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General data-binding functionality for Jackson: works on core streaming API
package com.fasterxml.jackson.databind.node;
import java.util.*;
import com.fasterxml.jackson.core.*;
import com.fasterxml.jackson.databind.JsonNode;
/**
* Helper class used by {@link TreeTraversingParser} to keep track
* of current location within traversed JSON tree.
*/
abstract class NodeCursor
extends JsonStreamContext
{
/**
* Parent cursor of this cursor, if any; null for root
* cursors.
*/
protected final NodeCursor _parent;
/**
* Current field name
*/
protected String _currentName;
/**
* @since 2.5
*/
protected java.lang.Object _currentValue;
public NodeCursor(int contextType, NodeCursor p)
{
super();
_type = contextType;
_index = -1;
_parent = p;
}
/*
/**********************************************************
/* JsonStreamContext impl
/**********************************************************
*/
// note: co-variant return type
@Override
public final NodeCursor getParent() { return _parent; }
@Override
public final String getCurrentName() {
return _currentName;
}
/**
* @since 2.0
*/
public void overrideCurrentName(String name) {
_currentName = name;
}
@Override
public java.lang.Object getCurrentValue() {
return _currentValue;
}
@Override
public void setCurrentValue(java.lang.Object v) {
_currentValue = v;
}
/*
/**********************************************************
/* Extended API
/**********************************************************
*/
public abstract JsonToken nextToken();
public abstract JsonToken nextValue();
public abstract JsonToken endToken();
public abstract JsonNode currentNode();
public abstract boolean currentHasChildren();
/**
* Method called to create a new context for iterating all
* contents of the current structured value (JSON array or object)
*/
public final NodeCursor iterateChildren() {
JsonNode n = currentNode();
if (n == null) throw new IllegalStateException("No current node");
if (n.isArray()) { // false since we have already returned START_ARRAY
return new ArrayCursor(n, this);
}
if (n.isObject()) {
return new ObjectCursor(n, this);
}
throw new IllegalStateException("Current node of type "+n.getClass().getName());
}
/*
/**********************************************************
/* Concrete implementations
/**********************************************************
*/
/**
* Context matching root-level value nodes (i.e. anything other
* than JSON Object and Array).
* Note that context is NOT created for leaf values.
*/
protected final static class RootCursor
extends NodeCursor
{
protected JsonNode _node;
protected boolean _done = false;
public RootCursor(JsonNode n, NodeCursor p) {
super(JsonStreamContext.TYPE_ROOT, p);
_node = n;
}
@Override
public void overrideCurrentName(String name) {
}
@Override
public JsonToken nextToken() {
if (!_done) {
_done = true;
return _node.asToken();
}
_node = null;
return null;
}
@Override
public JsonToken nextValue() { return nextToken(); }
@Override
public JsonToken endToken() { return null; }
@Override
public JsonNode currentNode() { return _node; }
@Override
public boolean currentHasChildren() { return false; }
}
/**
* Cursor used for traversing non-empty JSON Array nodes
*/
protected final static class ArrayCursor
extends NodeCursor
{
protected Iterator _contents;
protected JsonNode _currentNode;
public ArrayCursor(JsonNode n, NodeCursor p) {
super(JsonStreamContext.TYPE_ARRAY, p);
_contents = n.elements();
}
@Override
public JsonToken nextToken()
{
if (!_contents.hasNext()) {
_currentNode = null;
return null;
}
_currentNode = _contents.next();
return _currentNode.asToken();
}
@Override
public JsonToken nextValue() { return nextToken(); }
@Override
public JsonToken endToken() { return JsonToken.END_ARRAY; }
@Override
public JsonNode currentNode() { return _currentNode; }
@Override
public boolean currentHasChildren() {
// note: ONLY to be called for container nodes
return ((ContainerNode) currentNode()).size() > 0;
}
}
/**
* Cursor used for traversing non-empty JSON Object nodes
*/
protected final static class ObjectCursor
extends NodeCursor
{
protected Iterator> _contents;
protected Map.Entry _current;
protected boolean _needEntry;
public ObjectCursor(JsonNode n, NodeCursor p)
{
super(JsonStreamContext.TYPE_OBJECT, p);
_contents = ((ObjectNode) n).fields();
_needEntry = true;
}
@Override
public JsonToken nextToken()
{
// Need a new entry?
if (_needEntry) {
if (!_contents.hasNext()) {
_currentName = null;
_current = null;
return null;
}
_needEntry = false;
_current = _contents.next();
_currentName = (_current == null) ? null : _current.getKey();
return JsonToken.FIELD_NAME;
}
_needEntry = true;
return _current.getValue().asToken();
}
@Override
public JsonToken nextValue()
{
JsonToken t = nextToken();
if (t == JsonToken.FIELD_NAME) {
t = nextToken();
}
return t;
}
@Override
public JsonToken endToken() { return JsonToken.END_OBJECT; }
@Override
public JsonNode currentNode() {
return (_current == null) ? null : _current.getValue();
}
@Override
public boolean currentHasChildren() {
// note: ONLY to be called for container nodes
return ((ContainerNode) currentNode()).size() > 0;
}
}
}