nativearray.java

java中比较著名的js引擎当属mozilla开源的rhino

            argc--;
        }

        long end = begin + count;

        /* If there are elements to remove, put them into the return value. */
        if (count != 0) {
            if (count == 1
                && (cx.getLanguageVersion() == Context.VERSION_1_2))
            {
                /*
                 * JS lacks "list context", whereby in Perl one turns the
                 * single scalar that's spliced out into an array just by
                 * assigning it to @single instead of $single, or by using it
                 * as Perl push's first argument, for instance.
                 *
                 * JS1.2 emulated Perl too closely and returned a non-Array for
                 * the single-splice-out case, requiring callers to test and
                 * wrap in [] if necessary.  So JS1.3, default, and other
                 * versions all return an array of length 1 for uniformity.
                 */
                result = getElem(cx, thisObj, begin);
            } else {
                for (long last = begin; last != end; last++) {
                    Scriptable resultArray = (Scriptable)result;
                    Object temp = getElem(cx, thisObj, last);
                    setElem(cx, resultArray, last - begin, temp);
                }
            }
        } else if (count == 0
                   && cx.getLanguageVersion() == Context.VERSION_1_2)
        {
            /* Emulate C JS1.2; if no elements are removed, return undefined. */
            result = Undefined.instance;
        }

        /* Find the direction (up or down) to copy and make way for argv. */
        long delta = argc - count;

        if (delta > 0) {
            for (long last = length - 1; last >= end; last--) {
                Object temp = getElem(cx, thisObj, last);
                setElem(cx, thisObj, last + delta, temp);
            }
        } else if (delta < 0) {
            for (long last = end; last < length; last++) {
                Object temp = getElem(cx, thisObj, last);
                setElem(cx, thisObj, last + delta, temp);
            }
        }

        /* Copy from argv into the hole to complete the splice. */
        int argoffset = args.length - argc;
        for (int i = 0; i < argc; i++) {
            setElem(cx, thisObj, begin + i, args[i + argoffset]);
        }

        /* Update length in case we deleted elements from the end. */
        setLengthProperty(cx, thisObj, length + delta);
        return result;
    }

    /*
     * See Ecma 262v3 15.4.4.4
     */
    private static Scriptable js_concat(Context cx, Scriptable scope,
                                        Scriptable thisObj, Object[] args)
    {
        // create an empty Array to return.
        scope = getTopLevelScope(scope);
        Function ctor = ScriptRuntime.getExistingCtor(cx, scope, "Array");
        Scriptable result = ctor.construct(cx, scope, ScriptRuntime.emptyArgs);
        long length;
        long slot = 0;

        /* Put the target in the result array; only add it as an array
         * if it looks like one.
         */
        if (ScriptRuntime.instanceOf(thisObj, ctor, cx)) {
            length = getLengthProperty(cx, thisObj);

            // Copy from the target object into the result
            for (slot = 0; slot < length; slot++) {
                Object temp = getElem(cx, thisObj, slot);
                setElem(cx, result, slot, temp);
            }
        } else {
            setElem(cx, result, slot++, thisObj);
        }

        /* Copy from the arguments into the result.  If any argument
         * has a numeric length property, treat it as an array and add
         * elements separately; otherwise, just copy the argument.
         */
        for (int i = 0; i < args.length; i++) {
            if (ScriptRuntime.instanceOf(args[i], ctor, cx)) {
                // ScriptRuntime.instanceOf => instanceof Scriptable
                Scriptable arg = (Scriptable)args[i];
                length = getLengthProperty(cx, arg);
                for (long j = 0; j < length; j++, slot++) {
                    Object temp = getElem(cx, arg, j);
                    setElem(cx, result, slot, temp);
                }
            } else {
                setElem(cx, result, slot++, args[i]);
            }
        }
        return result;
    }

    private Scriptable js_slice(Context cx, Scriptable thisObj,
                                Object[] args)
    {
        Scriptable scope = getTopLevelScope(this);
        Scriptable result = ScriptRuntime.newObject(cx, scope, "Array", null);
        long length = getLengthProperty(cx, thisObj);

        long begin, end;
        if (args.length == 0) {
            begin = 0;
            end = length;
        } else {
            begin = toSliceIndex(ScriptRuntime.toInteger(args[0]), length);
            if (args.length == 1) {
                end = length;
            } else {
                end = toSliceIndex(ScriptRuntime.toInteger(args[1]), length);
            }
        }

        for (long slot = begin; slot < end; slot++) {
            Object temp = getElem(cx, thisObj, slot);
            setElem(cx, result, slot - begin, temp);
        }

        return result;
    }

    private static long toSliceIndex(double value, long length) {
        long result;
        if (value < 0.0) {
            if (value + length < 0.0) {
                result = 0;
            } else {
                result = (long)(value + length);
            }
        } else if (value > length) {
            result = length;
        } else {
            result = (long)value;
        }
        return result;
    }

    /**
     * Implements the methods "indexOf" and "lastIndexOf".
     */
    private Object indexOfHelper(Context cx, Scriptable thisObj,
                                 Object[] args, boolean isLast)
    {
        Object compareTo = args.length > 0 ? args[0] : Undefined.instance;
        long length = getLengthProperty(cx, thisObj);
        long start = args.length > 1 
            ? ScriptRuntime.toInt32(ScriptRuntime.toNumber(args[1]))
            : (isLast ? length : 0);
        if (start < 0) {
            start += length;
            if (start < 0)
                start = 0;
        }
        if (isLast) {
          for (long i=start; i >= 0 ; i--) {
              if (ScriptRuntime.shallowEq(getElem(cx, thisObj, i), compareTo)) {
                  return new Long(i);
              }
          }
        } else {
          for (long i=start; i < length; i++) {
              if (ScriptRuntime.shallowEq(getElem(cx, thisObj, i), compareTo)) {
                  return new Long(i);
              }
          }
        }
        return NEGATIVE_ONE;
    }

    /**
     * Implements the methods "every", "filter", "forEach", "map", and "some".
     */
    private Object iterativeMethod(Context cx, int id, Scriptable scope, 
                                   Scriptable thisObj, Object[] args)
    {
        Object callbackArg = args.length > 0 ? args[0] : Undefined.instance;
        if (callbackArg == null || !(callbackArg instanceof Function)) {
            throw ScriptRuntime.notFunctionError(
                     ScriptRuntime.toString(callbackArg));
        }
        Function f = (Function) callbackArg;
        Scriptable parent = ScriptableObject.getTopLevelScope(f);
        Scriptable thisArg = args.length > 1 && args[1] instanceof Scriptable
                             ? (Scriptable) args[1]
                             : parent;
        long length = getLengthProperty(cx, thisObj);
        Scriptable array = null;
        if (id == Id_filter) {
            array = ScriptRuntime.newObject(cx, scope, "Array", null);
        } else if (id == Id_map) {
            // allocate dense array for efficiency
            Object[] ctorArgs = { new Long(length) };
            array = ScriptRuntime.newObject(cx, scope, "Array", ctorArgs);
        }
        Object[] innerArgs = new Object[3];
        long j=0;
        for (long i=0; i < length; i++) {
            innerArgs[0] = getElem(cx, thisObj, i);
            innerArgs[1] = new Long(i);
            innerArgs[2] = thisObj;
            Object result = f.call(cx, parent, thisArg, innerArgs);
            switch (id) {
              case Id_every:
                if (!ScriptRuntime.toBoolean(result))
                    return Boolean.FALSE;
                break;
              case Id_filter:
                if (ScriptRuntime.toBoolean(result))
                  setElem(cx, array, j++, innerArgs[0]);
                break;
              case Id_forEach:
                break;
              case Id_map:
                setElem(cx, array, j++, result);
                break;
              case Id_some:
                if (ScriptRuntime.toBoolean(result))
                    return Boolean.TRUE;
                break;
            }
        }
        switch (id) {
          case Id_every:
            return Boolean.TRUE;
          case Id_filter:
          case Id_map:
            return array;
          case Id_some:
            return Boolean.FALSE;
          case Id_forEach:
          default:
            return Undefined.instance;
        }
    }

// #string_id_map#

    protected int findPrototypeId(String s)
    {
        int id;
// #generated# Last update: 2005-09-26 15:47:42 EDT
        L0: { id = 0; String X = null; int c;
            L: switch (s.length()) {
            case 3: c=s.charAt(0);
                if (c=='m') { if (s.charAt(2)=='p' && s.charAt(1)=='a') {id=Id_map; break L0;} }
                else if (c=='p') { if (s.charAt(2)=='p' && s.charAt(1)=='o') {id=Id_pop; break L0;} }
                break L;
            case 4: switch (s.charAt(2)) {
                case 'i': X="join";id=Id_join; break L;
                case 'm': X="some";id=Id_some; break L;
                case 'r': X="sort";id=Id_sort; break L;
                case 's': X="push";id=Id_push; break L;
                } break L;
            case 5: c=s.charAt(1);
                if (c=='h') { X="shift";id=Id_shift; }
                else if (c=='l') { X="slice";id=Id_slice; }
                else if (c=='v') { X="every";id=Id_every; }
                break L;
            case 6: c=s.charAt(0);
                if (c=='c') { X="concat";id=Id_concat; }
                else if (c=='f') { X="filter";id=Id_filter; }
                else if (c=='s') { X="splice";id=Id_splice; }
                break L;
            case 7: switch (s.charAt(0)) {
                case 'f': X="forEach";id=Id_forEach; break L;
                case 'i': X="indexOf";id=Id_indexOf; break L;
                case 'r': X="reverse";id=Id_reverse; break L;
                case 'u': X="unshift";id=Id_unshift; break L;
                } break L;
            case 8: c=s.charAt(3);
                if (c=='o') { X="toSource";id=Id_toSource; }
                else if (c=='t') { X="toString";id=Id_toString; }
                break L;
            case 11: c=s.charAt(0);
                if (c=='c') { X="constructor";id=Id_constructor; }
                else if (c=='l') { X="lastIndexOf";id=Id_lastIndexOf; }
                break L;
            case 14: X="toLocaleString";id=Id_toLocaleString; break L;
            }
            if (X!=null && X!=s && !X.equals(s)) id = 0;
        }
// #/generated#
        return id;
    }

    private static final int
        Id_constructor          = 1,
        Id_toString             = 2,
        Id_toLocaleString       = 3,
        Id_toSource             = 4,
        Id_join                 = 5,
        Id_reverse              = 6,
        Id_sort                 = 7,
        Id_push                 = 8,
        Id_pop                  = 9,
        Id_shift                = 10,
        Id_unshift              = 11,
        Id_splice               = 12,
        Id_concat               = 13,
        Id_slice                = 14,
        Id_indexOf              = 15,
        Id_lastIndexOf          = 16,
        Id_every                = 17,
        Id_filter               = 18,
        Id_forEach              = 19,
        Id_map                  = 20,
        Id_some                 = 21,

        MAX_PROTOTYPE_ID        = 21;

// #/string_id_map#

    private long length;
    private Object[] dense;
    private static final int maximumDenseLength = 10000;
}