jsarray.c

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/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 * vim: set sw=4 ts=8 et tw=80:
 *
 * ***** 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 array class.
 */
#include "jsstddef.h"
#include <stdlib.h>
#include <string.h>
#include "jstypes.h"
#include "jsutil.h" /* Added by JSIFY */
#include "jsapi.h"
#include "jsarray.h"
#include "jsatom.h"
#include "jsbool.h"
#include "jscntxt.h"
#include "jsconfig.h"
#include "jsfun.h"
#include "jsgc.h"
#include "jsinterp.h"
#include "jslock.h"
#include "jsnum.h"
#include "jsobj.h"
#include "jsstr.h"

/* 2^32 - 1 as a number and a string */
#define MAXINDEX 4294967295u
#define MAXSTR   "4294967295"

/*
 * Determine if the id represents an array index or an XML property index.
 *
 * An id is an array index according to ECMA by (15.4):
 *
 * "Array objects give special treatment to a certain class of property names.
 * A property name P (in the form of a string value) is an array index if and
 * only if ToString(ToUint32(P)) is equal to P and ToUint32(P) is not equal
 * to 2^32-1."
 *
 * In our implementation, it would be sufficient to check for JSVAL_IS_INT(id)
 * except that by using signed 32-bit integers we miss the top half of the
 * valid range. This function checks the string representation itself; note
 * that calling a standard conversion routine might allow strings such as
 * "08" or "4.0" as array indices, which they are not.
 */
JSBool
js_IdIsIndex(jsval id, jsuint *indexp)
{
    JSString *str;
    jschar *cp;

    if (JSVAL_IS_INT(id)) {
        jsint i;
        i = JSVAL_TO_INT(id);
        if (i < 0)
            return JS_FALSE;
        *indexp = (jsuint)i;
        return JS_TRUE;
    }

    /* NB: id should be a string, but jsxml.c may call us with an object id. */
    if (!JSVAL_IS_STRING(id))
        return JS_FALSE;

    str = JSVAL_TO_STRING(id);
    cp = JSSTRING_CHARS(str);
    if (JS7_ISDEC(*cp) && JSSTRING_LENGTH(str) < sizeof(MAXSTR)) {
        jsuint index = JS7_UNDEC(*cp++);
        jsuint oldIndex = 0;
        jsuint c = 0;
        if (index != 0) {
            while (JS7_ISDEC(*cp)) {
                oldIndex = index;
                c = JS7_UNDEC(*cp);
                index = 10*index + c;
                cp++;
            }
        }

        /* Ensure that all characters were consumed and we didn't overflow. */
        if (*cp == 0 &&
             (oldIndex < (MAXINDEX / 10) ||
              (oldIndex == (MAXINDEX / 10) && c < (MAXINDEX % 10))))
        {
            *indexp = index;
            return JS_TRUE;
        }
    }
    return JS_FALSE;
}

static JSBool
ValueIsLength(JSContext *cx, jsval v, jsuint *lengthp)
{
    jsint i;
    jsdouble d;

    if (JSVAL_IS_INT(v)) {
        i = JSVAL_TO_INT(v);
        if (i < 0) {
            JS_ReportErrorNumber(cx, js_GetErrorMessage, NULL,
                                 JSMSG_BAD_ARRAY_LENGTH);
            return JS_FALSE;
        }
        *lengthp = (jsuint) i;
        return JS_TRUE;
    }

    if (!js_ValueToNumber(cx, v, &d)) {
        JS_ReportErrorNumber(cx, js_GetErrorMessage, NULL,
                             JSMSG_BAD_ARRAY_LENGTH);
        return JS_FALSE;
    }
    if (!js_DoubleToECMAUint32(cx, d, (uint32 *)lengthp)) {
        JS_ReportErrorNumber(cx, js_GetErrorMessage, NULL,
                             JSMSG_BAD_ARRAY_LENGTH);
        return JS_FALSE;
    }
    if (JSDOUBLE_IS_NaN(d) || d != *lengthp) {
        JS_ReportErrorNumber(cx, js_GetErrorMessage, NULL,
                             JSMSG_BAD_ARRAY_LENGTH);
        return JS_FALSE;
    }
    return JS_TRUE;
}

JSBool
js_GetLengthProperty(JSContext *cx, JSObject *obj, jsuint *lengthp)
{
    JSTempValueRooter tvr;
    jsid id;
    JSBool ok;
    jsint i;

    JS_PUSH_SINGLE_TEMP_ROOT(cx, JSVAL_NULL, &tvr);
    id = ATOM_TO_JSID(cx->runtime->atomState.lengthAtom);
    ok = OBJ_GET_PROPERTY(cx, obj, id, &tvr.u.value);
    if (ok) {
        /*
         * Short-circuit, because js_ValueToECMAUint32 fails when called
         * during init time.
         */
        if (JSVAL_IS_INT(tvr.u.value)) {
            i = JSVAL_TO_INT(tvr.u.value);
            *lengthp = (jsuint)i;       /* jsuint cast does ToUint32 */
        } else {
            ok = js_ValueToECMAUint32(cx, tvr.u.value, (uint32 *)lengthp);
        }
    }
    JS_POP_TEMP_ROOT(cx, &tvr);
    return ok;
}

static JSBool
IndexToValue(JSContext *cx, jsuint index, jsval *vp)
{
    if (index <= JSVAL_INT_MAX) {
        *vp = INT_TO_JSVAL(index);
        return JS_TRUE;
    }
    return js_NewDoubleValue(cx, (jsdouble)index, vp);
}

static JSBool
BigIndexToId(JSContext *cx, JSObject *obj, jsuint index, JSBool createAtom,
             jsid *idp)
{
    jschar buf[10], *start;
    JSClass *clasp;
    JSAtom *atom;

//    JS_STATIC_ASSERT((jsuint)-1 == 4294967295U);
    JS_ASSERT(index > JSVAL_INT_MAX);

    start = JS_ARRAY_END(buf);
    do {
        --start;
        *start = (jschar)('0' + index % 10);
        index /= 10;
    } while (index != 0);

    /*
     * Skip the atomization if the class is known to store atoms corresponding
     * to big indexes together with elements. In such case we know that the
     * array does not have an element at the given index if its atom does not
     * exist.
     */
    if (!createAtom &&
        ((clasp = OBJ_GET_CLASS(cx, obj)) == &js_ArrayClass ||
         clasp == &js_ArgumentsClass ||
         clasp == &js_ObjectClass)) {
        atom = js_GetExistingStringAtom(cx, start, JS_ARRAY_END(buf) - start);
        if (!atom) {
            *idp = JSVAL_VOID;
            return JS_TRUE;
        }
    } else {
        atom = js_AtomizeChars(cx, start, JS_ARRAY_END(buf) - start, 0);
        if (!atom)
            return JS_FALSE;
    }

    *idp = ATOM_TO_JSID(atom);
    return JS_TRUE;
}

/*
 * If the property at the given index exists, get its value into location
 * pointed by vp and set *hole to false. Otherwise set *hole to true and *vp
 * to JSVAL_VOID. This function assumes that the location pointed by vp is
 * properly rooted and can be used as GC-protected storage for temporaries.
 */
static JSBool
GetArrayElement(JSContext *cx, JSObject *obj, jsuint index, JSBool *hole,
                jsval *vp)
{
    jsid id;
    JSObject *obj2;
    JSProperty *prop;

    if (index <= JSVAL_INT_MAX) {
        id = INT_TO_JSID(index);
    } else {
        if (!BigIndexToId(cx, obj, index, JS_FALSE, &id))
            return JS_FALSE;
        if (id == JSVAL_VOID) {
            *hole = JS_TRUE;
            *vp = JSVAL_VOID;
            return JS_TRUE;
        }
    }

    if (!OBJ_LOOKUP_PROPERTY(cx, obj, id, &obj2, &prop))
        return JS_FALSE;
    if (!prop) {
        *hole = JS_TRUE;
        *vp = JSVAL_VOID;
    } else {
        OBJ_DROP_PROPERTY(cx, obj2, prop);
        if (!OBJ_GET_PROPERTY(cx, obj, id, vp))
            return JS_FALSE;
        *hole = JS_FALSE;
    }
    return JS_TRUE;
}

/*
 * Set the value of the property at the given index to v assuming v is rooted.
 */
static JSBool
SetArrayElement(JSContext *cx, JSObject *obj, jsuint index, jsval v)
{
    jsid id;

    if (index <= JSVAL_INT_MAX) {
        id = INT_TO_JSID(index);
    } else {
        if (!BigIndexToId(cx, obj, index, JS_TRUE, &id))
            return JS_FALSE;
        JS_ASSERT(id != JSVAL_VOID);
    }
    return OBJ_SET_PROPERTY(cx, obj, id, &v);
}

static JSBool
DeleteArrayElement(JSContext *cx, JSObject *obj, jsuint index)
{
    jsid id;
    jsval junk;

    if (index <= JSVAL_INT_MAX) {
        id = INT_TO_JSID(index);
    } else {
        if (!BigIndexToId(cx, obj, index, JS_FALSE, &id))
            return JS_FALSE;
        if (id == JSVAL_VOID)
            return JS_TRUE;
    }
    return OBJ_DELETE_PROPERTY(cx, obj, id, &junk);
}

/*
 * When hole is true, delete the property at the given index. Otherwise set
 * its value to v assuming v is rooted.
 */
static JSBool
SetOrDeleteArrayElement(JSContext *cx, JSObject *obj, jsuint index,
                        JSBool hole, jsval v)
{
    if (hole) {
        JS_ASSERT(v == JSVAL_VOID);
        return DeleteArrayElement(cx, obj, index);
    } else {
        return SetArrayElement(cx, obj, index, v);
    }
}


JSBool
js_SetLengthProperty(JSContext *cx, JSObject *obj, jsuint length)
{
    jsval v;
    jsid id;

    if (!IndexToValue(cx, length, &v))
        return JS_FALSE;
    id = ATOM_TO_JSID(cx->runtime->atomState.lengthAtom);
    return OBJ_SET_PROPERTY(cx, obj, id, &v);
}

JSBool
js_HasLengthProperty(JSContext *cx, JSObject *obj, jsuint *lengthp)
{
    JSErrorReporter older;
    JSTempValueRooter tvr;
    jsid id;
    JSBool ok;

    older = JS_SetErrorReporter(cx, NULL);
    JS_PUSH_SINGLE_TEMP_ROOT(cx, JSVAL_NULL, &tvr);
    id = ATOM_TO_JSID(cx->runtime->atomState.lengthAtom);
    ok = OBJ_GET_PROPERTY(cx, obj, id, &tvr.u.value);
    JS_SetErrorReporter(cx, older);
    if (ok)
        ok = ValueIsLength(cx, tvr.u.value, lengthp);
    JS_POP_TEMP_ROOT(cx, &tvr);
    return ok;
}

JSBool
js_IsArrayLike(JSContext *cx, JSObject *obj, JSBool *answerp, jsuint *lengthp)
{
    JSClass *clasp;

    clasp = OBJ_GET_CLASS(cx, obj);
    *answerp = (clasp == &js_ArgumentsClass || clasp == &js_ArrayClass);
    if (!*answerp) {
        *lengthp = 0;
        return JS_TRUE;
    }
    return js_GetLengthProperty(cx, obj, lengthp);
}

/*
 * This get function is specific to Array.prototype.length and other array
 * instance length properties.  It calls back through the class get function
 * in case some magic happens there (see call_getProperty in jsfun.c).
 */
static JSBool
array_length_getter(JSContext *cx, JSObject *obj, jsval id, jsval *vp)
{
    return OBJ_GET_CLASS(cx, obj)->getProperty(cx, obj, id, vp);
}

static JSBool
array_length_setter(JSContext *cx, JSObject *obj, jsval id, jsval *vp)
{
    jsuint newlen, oldlen, gap, index;
    jsid id2;
    jsval junk;
    JSObject *iter;
    JSTempValueRooter tvr;
    JSBool ok;

    if (!ValueIsLength(cx, *vp, &newlen))
        return JS_FALSE;
    if (!js_GetLengthProperty(cx, obj, &oldlen))
        return JS_FALSE;
    if (oldlen > newlen) {
        if (oldlen - newlen < (1 << 24)) {
            do {
                --oldlen;
                if (!DeleteArrayElement(cx, obj, oldlen))
                    return JS_FALSE;
            } while (oldlen != newlen);
        } else {
            /*
             * We are going to remove a lot of indexes in a presumably sparse
             * array. So instead of looping through indexes between newlen and
             * oldlen, we iterate through all properties and remove those that
             * correspond to indexes from the [newlen, oldlen) range.
             * See bug 322135.
             */
            iter = JS_NewPropertyIterator(cx, obj);
            if (!iter)
                return JS_FALSE;

            /* Protect iter against GC in OBJ_DELETE_PROPERTY. */
            JS_PUSH_TEMP_ROOT_OBJECT(cx, iter, &tvr);
            gap = oldlen - newlen;
            for (;;) {
                ok = JS_NextProperty(cx, iter, &id2);
                if (!ok)
                    break;
                if (id2 == JSVAL_VOID)
                    break;
                if (js_IdIsIndex(id2, &index) && index - newlen < gap) {
                    ok = OBJ_DELETE_PROPERTY(cx, obj, id2, &junk);
                    if (!ok)
                        break;
                }
            }
            JS_POP_TEMP_ROOT(cx, &tvr);
            if (!ok)
                return JS_FALSE;
        }
    }
    return IndexToValue(cx, newlen, vp);
}

static JSBool
array_addProperty(JSContext *cx, JSObject *obj, jsval id, jsval *vp)
{
    jsuint index, length;

    if (!js_IdIsIndex(id, &index))
        return JS_TRUE;
    if (!js_GetLengthProperty(cx, obj, &length))
        return JS_FALSE;
    if (index >= length) {
        length = index + 1;
        return js_SetLengthProperty(cx, obj, length);
    }
    return JS_TRUE;
}

static JSBool
array_convert(JSContext *cx, JSObject *obj, JSType type, jsval *vp)
{
    return js_TryValueOf(cx, obj, type, vp);