/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package groovy.json.internal;
import java.util.*;
import static groovy.json.internal.Exceptions.die;
/**
* This class is important to the performance of the parser.
* It stores Value objects in a map where they are evaluated lazily.
* This is great for JSONPath types of application, and Object Serialization but not for maps that are going to be stored in a cache.
* <p/>
* This is because the Value construct is a type of index overlay that merely tracks where the token is located in the buffer,
* and what if any thing we noted about it (like can be converted to a decimal number, etc.).
* <p/>
* To mitigate memory leaks this class along with CharSequenceValue implement two constructs, namely,
* chop, and lazyChop.
* <p/>
* A chop is when we convert backing buffer of a Value object into a smaller buffer.
* A lazyChop is when we do a chop but only when a get operation is called.
* <p/>
* The lazyChop is performed on the tree that is touched by the JSONPath expression or its ilk.
* <p/>
* The chop operation can be done during parsing or lazily by storing the values in this construct.
*
* @author Rick Hightower (insane chipmonk)
*/
public class LazyValueMap extends AbstractMap<String, Object> implements ValueMap<String, Object> {
/**
* holds the map that gets lazily created on first access.
*/
private Map<String, Object> map = null;
/**
* holds the list of items that we are managing.
*/
private Entry<String, Value>[] items;
/**
* Holds the current number mapping managed by this map.
*/
private int len = 0;
/**
* Holds whether or not we ae in lazy chop mode or not.
*/
private final boolean lazyChop;
/**
* Keep track if this map has already been chopped so we don't waste time trying to chop it again.
*/
boolean mapChopped = false;
public LazyValueMap(boolean lazyChop) {
this.items = new Entry[5];
this.lazyChop = lazyChop;
}
public LazyValueMap(boolean lazyChop, int initialSize) {
this.items = new Entry[initialSize];
this.lazyChop = lazyChop;
}
/**
* Adds a new MapItemValue to the mapping.
*
* @param miv miv we are adding.
*/
public final void add(MapItemValue miv) {
if (len >= items.length) {
items = LazyMap.grow(items);
}
items[len] = miv;
len++;
}
/**
* Gets the item by key from the mapping.
*
* @param key to lookup
* @return the item for the given key
*/
public final Object get(Object key) {
Object object = null;
/* if the map is null, then we create it. */
if (map == null) {
buildMap();
}
object = map.get(key);
lazyChopIfNeeded(object);
return object;
}
/**
* If in lazy chop mode, and the object is a Lazy Value Map or a ValueList
* then we force a chop operation for each of its items.
*/
private void lazyChopIfNeeded(Object object) {
if (lazyChop) {
if (object instanceof LazyValueMap) {
LazyValueMap m = (LazyValueMap) object;
m.chopMap();
} else if (object instanceof ValueList) {
ValueList list = (ValueList) object;
list.chopList();
}
}
}
/**
* Chop this map.
*/
public final void chopMap() {
/* if it has been chopped then you have to return. */
if (mapChopped) {
return;
}
mapChopped = true;
/* If the internal map was not create yet, don't. We can chop the value w/o creating the internal map.*/
if (this.map == null) {
for (int index = 0; index < len; index++) {
MapItemValue entry = (MapItemValue) items[index];
Value value = entry.getValue();
if (value == null) continue;
if (value.isContainer()) {
chopContainer(value);
} else {
value.chop();
}
}
} else {
/* Iterate through the map and do the same thing. Make sure children and children of children are chopped. */
for (Map.Entry<String, Object> entry : map.entrySet()) {
Object object = entry.getValue();
if (object instanceof Value) {
Value value = (Value) object;
if (value.isContainer()) {
chopContainer(value);
} else {
value.chop();
}
} else if (object instanceof LazyValueMap) {
LazyValueMap m = (LazyValueMap) object;
m.chopMap();
} else if (object instanceof ValueList) {
ValueList list = (ValueList) object;
list.chopList();
}
}
}
}
/* We need to chop up this child container. */
private static void chopContainer(Value value) {
Object obj = value.toValue();
if (obj instanceof LazyValueMap) {
LazyValueMap map = (LazyValueMap) obj;
map.chopMap();
} else if (obj instanceof ValueList) {
ValueList list = (ValueList) obj;
list.chopList();
}
}
public Value put(String key, Object value) {
die("Not that kind of map");
return null;
}
public Set<Entry<String, Object>> entrySet() {
if (map == null) {
buildMap();
}
return map.entrySet();
}
private void buildMap() {
// added to avoid hash collision attack
if (Sys.is1_8OrLater() || (Sys.is1_7() && LazyMap.JDK_MAP_ALTHASHING_SYSPROP != null)) {
map = new HashMap<String, Object>(items.length);
} else {
map = new TreeMap<String, Object>();
}
for (Entry<String, Value> miv : items) {
if (miv == null) {
break;
}
map.put(miv.getKey(), miv.getValue().toValue());
}
len = 0;
items = null;
}
public Collection<Object> values() {
if (map == null) buildMap();
return map.values();
}
public int size() {
if (map == null) buildMap();
return map.size();
}
public String toString() {
if (map == null) buildMap();
return map.toString();
}
public int len() {
return len;
}
public boolean hydrated() {
return map != null;
}
public Entry<String, Value>[] items() {
return items;
}
}