Mozilla/mozilla/js/src/jsatom.c

/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 *
 * The contents of this file are subject to the Netscape 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/NPL/
 *
 * Software distributed under the License is distributed on an "AS
 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express oqr
 * 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 Netscape are
 * Copyright (C) 1998 Netscape Communications Corporation. All
 * Rights Reserved.
 *
 * Contributor(s): 
 *
 * Alternatively, the contents of this file may be used under the
 * terms of the GNU Public License (the "GPL"), in which case the
 * provisions of the GPL are applicable instead of those above.
 * If you wish to allow use of your version of this file only
 * under the terms of the GPL and not to allow others to use your
 * version of this file under the NPL, indicate your decision by
 * deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL.  If you do not delete
 * the provisions above, a recipient may use your version of this
 * file under either the NPL or the GPL.
 */

/*
 * JS atom table.
 */
#include "jsstddef.h"
#include <stdlib.h>
#include <string.h>
#include "jstypes.h"
#include "jsutil.h" /* Added by JSIFY */
#include "jshash.h" /* Added by JSIFY */
#include "jsprf.h"
#include "jsapi.h"
#include "jsatom.h"
#include "jscntxt.h"
#include "jsgc.h"
#include "jslock.h"
#include "jsnum.h"
#include "jsopcode.h"
#include "jsstr.h"

extern const char js_Error_str[];       /* trivial, from jsexn.h */

/*
 * Keep this in sync with jspubtd.h -- an assertion below will insist that
 * its length match the JSType enum's JSTYPE_LIMIT limit value.
 */
const char *js_type_str[] = {
    "undefined",
    "object",
    "function",
    "string",
    "number",
    "boolean",
};

const char *js_boolean_str[] = {
    js_false_str,
    js_true_str
};

const char js_Arguments_str[]       = "Arguments";
const char js_Array_str[]           = "Array";
const char js_Boolean_str[]         = "Boolean";
const char js_Call_str[]            = "Call";
const char js_Date_str[]            = "Date";
const char js_Function_str[]        = "Function";
const char js_Math_str[]            = "Math";
const char js_Number_str[]          = "Number";
const char js_Object_str[]          = "Object";
const char js_RegExp_str[]          = "RegExp";
const char js_Script_str[]          = "Script";
const char js_String_str[]          = "String";
const char js_anonymous_str[]       = "anonymous";
const char js_arguments_str[]       = "arguments";
const char js_arity_str[]           = "arity";
const char js_callee_str[]          = "callee";
const char js_caller_str[]          = "caller";
const char js_class_prototype_str[] = "prototype";
const char js_constructor_str[]     = "constructor";
const char js_count_str[]           = "__count__";
const char js_eval_str[]            = "eval";
const char js_getter_str[]          = "getter";
const char js_get_str[]             = "get";
const char js_index_str[]           = "index";
const char js_input_str[]           = "input";
const char js_length_str[]          = "length";
const char js_name_str[]            = "name";
const char js_parent_str[]          = "__parent__";
const char js_proto_str[]           = "__proto__";
const char js_setter_str[]          = "setter";
const char js_set_str[]             = "set";
const char js_toSource_str[]        = "toSource";
const char js_toString_str[]        = "toString";
const char js_toLocaleString_str[]  = "toLocaleString";
const char js_valueOf_str[]         = "valueOf";

#define HASH_OBJECT(o)  ((JSHashNumber)(o) >> JSVAL_TAGBITS)
#define HASH_INT(i)     ((JSHashNumber)(i))
#define HASH_DOUBLE(dp) ((JSHashNumber)(((uint32*)(dp))[0] ^ ((uint32*)(dp))[1]))
#define HASH_BOOLEAN(b) ((JSHashNumber)(b))

JS_STATIC_DLL_CALLBACK(JSHashNumber)
js_hash_atom_key(const void *key)
{
    jsval v;
    jsdouble *dp;

    /* Order JSVAL_IS_* tests by likelihood of success. */
    v = (jsval)key;
    if (JSVAL_IS_STRING(v))
	return js_HashString(JSVAL_TO_STRING(v));
    if (JSVAL_IS_INT(v))
	return HASH_INT(JSVAL_TO_INT(v));
    if (JSVAL_IS_DOUBLE(v)) {
	dp = JSVAL_TO_DOUBLE(v);
	return HASH_DOUBLE(dp);
    }
    if (JSVAL_IS_OBJECT(v))
	return HASH_OBJECT(JSVAL_TO_OBJECT(v));
    if (JSVAL_IS_BOOLEAN(v))
	return HASH_BOOLEAN(JSVAL_TO_BOOLEAN(v));
    return (JSHashNumber)v;
}

JS_STATIC_DLL_CALLBACK(intN)
js_compare_atom_keys(const void *k1, const void *k2)
{
    jsval v1, v2;

    v1 = (jsval)k1, v2 = (jsval)k2;
    if (JSVAL_IS_STRING(v1) && JSVAL_IS_STRING(v2))
	return !js_CompareStrings(JSVAL_TO_STRING(v1), JSVAL_TO_STRING(v2));
    if (JSVAL_IS_DOUBLE(v1) && JSVAL_IS_DOUBLE(v2)) {
	double d1 = *JSVAL_TO_DOUBLE(v1);
	double d2 = *JSVAL_TO_DOUBLE(v2);
	if (JSDOUBLE_IS_NaN(d1))
	    return JSDOUBLE_IS_NaN(d2);
#ifdef XP_PC
	/* XXX MSVC miscompiles such that (NaN == 0) */
	if (JSDOUBLE_IS_NaN(d2))
	    return JS_FALSE;
#endif
	return d1 == d2;
    }
    return v1 == v2;
}

JS_STATIC_DLL_CALLBACK(int)
js_compare_stub(const void *v1, const void *v2)
{
    return 1;
}

JS_STATIC_DLL_CALLBACK(void *)
js_alloc_atom_space(void *priv, size_t size)
{
    return malloc(size);
}

JS_STATIC_DLL_CALLBACK(void)
js_free_atom_space(void *priv, void *item)
{
    free(item);
}

JS_STATIC_DLL_CALLBACK(JSHashEntry *)
js_alloc_atom(void *priv, const void *key)
{
    JSAtomState *state = (JSAtomState *) priv;
    JSAtom *atom;

    atom = (JSAtom *) malloc(sizeof(JSAtom));
    if (!atom)
	return NULL;
#ifdef JS_THREADSAFE
    state->tablegen++;
#endif
    atom->entry.key = key;
    atom->entry.value = NULL;
    atom->flags = 0;
    atom->kwindex = -1;
    atom->number = state->number++;
    return &atom->entry;
}

JS_STATIC_DLL_CALLBACK(void)
js_free_atom(void *priv, JSHashEntry *he, uintN flag)
{
    if (flag != HT_FREE_ENTRY)
	return;
#ifdef JS_THREADSAFE
    ((JSAtomState *)priv)->tablegen++;
#endif
    free(he);
}

static JSHashAllocOps atom_alloc_ops = {
    js_alloc_atom_space,    js_free_atom_space,
    js_alloc_atom,          js_free_atom
};

#define JS_ATOM_HASH_SIZE   1024

JSBool
js_InitAtomState(JSContext *cx, JSAtomState *state)
{
    uintN i;

    memset(state, 0, sizeof *state);
    state->runtime = cx->runtime;
    state->table = JS_NewHashTable(JS_ATOM_HASH_SIZE, js_hash_atom_key,
				   js_compare_atom_keys, js_compare_stub,
				   &atom_alloc_ops, state);
    if (!state->table) {
	JS_ReportOutOfMemory(cx);
	return JS_FALSE;
    }
#ifdef JS_THREADSAFE
    js_InitLock(&state->lock);
    state->tablegen = 0;
#endif

#define FROB(lval,str)                                                        \
    JS_BEGIN_MACRO                                                            \
	if (!(state->lval = js_Atomize(cx, str, strlen(str), ATOM_PINNED)))   \
	    goto bad;                                                         \
    JS_END_MACRO

    JS_ASSERT(sizeof js_type_str / sizeof js_type_str[0] == JSTYPE_LIMIT);
    for (i = 0; i < JSTYPE_LIMIT; i++)
	FROB(typeAtoms[i],        js_type_str[i]);

    FROB(booleanAtoms[0],         js_false_str);
    FROB(booleanAtoms[1],         js_true_str);
    FROB(nullAtom,                js_null_str);

    FROB(ArgumentsAtom,           js_Arguments_str);
    FROB(ArrayAtom,               js_Array_str);
    FROB(BooleanAtom,             js_Boolean_str);
    FROB(CallAtom,                js_Call_str);
    FROB(DateAtom,                js_Date_str);
    FROB(ErrorAtom,               js_Error_str);
    FROB(FunctionAtom,            js_Function_str);
    FROB(MathAtom,                js_Math_str);
    FROB(NumberAtom,              js_Number_str);
    FROB(ObjectAtom,              js_Object_str);
    FROB(RegExpAtom,              js_RegExp_str);
    FROB(ScriptAtom,              js_Script_str);
    FROB(StringAtom,              js_String_str);
    FROB(anonymousAtom,           js_anonymous_str);
    FROB(argumentsAtom,           js_arguments_str);
    FROB(arityAtom,               js_arity_str);
    FROB(calleeAtom,              js_callee_str);
    FROB(callerAtom,              js_caller_str);
    FROB(classPrototypeAtom,      js_class_prototype_str);
    FROB(constructorAtom,         js_constructor_str);
    FROB(countAtom,               js_count_str);
    FROB(evalAtom,                js_eval_str);
    FROB(getAtom,                 js_get_str);
    FROB(getterAtom,              js_getter_str);
    FROB(indexAtom,               js_index_str);
    FROB(inputAtom,               js_input_str);
    FROB(lengthAtom,              js_length_str);
    FROB(nameAtom,                js_name_str);
    FROB(parentAtom,              js_parent_str);
    FROB(protoAtom,               js_proto_str);
    FROB(setAtom,                 js_set_str);
    FROB(setterAtom,              js_setter_str);
    FROB(toSourceAtom,            js_toSource_str);
    FROB(toStringAtom,            js_toString_str);
    FROB(toLocaleStringAtom,      js_toLocaleString_str);
    FROB(valueOfAtom,             js_valueOf_str);

#undef FROB

    return JS_TRUE;

bad:
    js_FreeAtomState(cx, state);
    return JS_FALSE;
}

void
js_FreeAtomState(JSContext *cx, JSAtomState *state)
{
    state->runtime = NULL;
    JS_HashTableDestroy(state->table);
    state->table = NULL;
    state->number = 0;
#ifdef JS_THREADSAFE
    js_FinishLock(&state->lock);
#endif
}

typedef struct MarkArgs {
    uintN           gcflags;
    JSGCThingMarker mark;
    void            *data;
} MarkArgs;

JS_STATIC_DLL_CALLBACK(intN)
js_atom_marker(JSHashEntry *he, intN i, void *arg)
{
    JSAtom *atom;
    MarkArgs *args;
    jsval key;

    atom = (JSAtom *)he;
    args = (MarkArgs *) arg;
    if ((atom->flags & ATOM_PINNED) || (args->gcflags & GC_KEEP_ATOMS)) {
	atom->flags |= ATOM_MARK;
	key = ATOM_KEY(atom);
	if (JSVAL_IS_GCTHING(key)) {
	    args->mark(JSVAL_TO_GCTHING(key), args->data);
	}
    }
    return HT_ENUMERATE_NEXT;
}

void
js_MarkAtomState(JSAtomState *state, uintN gcflags, JSGCThingMarker mark,
                 void *data)
{
    MarkArgs args;

    args.gcflags = gcflags;
    args.mark = mark;
    args.data = data;
    JS_HashTableEnumerateEntries(state->table, js_atom_marker, &args);
}

JS_STATIC_DLL_CALLBACK(intN)
js_atom_sweeper(JSHashEntry *he, intN i, void *arg)
{
    JSAtom *atom;

    atom = (JSAtom *)he;
    if (atom->flags & ATOM_MARK) {
        atom->flags &= ~ATOM_MARK;
        return HT_ENUMERATE_NEXT;
    }
    JS_ASSERT((atom->flags & ATOM_PINNED) == 0);
    atom->entry.key = NULL;
    atom->flags = 0;
    return HT_ENUMERATE_REMOVE;
}

void
js_SweepAtomState(JSAtomState *state)
{
    JS_HashTableEnumerateEntries(state->table, js_atom_sweeper, NULL);
}

JS_STATIC_DLL_CALLBACK(intN)
js_atom_unpinner(JSHashEntry *he, intN i, void *arg)
{
    JSAtom *atom;

    atom = (JSAtom *)he;
    atom->flags &= ~ATOM_PINNED;
    return HT_ENUMERATE_NEXT;
}

void
js_UnpinPinnedAtoms(JSAtomState *state)
{
    JS_HashTableEnumerateEntries(state->table, js_atom_unpinner, NULL);
}

static JSAtom *
js_AtomizeHashedKey(JSContext *cx, jsval key, JSHashNumber keyHash, uintN flags)
{
    JSAtomState *state;
    JSHashTable *table;
    JSHashEntry *he, **hep;
    JSAtom *atom;

    state = &cx->runtime->atomState;
    JS_LOCK(&state->lock, cx);
    table = state->table;
    hep = JS_HashTableRawLookup(table, keyHash, (void *)key);
    if ((he = *hep) == NULL) {
	he = JS_HashTableRawAdd(table, hep, keyHash, (void *)key, NULL);
	if (!he) {
	    JS_ReportOutOfMemory(cx);
	    atom = NULL;
	    goto out;
	}
    }

    atom = (JSAtom *)he;
    atom->flags |= flags;
out:
    JS_UNLOCK(&state->lock,cx);
    return atom;
}

JSAtom *
js_AtomizeObject(JSContext *cx, JSObject *obj, uintN flags)
{
    jsval key;
    JSHashNumber keyHash;

    /* XXX must be set in the following order or MSVC1.52 will crash */
    keyHash = HASH_OBJECT(obj);
    key = OBJECT_TO_JSVAL(obj);
    return js_AtomizeHashedKey(cx, key, keyHash, flags);
}

JSAtom *
js_AtomizeBoolean(JSContext *cx, JSBool b, uintN flags)
{
    jsval key;
    JSHashNumber keyHash;

    key = BOOLEAN_TO_JSVAL(b);
    keyHash = HASH_BOOLEAN(b);
    return js_AtomizeHashedKey(cx, key, keyHash, flags);
}

JSAtom *
js_AtomizeInt(JSContext *cx, jsint i, uintN flags)
{
    jsval key;
    JSHashNumber keyHash;

    key = INT_TO_JSVAL(i);
    keyHash = HASH_INT(i);
    return js_AtomizeHashedKey(cx, key, keyHash, flags);
}

/* Worst-case alignment grain and aligning macro for 2x-sized buffer. */
#define ALIGNMENT(t)    JS_MAX(JSVAL_ALIGN, sizeof(t))
#define ALIGN(b,t)      ((t*) &(b)[ALIGNMENT(t) - (jsuword)(b) % ALIGNMENT(t)])

JSAtom *
js_AtomizeDouble(JSContext *cx, jsdouble d, uintN flags)
{
    jsdouble *dp;
    JSHashNumber keyHash;
    jsval key;
    JSAtomState *state;
    JSHashTable *table;
    JSHashEntry *he, **hep;
    JSAtom *atom;
    char buf[2 * ALIGNMENT(double)];

    dp = ALIGN(buf, double);
    *dp = d;
    keyHash = HASH_DOUBLE(dp);
    key = DOUBLE_TO_JSVAL(dp);
    state = &cx->runtime->atomState;
    JS_LOCK(&state->lock, cx);
    table = state->table;
    hep = JS_HashTableRawLookup(table, keyHash, (void *)key);
    if ((he = *hep) == NULL) {
#ifdef JS_THREADSAFE
	uint32 gen = state->tablegen;
#endif
	JS_UNLOCK(&state->lock,cx);
	if (!js_NewDoubleValue(cx, d, &key))
	    return NULL;
	JS_LOCK(&state->lock, cx);
#ifdef JS_THREADSAFE
	if (state->tablegen != gen) {
	    hep = JS_HashTableRawLookup(table, keyHash, (void *)key);
	    if ((he = *hep) != NULL) {
		atom = (JSAtom *)he;
		goto out;
	    }
	}
#endif
	he = JS_HashTableRawAdd(table, hep, keyHash, (void *)key, NULL);
	if (!he) {
	    JS_ReportOutOfMemory(cx);
	    atom = NULL;
	    goto out;
	}
    }

    atom = (JSAtom *)he;
    atom->flags |= flags;
out:
    JS_UNLOCK(&state->lock,cx);
    return atom;
}

JSAtom *
js_AtomizeString(JSContext *cx, JSString *str, uintN flags)
{
    JSHashNumber keyHash;
    jsval key;
    JSAtomState *state;
    JSHashTable *table;
    JSHashEntry *he, **hep;
    JSAtom *atom;

    keyHash = js_HashString(str);
    key = STRING_TO_JSVAL(str);
    state = &cx->runtime->atomState;
    JS_LOCK(&state->lock, cx);
    table = state->table;
    hep = JS_HashTableRawLookup(table, keyHash, (void *)key);
    if ((he = *hep) == NULL) {
	if (flags & ATOM_TMPSTR) {
#ifdef JS_THREADSAFE
	    uint32 gen = state->tablegen;
#endif
	    JS_UNLOCK(&state->lock, cx);
            str = (flags & ATOM_NOCOPY)
                  ? js_NewString(cx, str->chars, str->length, 0)
                  : js_NewStringCopyN(cx, str->chars, str->length, 0);
	    if (!str)
		return NULL;
	    key = STRING_TO_JSVAL(str);
	    JS_LOCK(&state->lock, cx);
#ifdef JS_THREADSAFE
	    if (state->tablegen != gen) {
		hep = JS_HashTableRawLookup(table, keyHash, (void *)key);
		if ((he = *hep) != NULL) {
		    atom = (JSAtom *)he;
		    if (flags & ATOM_NOCOPY)
			str->chars = NULL;
		    goto out;
		}
	    }
#endif
	}
	he = JS_HashTableRawAdd(table, hep, keyHash, (void *)key, NULL);
	if (!he) {
	    JS_ReportOutOfMemory(cx);
	    atom = NULL;
	    goto out;
	}
    }

    atom = (JSAtom *)he;
    atom->flags |= flags & ATOM_PINNED;
out:
    JS_UNLOCK(&state->lock,cx);
    return atom;
}

JS_FRIEND_API(JSAtom *)
js_Atomize(JSContext *cx, const char *bytes, size_t length, uintN flags)
{
    jschar *chars;
    JSString *str;
    JSAtom *atom;
    char buf[2 * ALIGNMENT(JSString)];

    /*
     * Avoiding the malloc in js_InflateString on shorter strings saves us
     * over 20,000 malloc calls on mozilla browser startup. This compares to
     * only 131 calls where the string is longer than a 31 char (net) buffer.
     * The vast majority of atomized strings are already in the hashtable. So
     * js_AtomizeString rarely has to copy the temp string we make.
     */
#define ATOMIZE_BUF_MAX 32
    jschar inflated[ATOMIZE_BUF_MAX];

    if (length < ATOMIZE_BUF_MAX) {
        js_InflateStringToBuffer(inflated, bytes, length);
        chars = inflated;
    } else {
        chars = js_InflateString(cx, bytes, length);
        if (!chars)
	    return NULL;
        flags |= ATOM_NOCOPY;
    }

    str = ALIGN(buf, JSString);

    str->chars = chars;
    str->length = length;
    atom = js_AtomizeString(cx, str, ATOM_TMPSTR | flags);
    if (chars != inflated && (!atom || ATOM_TO_STRING(atom)->chars != chars))
	JS_free(cx, chars);
    return atom;
}

JS_FRIEND_API(JSAtom *)
js_AtomizeChars(JSContext *cx, const jschar *chars, size_t length, uintN flags)
{
    JSString *str;
    char buf[2 * ALIGNMENT(JSString)];

    str = ALIGN(buf, JSString);
    str->chars = (jschar *)chars;
    str->length = length;
    return js_AtomizeString(cx, str, ATOM_TMPSTR | flags);
}

JSAtom *
js_AtomizeValue(JSContext *cx, jsval value, uintN flags)
{
    if (JSVAL_IS_STRING(value))
	return js_AtomizeString(cx, JSVAL_TO_STRING(value), flags);
    if (JSVAL_IS_INT(value))
	return js_AtomizeInt(cx, JSVAL_TO_INT(value), flags);
    if (JSVAL_IS_DOUBLE(value))
	return js_AtomizeDouble(cx, *JSVAL_TO_DOUBLE(value), flags);
    if (JSVAL_IS_OBJECT(value))
	return js_AtomizeObject(cx, JSVAL_TO_OBJECT(value), flags);
    if (JSVAL_IS_BOOLEAN(value))
	return js_AtomizeBoolean(cx, JSVAL_TO_BOOLEAN(value), flags);
    return js_AtomizeHashedKey(cx, value, (JSHashNumber)value, flags);
}

JSAtom *
js_ValueToStringAtom(JSContext *cx, jsval v)
{
    JSString *str;

    str = js_ValueToString(cx, v);
    if (!str)
	return NULL;
    return js_AtomizeString(cx, str, 0);
}

JS_STATIC_DLL_CALLBACK(JSHashNumber)
js_hash_atom_ptr(const void *key)
{
    const JSAtom *atom = key;
    return atom->number;
}

JS_STATIC_DLL_CALLBACK(void *)
js_alloc_temp_space(void *priv, size_t size)
{
    JSContext *cx = priv;
    void *space;

    JS_ARENA_ALLOCATE(space, &cx->tempPool, size);
    if (!space)
        JS_ReportOutOfMemory(cx);
    return space;
}

JS_STATIC_DLL_CALLBACK(void)
js_free_temp_space(void *priv, void *item)
{
}

JS_STATIC_DLL_CALLBACK(JSHashEntry *)
js_alloc_temp_entry(void *priv, const void *key)
{
    JSContext *cx = priv;
    JSAtomListElement *ale;

    JS_ARENA_ALLOCATE_TYPE(ale, JSAtomListElement, &cx->tempPool);
    if (!ale) {
        JS_ReportOutOfMemory(cx);
        return NULL;
    }
    return &ale->entry;
}

JS_STATIC_DLL_CALLBACK(void)
js_free_temp_entry(void *priv, JSHashEntry *he, uintN flag)
{
}

static JSHashAllocOps temp_alloc_ops = {
    js_alloc_temp_space,    js_free_temp_space,
    js_alloc_temp_entry,    js_free_temp_entry
};

JSAtomListElement *
js_IndexAtom(JSContext *cx, JSAtom *atom, JSAtomList *al)
{
    JSAtomListElement *ale, *ale2, *next;
    JSHashEntry **hep;

    ATOM_LIST_LOOKUP(ale, hep, al, atom);
    if (!ale) {
        if (al->count <= 5) {
            /* Few enough for linear search, no hash table needed. */
            JS_ASSERT(!al->table);
            ale = (JSAtomListElement *)js_alloc_temp_entry(cx, atom);
            if (!ale)
                return NULL;
            ALE_SET_ATOM(ale, atom);
            ALE_SET_NEXT(ale, al->list);
            al->list = ale;
        } else {
            /* We want to hash.  Have we already made a hash table? */
            if (!al->table) {
                /* No hash table yet, so hep had better be null! */
                JS_ASSERT(!hep);
                al->table = JS_NewHashTable(8, js_hash_atom_ptr,
                                            JS_CompareValues, JS_CompareValues,
                                            &temp_alloc_ops, cx);
                if (!al->table)
                    return NULL;

                /* Insert each ale on al->list into the new hash table. */
                for (ale2 = al->list; ale2; ale2 = next) {
                    next = ALE_NEXT(ale2);
                    ale2->entry.keyHash = ALE_ATOM(ale2)->number;
                    hep = JS_HashTableRawLookup(al->table, ale2->entry.keyHash,
                                                ale2->entry.key);
                    ALE_SET_NEXT(ale2, *hep);
                    *hep = &ale2->entry;
                }
                al->list = NULL;

                /* Set hep for insertion of atom's ale, immediately below. */
                hep = JS_HashTableRawLookup(al->table, atom->number, atom);
            }

            /* Finally, add an entry for atom into the hash bucket at hep. */
            ale = (JSAtomListElement *)
                JS_HashTableRawAdd(al->table, hep, atom->number, atom, NULL);
            if (!ale)
                return NULL;
        }

	ALE_SET_INDEX(ale, al->count++);
    }
    return ale;
}

JS_FRIEND_API(JSAtom *)
js_GetAtom(JSContext *cx, JSAtomMap *map, jsatomid i)
{
    JSAtom *atom;
    static JSAtom dummy;

    JS_ASSERT(map->vector && i < map->length);
    if (!map->vector || i >= map->length) {
	char numBuf[12];
	JS_snprintf(numBuf, sizeof numBuf, "%lu", (unsigned long)i);
	JS_ReportErrorNumber(cx, js_GetErrorMessage, NULL,
			     JSMSG_BAD_ATOMIC_NUMBER, numBuf);
	return &dummy;
    }
    atom = map->vector[i];
    JS_ASSERT(atom);
    return atom;
}

JS_STATIC_DLL_CALLBACK(intN)
js_map_atom(JSHashEntry *he, intN i, void *arg)
{
    JSAtomListElement *ale = (JSAtomListElement *)he;
    JSAtom **vector = arg;

    vector[ALE_INDEX(ale)] = ALE_ATOM(ale);
    return HT_ENUMERATE_NEXT;
}

#ifdef DEBUG
jsrefcount js_atom_map_count;
jsrefcount js_atom_map_hash_table_count;
#endif

JS_FRIEND_API(JSBool)
js_InitAtomMap(JSContext *cx, JSAtomMap *map, JSAtomList *al)
{
    JSAtom **vector;
    JSAtomListElement *ale;
    uint32 count;

#ifdef DEBUG
    JS_ATOMIC_INCREMENT(&js_atom_map_count);
#endif
    ale = al->list;
    if (!ale && !al->table) {
	map->vector = NULL;
	map->length = 0;
	return JS_TRUE;
    }

    count = al->count;
    if (count >= ATOM_INDEX_LIMIT) {
	JS_ReportErrorNumber(cx, js_GetErrorMessage, NULL,
			     JSMSG_TOO_MANY_LITERALS);
	return JS_FALSE;
    }
    vector = (JSAtom **) JS_malloc(cx, (size_t) count * sizeof *vector);
    if (!vector)
	return JS_FALSE;

    if (al->table) {
#ifdef DEBUG
        JS_ATOMIC_INCREMENT(&js_atom_map_hash_table_count);
#endif
        JS_HashTableEnumerateEntries(al->table, js_map_atom, vector);
    } else {
        do {
            vector[ALE_INDEX(ale)] = ALE_ATOM(ale);
        } while ((ale = ALE_NEXT(ale)) != NULL);
    }
    ATOM_LIST_INIT(al);

    map->vector = vector;
    map->length = (jsatomid)count;
    return JS_TRUE;
}

JS_FRIEND_API(void)
js_FreeAtomMap(JSContext *cx, JSAtomMap *map)
{
    if (map->vector) {
	free(map->vector);
	map->vector = NULL;
    }
    map->length = 0;
}