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

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

You can also browse Jackson Core Source Code below:

⏎ com/fasterxml/jackson/core/json/JsonReadContext.java

package com.fasterxml.jackson.core.json;

import com.fasterxml.jackson.core.*;
import com.fasterxml.jackson.core.io.ContentReference;

/**
 * Extension of {@link JsonStreamContext}, which implements
 * core methods needed, and also exposes
 * more complete API to parser implementation classes.
 */
public final class JsonReadContext extends JsonStreamContext
{
    // // // Configuration

    /**
     * Parent context for this context; null for root context.
     */
    protected final JsonReadContext _parent;

    // // // Optional duplicate detection

    protected DupDetector _dups;

    /*
    /**********************************************************
    /* Simple instance reuse slots; speeds up things a bit (10-15%)
    /* for docs with lots of small arrays/objects (for which
    /* allocation was visible in profile stack frames)
    /**********************************************************
     */

    protected JsonReadContext _child;

    /*
    /**********************************************************
    /* Location/state information (minus source reference)
    /**********************************************************
     */

    protected String _currentName;

    /**
     * @since 2.5
     */
    protected Object _currentValue;
    
    protected int _lineNr;
    protected int _columnNr;

    /*
    /**********************************************************
    /* Instance construction, config, reuse
    /**********************************************************
     */

    public JsonReadContext(JsonReadContext parent, DupDetector dups, int type, int lineNr, int colNr) {
        super();
        _parent = parent;
        _dups = dups;
        _type = type;
        _lineNr = lineNr;
        _columnNr = colNr;
        _index = -1;
    }

    /**
     * Internal method to allow instance reuse: DO NOT USE unless you absolutely
     * know what you are doing.
     * Clears up state (including "current value"), changes type to one specified;
     * resets current duplicate-detection state (if any).
     * Parent link left as-is since it is {@code final}.
     *<p>
     * NOTE: Public since 2.12.
     *
     * @param type Type to assign to this context node
     * @param lineNr Line of the starting position of this context
     * @param colNr Column of the starting position of this context
     */
    public void reset(int type, int lineNr, int colNr) {
        _type = type;
        _index = -1;
        _lineNr = lineNr;
        _columnNr = colNr;
        _currentName = null;
        _currentValue = null;
        if (_dups != null) {
            _dups.reset();
        }
    }

    /*
    public void trackDups(JsonParser p) {
        _dups = DupDetector.rootDetector(p);
    }
    */

    public JsonReadContext withDupDetector(DupDetector dups) {
        _dups = dups;
        return this;
    }

    @Override
    public Object getCurrentValue() {
        return _currentValue;
    }

    @Override
    public void setCurrentValue(Object v) {
        _currentValue = v;
    }

    /*
    /**********************************************************
    /* Factory methods
    /**********************************************************
     */

    public static JsonReadContext createRootContext(int lineNr, int colNr, DupDetector dups) {
        return new JsonReadContext(null, dups, TYPE_ROOT, lineNr, colNr);
    }

    public static JsonReadContext createRootContext(DupDetector dups) {
        return new JsonReadContext(null, dups, TYPE_ROOT, 1, 0);
    }

    public JsonReadContext createChildArrayContext(int lineNr, int colNr) {
        JsonReadContext ctxt = _child;
        if (ctxt == null) {
            _child = ctxt = new JsonReadContext(this,
                    (_dups == null) ? null : _dups.child(), TYPE_ARRAY, lineNr, colNr);
        } else {
            ctxt.reset(TYPE_ARRAY, lineNr, colNr);
        }
        return ctxt;
    }

    public JsonReadContext createChildObjectContext(int lineNr, int colNr) {
        JsonReadContext ctxt = _child;
        if (ctxt == null) {
            _child = ctxt = new JsonReadContext(this,
                    (_dups == null) ? null : _dups.child(), TYPE_OBJECT, lineNr, colNr);
            return ctxt;
        }
        ctxt.reset(TYPE_OBJECT, lineNr, colNr);
        return ctxt;
    }

    /*
    /**********************************************************
    /* Abstract method implementations, overrides
    /**********************************************************
     */

    @Override public String getCurrentName() { return _currentName; }

    // @since 2.9
    @Override public boolean hasCurrentName() { return _currentName != null; }

    @Override public JsonReadContext getParent() { return _parent; }

    @Override
    public JsonLocation startLocation(ContentReference srcRef) {
        // We don't keep track of offsets at this level (only reader does)
        long totalChars = -1L;
        return new JsonLocation(srcRef, totalChars, _lineNr, _columnNr);
    }

    @Override
    @Deprecated // since 2.13
    public JsonLocation getStartLocation(Object rawSrc) {
        return startLocation(ContentReference.rawReference(rawSrc));
    }

    /*
    /**********************************************************
    /* Extended API
    /**********************************************************
     */

    /**
     * Method that can be used to both clear the accumulated references
     * (specifically value set with {@link #setCurrentValue(Object)})
     * that should not be retained, and returns parent (as would
     * {@link #getParent()} do). Typically called when closing the active
     * context when encountering {@link JsonToken#END_ARRAY} or
     * {@link JsonToken#END_OBJECT}.
     *
     * @return Parent context of this context node, if any; {@code null} for root context
     *
     * @since 2.7
     */
    public JsonReadContext clearAndGetParent() {
        _currentValue = null;
        // could also clear the current name, but seems cheap enough to leave?
        return _parent;
    }

    public DupDetector getDupDetector() {
        return _dups;
    }

    /*
    /**********************************************************
    /* State changes
    /**********************************************************
     */

    public boolean expectComma() {
        /* Assumption here is that we will be getting a value (at least
         * before calling this method again), and
         * so will auto-increment index to avoid having to do another call
         */
        int ix = ++_index; // starts from -1
        return (_type != TYPE_ROOT && ix > 0);
    }

    public void setCurrentName(String name) throws JsonProcessingException {
        _currentName = name;
        if (_dups != null) { _checkDup(_dups, name); }
    }

    private void _checkDup(DupDetector dd, String name) throws JsonProcessingException {
        if (dd.isDup(name)) {
            Object src = dd.getSource();
            throw new JsonParseException(((src instanceof JsonParser) ? ((JsonParser) src) : null),
                    "Duplicate field '"+name+"'");
        }
    }
}

⏎ com/fasterxml/jackson/core/json/JsonReadContext.java

Or download all of them as a single archive file:

File name: jackson-core-2.14.0-sources.jar
File size: 497693 bytes
Release date: 2022-11-05
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