/* -*- Mode: java; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
package org.mozilla.javascript;
import java.io.Serializable;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
/**
Implementation of resizable array with focus on minimizing memory usage by storing few initial array elements in object fields. Can also be used as a stack.
*/
public class ObjArray implements Serializable
{
static final long serialVersionUID = 4174889037736658296L;
public ObjArray() { }
public final boolean isSealed()
{
return sealed;
}
public final void seal()
{
sealed = true;
}
public final boolean isEmpty()
{
return size == 0;
}
public final int size()
{
return size;
}
public final void setSize(int newSize)
{
if (newSize < 0) throw new IllegalArgumentException();
if (sealed) throw onSeledMutation();
int N = size;
if (newSize < N) {
for (int i = newSize; i != N; ++i) {
setImpl(i, null);
}
} else if (newSize > N) {
if (newSize > FIELDS_STORE_SIZE) {
ensureCapacity(newSize);
}
}
size = newSize;
}
public final Object get(int index)
{
if (!(0 <= index && index < size)) throw onInvalidIndex(index, size);
return getImpl(index);
}
public final void set(int index, Object value)
{
if (!(0 <= index && index < size)) throw onInvalidIndex(index, size);
if (sealed) throw onSeledMutation();
setImpl(index, value);
}
private Object getImpl(int index)
{
switch (index) {
case 0: return f0;
case 1: return f1;
case 2: return f2;
case 3: return f3;
case 4: return f4;
}
return data[index - FIELDS_STORE_SIZE];
}
private void setImpl(int index, Object value)
{
switch (index) {
case 0: f0 = value; break;
case 1: f1 = value; break;
case 2: f2 = value; break;
case 3: f3 = value; break;
case 4: f4 = value; break;
default: data[index - FIELDS_STORE_SIZE] = value;
}
}
public int indexOf(Object obj)
{
int N = size;
for (int i = 0; i != N; ++i) {
Object current = getImpl(i);
if (current == obj || (current != null && current.equals(obj))) {
return i;
}
}
return -1;
}
public int lastIndexOf(Object obj)
{
for (int i = size; i != 0;) {
--i;
Object current = getImpl(i);
if (current == obj || (current != null && current.equals(obj))) {
return i;
}
}
return -1;
}
public final Object peek()
{
int N = size;
if (N == 0) throw onEmptyStackTopRead();
return getImpl(N - 1);
}
public final Object pop()
{
if (sealed) throw onSeledMutation();
int N = size;
--N;
Object top;
switch (N) {
case -1: throw onEmptyStackTopRead();
case 0: top = f0; f0 = null; break;
case 1: top = f1; f1 = null; break;
case 2: top = f2; f2 = null; break;
case 3: top = f3; f3 = null; break;
case 4: top = f4; f4 = null; break;
default:
top = data[N - FIELDS_STORE_SIZE];
data[N - FIELDS_STORE_SIZE] = null;
}
size = N;
return top;
}
public final void push(Object value)
{
add(value);
}
public final void add(Object value)
{
if (sealed) throw onSeledMutation();
int N = size;
if (N >= FIELDS_STORE_SIZE) {
ensureCapacity(N + 1);
}
size = N + 1;
setImpl(N, value);
}
public final void add(int index, Object value)
{
int N = size;
if (!(0 <= index && index <= N)) throw onInvalidIndex(index, N + 1);
if (sealed) throw onSeledMutation();
Object tmp;
switch (index) {
case 0:
if (N == 0) { f0 = value; break; }
tmp = f0; f0 = value; value = tmp;
case 1:
if (N == 1) { f1 = value; break; }
tmp = f1; f1 = value; value = tmp;
case 2:
if (N == 2) { f2 = value; break; }
tmp = f2; f2 = value; value = tmp;
case 3:
if (N == 3) { f3 = value; break; }
tmp = f3; f3 = value; value = tmp;
case 4:
if (N == 4) { f4 = value; break; }
tmp = f4; f4 = value; value = tmp;
index = FIELDS_STORE_SIZE;
default:
ensureCapacity(N + 1);
if (index != N) {
System.arraycopy(data, index - FIELDS_STORE_SIZE,
data, index - FIELDS_STORE_SIZE + 1,
N - index);
}
data[index - FIELDS_STORE_SIZE] = value;
}
size = N + 1;
}
public final void remove(int index)
{
int N = size;
if (!(0 <= index && index < N)) throw onInvalidIndex(index, N);
if (sealed) throw onSeledMutation();
--N;
switch (index) {
case 0:
if (N == 0) { f0 = null; break; }
f0 = f1;
case 1:
if (N == 1) { f1 = null; break; }
f1 = f2;
case 2:
if (N == 2) { f2 = null; break; }
f2 = f3;
case 3:
if (N == 3) { f3 = null; break; }
f3 = f4;
case 4:
if (N == 4) { f4 = null; break; }
f4 = data[0];
index = FIELDS_STORE_SIZE;
default:
if (index != N) {
System.arraycopy(data, index - FIELDS_STORE_SIZE + 1,
data, index - FIELDS_STORE_SIZE,
N - index);
}
data[N - FIELDS_STORE_SIZE] = null;
}
size = N;
}
public final void clear()
{
if (sealed) throw onSeledMutation();
int N = size;
for (int i = 0; i != N; ++i) {
setImpl(i, null);
}
size = 0;
}
public final Object[] toArray()
{
Object[] array = new Object[size];
toArray(array, 0);
return array;
}
public final void toArray(Object[] array)
{
toArray(array, 0);
}
public final void toArray(Object[] array, int offset)
{
int N = size;
switch (N) {
default:
System.arraycopy(data, 0, array, offset + FIELDS_STORE_SIZE,
N - FIELDS_STORE_SIZE);
case 5: array[offset + 4] = f4;
case 4: array[offset + 3] = f3;
case 3: array[offset + 2] = f2;
case 2: array[offset + 1] = f1;
case 1: array[offset + 0] = f0;
case 0: break;
}
}
private void ensureCapacity(int minimalCapacity)
{
int required = minimalCapacity - FIELDS_STORE_SIZE;
if (required <= 0) throw new IllegalArgumentException();
if (data == null) {
int alloc = FIELDS_STORE_SIZE * 2;
if (alloc < required) {
alloc = required;
}
data = new Object[alloc];
} else {
int alloc = data.length;
if (alloc < required) {
if (alloc <= FIELDS_STORE_SIZE) {
alloc = FIELDS_STORE_SIZE * 2;
} else {
alloc *= 2;
}
if (alloc < required) {
alloc = required;
}
Object[] tmp = new Object[alloc];
if (size > FIELDS_STORE_SIZE) {
System.arraycopy(data, 0, tmp, 0,
size - FIELDS_STORE_SIZE);
}
data = tmp;
}
}
}
private static RuntimeException onInvalidIndex(int index, int upperBound)
{
// \u2209 is "NOT ELEMENT OF"
String msg = index+" \u2209 [0, "+upperBound+')';
throw new IndexOutOfBoundsException(msg);
}
private static RuntimeException onEmptyStackTopRead()
{
throw new RuntimeException("Empty stack");
}
private static RuntimeException onSeledMutation()
{
throw new IllegalStateException("Attempt to modify sealed array");
}
private void writeObject(ObjectOutputStream os) throws IOException
{
os.defaultWriteObject();
int N = size;
for (int i = 0; i != N; ++i) {
Object obj = getImpl(i);
os.writeObject(obj);
}
}
private void readObject(ObjectInputStream is)
throws IOException, ClassNotFoundException
{
is.defaultReadObject(); // It reads size
int N = size;
if (N > FIELDS_STORE_SIZE) {
data = new Object[N - FIELDS_STORE_SIZE];
}
for (int i = 0; i != N; ++i) {
Object obj = is.readObject();
setImpl(i, obj);
}
}
// Number of data elements
private int size;
private boolean sealed;
private static final int FIELDS_STORE_SIZE = 5;
private transient Object f0, f1, f2, f3, f4;
private transient Object[] data;
}