kit.java

javascript语言的解释器源码

     *                     break;
     *                 ((PropertyChangeListener)l).propertyChange(e);
     *             }
     *         }
     *     }
     * </pre>
     *
     * @param listener Listener to add to <i>bag</i>
     * @param bag Current collection of listeners.
     * @return A new bag containing all listeners from <i>bag</i> and
     *          <i>listener</i>.
     * @see #removeListener(Object bag, Object listener)
     * @see #getListener(Object bag, int index)
     */
    public static Object addListener(Object bag, Object listener)
    {
        if (listener == null) throw new IllegalArgumentException();
        if (listener instanceof Object[]) throw new IllegalArgumentException();

        if (bag == null) {
            bag = listener;
        } else if (!(bag instanceof Object[])) {
            bag = new Object[] { bag, listener };
        } else {
            Object[] array = (Object[])bag;
            int L = array.length;
            // bag has at least 2 elements if it is array
            if (L < 2) throw new IllegalArgumentException();
            Object[] tmp = new Object[L + 1];
            System.arraycopy(array, 0, tmp, 0, L);
            tmp[L] = listener;
            bag = tmp;
        }

        return bag;
    }

    /**
     * Remove <i>listener</i> from <i>bag</i> of listeners.
     * The function does not modify <i>bag</i> and return a new collection
     * containing all listeners from <i>bag</i> except <i>listener</i>.
     * If <i>bag</i> does not contain <i>listener</i>, the function returns
     * <i>bag</i>.
     * <p>
     * For usage example, see {@link addListener(Object bag, Object listener)}.
     *
     * @param listener Listener to remove from <i>bag</i>
     * @param bag Current collection of listeners.
     * @return A new bag containing all listeners from <i>bag</i> except
     *          <i>listener</i>.
     * @see #addListener(Object bag, Object listener)
     * @see #getListener(Object bag, int index)
     */
    public static Object removeListener(Object bag, Object listener)
    {
        if (listener == null) throw new IllegalArgumentException();
        if (listener instanceof Object[]) throw new IllegalArgumentException();

        if (bag == listener) {
            bag = null;
        } else if (bag instanceof Object[]) {
            Object[] array = (Object[])bag;
            int L = array.length;
            // bag has at least 2 elements if it is array
            if (L < 2) throw new IllegalArgumentException();
            if (L == 2) {
                if (array[1] == listener) {
                    bag = array[0];
                } else if (array[0] == listener) {
                    bag = array[1];
                }
            } else {
                int i = L;
                do {
                    --i;
                    if (array[i] == listener) {
                        Object[] tmp = new Object[L - 1];
                        System.arraycopy(array, 0, tmp, 0, i);
                        System.arraycopy(array, i + 1, tmp, i, L - (i + 1));
                        bag = tmp;
                        break;
                    }
                } while (i != 0);
            }
        }

        return bag;
    }

    /**
     * Get listener at <i>index</i> position in <i>bag</i> or null if
     * <i>index</i> equals to number of listeners in <i>bag</i>.
     * <p>
     * For usage example, see {@link addListener(Object bag, Object listener)}.
     *
     * @param bag Current collection of listeners.
     * @param index Index of the listener to access.
     * @return Listener at the given index or null.
     * @see #addListener(Object bag, Object listener)
     * @see #removeListener(Object bag, Object listener)
     */
    public static Object getListener(Object bag, int index)
    {
        if (index == 0) {
            if (bag == null)
                return null;
            if (!(bag instanceof Object[]))
                return bag;
            Object[] array = (Object[])bag;
            // bag has at least 2 elements if it is array
            if (array.length < 2) throw new IllegalArgumentException();
            return array[0];
        } else if (index == 1) {
            if (!(bag instanceof Object[])) {
                if (bag == null) throw new IllegalArgumentException();
                return null;
            }
            Object[] array = (Object[])bag;
            // the array access will check for index on its own
            return array[1];
        } else {
            // bag has to array
            Object[] array = (Object[])bag;
            int L = array.length;
            if (L < 2) throw new IllegalArgumentException();
            if (index == L)
                return null;
            return array[index];
        }
    }

    static Object initHash(Hashtable h, Object key, Object initialValue)
    {
        synchronized (h) {
            Object current = h.get(key);
            if (current == null) {
                h.put(key, initialValue);
            } else {
                initialValue = current;
            }
        }
        return initialValue;
    }

    private final static class ComplexKey
    {
        private Object key1;
        private Object key2;
        private int hash;

        ComplexKey(Object key1, Object key2)
        {
            this.key1 = key1;
            this.key2 = key2;
        }

        public boolean equals(Object anotherObj)
        {
            if (!(anotherObj instanceof ComplexKey))
                return false;
            ComplexKey another = (ComplexKey)anotherObj;
            return key1.equals(another.key1) && key2.equals(another.key2);
        }

        public int hashCode()
        {
            if (hash == 0) {
                hash = key1.hashCode() ^ key2.hashCode();
            }
            return hash;
        }
    }

    public static Object makeHashKeyFromPair(Object key1, Object key2)
    {
        if (key1 == null) throw new IllegalArgumentException();
        if (key2 == null) throw new IllegalArgumentException();
        return new ComplexKey(key1, key2);
    }

    public static String readReader(Reader r)
        throws IOException
    {
        char[] buffer = new char[512];
        int cursor = 0;
        for (;;) {
            int n = r.read(buffer, cursor, buffer.length - cursor);
            if (n < 0) { break; }
            cursor += n;
            if (cursor == buffer.length) {
                char[] tmp = new char[buffer.length * 2];
                System.arraycopy(buffer, 0, tmp, 0, cursor);
                buffer = tmp;
            }
        }
        return new String(buffer, 0, cursor);
    }

    public static byte[] readStream(InputStream is, int initialBufferCapacity)
        throws IOException
    {
        if (initialBufferCapacity <= 0) {
            throw new IllegalArgumentException(
                "Bad initialBufferCapacity: "+initialBufferCapacity);
        }
        byte[] buffer = new byte[initialBufferCapacity];
        int cursor = 0;
        for (;;) {
            int n = is.read(buffer, cursor, buffer.length - cursor);
            if (n < 0) { break; }
            cursor += n;
            if (cursor == buffer.length) {
                byte[] tmp = new byte[buffer.length * 2];
                System.arraycopy(buffer, 0, tmp, 0, cursor);
                buffer = tmp;
            }
        }
        if (cursor != buffer.length) {
            byte[] tmp = new byte[cursor];
            System.arraycopy(buffer, 0, tmp, 0, cursor);
            buffer = tmp;
        }
        return buffer;
    }

    /**
     * Throws RuntimeException to indicate failed assertion.
     * The function never returns and its return type is RuntimeException
     * only to be able to write <tt>throw Kit.codeBug()</tt> if plain
     * <tt>Kit.codeBug()</tt> triggers unreachable code error.
     */
    public static RuntimeException codeBug()
        throws RuntimeException
    {
        RuntimeException ex = new IllegalStateException("FAILED ASSERTION");
        // Print stack trace ASAP
        ex.printStackTrace(System.err);
        throw ex;
    }
}