObjects, to
         * ensure that such a call doesn't free the hash table we're
         * still using.
         */
        ++map->depth;
        he = MarkSharpObjects(cx, obj, &ida);
        --map->depth;
        if (!he)
            goto bad;
        JS_ASSERT((JS_PTR_TO_UINT32(he->value) & SHARP_BIT) == 0);
        if (!idap) {
            JS_DestroyIdArray(cx, ida);
            ida = NULL;
        }
    } else {
        hash = js_hash_object(obj);
        hep = JS_HashTableRawLookup(table, hash, obj);
        he = *hep;

        /*
         * It's possible that the value of a property has changed from the
         * first time the object's properties are traversed (when the property
         * ids are entered into the hash table) to the second (when they are
         * converted to strings), i.e., the JSObject::getProperty() call is not
         * idempotent.
         */
        if (!he) {
            he = JS_HashTableRawAdd(table, hep, hash, obj, NULL);
            if (!he) {
                JS_ReportOutOfMemory(cx);
                goto bad;
            }
            sharpid = 0;
            goto out;
        }
    }

    sharpid = JS_PTR_TO_UINT32(he->value);
    if (sharpid != 0) {
        len = JS_snprintf(buf, sizeof buf, "#%u%c",
                          sharpid >> SHARP_ID_SHIFT,
                          (sharpid & SHARP_BIT) ? '#' : '=');
        *sp = js_InflateString(cx, buf, &len);
        if (!*sp) {
            if (ida)
                JS_DestroyIdArray(cx, ida);
            goto bad;
        }
    }

out:
    JS_ASSERT(he);
    if ((sharpid & SHARP_BIT) == 0) {
        if (idap && !ida) {
            ida = JS_Enumerate(cx, obj);
            if (!ida) {
                if (*sp) {
                    cx->free(*sp);
                    *sp = NULL;
                }
                goto bad;
            }
        }
        map->depth++;
    }

    if (idap)
        *idap = ida;
    return he;

bad:
    /* Clean up the sharpObjectMap table on outermost error. */
    if (map->depth == 0) {
        JS_UNKEEP_ATOMS(cx->runtime);
        map->sharpgen = 0;
        JS_HashTableDestroy(map->table);
        map->table = NULL;
    }
    return NULL;
}

void
js_LeaveSharpObject(JSContext *cx, JSIdArray **idap)
{
    JSSharpObjectMap *map;
    JSIdArray *ida;

    map = &cx->sharpObjectMap;
    JS_ASSERT(map->depth > 0);
    if (--map->depth == 0) {
        JS_UNKEEP_ATOMS(cx->runtime);
        map->sharpgen = 0;
        JS_HashTableDestroy(map->table);
        map->table = NULL;
    }
    if (idap) {
        ida = *idap;
        if (ida) {
            JS_DestroyIdArray(cx, ida);
            *idap = NULL;
        }
    }
}

static intN
gc_sharp_table_entry_marker(JSHashEntry *he, intN i, void *arg)
{
    JS_CALL_OBJECT_TRACER((JSTracer *)arg, (JSObject *)he->key,
                          "sharp table entry");
    return JS_DHASH_NEXT;
}

void
js_TraceSharpMap(JSTracer *trc, JSSharpObjectMap *map)
{
    JS_ASSERT(map->depth > 0);
    JS_ASSERT(map->table);

    /*
     * During recursive calls to MarkSharpObjects a non-native object or
     * object with a custom getProperty method can potentially return an
     * unrooted value or even cut from the object graph an argument of one of
     * MarkSharpObjects recursive invocations. So we must protect map->table
     * entries against GC.
     *
     * We can not simply use JSTempValueRooter to mark the obj argument of
     * MarkSharpObjects during recursion as we have to protect *all* entries
     * in JSSharpObjectMap including those that contains otherwise unreachable
     * objects just allocated through custom getProperty. Otherwise newer
     * allocations can re-use the address of an object stored in the hashtable
     * confusing js_EnterSharpObject. So to address the problem we simply
     * mark all objects from map->table.
     *
     * An alternative "proper" solution is to use JSTempValueRooter in
     * MarkSharpObjects with code to remove during finalization entries
     * with otherwise unreachable objects. But this is way too complex
     * to justify spending efforts.
     */
    JS_HashTableEnumerateEntries(map->table, gc_sharp_table_entry_marker, trc);
}

#if JS_HAS_TOSOURCE
static JSBool
obj_toSource(JSContext *cx, uintN argc, jsval *vp)
{
    JSBool ok, outermost;
    JSObject *obj;
    JSHashEntry *he;
    JSIdArray *ida;
    jschar *chars, *ochars, *vsharp;
    const jschar *idstrchars, *vchars;
    size_t nchars, idstrlength, gsoplength, vlength, vsharplength, curlen;
    const char *comma;
    jsint i, j, length, valcnt;
    jsid id;
#if JS_HAS_GETTER_SETTER
    JSObject *obj2;
    JSProperty *prop;
    uintN attrs;
#endif
    jsval *val;
    jsval localroot[4] = {JSVAL_NULL, JSVAL_NULL, JSVAL_NULL, JSVAL_NULL};
    JSTempValueRooter tvr;
    JSString *gsopold[2];
    JSString *gsop[2];
    JSString *idstr, *valstr, *str;

    JS_CHECK_RECURSION(cx, return JS_FALSE);

    MUST_FLOW_THROUGH("out");
    JS_PUSH_TEMP_ROOT(cx, 4, localroot, &tvr);

    /* If outermost, we need parentheses to be an expression, not a block. */
    outermost = (cx->sharpObjectMap.depth == 0);
    obj = JS_THIS_OBJECT(cx, vp);
    if (!obj || !(he = js_EnterSharpObject(cx, obj, &ida, &chars))) {
        ok = JS_FALSE;
        goto out;
    }
    if (IS_SHARP(he)) {
        /*
         * We didn't enter -- obj is already "sharp", meaning we've visited it
         * already in our depth first search, and therefore chars contains a
         * string of the form "#n#".
         */
        JS_ASSERT(!ida);
#if JS_HAS_SHARP_VARS
        nchars = js_strlen(chars);
#else
        chars[0] = '{';
        chars[1] = '}';
        chars[2] = 0;
        nchars = 2;
#endif
        goto make_string;
    }
    JS_ASSERT(ida);
    ok = JS_TRUE;

    if (!chars) {
        /* If outermost, allocate 4 + 1 for "({})" and the terminator. */
        chars = (jschar *) js_malloc(((outermost ? 4 : 2) + 1) * sizeof(jschar));
        nchars = 0;
        if (!chars)
            goto error;
        if (outermost)
            chars[nchars++] = '(';
    } else {
        /* js_EnterSharpObject returned a string of the form "#n=" in chars. */
        MAKE_SHARP(he);
        nchars = js_strlen(chars);
        chars = (jschar *)
            js_realloc((ochars = chars), (nchars + 2 + 1) * sizeof(jschar));
        if (!chars) {
            js_free(ochars);
            goto error;
        }
        if (outermost) {
            /*
             * No need for parentheses around the whole shebang, because #n=
             * unambiguously begins an object initializer, and never a block
             * statement.
             */
            outermost = JS_FALSE;
        }
    }

    chars[nchars++] = '{';

    comma = NULL;

    /*
     * We have four local roots for cooked and raw value GC safety.  Hoist the
     * "localroot + 2" out of the loop using the val local, which refers to
     * the raw (unconverted, "uncooked") values.
     */
    val = localroot + 2;

    for (i = 0, length = ida->length; i < length; i++) {
        JSBool idIsLexicalIdentifier, needOldStyleGetterSetter;

        /* Get strings for id and value and GC-root them via vp. */
        id = ida->vector[i];

#if JS_HAS_GETTER_SETTER
        ok = obj->lookupProperty(cx, id, &obj2, &prop);
        if (!ok)
            goto error;
#endif

        /*
         * Convert id to a jsval and then to a string.  Decide early whether we
         * prefer get/set or old getter/setter syntax.
         */
        idstr = js_ValueToString(cx, ID_TO_VALUE(id));
        if (!idstr) {
            ok = JS_FALSE;
            obj2->dropProperty(cx, prop);
            goto error;
        }
        *vp = STRING_TO_JSVAL(idstr);                   /* local root */
        idIsLexicalIdentifier = js_IsIdentifier(idstr);
        needOldStyleGetterSetter =
            !idIsLexicalIdentifier ||
            js_CheckKeyword(idstr->chars(), idstr->length()) != TOK_EOF;

#if JS_HAS_GETTER_SETTER

        valcnt = 0;
        if (prop) {
            ok = obj2->getAttributes(cx, id, prop, &attrs);
            if (!ok) {
                obj2->dropProperty(cx, prop);
                goto error;
            }
            if (OBJ_IS_NATIVE(obj2) &&
                (attrs & (JSPROP_GETTER | JSPROP_SETTER))) {
                JSScopeProperty *sprop = (JSScopeProperty *) prop;
                if (attrs & JSPROP_GETTER) {
                    val[valcnt] = js_CastAsObjectJSVal(sprop->getter);
                    gsopold[valcnt] =
                        ATOM_TO_STRING(cx->runtime->atomState.getterAtom);
                    gsop[valcnt] =
                        ATOM_TO_STRING(cx->runtime->atomState.getAtom);

                    valcnt++;
                }
                if (attrs & JSPROP_SETTER) {
                    val[valcnt] = js_CastAsObjectJSVal(sprop->setter);
                    gsopold[valcnt] =
                        ATOM_TO_STRING(cx->runtime->atomState.setterAtom);
                    gsop[valcnt] =
                        ATOM_TO_STRING(cx->runtime->atomState.setAtom);

                    valcnt++;
                }
            } else {
                valcnt = 1;
                gsop[0] = NULL;
                gsopold[0] = NULL;
                ok = obj->getProperty(cx, id, &val[0]);
            }
            obj2->dropProperty(cx, prop);
        }

#else  /* !JS_HAS_GETTER_SETTER */

        /*
         * We simplify the source code at the price of minor dead code bloat in
         * the ECMA version (for testing only, see jsversion.h).  The null
         * default values in gsop[j] suffice to disable non-ECMA getter and
         * setter code.
         */
        valcnt = 1;
        gsop[0] = NULL;
        gsopold[0] = NULL;
        ok = obj->getProperty(cx, id, &val[0]);

#endif /* !JS_HAS_GETTER_SETTER */

        if (!ok)
            goto error;

        /*
         * If id is a string that's not an identifier, then it needs to be
         * quoted.  Also, negative integer ids must be quoted.
         */
        if (JSID_IS_ATOM(id)
            ? !idIsLexicalIdentifier
            : (!JSID_IS_INT(id) || JSID_TO_INT(id) < 0)) {
            idstr = js_QuoteString(cx, idstr, (jschar)'\'');
            if (!idstr) {
                ok = JS_FALSE;
                goto error;
            }
            *vp = STRING_TO_JSVAL(idstr);               /* local root */
        }
        idstr->getCharsAndLength(idstrchars, idstrlength);

        for (j = 0; j < valcnt; j++) {
            /* Convert val[j] to its canonical source form. */
            valstr = js_ValueToSource(cx, val[j]);
            if (!valstr) {
                ok = JS_FALSE;
                goto error;
            }
            localroot[j] = STRING_TO_JSVAL(valstr);     /* local root */
            valstr->getCharsAndLength(vchars, vlength);

            if (vchars[0] == '#')
                needOldStyleGetterSetter = JS_TRUE;

            if (needOldStyleGetterSetter)
                gsop[j] = gsopold[j];

            /* If val[j] is a non-sharp object, consider sharpening it. */
            vsharp = NULL;
            vsharplength = 0;
#if JS_HAS_SHARP_VARS
            if (!JSVAL_IS_PRIMITIVE(val[j]) && vchars[0] != '#') {
                he = js_EnterSharpObject(cx, JSVAL_TO_OBJECT(val[j]), NULL,
                                         &vsharp);
                if (!he) {
                    ok = JS_FALSE;
                    goto error;
                }
                if (IS_SHARP(he)) {
                    vchars = vsharp;
                    vlength = js_strlen(vchars);
                    needOldStyleGetterSetter = JS_TRUE;
                    gsop[j] = gsopold[j];
                } else {
                    if (vsharp) {
                        vsharplength = js_strlen(vsharp);
                        MAKE_SHARP(he);
                        needOldStyleGetterSetter = JS_TRUE;
                        gsop[j] = gsopold[j];
                    }
                    js_LeaveSharpObject(cx, NULL);
                }
            }
#endif

#ifndef OLD_GETTER_SETTER
            /*
             * Remove '(function ' from the beginning of valstr and ')' from the
             * end so that we can put "get" in front of the function definition.
             */
            if (gsop[j] && VALUE_IS_FUNCTION(cx, val[j]) &&
                !needOldStyleGetterSetter) {
                JSFunction *fun = JS_ValueToFunction(cx, val[j]);
                const jschar *start = vchars;
                const jschar *end = vchars + vlength;

                uint8 parenChomp = 0;
                if (vchars[0] == '(') {
                    vchars++;
                    parenChomp = 1;
                }

                /*
                 * Try to jump "getter" or "setter" keywords, if we suspect
                 * they might appear here.  This code can be confused by people
                 * defining Function.prototype.toString, so let's be cautious.
                 */
                if (JSFUN_GETTER_TEST(fun->flags) ||
                    JSFUN_SETTER_TEST(fun->flags)) { /* skip "getter/setter" */
                    const jschar *tmp = js_strchr_limit(vchars, ' ', end);
                    if (tmp)
                        vchars = tmp + 1;
                }

                /* Try to jump "function" keyword. */
                if (vchars)
                    vchars = js_strchr_limit(vchars, ' ', end);

                if (vchars) {
                    if (*vchars == ' ')
                        vchars++;
                    vlength = end - vchars - parenChomp;
                } else {
                    gsop[j] = NULL;
                    vchars = start;
                }
            }
#else
            needOldStyleGetterSetter = JS_TRUE;
            gsop[j] = gsopold[j];
#endif

#define SAFE_ADD(n)                                                          \
    JS_BEGIN_MACRO                                                           \
        size_t n_ = (n);                                                     \
        curlen += n_;                                                        \
        if (curlen < n_)                                                     \
            goto overflow;                                                   \
    JS_END_MACRO

            curlen = nchars;
            if (comma)
                SAFE_ADD(2);
            SAFE_ADD(idstrlength + 1);
            if (gsop[j])
                SAFE_ADD(gsop[j]->length() + 1);
            SAFE_ADD(vsharplength);
            SAFE_ADD(vlength);
            /* Account for the trailing null. */
            SAFE_ADD((outermost ? 2 : 1) + 1);
#undef SAFE_ADD

            if (curlen > (size_t)-1 / sizeof(jschar))
                goto overflow;

            /* Allocate 1 + 1 at end for closing brace and terminating 0. */
            chars = (jschar *)
                js_realloc((ochars = chars), curlen * sizeof(jschar));
            if (!chars) {
                /* Save code space on error: let JS_free ignore null vsharp. */
                cx->free(vsharp);
                js_free(ochars);
                goto error;
            }

            if (comma) {
                chars[nchars++] = comma[0];
                chars[nchars++] = comma[1];
            }
            comma = ", ";

            if (needOldStyleGetterSetter) {
                js_strncpy(&chars[nchars], idstrchars, idstrlength);
                nchars += idstrlength;
                if (gsop[j]) {
                    chars[nchars++] = ' ';
                    gsoplength = gsop[j]->length();
                    js_strncpy(&chars[nchars], gsop[j]->chars(),
                               gsoplength);
                    nchars += gsoplength;
                }
                chars[nchars++] = ':';
            } else {  /* New style "decompilation" */
                if (gsop[j]) {
                    gsoplength = gsop[j]->length();
                    js_strncpy(&chars[nchars], gsop[j]->chars(),
                               gsoplength);
                    nchars += gsoplength;
                    chars[nchars++] = ' ';
                }
                js_strncpy(&chars[nchars], idstrchars, idstrlength);
                nchars += idstrlength;
                /* Extraneous space after id here will be extracted later */
                chars[nchars++] = gsop[j] ? ' ' : ':';
            }

            if (vsharplength) {
                js_strncpy(&chars[nchars], vsharp, vsharplength);
                nchars += vsharplength;
            }
            js_strncpy(&chars[nchars], vchars, vlength);
            nchars += vlength;

            if (vsharp)
                cx->free(vsharp);
        }
    }

    chars[nchars++] = '}';
    if (outermost)
        chars[nchars++] = ')';
    chars[nchars] = 0;

  error:
    js_LeaveSharpObject(cx, &ida);

    if (!ok) {
        if (chars)
            js_free(chars);
        goto out;
    }

    if (!chars) {
        JS_ReportOutOfMemory(cx);
        ok = JS_FALSE;
        goto out;
    }
  make_string:
    str = js_NewString(cx, chars, nchars);
    if (!str) {
        js_free(chars);
        ok = JS_FALSE;
        goto out;
    }
    *vp = STRING_TO_JSVAL(str);
    ok = JS_TRUE;
  out:
    JS_POP_TEMP_ROOT(cx, &tvr);
    return ok;

  overflow:
    cx->free(vsharp);
    js_free(chars);
    chars = NULL;
    goto error;
}
#endif /* JS_HAS_TOSOURCE */

static JSBool
obj_toString(JSContext *cx, uintN argc, jsval *vp)
{
    JSObject *obj;
    jschar *chars;
    size_t nchars;
    const char *clazz, *prefix;
    JSString *str;

    obj = JS_THIS_OBJECT(cx, vp);
    if (!obj)
        return JS_FALSE;
    obj = js_GetWrappedObject(cx, obj);
    clazz = OBJ_GET_CLASS(cx, obj)->name;
    nchars = 9 + strlen(clazz);         /* 9 for "[object ]" */
    chars = (jschar *) cx->malloc((nchars + 1) * sizeof(jschar));
    if (!chars)
        return JS_FALSE;

    prefix = "[object ";
    nchars = 0;
    while ((chars[nchars] = (jschar)*prefix) != 0)
        nchars++, prefix++;
    while ((chars[nchars] = (jschar)*clazz) != 0)
        nchars++, clazz++;
    chars[nchars++] = ']';
    chars[nchars] = 0;

    str = js_NewString(cx, chars, nchars);
    if (!str) {
        cx->free(chars);
        return JS_FALSE;
    }
    *vp = STRING_TO_JSVAL(str);
    return JS_TRUE;
}

static JSBool
obj_toLocaleString(JSContext *cx, uintN argc, jsval *vp)
{
    jsval thisv;
    JSString *str;

    thisv = JS_THIS(cx, vp);
    if (JSVAL_IS_NULL(thisv))
        return JS_FALSE;

    str = js_ValueToString(cx, thisv);
    if (!str)
        return JS_FALSE;

    *vp = STRING_TO_JSVAL(str);
    return JS_TRUE;
}

static JSBool
obj_valueOf(JSContext *cx, uintN argc, jsval *vp)
{
    *vp = JS_THIS(cx, vp);
    return !JSVAL_IS_NULL(*vp);
}

#ifdef JS_TRACER
static jsval FASTCALL
Object_p_valueOf(JSContext* cx, JSObject* obj, JSString *hint)
{
    return OBJECT_TO_JSVAL(obj);
}
#endif

/*
 * Check whether principals subsumes scopeobj's principals, and return true
 * if so (or if scopeobj has no principals, for backward compatibility with
 * the JS API, which does not require principals), and false otherwise.
 */
JSBool
js_CheckPrincipalsAccess(JSContext *cx, JSObject *scopeobj,
                         JSPrincipals *principals, JSAtom *caller)
{
    JSSecurityCallbacks *callbacks;
    JSPrincipals *scopePrincipals;
    const char *callerstr;

    callbacks = JS_GetSecurityCallbacks(cx);
    if (callbacks && callbacks->findObjectPrincipals) {
        scopePrincipals = callbacks->findObjectPrincipals(cx, scopeobj);
        if (!principals || !scopePrincipals ||
            !principals->subsume(principals, scopePrincipals)) {
            callerstr = js_AtomToPrintableString(cx, caller);
            if (!callerstr)
                return JS_FALSE;
            JS_ReportErrorNumber(cx, js_GetErrorMessage, NULL,
                                 JSMSG_BAD_INDIRECT_CALL, callerstr);
            return JS_FALSE;
        }
    }
    return JS_TRUE;
}

JSObject *
js_CheckScopeChainValidity(JSContext *cx, JSObject *scopeobj, const char *caller)
{
    JSClass *clasp;
    JSExtendedClass *xclasp;
    JSObject *inner;

    if (!scopeobj)
        goto bad;

    OBJ_TO_INNER_OBJECT(cx, scopeobj);
    if (!scopeobj)
        return NULL;

    inner = scopeobj;

    /* XXX This is an awful gross hack. */
    while (scopeobj) {
        clasp = OBJ_GET_CLASS(cx, scopeobj);
        if (clasp->flags & JSCLASS_IS_EXTENDED) {
            xclasp = (JSExtendedClass*)clasp;
            if (xclasp->innerObject &&
                xclasp->innerObject(cx, scopeobj) != scopeobj) {
                goto bad;
            }
        }

        scopeobj = OBJ_GET_PARENT(cx, scopeobj);
    }

    return inner;

bad:
    JS_ReportErrorNumber(cx, js_GetErrorMessage, NULL,
                         JSMSG_BAD_INDIRECT_CALL, caller);
    return NULL;
}

const char *
js_ComputeFilename(JSContext *cx, JSStackFrame *caller,
                   JSPrincipals *principals, uintN *linenop)
{
    uint32 flags;
#ifdef DEBUG
    JSSecurityCallbacks *callbacks = JS_GetSecurityCallbacks(cx);
#endif

    JS_ASSERT(principals || !(callbacks  && callbacks->findObjectPrincipals));
    flags = JS_GetScriptFilenameFlags(caller->script);
    if ((flags & JSFILENAME_PROTECTED) &&
        principals &&
        strcmp(principals->codebase, "[System Principal]")) {
        *linenop = 0;
        return principals->codebase;
    }

    if (caller->regs && js_GetOpcode(cx, caller->script, caller->regs->pc) == JSOP_EVAL) {
        JS_ASSERT(js_GetOpcode(cx, caller->script, caller->regs->pc + JSOP_EVAL_LENGTH) == JSOP_LINENO);
        *linenop = GET_UINT16(caller->regs->pc + JSOP_EVAL_LENGTH);
    } else {
        *linenop = js_FramePCToLineNumber(cx, caller);
    }
    return caller->script->filename;
}

#ifndef EVAL_CACHE_CHAIN_LIMIT
# define EVAL_CACHE_CHAIN_LIMIT 4
#endif

static inline JSScript **
EvalCacheHash(JSContext *cx, JSString *str)
{
    const jschar *s;
    size_t n;
    uint32 h;

    str->getCharsAndLength(s, n);
    if (n > 100)
        n = 100;
    for (h = 0; n; s++, n--)
        h = JS_ROTATE_LEFT32(h, 4) ^ *s;

    h *= JS_GOLDEN_RATIO;
    h >>= 32 - JS_EVAL_CACHE_SHIFT;
    return &JS_SCRIPTS_TO_GC(cx)[h];
}

static JSBool
obj_eval(JSContext *cx, JSObject *obj, uintN argc, jsval *argv, jsval *rval)
{
    JSStackFrame *fp, *caller;
    JSBool indirectCall;
    uint32 tcflags;
    JSPrincipals *principals;
    const char *file;
    uintN line;
    JSString *str;
    JSScript *script;
    JSBool ok;
    JSScript **bucket = NULL;   /* avoid GCC warning with early decl&init */
#if JS_HAS_EVAL_THIS_SCOPE
    JSObject *callerScopeChain = NULL, *callerVarObj = NULL;
    JSObject *setCallerScopeChain = NULL;
    JSBool setCallerVarObj = JS_FALSE;
#endif

    fp = js_GetTopStackFrame(cx);
    caller = js_GetScriptedCaller(cx, fp);
    if (!caller) {
        JS_ReportErrorNumber(cx, js_GetErrorMessage, NULL,
                             JSMSG_BAD_INDIRECT_CALL, js_eval_str);
        return JS_FALSE;
    }
    indirectCall = (caller->regs && *caller->regs->pc != JSOP_EVAL);
    uintN staticLevel = caller->script->staticLevel + 1;

    /*
     * This call to js_GetWrappedObject is safe because of the security checks
     * we do below. However, the control flow below is confusing, so we double
     * check. There are two cases:
     * - Direct call: This object is never used. So unwrapping can't hurt.
     * - Indirect call: If this object isn't already the scope chain (which
     *   we're guaranteed to be allowed to access) then we do a security
     *   check.
     */
    obj = js_GetWrappedObject(cx, obj);

    /*
     * Ban all indirect uses of eval (global.foo = eval; global.foo(...)) and
     * calls that attempt to use a non-global object as the "with" object in
     * the former indirect case.
     */
    {
        JSObject *parent = OBJ_GET_PARENT(cx, obj);
        if (indirectCall || parent) {
            uintN flags = parent
                          ? JSREPORT_ERROR
                          : JSREPORT_STRICT | JSREPORT_WARNING;
            if (!JS_ReportErrorFlagsAndNumber(cx, flags, js_GetErrorMessage, NULL,
                                              JSMSG_BAD_INDIRECT_CALL,
                                              js_eval_str)) {
                return JS_FALSE;
            }
        }
    }

    if (!JSVAL_IS_STRING(argv[0])) {
        *rval = argv[0];
        return JS_TRUE;
    }

    /*
     * If the caller is a lightweight function and doesn't have a variables
     * object, then we need to provide one for the compiler to stick any
     * declared (var) variables into.
     */
    if (!caller->varobj && !js_GetCallObject(cx, caller))
        return JS_FALSE;

    /* Accept an optional trailing argument that overrides the scope object. */
    JSObject *scopeobj = NULL;
    if (argc >= 2) {
        if (!js_ValueToObject(cx, argv[1], &scopeobj))
            return JS_FALSE;
        argv[1] = OBJECT_TO_JSVAL(scopeobj);
    }

    /* From here on, control must exit through label out with ok set. */
    MUST_FLOW_THROUGH("out");
    if (!scopeobj) {
#if JS_HAS_EVAL_THIS_SCOPE
        /* If obj.eval(str), emulate 'with (obj) eval(str)' in the caller. */
        if (indirectCall) {
            callerScopeChain = js_GetScopeChain(cx, caller);
            if (!callerScopeChain) {
                ok = JS_FALSE;
                goto out;
            }
            OBJ_TO_INNER_OBJECT(cx, obj);
            if (!obj) {
                ok = JS_FALSE;
                goto out;
            }
            if (obj != callerScopeChain) {
                ok = js_CheckPrincipalsAccess(cx, obj,
                                              JS_StackFramePrincipals(cx, caller),
                                              cx->runtime->atomState.evalAtom);
                if (!ok)
                    goto out;

                scopeobj = js_NewWithObject(cx, obj, callerScopeChain, -1);
                if (!scopeobj) {
                    ok = JS_FALSE;
                    goto out;
                }

                /* Set fp->scopeChain too, for the compiler. */
                caller->scopeChain = fp->scopeChain = scopeobj;

                /* Remember scopeobj so we can null its private when done. */
                setCallerScopeChain = scopeobj;
            }

            callerVarObj = caller->varobj;
            if (obj != callerVarObj) {
                /* Set fp->varobj too, for the compiler. */
                caller->varobj = fp->varobj = obj;
                setCallerVarObj = JS_TRUE;
            }
        }
#endif

        /* Compile using caller's current scope object. */
        scopeobj = js_GetScopeChain(cx, caller);
        if (!scopeobj) {
            ok = JS_FALSE;
            goto out;
        }
    } else {
        scopeobj = js_GetWrappedObject(cx, scopeobj);
        OBJ_TO_INNER_OBJECT(cx, scopeobj);
        if (!scopeobj) {
            ok = JS_FALSE;
            goto out;
        }
        ok = js_CheckPrincipalsAccess(cx, scopeobj,
                                      JS_StackFramePrincipals(cx, caller),
                                      cx->runtime->atomState.evalAtom);
        if (!ok)
            goto out;

        scopeobj = js_NewWithObject(cx, scopeobj,
                                    JS_GetGlobalForObject(cx, scopeobj), -1);
        if (!scopeobj) {
            ok = JS_FALSE;
            goto out;
        }
        argv[1] = OBJECT_TO_JSVAL(scopeobj);
    }

    /* Ensure we compile this eval with the right object in the scope chain. */
    scopeobj = js_CheckScopeChainValidity(cx, scopeobj, js_eval_str);
    if (!scopeobj) {
        ok = JS_FALSE;
        goto out;
    }

    tcflags = TCF_COMPILE_N_GO | TCF_PUT_STATIC_LEVEL(staticLevel);
    principals = JS_EvalFramePrincipals(cx, fp, caller);
    file = js_ComputeFilename(cx, caller, principals, &line);

    str = JSVAL_TO_STRING(argv[0]);
    script = NULL;

    /* Cache local eval scripts indexed by source qualified by scope. */
    bucket = EvalCacheHash(cx, str);
    if (!indirectCall && argc == 1 && caller->fun) {
        uintN count = 0;
        JSScript **scriptp = bucket;

        EVAL_CACHE_METER(probe);
        while ((script = *scriptp) != NULL) {
            if ((script->flags & JSSF_SAVED_CALLER_FUN) &&
                script->staticLevel == staticLevel &&
                script->version == cx->version &&
                (script->principals == principals ||
                 (principals->subsume(principals, script->principals) &&
                  script->principals->subsume(script->principals, principals)))) {
                /*
                 * Get the prior (cache-filling) eval's saved caller function.
                 * See JSCompiler::compileScript in jsparse.cpp.
                 */
                JSFunction *fun;
                fun = script->getFunction(0);

                if (fun == caller->fun) {
                    /*
                     * Get the source string passed for safekeeping in the
                     * atom map by the prior eval to JSCompiler::compileScript.
                     */
                    JSString *src = ATOM_TO_STRING(script->atomMap.vector[0]);

                    if (src == str || js_EqualStrings(src, str)) {
                        /*
                         * Source matches, qualify by comparing scopeobj to the
                         * COMPILE_N_GO-memoized parent of the first literal
                         * function or regexp object if any. If none, then this
                         * script has no compiled-in dependencies on the prior
                         * eval's scopeobj.
                         */
                        JSObjectArray *objarray = script->objects();
                        int i = 1;
                        if (objarray->length == 1) {
                            if (script->regexpsOffset != 0) {
                                objarray = script->regexps();
                                i = 0;
                            } else {
                                EVAL_CACHE_METER(noscope);
                                i = -1;
                            }
                        }
                        if (i < 0 ||
                            STOBJ_GET_PARENT(objarray->vector[i]) == scopeobj) {
                            JS_ASSERT(staticLevel == script->staticLevel);
                            EVAL_CACHE_METER(hit);
                            *scriptp = script->u.nextToGC;
                            script->u.nextToGC = NULL;
                            break;
                        }
                    }
                }
            }

            if (++count == EVAL_CACHE_CHAIN_LIMIT) {
                script = NULL;
                break;
            }
            EVAL_CACHE_METER(step);
            scriptp = &script->u.nextToGC;
        }
    }

    if (!script) {
        script = JSCompiler::compileScript(cx, scopeobj, caller, principals, tcflags,
                                           str->chars(), str->length(),
                                           NULL, file, line, str);
        if (!script) {
            ok = JS_FALSE;
            goto out;
        }
    }

    if (argc < 2) {
        /* Execute using caller's new scope object (might be a Call object). */
        scopeobj = caller->scopeChain;
    }

    /*
     * Belt-and-braces: check that the lesser of eval's principals and the
     * caller's principals has access to scopeobj.
     */
    ok = js_CheckPrincipalsAccess(cx, scopeobj, principals,
                                  cx->runtime->atomState.evalAtom);
    if (ok)
        ok = js_Execute(cx, scopeobj, script, caller, JSFRAME_EVAL, rval);

    script->u.nextToGC = *bucket;
    *bucket = script;
#ifdef CHECK_SCRIPT_OWNER
    script->owner = NULL;
#endif

out:
#if JS_HAS_EVAL_THIS_SCOPE
    /* Restore OBJ_GET_PARENT(scopeobj) not callerScopeChain in case of Call. */
    if (setCallerScopeChain) {
        caller->scopeChain = callerScopeChain;
        JS_ASSERT(OBJ_GET_CLASS(cx, setCallerScopeChain) == &js_WithClass);
        setCallerScopeChain->setPrivate(NULL);
    }
    if (setCallerVarObj)
        caller->varobj = callerVarObj;
#endif
    return ok;
}

#if JS_HAS_OBJ_WATCHPOINT

static JSBool
obj_watch_handler(JSContext *cx, JSObject *obj, jsval id, jsval old, jsval *nvp,
                  void *closure)
{
    JSObject *callable;
    JSSecurityCallbacks *callbacks;
    JSStackFrame *caller;
    JSPrincipals *subject, *watcher;
    JSResolvingKey key;
    JSResolvingEntry *entry;
    uint32 generation;
    jsval argv[3];
    JSBool ok;

    callable = (JSObject *) closure;

    callbacks = JS_GetSecurityCallbacks(cx);
    if (callbacks && callbacks->findObjectPrincipals) {
        /* Skip over any obj_watch_* frames between us and the real subject. */
        caller = js_GetScriptedCaller(cx, NULL);
        if (caller) {
            /*
             * Only call the watch handler if the watcher is allowed to watch
             * the currently executing script.
             */
            watcher = callbacks->findObjectPrincipals(cx, callable);
            subject = JS_StackFramePrincipals(cx, caller);

            if (watcher && subject && !watcher->subsume(watcher, subject)) {
                /* Silently don't call the watch handler. */
                return JS_TRUE;
            }
        }
    }

    /* Avoid recursion on (obj, id) already being watched on cx. */
    key.obj = obj;
    key.id = id;
    if (!js_StartResolving(cx, &key, JSRESFLAG_WATCH, &entry))
        return JS_FALSE;
    if (!entry)
        return JS_TRUE;
    generation = cx->resolvingTable->generation;

    argv[0] = id;
    argv[1] = old;
    argv[2] = *nvp;
    ok = js_InternalCall(cx, obj, OBJECT_TO_JSVAL(callable), 3, argv, nvp);
    js_StopResolving(cx, &key, JSRESFLAG_WATCH, entry, generation);
    return ok;
}

static JSBool
obj_watch(JSContext *cx, uintN argc, jsval *vp)
{
    JSObject *callable;
    jsval userid, value;
    jsid propid;
    JSObject *obj;
    uintN attrs;

    if (argc <= 1) {
        js_ReportMissingArg(cx, vp, 1);
        return JS_FALSE;
    }

    callable = js_ValueToCallableObject(cx, &vp[3], 0);
    if (!callable)
        return JS_FALSE;

    /* Compute the unique int/atom symbol id needed by js_LookupProperty. */
    userid = vp[2];
    if (!JS_ValueToId(cx, userid, &propid))
        return JS_FALSE;

    obj = JS_THIS_OBJECT(cx, vp);
    if (!obj || !obj->checkAccess(cx, propid, JSACC_WATCH, &value, &attrs))
        return JS_FALSE;
    if (attrs & JSPROP_READONLY)
        return JS_TRUE;
    *vp = JSVAL_VOID;

    if (OBJ_IS_DENSE_ARRAY(cx, obj) && !js_MakeArraySlow(cx, obj))
        return JS_FALSE;
    return JS_SetWatchPoint(cx, obj, userid, obj_watch_handler, callable);
}

static JSBool
obj_unwatch(JSContext *cx, uintN argc, jsval *vp)
{
    JSObject *obj;

    obj = JS_THIS_OBJECT(cx, vp);
    if (!obj)
        return JS_FALSE;
    *vp = JSVAL_VOID;
    return JS_ClearWatchPoint(cx, obj, argc != 0 ? vp[2] : JSVAL_VOID,
                              NULL, NULL);
}

#endif /* JS_HAS_OBJ_WATCHPOINT */

/*
 * Prototype and property query methods, to complement the 'in' and
 * 'instanceof' operators.
 */

/* Proposed ECMA 15.2.4.5. */
static JSBool
obj_hasOwnProperty(JSContext *cx, uintN argc, jsval *vp)
{
    JSObject *obj;

    obj = JS_THIS_OBJECT(cx, vp);
    return obj &&
           js_HasOwnPropertyHelper(cx, obj->map->ops->lookupProperty, argc, vp);
}

JSBool
js_HasOwnPropertyHelper(JSContext *cx, JSLookupPropOp lookup, uintN argc,
                        jsval *vp)
{
    jsid id;
    JSObject *obj;

    if (!JS_ValueToId(cx, argc != 0 ? vp[2] : JSVAL_VOID, &id))
        return JS_FALSE;
    obj = JS_THIS_OBJECT(cx, vp);
    return obj && js_HasOwnProperty(cx, lookup, obj, id, vp);
}

JSBool
js_HasOwnProperty(JSContext *cx, JSLookupPropOp lookup, JSObject *obj, jsid id,
                  jsval *vp)
{
    JSObject *obj2;
    JSProperty *prop;
    JSScopeProperty *sprop;

    if (!lookup(cx, obj, id, &obj2, &prop))
        return JS_FALSE;
    if (!prop) {
        *vp = JSVAL_FALSE;
    } else if (obj2 == obj) {
        *vp = JSVAL_TRUE;
    } else {
        JSClass *clasp;
        JSExtendedClass *xclasp;
        JSObject *outer;

        clasp = OBJ_GET_CLASS(cx, obj2);
        if (!(clasp->flags & JSCLASS_IS_EXTENDED) ||
            !(xclasp = (JSExtendedClass *) clasp)->outerObject) {
            outer = NULL;
        } else {
            outer = xclasp->outerObject(cx, obj2);
            if (!outer)
                return JS_FALSE;
        }
        if (outer == obj) {
            *vp = JSVAL_TRUE;
        } else if (OBJ_IS_NATIVE(obj2) && OBJ_GET_CLASS(cx, obj) == clasp) {
            /*
             * The combination of JSPROP_SHARED and JSPROP_PERMANENT in a
             * delegated property makes that property appear to be direct in
             * all delegating instances of the same native class.  This hack
             * avoids bloating every function instance with its own 'length'
             * (AKA 'arity') property.  But it must not extend across class
             * boundaries, to avoid making hasOwnProperty lie (bug 320854).
             *
             * It's not really a hack, of course: a permanent property can't
             * be deleted, and JSPROP_SHARED means "don't allocate a slot in
             * any instance, prototype or delegating".  Without a slot, and
             * without the ability to remove and recreate (with differences)
             * the property, there is no way to tell whether it is directly
             * owned, or indirectly delegated.
             */
            sprop = (JSScopeProperty *)prop;
            *vp = BOOLEAN_TO_JSVAL(SPROP_IS_SHARED_PERMANENT(sprop));
        } else {
            *vp = JSVAL_FALSE;
        }
    }
    if (prop)
        obj2->dropProperty(cx, prop);
    return JS_TRUE;
}

#ifdef JS_TRACER
static JSBool FASTCALL
Object_p_hasOwnProperty(JSContext* cx, JSObject* obj, JSString *str)
{
    jsid id;
    jsval v;

    if (!js_ValueToStringId(cx, STRING_TO_JSVAL(str), &id) ||
        !js_HasOwnProperty(cx, obj->map->ops->lookupProperty, obj, id, &v)) {
        js_SetBuiltinError(cx);
        return JSVAL_TO_BOOLEAN(JSVAL_VOID);
    }

    JS_ASSERT(JSVAL_IS_BOOLEAN(v));
    return JSVAL_TO_BOOLEAN(v);
}
#endif

/* Proposed ECMA 15.2.4.6. */
static JSBool
obj_isPrototypeOf(JSContext *cx, uintN argc, jsval *vp)
{
    JSBool b;

    if (!js_IsDelegate(cx, JS_THIS_OBJECT(cx, vp),
                       argc != 0 ? vp[2] : JSVAL_VOID, &b)) {
        return JS_FALSE;
    }
    *vp = BOOLEAN_TO_JSVAL(b);
    return JS_TRUE;
}

/* Proposed ECMA 15.2.4.7. */
static JSBool
obj_propertyIsEnumerable(JSContext *cx, uintN argc, jsval *vp)
{
    jsid id;
    JSObject *obj;

    if (!JS_ValueToId(cx, argc != 0 ? vp[2] : JSVAL_VOID, &id))
        return JS_FALSE;

    obj = JS_THIS_OBJECT(cx, vp);
    return obj && js_PropertyIsEnumerable(cx, obj, id, vp);
}

#ifdef JS_TRACER
static JSBool FASTCALL
Object_p_propertyIsEnumerable(JSContext* cx, JSObject* obj, JSString *str)
{
    jsid id = ATOM_TO_JSID(STRING_TO_JSVAL(str));
    jsval v;

    if (!js_PropertyIsEnumerable(cx, obj, id, &v)) {
        js_SetBuiltinError(cx);
        return JSVAL_TO_BOOLEAN(JSVAL_VOID);
    }

    JS_ASSERT(JSVAL_IS_BOOLEAN(v));
    return JSVAL_TO_BOOLEAN(v);
}
#endif

JSBool
js_PropertyIsEnumerable(JSContext *cx, JSObject *obj, jsid id, jsval *vp)
{
    JSObject *pobj;
    uintN attrs;
    JSProperty *prop;
    JSBool ok;

    if (!obj->lookupProperty(cx, id, &pobj, &prop))
        return JS_FALSE;

    if (!prop) {
        *vp = JSVAL_FALSE;
        return JS_TRUE;
    }

    /*
     * XXX ECMA spec error compatible: return false unless hasOwnProperty.
     * The ECMA spec really should be fixed so propertyIsEnumerable and the
     * for..in loop agree on whether prototype properties are enumerable,
     * obviously by fixing this method (not by breaking the for..in loop!).
     *
     * We check here for shared permanent prototype properties, which should
     * be treated as if they are local to obj.  They are an implementation
     * technique used to satisfy ECMA requirements; users should not be able
     * to distinguish a shared permanent proto-property from a local one.
     */
    if (pobj != obj &&
        !(OBJ_IS_NATIVE(pobj) &&
          SPROP_IS_SHARED_PERMANENT((JSScopeProperty *)prop))) {
        pobj->dropProperty(cx, prop);
        *vp = JSVAL_FALSE;
        return JS_TRUE;
    }

    ok = pobj->getAttributes(cx, id, prop, &attrs);
    pobj->dropProperty(cx, prop);
    if (ok)
        *vp = BOOLEAN_TO_JSVAL((attrs & JSPROP_ENUMERATE) != 0);
    return ok;
}

#if JS_HAS_GETTER_SETTER
JS_FRIEND_API(JSBool)
js_obj_defineGetter(JSContext *cx, uintN argc, jsval *vp)
{
    jsval fval, junk;
    jsid id;
    JSObject *obj;
    uintN attrs;

    if (argc <= 1 || JS_TypeOfValue(cx, vp[3]) != JSTYPE_FUNCTION) {
        JS_ReportErrorNumber(cx, js_GetErrorMessage, NULL,
                             JSMSG_BAD_GETTER_OR_SETTER,
                             js_getter_str);
        return JS_FALSE;
    }
    fval = vp[3];

    if (!JS_ValueToId(cx, vp[2], &id))
        return JS_FALSE;
    obj = JS_THIS_OBJECT(cx, vp);
    if (!obj || !js_CheckRedeclaration(cx, obj, id, JSPROP_GETTER, NULL, NULL))
        return JS_FALSE;
    /*
     * Getters and setters are just like watchpoints from an access
     * control point of view.
     */
    if (!obj->checkAccess(cx, id, JSACC_WATCH, &junk, &attrs))
        return JS_FALSE;
    *vp = JSVAL_VOID;
    return obj->defineProperty(cx, id, JSVAL_VOID,
                               js_CastAsPropertyOp(JSVAL_TO_OBJECT(fval)), JS_PropertyStub,
                               JSPROP_ENUMERATE | JSPROP_GETTER | JSPROP_SHARED);
}

JS_FRIEND_API(JSBool)
js_obj_defineSetter(JSContext *cx, uintN argc, jsval *vp)
{
    jsval fval, junk;
    jsid id;
    JSObject *obj;
    uintN attrs;

    if (argc <= 1 || JS_TypeOfValue(cx, vp[3]) != JSTYPE_FUNCTION) {
        JS_ReportErrorNumber(cx, js_GetErrorMessage, NULL,
                             JSMSG_BAD_GETTER_OR_SETTER,
                             js_setter_str);
        return JS_FALSE;
    }
    fval = vp[3];

    if (!JS_ValueToId(cx, vp[2], &id))
        return JS_FALSE;
    obj = JS_THIS_OBJECT(cx, vp);
    if (!obj || !js_CheckRedeclaration(cx, obj, id, JSPROP_SETTER, NULL, NULL))
        return JS_FALSE;
    /*
     * Getters and setters are just like watchpoints from an access
     * control point of view.
     */
    if (!obj->checkAccess(cx, id, JSACC_WATCH, &junk, &attrs))
        return JS_FALSE;
    *vp = JSVAL_VOID;
    return obj->defineProperty(cx, id, JSVAL_VOID,
                               JS_PropertyStub, js_CastAsPropertyOp(JSVAL_TO_OBJECT(fval)),
                               JSPROP_ENUMERATE | JSPROP_SETTER | JSPROP_SHARED);
}

static JSBool
obj_lookupGetter(JSContext *cx, uintN argc, jsval *vp)
{
    jsid id;
    JSObject *obj, *pobj;
    JSProperty *prop;
    JSScopeProperty *sprop;

    if (!JS_ValueToId(cx, argc != 0 ? vp[2] : JSVAL_VOID, &id))
        return JS_FALSE;
    obj = JS_THIS_OBJECT(cx, vp);
    if (!obj || !obj->lookupProperty(cx, id, &pobj, &prop))
        return JS_FALSE;
    *vp = JSVAL_VOID;
    if (prop) {
        if (OBJ_IS_NATIVE(pobj)) {
            sprop = (JSScopeProperty *) prop;
            if (sprop->attrs & JSPROP_GETTER)
                *vp = js_CastAsObjectJSVal(sprop->getter);
        }
        pobj->dropProperty(cx, prop);
    }
    return JS_TRUE;
}

static JSBool
obj_lookupSetter(JSContext *cx, uintN argc, jsval *vp)
{
    jsid id;
    JSObject *obj, *pobj;
    JSProperty *prop;
    JSScopeProperty *sprop;

    if (!JS_ValueToId(cx, argc != 0 ? vp[2] : JSVAL_VOID, &id))
        return JS_FALSE;
    obj = JS_THIS_OBJECT(cx, vp);
    if (!obj || !obj->lookupProperty(cx, id, &pobj, &prop))
        return JS_FALSE;
    *vp = JSVAL_VOID;
    if (prop) {
        if (OBJ_IS_NATIVE(pobj)) {
            sprop = (JSScopeProperty *) prop;
            if (sprop->attrs & JSPROP_SETTER)
                *vp = js_CastAsObjectJSVal(sprop->setter);
        }
        pobj->dropProperty(cx, prop);
    }
    return JS_TRUE;
}
#endif /* JS_HAS_GETTER_SETTER */

JSBool
obj_getPrototypeOf(JSContext *cx, uintN argc, jsval *vp)
{
    JSObject *obj;
    uintN attrs;

    if (argc == 0) {
        js_ReportMissingArg(cx, vp, 0);
        return JS_FALSE;
    }

    obj = js_ValueToNonNullObject(cx, vp[2]);
    if (!obj)
        return JS_FALSE;
    vp[2] = OBJECT_TO_JSVAL(obj);

    return obj->checkAccess(cx, ATOM_TO_JSID(cx->runtime->atomState.protoAtom),
                            JSACC_PROTO, vp, &attrs);
}

#if JS_HAS_OBJ_WATCHPOINT
const char js_watch_str[] = "watch";
const char js_unwatch_str[] = "unwatch";
#endif
const char js_hasOwnProperty_str[] = "hasOwnProperty";
const char js_isPrototypeOf_str[] = "isPrototypeOf";
const char js_propertyIsEnumerable_str[] = "propertyIsEnumerable";
#if JS_HAS_GETTER_SETTER
const char js_defineGetter_str[] = "__defineGetter__";
const char js_defineSetter_str[] = "__defineSetter__";
const char js_lookupGetter_str[] = "__lookupGetter__";
const char js_lookupSetter_str[] = "__lookupSetter__";
#endif

JS_DEFINE_TRCINFO_1(obj_valueOf,
    (3, (static, JSVAL,     Object_p_valueOf,               CONTEXT, THIS, STRING,  0, 0)))
JS_DEFINE_TRCINFO_1(obj_hasOwnProperty,
    (3, (static, BOOL_FAIL, Object_p_hasOwnProperty,        CONTEXT, THIS, STRING,  0, 0)))
JS_DEFINE_TRCINFO_1(obj_propertyIsEnumerable,
    (3, (static, BOOL_FAIL, Object_p_propertyIsEnumerable,  CONTEXT, THIS, STRING,  0, 0)))

static JSFunctionSpec object_methods[] = {
#if JS_HAS_TOSOURCE
    JS_FN(js_toSource_str,             obj_toSource,                0,0),
#endif
    JS_FN(js_toString_str,             obj_toString,                0,0),
    JS_FN(js_toLocaleString_str,       obj_toLocaleString,          0,0),
    JS_TN(js_valueOf_str,              obj_valueOf,                 0,0, &obj_valueOf_trcinfo),
#if JS_HAS_OBJ_WATCHPOINT
    JS_FN(js_watch_str,                obj_watch,                   2,0),
    JS_FN(js_unwatch_str,              obj_unwatch,                 1,0),
#endif
    JS_TN(js_hasOwnProperty_str,       obj_hasOwnProperty,          1,0, &obj_hasOwnProperty_trcinfo),
    JS_FN(js_isPrototypeOf_str,        obj_isPrototypeOf,           1,0),
    JS_TN(js_propertyIsEnumerable_str, obj_propertyIsEnumerable,    1,0, &obj_propertyIsEnumerable_trcinfo),
#if JS_HAS_GETTER_SETTER
    JS_FN(js_defineGetter_str,         js_obj_defineGetter,         2,0),
    JS_FN(js_defineSetter_str,         js_obj_defineSetter,         2,0),
    JS_FN(js_lookupGetter_str,         obj_lookupGetter,            1,0),
    JS_FN(js_lookupSetter_str,         obj_lookupSetter,            1,0),
#endif
    JS_FS_END
};

static JSFunctionSpec object_static_methods[] = {
    JS_FN("getPrototypeOf",            obj_getPrototypeOf,          1,0),
    JS_FS_END
};

static bool
AllocSlots(JSContext *cx, JSObject *obj, size_t nslots);

static inline bool
InitScopeForObject(JSContext* cx, JSObject* obj, JSObject* proto, JSObjectOps* ops)
{
    JS_ASSERT(OPS_IS_NATIVE(ops));
    JS_ASSERT(proto == OBJ_GET_PROTO(cx, obj));

    /* Share proto's emptyScope only if obj is similar to proto. */
    JSClass *clasp = OBJ_GET_CLASS(cx, obj);
    JSScope *scope;
    if (proto && OBJ_IS_NATIVE(proto) &&
        (scope = OBJ_SCOPE(proto))->canProvideEmptyScope(ops, clasp)) {
        scope = scope->getEmptyScope(cx, clasp);
        if (!scope)
            goto bad;
    } else {
        scope = JSScope::create(cx, ops, clasp, obj, js_GenerateShape(cx, false));
        if (!scope)
            goto bad;

        /* Let JSScope::create set freeslot so as to reserve slots. */
        JS_ASSERT(scope->freeslot >= JSSLOT_PRIVATE);
        if (scope->freeslot > JS_INITIAL_NSLOTS &&
            !AllocSlots(cx, obj, scope->freeslot)) {
            JSScope::destroy(cx, scope);
            goto bad;
        }
    }
    obj->map = scope;
    return true;

  bad:
    /* The GC nulls map initially. It should still be null on error. */
    JS_ASSERT(!obj->map);
    return false;
}

JSObject *
js_NewObjectWithGivenProto(JSContext *cx, JSClass *clasp, JSObject *proto,
                           JSObject *parent, size_t objectSize)
{
#ifdef INCLUDE_MOZILLA_DTRACE
    if (JAVASCRIPT_OBJECT_CREATE_START_ENABLED())
        jsdtrace_object_create_start(cx->fp, clasp);
#endif

    /* Assert that the class is a proper class. */
    JS_ASSERT_IF(clasp->flags & JSCLASS_IS_EXTENDED,
                 ((JSExtendedClass *)clasp)->equality);

    /* Always call the class's getObjectOps hook if it has one. */
    JSObjectOps *ops = clasp->getObjectOps
                       ? clasp->getObjectOps(cx, clasp)
                       : &js_ObjectOps;

    /*
     * Allocate an object from the GC heap and initialize all its fields before
     * doing any operation that can potentially trigger GC. Functions have a
     * larger non-standard allocation size.
     */
    JSObject* obj;
    if (clasp == &js_FunctionClass && !objectSize) {
        obj = (JSObject*) js_NewGCFunction(cx, GCX_OBJECT);
#ifdef DEBUG
        memset((uint8 *) obj + sizeof(JSObject), JS_FREE_PATTERN,
               sizeof(JSFunction) - sizeof(JSObject));
#endif
    } else {
        JS_ASSERT(!objectSize || objectSize == sizeof(JSObject));
        obj = js_NewGCObject(cx, GCX_OBJECT);
    }
    if (!obj)
        goto out;

    /*
     * Default parent to the parent of the prototype, which was set from
     * the parent of the prototype's constructor.
     */
    obj->init(clasp,
              proto,
              (!parent && proto) ? proto->getParent() : parent,
              JSObject::defaultPrivate(clasp));

    if (OPS_IS_NATIVE(ops)) {
        if (!InitScopeForObject(cx, obj, proto, ops)) {
            obj = NULL;
            goto out;
        }
    } else {
        JS_ASSERT(ops->objectMap->ops == ops);
        obj->map = const_cast<JSObjectMap *>(ops->objectMap);
    }

    /* Check that the newborn root still holds the object. */
    JS_ASSERT_IF(!cx->localRootStack, cx->weakRoots.newborn[GCX_OBJECT] == obj);

    /*
     * Do not call debug hooks on trace, because we might be in a non-_FAIL
     * builtin. See bug 481444.
     */
    if (cx->debugHooks->objectHook && !JS_ON_TRACE(cx)) {
        JSAutoTempValueRooter tvr(cx, obj);
        JS_KEEP_ATOMS(cx->runtime);
        cx->debugHooks->objectHook(cx, obj, JS_TRUE,
                                   cx->debugHooks->objectHookData);
        JS_UNKEEP_ATOMS(cx->runtime);
        cx->weakRoots.newborn[GCX_OBJECT] = obj;
    }

out:
#ifdef INCLUDE_MOZILLA_DTRACE
    if (JAVASCRIPT_OBJECT_CREATE_ENABLED())
        jsdtrace_object_create(cx, clasp, obj);
    if (JAVASCRIPT_OBJECT_CREATE_DONE_ENABLED())
        jsdtrace_object_create_done(cx->fp, clasp);
#endif
    return obj;
}

JSObject *
js_NewObject(JSContext *cx, JSClass *clasp, JSObject *proto,
             JSObject *parent, size_t objectSize)
{
    jsid id;

    /* Bootstrap the ur-object, and make it the default prototype object. */
    if (!proto) {
        if (!js_GetClassId(cx, clasp, &id))
            return NULL;
        if (!js_GetClassPrototype(cx, parent, id, &proto))
            return NULL;
        if (!proto &&
            !js_GetClassPrototype(cx, parent, INT_TO_JSID(JSProto_Object),
                                  &proto)) {
            return NULL;
        }
    }

    return js_NewObjectWithGivenProto(cx, clasp, proto, parent, objectSize);
}

JSBool
js_Object(JSContext *cx, JSObject *obj, uintN argc, jsval *argv, jsval *rval)
{
    if (argc == 0) {
        /* Trigger logic below to construct a blank object. */
        obj = NULL;
    } else {
        /* If argv[0] is null or undefined, obj comes back null. */
        if (!js_ValueToObject(cx, argv[0], &obj))
            return JS_FALSE;
    }
    if (!obj) {
        JS_ASSERT(!argc || JSVAL_IS_NULL(argv[0]) || JSVAL_IS_VOID(argv[0]));
        if (JS_IsConstructing(cx))
            return JS_TRUE;
        obj = js_NewObject(cx, &js_ObjectClass, NULL, NULL);
        if (!obj)
            return JS_FALSE;
    }
    *rval = OBJECT_TO_JSVAL(obj);
    return JS_TRUE;
}

#ifdef JS_TRACER

JSObject*
js_NewObjectWithClassProto(JSContext *cx, JSClass *clasp, JSObject *proto,
                           jsval privateSlotValue)
{
    JS_ASSERT(!clasp->getObjectOps);
    JS_ASSERT(proto->map->ops == &js_ObjectOps);

    JSObject* obj = js_NewGCObject(cx, GCX_OBJECT);
    if (!obj)
        return NULL;

    obj->initSharingEmptyScope(clasp, proto, proto->getParent(), privateSlotValue);
    return obj;
}

JSObject* FASTCALL
js_Object_tn(JSContext* cx, JSObject* proto)
{
    JS_ASSERT(!(js_ObjectClass.flags & JSCLASS_HAS_PRIVATE));
    return js_NewObjectWithClassProto(cx, &js_ObjectClass, proto, JSVAL_VOID);
}

JS_DEFINE_TRCINFO_1(js_Object,
    (2, (extern, CONSTRUCTOR_RETRY, js_Object_tn, CONTEXT, CALLEE_PROTOTYPE, 0, 0)))

static inline JSObject*
NewNativeObject(JSContext* cx, JSClass* clasp, JSObject* proto,
                JSObject *parent, jsval privateSlotValue)
{
    JS_ASSERT(JS_ON_TRACE(cx));
    JSObject* obj = js_NewGCObject(cx, GCX_OBJECT);
    if (!obj)
        return NULL;

    obj->init(clasp, proto, parent, privateSlotValue);
    return InitScopeForObject(cx, obj, proto, &js_ObjectOps) ? obj : NULL;
}

JSObject* FASTCALL
js_NewInstance(JSContext *cx, JSClass *clasp, JSObject *ctor)
{
    JS_ASSERT(HAS_FUNCTION_CLASS(ctor));

    JSAtom *atom = cx->runtime->atomState.classPrototypeAtom;

    JSScope *scope = OBJ_SCOPE(ctor);
#ifdef JS_THREADSAFE
    if (scope->title.ownercx != cx)
        return NULL;
#endif
    if (!scope->owned()) {
        scope = js_GetMutableScope(cx, ctor);
        if (!scope)
            return NULL;
    }

    JSScopeProperty *sprop = scope->lookup(ATOM_TO_JSID(atom));
    jsval pval = sprop ? STOBJ_GET_SLOT(ctor, sprop->slot) : JSVAL_HOLE;

    JSObject *proto;
    if (!JSVAL_IS_PRIMITIVE(pval)) {
        /* An object in ctor.prototype, let's use it as the new instance's proto. */
        proto = JSVAL_TO_OBJECT(pval);
    } else if (pval == JSVAL_HOLE) {
        /* No ctor.prototype yet, inline and optimize fun_resolve's prototype code. */
        proto = js_NewObject(cx, clasp, NULL, OBJ_GET_PARENT(cx, ctor));
        if (!proto)
            return NULL;
        if (!js_SetClassPrototype(cx, ctor, proto, JSPROP_ENUMERATE | JSPROP_PERMANENT))
            return NULL;
    } else {
        /* Primitive value in .prototype means we use Object.prototype for proto. */
        if (!js_GetClassPrototype(cx, JSVAL_TO_OBJECT(ctor->fslots[JSSLOT_PARENT]),
                                  INT_TO_JSID(JSProto_Object), &proto)) {
            return NULL;
        }
    }

    return NewNativeObject(cx, clasp, proto, ctor->getParent(),
                           JSObject::defaultPrivate(clasp));
}

JS_DEFINE_CALLINFO_3(extern, CONSTRUCTOR_RETRY, js_NewInstance, CONTEXT, CLASS, OBJECT, 0, 0)

#else  /* !JS_TRACER */

# define js_Object_trcinfo NULL

#endif /* !JS_TRACER */

/*
 * Given pc pointing after a property accessing bytecode, return true if the
 * access is "object-detecting" in the sense used by web scripts, e.g., when
 * checking whether document.all is defined.
 */
JS_REQUIRES_STACK JSBool
Detecting(JSContext *cx, jsbytecode *pc)
{
    JSScript *script;
    jsbytecode *endpc;
    JSOp op;
    JSAtom *atom;

    script = cx->fp->script;
    endpc = script->code + script->length;
    for (;; pc += js_CodeSpec[op].length) {
        JS_ASSERT_IF(!cx->fp->imacpc, script->code <= pc && pc < endpc);

        /* General case: a branch or equality op follows the access. */
        op = js_GetOpcode(cx, script, pc);
        if (js_CodeSpec[op].format & JOF_DETECTING)
            return JS_TRUE;

        switch (op) {
          case JSOP_NULL:
            /*
             * Special case #1: handle (document.all == null).  Don't sweat
             * about JS1.2's revision of the equality operators here.
             */
            if (++pc < endpc) {
                op = js_GetOpcode(cx, script, pc);
                return *pc == JSOP_EQ || *pc == JSOP_NE;
            }
            return JS_FALSE;

          case JSOP_NAME:
            /*
             * Special case #2: handle (document.all == undefined).  Don't
             * worry about someone redefining undefined, which was added by
             * Edition 3, so is read/write for backward compatibility.
             */
            GET_ATOM_FROM_BYTECODE(script, pc, 0, atom);
            if (atom == cx->runtime->atomState.typeAtoms[JSTYPE_VOID] &&
                (pc += js_CodeSpec[op].length) < endpc) {
                op = js_GetOpcode(cx, script, pc);
                return op == JSOP_EQ || op == JSOP_NE ||
                       op == JSOP_STRICTEQ || op == JSOP_STRICTNE;
            }
            return JS_FALSE;

          default:
            /*
             * At this point, anything but an extended atom index prefix means
             * we're not detecting.
             */
            if (!(js_CodeSpec[op].format & JOF_INDEXBASE))
                return JS_FALSE;
            break;
        }
    }
}

/*
 * Infer lookup flags from the currently executing bytecode. This does
 * not attempt to infer JSRESOLVE_WITH, because the current bytecode
 * does not indicate whether we are in a with statement. Return defaultFlags
 * if a currently executing bytecode cannot be determined.
 */
uintN
js_InferFlags(JSContext *cx, uintN defaultFlags)
{
#ifdef JS_TRACER
    if (JS_ON_TRACE(cx))
        return cx->bailExit->lookupFlags;
#endif

    JS_ASSERT_NOT_ON_TRACE(cx);

    JSStackFrame *fp;
    jsbytecode *pc;
    const JSCodeSpec *cs;
    uint32 format;
    uintN flags = 0;

    fp = js_GetTopStackFrame(cx);
    if (!fp || !fp->regs)
        return defaultFlags;
    pc = fp->regs->pc;
    cs = &js_CodeSpec[js_GetOpcode(cx, fp->script, pc)];
    format = cs->format;
    if (JOF_MODE(format) != JOF_NAME)
        flags |= JSRESOLVE_QUALIFIED;
    if ((format & (JOF_SET | JOF_FOR)) ||
        (fp->flags & JSFRAME_ASSIGNING)) {
        flags |= JSRESOLVE_ASSIGNING;
    } else if (cs->length >= 0) {
        pc += cs->length;
        if (pc < cx->fp->script->code + cx->fp->script->length && Detecting(cx, pc))
            flags |= JSRESOLVE_DETECTING;
    }
    if (format & JOF_DECLARING)
        flags |= JSRESOLVE_DECLARING;
    return flags;
}

/*
 * ObjectOps and Class for with-statement stack objects.
 */
static JSBool
with_LookupProperty(JSContext *cx, JSObject *obj, jsid id, JSObject **objp,
                    JSProperty **propp)
{
    /* Fixes bug 463997 */
    uintN flags = cx->resolveFlags;
    if (flags == JSRESOLVE_INFER)
        flags = js_InferFlags(cx, flags);
    flags |= JSRESOLVE_WITH;
    JSAutoResolveFlags rf(cx, flags);
    JSObject *proto = OBJ_GET_PROTO(cx, obj);
    if (!proto)
        return js_LookupProperty(cx, obj, id, objp, propp);
    return proto->lookupProperty(cx, id, objp, propp);
}

static JSBool
with_GetProperty(JSContext *cx, JSObject *obj, jsid id, jsval *vp)
{
    JSObject *proto = OBJ_GET_PROTO(cx, obj);
    if (!proto)
        return js_GetProperty(cx, obj, id, vp);
    return proto->getProperty(cx, id, vp);
}

static JSBool
with_SetProperty(JSContext *cx, JSObject *obj, jsid id, jsval *vp)
{
    JSObject *proto = OBJ_GET_PROTO(cx, obj);
    if (!proto)
        return js_SetProperty(cx, obj, id, vp);
    return proto->setProperty(cx, id, vp);
}

static JSBool
with_GetAttributes(JSContext *cx, JSObject *obj, jsid id, JSProperty *prop,
                   uintN *attrsp)
{
    JSObject *proto = OBJ_GET_PROTO(cx, obj);
    if (!proto)
        return js_GetAttributes(cx, obj, id, prop, attrsp);
    return proto->getAttributes(cx, id, prop, attrsp);
}

static JSBool
with_SetAttributes(JSContext *cx, JSObject *obj, jsid id, JSProperty *prop,
                   uintN *attrsp)
{
    JSObject *proto = OBJ_GET_PROTO(cx, obj);
    if (!proto)
        return js_SetAttributes(cx, obj, id, prop, attrsp);
    return proto->setAttributes(cx, id, prop, attrsp);
}

static JSBool
with_DeleteProperty(JSContext *cx, JSObject *obj, jsid id, jsval *rval)
{
    JSObject *proto = OBJ_GET_PROTO(cx, obj);
    if (!proto)
        return js_DeleteProperty(cx, obj, id, rval);
    return proto->deleteProperty(cx, id, rval);
}

static JSBool
with_DefaultValue(JSContext *cx, JSObject *obj, JSType hint, jsval *vp)
{
    JSObject *proto = OBJ_GET_PROTO(cx, obj);
    if (!proto)
        return js_DefaultValue(cx, obj, hint, vp);
    return proto->defaultValue(cx, hint, vp);
}

static JSBool
with_Enumerate(JSContext *cx, JSObject *obj, JSIterateOp enum_op,
               jsval *statep, jsid *idp)
{
    JSObject *proto = OBJ_GET_PROTO(cx, obj);
    if (!proto)
        return js_Enumerate(cx, obj, enum_op, statep, idp);
    return proto->enumerate(cx, enum_op, statep, idp);
}

static JSBool
with_CheckAccess(JSContext *cx, JSObject *obj, jsid id, JSAccessMode mode,
                 jsval *vp, uintN *attrsp)
{
    JSObject *proto = OBJ_GET_PROTO(cx, obj);
    if (!proto)
        return js_CheckAccess(cx, obj, id, mode, vp, attrsp);
    return proto->checkAccess(cx, id, mode, vp, attrsp);
}

static JSObject *
with_ThisObject(JSContext *cx, JSObject *obj)
{
    JSObject *proto = OBJ_GET_PROTO(cx, obj);
    if (!proto)
        return obj;
    return proto->thisObject(cx);
}

JS_FRIEND_DATA(JSObjectOps) js_WithObjectOps = {
    NULL,
    with_LookupProperty,    js_DefineProperty,
    with_GetProperty,       with_SetProperty,
    with_GetAttributes,     with_SetAttributes,
    with_DeleteProperty,    with_DefaultValue,
    with_Enumerate,         with_CheckAccess,
    with_ThisObject,        NATIVE_DROP_PROPERTY,
    NULL,                   NULL,
    NULL,                   js_TraceObject,
    js_Clear
};

static JSObjectOps *
with_getObjectOps(JSContext *cx, JSClass *clasp)
{
    return &js_WithObjectOps;
}

JSClass js_WithClass = {
    "With",
    JSCLASS_HAS_PRIVATE | JSCLASS_HAS_RESERVED_SLOTS(1) | JSCLASS_IS_ANONYMOUS,
    JS_PropertyStub,  JS_PropertyStub,  JS_PropertyStub,  JS_PropertyStub,
    JS_EnumerateStub, JS_ResolveStub,   JS_ConvertStub,   NULL,
    with_getObjectOps,
    0,0,0,0,0,0,0
};

JS_REQUIRES_STACK JSObject *
js_NewWithObject(JSContext *cx, JSObject *proto, JSObject *parent, jsint depth)
{
    JSObject *obj;

    obj = js_NewObject(cx, &js_WithClass, proto, parent);
    if (!obj)
        return NULL;
    obj->setPrivate(cx->fp);
    OBJ_SET_BLOCK_DEPTH(cx, obj, depth);
    return obj;
}

JSObject *
js_NewBlockObject(JSContext *cx)
{
    /*
     * Null obj's proto slot so that Object.prototype.* does not pollute block
     * scopes and to give the block object its own scope.
     */
    JSObject *blockObj = js_NewObjectWithGivenProto(cx, &js_BlockClass, NULL, NULL);
    JS_ASSERT_IF(blockObj, !OBJ_IS_CLONED_BLOCK(blockObj));
    return blockObj;
}

JSObject *
js_CloneBlockObject(JSContext *cx, JSObject *proto, JSStackFrame *fp)
{
    JS_ASSERT(!OBJ_IS_CLONED_BLOCK(proto));
    JS_ASSERT(STOBJ_GET_CLASS(proto) == &js_BlockClass);

    JSObject *clone = js_NewGCObject(cx, GCX_OBJECT);
    if (!clone)
        return NULL;

    JSScope *scope = OBJ_SCOPE(proto);
    scope->hold();
    JS_ASSERT(!scope->owned());
    clone->map = scope;

    clone->classword = jsuword(&js_BlockClass);
    clone->setProto(proto);
    clone->setParent(NULL);  // caller's responsibility
    clone->setPrivate(fp);
    clone->fslots[JSSLOT_BLOCK_DEPTH] = proto->fslots[JSSLOT_BLOCK_DEPTH];
    JS_ASSERT(scope->freeslot == JSSLOT_BLOCK_DEPTH + 1);
    for (uint32 i = JSSLOT_BLOCK_DEPTH + 1; i < JS_INITIAL_NSLOTS; ++i)
        clone->fslots[i] = JSVAL_VOID;
    clone->dslots = NULL;
    JS_ASSERT(OBJ_IS_CLONED_BLOCK(clone));
    return clone;
}

JS_REQUIRES_STACK JSBool
js_PutBlockObject(JSContext *cx, JSBool normalUnwind)
{
    JSStackFrame *fp;
    JSObject *obj;
    uintN depth, count;

    /* Blocks have one fixed slot available for the first local.*/
    JS_STATIC_ASSERT(JS_INITIAL_NSLOTS == JSSLOT_BLOCK_DEPTH + 2);

    fp = cx->fp;
    obj = fp->scopeChain;
    JS_ASSERT(OBJ_GET_CLASS(cx, obj) == &js_BlockClass);
    JS_ASSERT(obj->getPrivate() == cx->fp);
    JS_ASSERT(OBJ_IS_CLONED_BLOCK(obj));

    /*
     * Block objects should never be exposed to scripts. Thus the clone should
     * not own the property map and rather always share it with the prototype
     * object. This allows us to skip updating OBJ_SCOPE(obj)->freeslot after
     * we copy the stack slots into reserved slots.
     */
    JS_ASSERT(OBJ_SCOPE(obj)->object != obj);

    /* Block objects should not have reserved slots before they are put. */
    JS_ASSERT(STOBJ_NSLOTS(obj) == JS_INITIAL_NSLOTS);

    /* The block and its locals must be on the current stack for GC safety. */
    depth = OBJ_BLOCK_DEPTH(cx, obj);
    count = OBJ_BLOCK_COUNT(cx, obj);
    JS_ASSERT(depth <= (size_t) (fp->regs->sp - StackBase(fp)));
    JS_ASSERT(count <= (size_t) (fp->regs->sp - StackBase(fp) - depth));

    /* See comments in CheckDestructuring from jsparse.c. */
    JS_ASSERT(count >= 1);

    depth += fp->script->nfixed;
    obj->fslots[JSSLOT_BLOCK_DEPTH + 1] = fp->slots[depth];
    if (normalUnwind && count > 1) {
        --count;
        JS_LOCK_OBJ(cx, obj);
        if (!AllocSlots(cx, obj, JS_INITIAL_NSLOTS + count))
            normalUnwind = JS_FALSE;
        else
            memcpy(obj->dslots, fp->slots + depth + 1, count * sizeof(jsval));
        JS_UNLOCK_OBJ(cx, obj);
    }

    /* We must clear the private slot even with errors. */
    obj->setPrivate(NULL);
    fp->scopeChain = OBJ_GET_PARENT(cx, obj);
    return normalUnwind;
}

static JSBool
block_getProperty(JSContext *cx, JSObject *obj, jsval id, jsval *vp)
{
    /*
     * Block objects are never exposed to script, and the engine handles them
     * with care. So unlike other getters, this one can assert (rather than
     * check) certain invariants about obj.
     */
    JS_ASSERT(obj->getClass() == &js_BlockClass);
    JS_ASSERT(OBJ_IS_CLONED_BLOCK(obj));
    uintN index = (uintN) JSVAL_TO_INT(id);
    JS_ASSERT(index < OBJ_BLOCK_COUNT(cx, obj));

    JSStackFrame *fp = (JSStackFrame *) obj->getPrivate();
    if (fp) {
        index += fp->script->nfixed + OBJ_BLOCK_DEPTH(cx, obj);
        JS_ASSERT(index < fp->script->nslots);
        *vp = fp->slots[index];
        return true;
    }

    /* Values are in reserved slots immediately following DEPTH. */
    uint32 slot = JSSLOT_BLOCK_DEPTH + 1 + index;
    JS_LOCK_OBJ(cx, obj);
    JS_ASSERT(slot < STOBJ_NSLOTS(obj));
    *vp = STOBJ_GET_SLOT(obj, slot);
    JS_UNLOCK_OBJ(cx, obj);
    return true;
}

static JSBool
block_setProperty(JSContext *cx, JSObject *obj, jsval id, jsval *vp)
{
    JS_ASSERT(obj->getClass() == &js_BlockClass);
    JS_ASSERT(OBJ_IS_CLONED_BLOCK(obj));
    uintN index = (uintN) JSVAL_TO_INT(id);
    JS_ASSERT(index < OBJ_BLOCK_COUNT(cx, obj));

    JSStackFrame *fp = (JSStackFrame *) obj->getPrivate();
    if (fp) {
        index += fp->script->nfixed + OBJ_BLOCK_DEPTH(cx, obj);
        JS_ASSERT(index < fp->script->nslots);
        fp->slots[index] = *vp;
        return true;
    }

    /* Values are in reserved slots immediately following DEPTH. */
    uint32 slot = JSSLOT_BLOCK_DEPTH + 1 + index;
    JS_LOCK_OBJ(cx, obj);
    JS_ASSERT(slot < STOBJ_NSLOTS(obj));
    STOBJ_SET_SLOT(obj, slot, *vp);
    JS_UNLOCK_OBJ(cx, obj);
    return true;
}

JSBool
js_DefineBlockVariable(JSContext *cx, JSObject *obj, jsid id, int16 index)
{
    JS_ASSERT(obj->getClass() == &js_BlockClass);
    JS_ASSERT(!OBJ_IS_CLONED_BLOCK(obj));

    /* Use JSPROP_ENUMERATE to aid the disassembler. */
    return js_DefineNativeProperty(cx, obj, id, JSVAL_VOID,
                                   block_getProperty, block_setProperty,
                                   JSPROP_ENUMERATE | JSPROP_PERMANENT | JSPROP_SHARED,
                                   SPROP_HAS_SHORTID, index, NULL);
}

#if JS_HAS_XDR

#define NO_PARENT_INDEX ((uint32)-1)

uint32
FindObjectIndex(JSObjectArray *array, JSObject *obj)
{
    size_t i;

    if (array) {
        i = array->length;
        do {

            if (array->vector[--i] == obj)
                return i;
        } while (i != 0);
    }

    return NO_PARENT_INDEX;
}

JSBool
js_XDRBlockObject(JSXDRState *xdr, JSObject **objp)
{
    JSContext *cx;
    uint32 parentId;
    JSObject *obj, *parent;
    uint16 depth, count, i;
    uint32 tmp;
    JSScopeProperty *sprop;
    jsid propid;
    JSAtom *atom;
    int16 shortid;
    JSBool ok;

    cx = xdr->cx;
#ifdef __GNUC__
    obj = NULL;         /* quell GCC overwarning */
#endif

    if (xdr->mode == JSXDR_ENCODE) {
        obj = *objp;
        parent = OBJ_GET_PARENT(cx, obj);
        parentId = (xdr->script->objectsOffset == 0)
                   ? NO_PARENT_INDEX
                   : FindObjectIndex(xdr->script->objects(), parent);
        depth = (uint16)OBJ_BLOCK_DEPTH(cx, obj);
        count = (uint16)OBJ_BLOCK_COUNT(cx, obj);
        tmp = (uint32)(depth << 16) | count;
    }
#ifdef __GNUC__ /* suppress bogus gcc warnings */
    else count = 0;
#endif

    /* First, XDR the parent atomid. */
    if (!JS_XDRUint32(xdr, &parentId))
        return JS_FALSE;

    if (xdr->mode == JSXDR_DECODE) {
        obj = js_NewBlockObject(cx);
        if (!obj)
            return JS_FALSE;
        *objp = obj;

        /*
         * If there's a parent id, then get the parent out of our script's
         * object array. We know that we XDR block object in outer-to-inner
         * order, which means that getting the parent now will work.
         */
        if (parentId == NO_PARENT_INDEX)
            parent = NULL;
        else
            parent = xdr->script->getObject(parentId);
        STOBJ_SET_PARENT(obj, parent);
    }

    JSAutoTempValueRooter tvr(cx, obj);

    if (!JS_XDRUint32(xdr, &tmp))
        return false;

    if (xdr->mode == JSXDR_DECODE) {
        depth = (uint16)(tmp >> 16);
        count = (uint16)tmp;
        STOBJ_SET_SLOT(obj, JSSLOT_BLOCK_DEPTH, INT_TO_JSVAL(depth));
    }

    /*
     * XDR the block object's properties. We know that there are 'count'
     * properties to XDR, stored as id/shortid pairs. We do not XDR any
     * non-native properties, only those that the compiler created.
     */
    sprop = NULL;
    ok = JS_TRUE;
    for (i = 0; i < count; i++) {
        if (xdr->mode == JSXDR_ENCODE) {
            /* Find a property to XDR. */
            do {
                /* If sprop is NULL, this is the first property. */
                sprop = sprop ? sprop->parent : OBJ_SCOPE(obj)->lastProp;
            } while (!(sprop->flags & SPROP_HAS_SHORTID));

            JS_ASSERT(sprop->getter == block_getProperty);
            propid = sprop->id;
            JS_ASSERT(JSID_IS_ATOM(propid));
            atom = JSID_TO_ATOM(propid);
            shortid = sprop->shortid;
            JS_ASSERT(shortid >= 0);
        }

        /* XDR the real id, then the shortid. */
        if (!js_XDRStringAtom(xdr, &atom) ||
            !JS_XDRUint16(xdr, (uint16 *)&shortid)) {
            return false;
        }

        if (xdr->mode == JSXDR_DECODE) {
            if (!js_DefineBlockVariable(cx, obj, ATOM_TO_JSID(atom), shortid))
                return false;
        }
    }

    if (xdr->mode == JSXDR_DECODE) {
        /* Do as the parser does and make this block scope shareable. */
        OBJ_SCOPE(obj)->object = NULL;
    }
    return true;
}

#endif

static uint32
block_reserveSlots(JSContext *cx, JSObject *obj)
{
    return OBJ_IS_CLONED_BLOCK(obj) ? OBJ_BLOCK_COUNT(cx, obj) : 0;
}

JSClass js_BlockClass = {
    "Block",
    JSCLASS_HAS_PRIVATE | JSCLASS_HAS_RESERVED_SLOTS(1) | JSCLASS_IS_ANONYMOUS,
    JS_PropertyStub,  JS_PropertyStub,  JS_PropertyStub,   JS_PropertyStub,
    JS_EnumerateStub, JS_ResolveStub,   JS_ConvertStub,    NULL,
    NULL, NULL, NULL, NULL, NULL, NULL, NULL, block_reserveSlots
};

JSObject *
js_InitEval(JSContext *cx, JSObject *obj)
{
    /* ECMA (15.1.2.1) says 'eval' is a property of the global object. */
    if (!js_DefineFunction(cx, obj, cx->runtime->atomState.evalAtom,
                           obj_eval, 1, 0)) {
        return NULL;
    }

    return obj;
}

JSObject *
js_InitObjectClass(JSContext *cx, JSObject *obj)
{
    return js_InitClass(cx, obj, NULL, &js_ObjectClass, js_Object, 1,
                        object_props, object_methods, NULL, object_static_methods);
}

JSObject *
js_InitClass(JSContext *cx, JSObject *obj, JSObject *parent_proto,
             JSClass *clasp, JSNative constructor, uintN nargs,
             JSPropertySpec *ps, JSFunctionSpec *fs,
             JSPropertySpec *static_ps, JSFunctionSpec *static_fs)
{
    JSAtom *atom;
    JSProtoKey key;
    JSObject *proto, *ctor;
    JSTempValueRooter tvr;
    jsval cval, rval;
    JSBool named;
    JSFunction *fun;

    atom = js_Atomize(cx, clasp->name, strlen(clasp->name), 0);
    if (!atom)
        return NULL;

    /*
     * When initializing a standard class, if no parent_proto (grand-proto of
     * instances of the class, parent-proto of the class's prototype object)
     * is given, we must use Object.prototype if it is available.  Otherwise,
     * we could look up the wrong binding for a class name in obj.  Example:
     *
     *   String = Array;
     *   print("hi there".join);
     *
     * should print undefined, not Array.prototype.join.  This is required by
     * ECMA-262, alas.  It might have been better to make String readonly and
     * permanent in the global object, instead -- but that's too big a change
     * to swallow at this point.
     */
    key = JSCLASS_CACHED_PROTO_KEY(clasp);
    if (key != JSProto_Null &&
        !parent_proto &&
        !js_GetClassPrototype(cx, obj, INT_TO_JSID(JSProto_Object),
                              &parent_proto)) {
        return NULL;
    }

    /* Create a prototype object for this class. */
    proto = js_NewObject(cx, clasp, parent_proto, obj);
    if (!proto)
        return NULL;

    /* After this point, control must exit via label bad or out. */
    JS_PUSH_TEMP_ROOT_OBJECT(cx, proto, &tvr);

    if (!constructor) {
        /*
         * Lacking a constructor, name the prototype (e.g., Math) unless this
         * class (a) is anonymous, i.e. for internal use only; (b) the class
         * of obj (the global object) is has a reserved slot indexed by key;
         * and (c) key is not the null key.
         */
        if ((clasp->flags & JSCLASS_IS_ANONYMOUS) &&
            (OBJ_GET_CLASS(cx, obj)->flags & JSCLASS_IS_GLOBAL) &&
            key != JSProto_Null) {
            named = JS_FALSE;
        } else {
            named = obj->defineProperty(cx, ATOM_TO_JSID(atom),
                                        OBJECT_TO_JSVAL(proto),
                                        JS_PropertyStub, JS_PropertyStub,
                                        (clasp->flags & JSCLASS_IS_ANONYMOUS)
                                        ? JSPROP_READONLY | JSPROP_PERMANENT
                                        : 0);
            if (!named)
                goto bad;
        }

        ctor = proto;
    } else {
        /* Define the constructor function in obj's scope. */
        fun = js_DefineFunction(cx, obj, atom, constructor, nargs,
                                JSFUN_STUB_GSOPS);
        named = (fun != NULL);
        if (!fun)
            goto bad;

        /*
         * Remember the class this function is a constructor for so that
         * we know to create an object of this class when we call the
         * constructor.
         */
        FUN_CLASP(fun) = clasp;

        /*
         * Optionally construct the prototype object, before the class has
         * been fully initialized.  Allow the ctor to replace proto with a
         * different object, as is done for operator new -- and as at least
         * XML support requires.
         */
        ctor = FUN_OBJECT(fun);
        if (clasp->flags & JSCLASS_CONSTRUCT_PROTOTYPE) {
            cval = OBJECT_TO_JSVAL(ctor);
            if (!js_InternalConstruct(cx, proto, cval, 0, NULL, &rval))
                goto bad;
            if (!JSVAL_IS_PRIMITIVE(rval) && JSVAL_TO_OBJECT(rval) != proto)
                proto = JSVAL_TO_OBJECT(rval);
        }

        /* Connect constructor and prototype by named properties. */
        if (!js_SetClassPrototype(cx, ctor, proto,
                                  JSPROP_READONLY | JSPROP_PERMANENT)) {
            goto bad;
        }

        /* Bootstrap Function.prototype (see also JS_InitStandardClasses). */
        if (OBJ_GET_CLASS(cx, ctor) == clasp)
            OBJ_SET_PROTO(cx, ctor, proto);
    }

    /* Add properties and methods to the prototype and the constructor. */
    if ((ps && !JS_DefineProperties(cx, proto, ps)) ||
        (fs && !JS_DefineFunctions(cx, proto, fs)) ||
        (static_ps && !JS_DefineProperties(cx, ctor, static_ps)) ||
        (static_fs && !JS_DefineFunctions(cx, ctor, static_fs))) {
        goto bad;
    }

    /*
     * Make sure proto's scope's emptyScope is available to be shared by
     * objects of this class.  JSScope::emptyScope is a one-slot cache. If we
     * omit this, some other class could snap it up. (The risk is particularly
     * great for Object.prototype.)
     *
     * All callers of JSObject::initSharingEmptyScope depend on this.
     */
    if (OBJ_IS_NATIVE(proto)) {
        JSScope *scope = OBJ_SCOPE(proto)->getEmptyScope(cx, clasp);
        if (!scope)
            goto bad;
        scope->drop(cx, NULL);
    }

    /* If this is a standard class, cache its prototype. */
    if (key != JSProto_Null && !js_SetClassObject(cx, obj, key, ctor))
        goto bad;

out:
    JS_POP_TEMP_ROOT(cx, &tvr);
    return proto;

bad:
    if (named)
        (void) obj->deleteProperty(cx, ATOM_TO_JSID(atom), &rval);
    proto = NULL;
    goto out;
}

#define SLOTS_TO_DYNAMIC_WORDS(nslots)                                        \
  (JS_ASSERT((nslots) > JS_INITIAL_NSLOTS), (nslots) + 1 - JS_INITIAL_NSLOTS)

#define DYNAMIC_WORDS_TO_SLOTS(words)                                         \
  (JS_ASSERT((words) > 1), (words) - 1 + JS_INITIAL_NSLOTS)


static bool
AllocSlots(JSContext *cx, JSObject *obj, size_t nslots)
{
    JS_ASSERT(!obj->dslots);
    JS_ASSERT(nslots > JS_INITIAL_NSLOTS);

    jsval* slots;
    slots = (jsval*) cx->malloc(SLOTS_TO_DYNAMIC_WORDS(nslots) * sizeof(jsval));
    if (!slots)
        return true;

    *slots++ = nslots;
    /* clear the newly allocated cells. */
    for (jsuint n = JS_INITIAL_NSLOTS; n < nslots; ++n)
        slots[n - JS_INITIAL_NSLOTS] = JSVAL_VOID;
    obj->dslots = slots;

    return true;
}

bool
js_GrowSlots(JSContext *cx, JSObject *obj, size_t nslots)
{
    /*
     * Minimal number of dynamic slots to allocate.
     */
    const size_t MIN_DYNAMIC_WORDS = 4;

    /*
     * The limit to switch to linear allocation strategy from the power of 2
     * growth no to waste too much memory.
     */
    const size_t LINEAR_GROWTH_STEP = JS_BIT(16);

    /* If we are allocating fslots, there is nothing to do. */
    if (nslots <= JS_INITIAL_NSLOTS)
        return JS_TRUE;

    size_t nwords = SLOTS_TO_DYNAMIC_WORDS(nslots);

    /*
     * Round up nslots so the number of bytes in dslots array is power
     * of 2 to ensure exponential grouth.
     */
    uintN log;
    if (nwords <= MIN_DYNAMIC_WORDS) {
        nwords = MIN_DYNAMIC_WORDS;
    } else if (nwords < LINEAR_GROWTH_STEP) {
        JS_CEILING_LOG2(log, nwords);
        nwords = JS_BIT(log);
    } else {
        nwords = JS_ROUNDUP(nwords, LINEAR_GROWTH_STEP);
    }
    nslots = DYNAMIC_WORDS_TO_SLOTS(nwords);

    /*
     * If nothing was allocated yet, treat it as initial allocation (but with
     * the exponential growth algorithm applied).
     */
    jsval* slots = obj->dslots;
    if (!slots)
        return AllocSlots(cx, obj, nslots);

    size_t oslots = size_t(slots[-1]);

    slots = (jsval*) cx->realloc(slots - 1, nwords * sizeof(jsval));
    *slots++ = nslots;
    obj->dslots = slots;

    /* Initialize the additional slots we added. */
    JS_ASSERT(nslots > oslots);
    for (size_t i = oslots; i < nslots; i++)
        slots[i - JS_INITIAL_NSLOTS] = JSVAL_VOID;

    return true;
}

void
js_ShrinkSlots(JSContext *cx, JSObject *obj, size_t nslots)
{
    jsval* slots = obj->dslots;

    /* Nothing to shrink? */
    if (!slots)
        return;

    JS_ASSERT(size_t(slots[-1]) > JS_INITIAL_NSLOTS);
    JS_ASSERT(nslots <= size_t(slots[-1]));

    if (nslots <= JS_INITIAL_NSLOTS) {
        cx->free(slots - 1);
        obj->dslots = NULL;
    } else {
        size_t nwords = SLOTS_TO_DYNAMIC_WORDS(nslots);
        slots = (jsval*) cx->realloc(slots - 1, nwords * sizeof(jsval));
        *slots++ = nslots;
        obj->dslots = slots;
    }
}

bool
js_EnsureReservedSlots(JSContext *cx, JSObject *obj, size_t nreserved)
{
    JS_ASSERT(OBJ_IS_NATIVE(obj));
    JS_ASSERT(!obj->dslots);

    uintN nslots = JSSLOT_FREE(STOBJ_GET_CLASS(obj)) + nreserved;
    if (nslots > STOBJ_NSLOTS(obj) && !AllocSlots(cx, obj, nslots))
        return false;

    JSScope *scope = OBJ_SCOPE(obj);
    if (scope->owned()) {
#ifdef JS_THREADSAFE
        JS_ASSERT(scope->title.ownercx->thread == cx->thread);
#endif
        JS_ASSERT(scope->freeslot == JSSLOT_FREE(STOBJ_GET_CLASS(obj)));
        if (scope->freeslot < nslots)
            scope->freeslot = nslots;
    }
    return true;
}

extern JSBool
js_GetClassId(JSContext *cx, JSClass *clasp, jsid *idp)
{
    JSProtoKey key;
    JSAtom *atom;

    key = JSCLASS_CACHED_PROTO_KEY(clasp);
    if (key != JSProto_Null) {
        *idp = INT_TO_JSID(key);
    } else if (clasp->flags & JSCLASS_IS_ANONYMOUS) {
        *idp = INT_TO_JSID(JSProto_Object);
    } else {
        atom = js_Atomize(cx, clasp->name, strlen(clasp->name), 0);
        if (!atom)
            return JS_FALSE;
        *idp = ATOM_TO_JSID(atom);
    }
    return JS_TRUE;
}

JS_BEGIN_EXTERN_C

static JSObject *
js_InitNullClass(JSContext *cx, JSObject *obj)
{
    JS_ASSERT(0);
    return NULL;
}

#define JS_PROTO(name,code,init) extern JSObject *init(JSContext *, JSObject *);
#include "jsproto.tbl"
#undef JS_PROTO

static JSObjectOp lazy_prototype_init[JSProto_LIMIT] = {
#define JS_PROTO(name,code,init) init,
#include "jsproto.tbl"
#undef JS_PROTO
};

JS_END_EXTERN_C

JSBool
js_GetClassObject(JSContext *cx, JSObject *obj, JSProtoKey key,
                  JSObject **objp)
{
    JSBool ok;
    JSObject *tmp, *cobj;
    JSResolvingKey rkey;
    JSResolvingEntry *rentry;
    uint32 generation;
    JSObjectOp init;
    jsval v;

    while ((tmp = OBJ_GET_PARENT(cx, obj)) != NULL)
        obj = tmp;
    if (!(OBJ_GET_CLASS(cx, obj)->flags & JSCLASS_IS_GLOBAL)) {
        *objp = NULL;
        return JS_TRUE;
    }

    ok = JS_GetReservedSlot(cx, obj, key, &v);
    if (!ok)
        return JS_FALSE;
    if (!JSVAL_IS_PRIMITIVE(v)) {
        *objp = JSVAL_TO_OBJECT(v);
        return JS_TRUE;
    }

    rkey.obj = obj;
    rkey.id = ATOM_TO_JSID(cx->runtime->atomState.classAtoms[key]);
    if (!js_StartResolving(cx, &rkey, JSRESFLAG_LOOKUP, &rentry))
        return JS_FALSE;
    if (!rentry) {
        /* Already caching key in obj -- suppress recursion. */
        *objp = NULL;
        return JS_TRUE;
    }
    generation = cx->resolvingTable->generation;

    cobj = NULL;
    init = lazy_prototype_init[key];
    if (init) {
        if (!init(cx, obj)) {
            ok = JS_FALSE;
        } else {
            ok = JS_GetReservedSlot(cx, obj, key, &v);
            if (ok && !JSVAL_IS_PRIMITIVE(v))
                cobj = JSVAL_TO_OBJECT(v);
        }
    }

    js_StopResolving(cx, &rkey, JSRESFLAG_LOOKUP, rentry, generation);
    *objp = cobj;
    return ok;
}

JSBool
js_SetClassObject(JSContext *cx, JSObject *obj, JSProtoKey key, JSObject *cobj)
{
    JS_ASSERT(!OBJ_GET_PARENT(cx, obj));
    if (!(OBJ_GET_CLASS(cx, obj)->flags & JSCLASS_IS_GLOBAL))
        return JS_TRUE;

    return JS_SetReservedSlot(cx, obj, key, OBJECT_TO_JSVAL(cobj));
}

JSBool
js_FindClassObject(JSContext *cx, JSObject *start, jsid id, jsval *vp)
{
    JSStackFrame *fp;
    JSObject *obj, *cobj, *pobj;
    JSProtoKey key;
    JSProperty *prop;
    jsval v;
    JSScopeProperty *sprop;

    /*
     * Find the global object. Use cx->fp directly to avoid falling off
     * trace; all JIT-elided stack frames have the same global object as
     * cx->fp.
     */
    VOUCH_DOES_NOT_REQUIRE_STACK();
    if (!start && (fp = cx->fp) != NULL)
        start = fp->scopeChain;

    if (start) {
        /* Find the topmost object in the scope chain. */
        do {
            obj = start;
            start = OBJ_GET_PARENT(cx, obj);
        } while (start);
    } else {
        obj = cx->globalObject;
        if (!obj) {
            *vp = JSVAL_VOID;
            return JS_TRUE;
        }
    }

    OBJ_TO_INNER_OBJECT(cx, obj);
    if (!obj)
        return JS_FALSE;

    if (JSID_IS_INT(id)) {
        key = (JSProtoKey) JSID_TO_INT(id);
        JS_ASSERT(key != JSProto_Null);
        if (!js_GetClassObject(cx, obj, key, &cobj))
            return JS_FALSE;
        if (cobj) {
            *vp = OBJECT_TO_JSVAL(cobj);
            return JS_TRUE;
        }
        id = ATOM_TO_JSID(cx->runtime->atomState.classAtoms[key]);
    }

    JS_ASSERT(OBJ_IS_NATIVE(obj));
    if (js_LookupPropertyWithFlags(cx, obj, id, JSRESOLVE_CLASSNAME,
                                   &pobj, &prop) < 0) {
        return JS_FALSE;
    }
    v = JSVAL_VOID;
    if (prop)  {
        if (OBJ_IS_NATIVE(pobj)) {
            sprop = (JSScopeProperty *) prop;
            if (SPROP_HAS_VALID_SLOT(sprop, OBJ_SCOPE(pobj))) {
                v = LOCKED_OBJ_GET_SLOT(pobj, sprop->slot);
                if (JSVAL_IS_PRIMITIVE(v))
                    v = JSVAL_VOID;
            }
        }
        pobj->dropProperty(cx, prop);
    }
    *vp = v;