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/util/JacksonFeatureSet.java

package com.fasterxml.jackson.core.util;

/**
 * Container similar to {@link java.util.EnumSet} meant for storing sets of
 * {@link JacksonFeature}s (usually {@link java.lang.Enum}s): main
 * difference being that these sets are immutable. Also only supports relatively
 * small sets of features: specifically, up to 31 features.
 *
 * @since 2.12
 */
public final class JacksonFeatureSet<F extends JacksonFeature>
{
    protected int _enabled;

    /**
     * Constructor for creating instance with specific bitmask, wherein
     * {@code 1} bit means matching {@link JacksonFeature} is enabled and
     * {@code 0} disabled.
     *
     * @param bitmask Bitmask for features that are enabled
     */
    protected JacksonFeatureSet(int bitmask) {
        _enabled = bitmask;
    }

    /**
     * "Default" factory which will calculate settings based on default-enabled
     * status of all features.
     *
     * @param <F> Self-reference type for convenience
     *
     * @param allFeatures Set of all features (enabled or disabled): usually from
     * {@code Enum.values()}
     *
     * @return Feature set instance constructed
     */
    public static <F extends JacksonFeature> JacksonFeatureSet<F> fromDefaults(F[] allFeatures) {
        // first sanity check
        if (allFeatures.length > 31) {
            final String desc = allFeatures[0].getClass().getName();
            throw new IllegalArgumentException(String.format(
"Can not use type `%s` with JacksonFeatureSet: too many entries (%d > 31)",
desc, allFeatures.length));
        }
        
        int flags = 0;
        for (F f : allFeatures) {
            if (f.enabledByDefault()) {
                flags |= f.getMask();
            }
        }
        return new JacksonFeatureSet<F>(flags);
    }

    public static <F extends JacksonFeature> JacksonFeatureSet<F> fromBitmask(int bitmask) {
        return new JacksonFeatureSet<F>(bitmask);
    }

    /**
     * Mutant factory for getting a set in which specified feature is enabled:
     * will either return this instance (if no change), or newly created set (if there
     * is change).
     *
     * @param feature Feature to enable in set returned
     *
     * @return Newly created set of state of feature changed; {@code this} if not
     */
    public JacksonFeatureSet<F> with(F feature) {
        int newMask = _enabled | feature.getMask();
        return (newMask == _enabled) ? this : new JacksonFeatureSet<F>(newMask);
    }

    /**
     * Mutant factory for getting a set in which specified feature is disabled:
     * will either return this instance (if no change), or newly created set (if there
     * is change).
     *
     * @param feature Feature to disable in set returned
     *
     * @return Newly created set of state of feature changed; {@code this} if not
     */
    public JacksonFeatureSet<F> without(F feature) {
        int newMask = _enabled & ~feature.getMask();
        return (newMask == _enabled) ? this : new JacksonFeatureSet<F>(newMask);
    }

    /**
     * Main accessor for checking whether given feature is enabled in this feature set.
     *
     * @param feature Feature to check
     *
     * @return True if feature is enabled in this set; false otherwise
     */
    public boolean isEnabled(F feature) {
        return (feature.getMask() & _enabled) != 0;
    }

    /**
     * Accessor for underlying bitmask
     * 
     * @return Bitmask of enabled features
     */
    public int asBitmask() {
        return _enabled;
    }
}

⏎ com/fasterxml/jackson/core/util/JacksonFeatureSet.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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