nativearray.java

javascript语言的解释器源码

                Object[] e = getIds(); // will only find in object itself
                for (int i=0; i < e.length; i++) {
                    Object id = e[i];
                    if (id instanceof String) {
                        // > MAXINT will appear as string
                        String strId = (String)id;
                        long index = toArrayIndex(strId);
                        if (index >= longVal)
                            delete(strId);
                    } else {
                        int index = ((Integer)id).intValue();
                        if (index >= longVal)
                            delete(index);
                    }
                }
            } else {
                // assume a dense representation
                for (long i = longVal; i < length; i++) {
                    deleteElem(this, i);
                }
            }
        }
        length = longVal;
    }

    /* Support for generic Array-ish objects.  Most of the Array
     * functions try to be generic; anything that has a length
     * property is assumed to be an array.
     * getLengthProperty returns 0 if obj does not have the length property
     * or its value is not convertible to a number.
     */
    static long getLengthProperty(Context cx, Scriptable obj) {
        // These will both give numeric lengths within Uint32 range.
        if (obj instanceof NativeString) {
            return ((NativeString)obj).getLength();
        } else if (obj instanceof NativeArray) {
            return ((NativeArray)obj).getLength();
        } else if (!(obj instanceof Scriptable)) {
            return 0;
        }
        return ScriptRuntime.toUint32(
            ScriptRuntime.getObjectProp(obj, "length", cx));
    }

    private static Object setLengthProperty(Context cx, Scriptable target,
                                            long length)
    {
        return ScriptRuntime.setObjectProp(
                   target, "length", ScriptRuntime.wrapNumber(length), cx);
    }

    /* Utility functions to encapsulate index > Integer.MAX_VALUE
     * handling.  Also avoids unnecessary object creation that would
     * be necessary to use the general ScriptRuntime.get/setElem
     * functions... though this is probably premature optimization.
     */
    private static void deleteElem(Scriptable target, long index) {
        int i = (int)index;
        if (i == index) { target.delete(i); }
        else { target.delete(Long.toString(index)); }
    }

    private static Object getElem(Context cx, Scriptable target, long index)
    {
        if (index > Integer.MAX_VALUE) {
            String id = Long.toString(index);
            return ScriptRuntime.getObjectProp(target, id, cx);
        } else {
            return ScriptRuntime.getObjectIndex(target, (int)index, cx);
        }
    }

    private static void setElem(Context cx, Scriptable target, long index,
                                Object value)
    {
        if (index > Integer.MAX_VALUE) {
            String id = Long.toString(index);
            ScriptRuntime.setObjectProp(target, id, value, cx);
        } else {
            ScriptRuntime.setObjectIndex(target, (int)index, value, cx);
        }
    }

    private static String toStringHelper(Context cx, Scriptable scope,
                                         Scriptable thisObj,
                                         boolean toSource, boolean toLocale)
    {
        /* It's probably redundant to handle long lengths in this
         * function; StringBuffers are limited to 2^31 in java.
         */

        long length = getLengthProperty(cx, thisObj);

        StringBuffer result = new StringBuffer(256);

        // whether to return '4,unquoted,5' or '[4, "quoted", 5]'
        String separator;

        if (toSource) {
            result.append('[');
            separator = ", ";
        } else {
            separator = ",";
        }

        boolean haslast = false;
        long i = 0;

        boolean toplevel, iterating;
        if (cx.iterating == null) {
            toplevel = true;
            iterating = false;
            cx.iterating = new ObjToIntMap(31);
        } else {
            toplevel = false;
            iterating = cx.iterating.has(thisObj);
        }

        // Make sure cx.iterating is set to null when done
        // so we don't leak memory
        try {
            if (!iterating) {
                cx.iterating.put(thisObj, 0); // stop recursion.
                for (i = 0; i < length; i++) {
                    if (i > 0) result.append(separator);
                    Object elem = getElem(cx, thisObj, i);
                    if (elem == null || elem == Undefined.instance) {
                        haslast = false;
                        continue;
                    }
                    haslast = true;

                    if (toSource) {
                        result.append(ScriptRuntime.uneval(cx, scope, elem));

                    } else if (elem instanceof String) {
                        String s = (String)elem;
                        if (toSource) {
                            result.append('\"');
                            result.append(ScriptRuntime.escapeString(s));
                            result.append('\"');
                        } else {
                            result.append(s);
                        }

                    } else {
                        if (toLocale && elem != Undefined.instance &&
                            elem != null)
                        {
                            Callable fun;
                            Scriptable funThis;
                            fun = ScriptRuntime.getPropFunctionAndThis(
                                      elem, "toLocaleString", cx);
                            funThis = ScriptRuntime.lastStoredScriptable(cx);
                            elem = fun.call(cx, scope, funThis,
                                            ScriptRuntime.emptyArgs);
                        }
                        result.append(ScriptRuntime.toString(elem));
                    }
                }
            }
        } finally {
            if (toplevel) {
                cx.iterating = null;
            }
        }

        if (toSource) {
            //for [,,].length behavior; we want toString to be symmetric.
            if (!haslast && i > 0)
                result.append(", ]");
            else
                result.append(']');
        }
        return result.toString();
    }

    /**
     * See ECMA 15.4.4.3
     */
    private static String js_join(Context cx, Scriptable thisObj,
                                  Object[] args)
    {
        String separator;

        long llength = getLengthProperty(cx, thisObj);
        int length = (int)llength;
        if (llength != length) {
            throw Context.reportRuntimeError1(
                "msg.arraylength.too.big", String.valueOf(llength));
        }
        // if no args, use "," as separator
        if (args.length < 1 || args[0] == Undefined.instance) {
            separator = ",";
        } else {
            separator = ScriptRuntime.toString(args[0]);
        }
        if (length == 0) {
            return "";
        }
        String[] buf = new String[length];
        int total_size = 0;
        for (int i = 0; i != length; i++) {
            Object temp = getElem(cx, thisObj, i);
            if (temp != null && temp != Undefined.instance) {
                String str = ScriptRuntime.toString(temp);
                total_size += str.length();
                buf[i] = str;
            }
        }
        total_size += (length - 1) * separator.length();
        StringBuffer sb = new StringBuffer(total_size);
        for (int i = 0; i != length; i++) {
            if (i != 0) {
                sb.append(separator);
            }
            String str = buf[i];
            if (str != null) {
                // str == null for undefined or null
                sb.append(str);
            }
        }
        return sb.toString();
    }

    /**
     * See ECMA 15.4.4.4
     */
    private static Scriptable js_reverse(Context cx, Scriptable thisObj,
                                         Object[] args)
    {
        long len = getLengthProperty(cx, thisObj);

        long half = len / 2;
        for(long i=0; i < half; i++) {
            long j = len - i - 1;
            Object temp1 = getElem(cx, thisObj, i);
            Object temp2 = getElem(cx, thisObj, j);
            setElem(cx, thisObj, i, temp2);
            setElem(cx, thisObj, j, temp1);
        }
        return thisObj;
    }

    /**
     * See ECMA 15.4.4.5
     */
    private static Scriptable js_sort(Context cx, Scriptable scope,
                                      Scriptable thisObj, Object[] args)
    {
        long length = getLengthProperty(cx, thisObj);

        if (length <= 1) { return thisObj; }

        Object compare;
        Object[] cmpBuf;

        if (args.length > 0 && Undefined.instance != args[0]) {
            // sort with given compare function
            compare = args[0];
            cmpBuf = new Object[2]; // Buffer for cmp arguments
        } else {
            // sort with default compare
            compare = null;
            cmpBuf = null;
        }

        // Should we use the extended sort function, or the faster one?
        if (length >= Integer.MAX_VALUE) {
            heapsort_extended(cx, scope, thisObj, length, compare, cmpBuf);
        }
        else {
            int ilength = (int)length;
            // copy the JS array into a working array, so it can be
            // sorted cheaply.
            Object[] working = new Object[ilength];
            for (int i = 0; i != ilength; ++i) {
                working[i] = getElem(cx, thisObj, i);
            }

            heapsort(cx, scope, working, ilength, compare, cmpBuf);

            // copy the working array back into thisObj
            for (int i = 0; i != ilength; ++i) {
                setElem(cx, thisObj, i, working[i]);
            }
        }
        return thisObj;
    }

    // Return true only if x > y
    private static boolean isBigger(Context cx, Scriptable scope,
                                    Object x, Object y,
                                    Object cmp, Object[] cmpBuf)
    {
        if (cmp == null) {
            if (cmpBuf != null) Kit.codeBug();
        } else {
            if (cmpBuf == null || cmpBuf.length != 2) Kit.codeBug();
        }

        Object undef = Undefined.instance;

        // sort undefined to end
        if (undef == y) {
            return false; // x can not be bigger then undef
        } else if (undef == x) {
            return true; // y != undef here, so x > y
        }

        if (cmp == null) {
            // if no cmp function supplied, sort lexicographically
            String a = ScriptRuntime.toString(x);
            String b = ScriptRuntime.toString(y);
            return a.compareTo(b) > 0;
        }
        else {
            // assemble args and call supplied JS cmp function
            cmpBuf[0] = x;
            cmpBuf[1] = y;
            Callable fun = ScriptRuntime.getValueFunctionAndThis(cmp, cx);
            Scriptable funThis = ScriptRuntime.lastStoredScriptable(cx);

            Object ret = fun.call(cx, scope, funThis, cmpBuf);
            double d = ScriptRuntime.toNumber(ret);

            // XXX what to do when cmp function returns NaN?  ECMA states
            // that it's then not a 'consistent compararison function'... but
            // then what do we do?  Back out and start over with the generic
            // cmp function when we see a NaN?  Throw an error?

            // for now, just ignore it:

            return d > 0;
        }
    }

/** Heapsort implementation.
 * See "Introduction to Algorithms" by Cormen, Leiserson, Rivest for details.
 * Adjusted for zero based indexes.
 */
    private static void heapsort(Context cx, Scriptable scope,
                                 Object[] array, int length,
                                 Object cmp, Object[] cmpBuf)
    {
        if (length <= 1) Kit.codeBug();

        // Build heap
        for (int i = length / 2; i != 0;) {
            --i;
            Object pivot = array[i];
            heapify(cx, scope, pivot, array, i, length, cmp, cmpBuf);
        }

        // Sort heap
        for (int i = length; i != 1;) {
            --i;
            Object pivot = array[i];
            array[i] = array[0];
            heapify(cx, scope, pivot, array, 0, i, cmp, cmpBuf);
        }
    }

/** pivot and child heaps of i should be made into heap starting at i,
 * original array[i] is never used to have less array access during sorting.
 */
    private static void heapify(Context cx, Scriptable scope,
                                Object pivot, Object[] array, int i, int end,
                                Object cmp, Object[] cmpBuf)
    {
        for (;;) {
            int child = i * 2 + 1;
            if (child >= end) {
                break;
            }
            Object childVal = array[child];
            if (child + 1 < end) {
                Object nextVal = array[child + 1];
                if (isBigger(cx, scope, nextVal, childVal, cmp, cmpBuf)) {
                    ++child; childVal = nextVal;
                }
            }
            if (!isBigger(cx, scope, childVal, pivot, cmp, cmpBuf)) {
                break;
            }
            array[i] = childVal;
            i = child;
        }
        array[i] = pivot;
    }

/** Version of heapsort that call getElem/setElem on target to query/assign
 * array elements instead of Java array access
 */
    private static void heapsort_extended(Context cx, Scriptable scope,
                                          Scriptable target, long length,
                                          Object cmp, Object[] cmpBuf)
    {
        if (length <= 1) Kit.codeBug();