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General data-binding functionality for Jackson: works on core streaming API
There is a newer version: 2.17.0
package com.fasterxml.jackson.databind.deser.impl;

import java.io.IOException;
import java.util.Collection;
import java.util.HashMap;

import com.fasterxml.jackson.core.JsonParser;

import com.fasterxml.jackson.databind.DeserializationContext;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.MapperFeature;
import com.fasterxml.jackson.databind.deser.SettableBeanProperty;
import com.fasterxml.jackson.databind.deser.ValueInstantiator;

/**
 * Object that is used to collect arguments for non-default creator
 * (non-default-constructor, or argument-taking factory method)
 * before creator can be called.
 * Since ordering of JSON properties is not guaranteed, this may
 * require buffering of values other than ones being passed to
 * creator.
 */
public final class PropertyBasedCreator
{
    /**
     * Number of properties: usually same as size of {@link #_propertyLookup},
     * but not necessarily, when we have unnamed injectable properties.
     */
    protected final int _propertyCount;

    /**
     * Helper object that knows how to actually construct the instance by
     * invoking creator method with buffered arguments.
     */
    protected final ValueInstantiator _valueInstantiator;

    /**
     * Map that contains property objects for either constructor or factory
     * method (whichever one is null: one property for each
     * parameter for that one), keyed by logical property name
     */
    protected final HashMap _propertyLookup;

    /**
     * Array that contains properties that expect value to inject, if any;
     * null if no injectable values are expected.
     */
    protected final SettableBeanProperty[] _allProperties;

    /*
    /**********************************************************
    /* Construction, initialization
    /**********************************************************
     */

    protected PropertyBasedCreator(ValueInstantiator valueInstantiator,
            SettableBeanProperty[] creatorProps,
            boolean caseInsensitive)
    {
        _valueInstantiator = valueInstantiator;
        if (caseInsensitive) {
            _propertyLookup = new CaseInsensitiveMap();
        } else {
            _propertyLookup = new HashMap();
        }
        final int len = creatorProps.length;
        _propertyCount = len;
        _allProperties = new SettableBeanProperty[len];
        for (int i = 0; i < len; ++i) {
            SettableBeanProperty prop = creatorProps[i];
            _allProperties[i] = prop;
            _propertyLookup.put(prop.getName(), prop);
        }
    }

    /**
     * Factory method used for building actual instances: resolves deserializers
     * and checks for "null values".
     */
    public static PropertyBasedCreator construct(DeserializationContext ctxt,
            ValueInstantiator valueInstantiator, SettableBeanProperty[] srcProps)
        throws JsonMappingException
    {
        final int len = srcProps.length;
        SettableBeanProperty[] creatorProps = new SettableBeanProperty[len];
        for (int i = 0; i < len; ++i) {
            SettableBeanProperty prop = srcProps[i];
            if (!prop.hasValueDeserializer()) {
                prop = prop.withValueDeserializer(ctxt.findContextualValueDeserializer(prop.getType(), prop));
            }
            creatorProps[i] = prop;
        }
        return new PropertyBasedCreator(valueInstantiator, creatorProps,
                ctxt.isEnabled(MapperFeature.ACCEPT_CASE_INSENSITIVE_PROPERTIES));
    }

    /*
    /**********************************************************
    /* Accessors
    /**********************************************************
     */

    public Collection properties() {
        return _propertyLookup.values();
    }

    public SettableBeanProperty findCreatorProperty(String name) {
        return _propertyLookup.get(name);
    }

    public SettableBeanProperty findCreatorProperty(int propertyIndex) {
        for (SettableBeanProperty prop : _propertyLookup.values()) {
            if (prop.getPropertyIndex() == propertyIndex) {
                return prop;
            }
        }
        return null;
    }

    /*
    /**********************************************************
    /* Building process
    /**********************************************************
     */

    /**
     * Method called when starting to build a bean instance.
     * 
     * @since 2.1 (added ObjectIdReader parameter -- existed in previous versions without)
     */
    public PropertyValueBuffer startBuilding(JsonParser p, DeserializationContext ctxt,
            ObjectIdReader oir) {
        return new PropertyValueBuffer(p, ctxt, _propertyCount, oir);
    }

    public Object build(DeserializationContext ctxt, PropertyValueBuffer buffer) throws IOException
    {
        Object bean = _valueInstantiator.createFromObjectWith(ctxt,
                _allProperties, buffer);
        // returning null isn't quite legal, but let's let caller deal with that
        if (bean != null) {
            // Object Id to handle?
            bean = buffer.handleIdValue(ctxt, bean);
            
            // Anything buffered?
            for (PropertyValue pv = buffer.buffered(); pv != null; pv = pv.next) {
                pv.assign(bean);
            }
        }
        return bean;
    }

    /*
    /**********************************************************
    /* Helper classes
    /**********************************************************
     */

    /**
     * Simple override of standard {@link java.util.HashMap} to support
     * case-insensitive access to creator properties.
     *
     * @since 2.8.5
     */
    static class CaseInsensitiveMap extends HashMap
    {
        private static final long serialVersionUID = 1L;

        @Override
        public SettableBeanProperty get(Object key0) {
            String key = (String) key0;
            return super.get(key.toLowerCase());
        }

        @Override
        public SettableBeanProperty put(String key, SettableBeanProperty value) {
            key = key.toLowerCase();
            return super.put(key, value);
        }
    }
}