Jackson is "the Java JSON library" or "the best JSON parser for Java". Or simply as "JSON for Java".

Jackson Databind Source Code files are provided in the source packge (jackson-databind-2.14.0-sources.jar). You can download it at Jackson Maven Website.

You can also browse Jackson Databind Source Code below:

⏎ com/fasterxml/jackson/databind/node/NodeCursor.java

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 JsonNode currentNode();

    public abstract NodeCursor startObject();
    public abstract NodeCursor startArray();
    
    /**
     * 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 for all root-level value nodes (including Arrays and Objects):
     * only context for scalar 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) {
                ++_index;
                _done = true;
                return _node.asToken();
            }
            _node = null;
            return null;
        }

        @Override
        public JsonNode currentNode() {
            // May look weird, but is necessary so as not to expose current node
            // before it has been traversed
            return _done ? _node : null;
        }

        @Override
        public NodeCursor startArray() { return new ArrayCursor(_node, this); }

        @Override
        public NodeCursor startObject() { return new ObjectCursor(_node, this); }
    }

    // Cursor used for traversing JSON Array nodes
    protected final static class ArrayCursor
        extends NodeCursor
    {
        protected Iterator<JsonNode> _contents;

        protected JsonNode _currentElement;

        public ArrayCursor(JsonNode n, NodeCursor p) {
            super(JsonStreamContext.TYPE_ARRAY, p);
            _contents = n.elements();
        }

        @Override
        public JsonToken nextToken()
        {
            if (!_contents.hasNext()) {
                _currentElement = null;
                return JsonToken.END_ARRAY;
            }
            ++_index;
            _currentElement = _contents.next();
            return _currentElement.asToken();
        }

        @Override
        public JsonNode currentNode() { return _currentElement; }

        @Override
        public NodeCursor startArray() { return new ArrayCursor(_currentElement, this); }

        @Override
        public NodeCursor startObject() { return new ObjectCursor(_currentElement, this); }
    }

    // Cursor used for traversing JSON Object nodes
    protected final static class ObjectCursor
        extends NodeCursor
    {
        protected Iterator<Map.Entry<String, JsonNode>> _contents;
        protected Map.Entry<String, JsonNode> _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 JsonToken.END_OBJECT;
                }
                ++_index;
                _needEntry = false;
                _current = _contents.next();
                _currentName = (_current == null) ? null : _current.getKey();
                return JsonToken.FIELD_NAME;
            }
            _needEntry = true;
            return _current.getValue().asToken();
        }

        @Override
        public JsonNode currentNode() {
            return (_current == null) ? null : _current.getValue();
        }

        @Override
        public NodeCursor startArray() { return new ArrayCursor(currentNode(), this); }

        @Override
        public NodeCursor startObject() { return new ObjectCursor(currentNode(), this); }
    }
}

⏎ com/fasterxml/jackson/databind/node/NodeCursor.java

Or download all of them as a single archive file:

File name: jackson-databind-2.14.0-sources.jar
File size: 1187952 bytes
Release date: 2022-11-05
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