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Neo4j kernel is a lightweight, embedded Java database designed to store data structured as graphs rather than tables. For more information, see http://neo4j.org.

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/*
 * Copyright (c) "Neo4j"
 * Neo4j Sweden AB [http://neo4j.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see .
 */
package org.neo4j.kernel.impl.newapi;

import java.util.Arrays;
import java.util.Iterator;

import org.neo4j.function.ThrowingConsumer;
import org.neo4j.internal.schema.SchemaDescriptor;
import org.neo4j.internal.schema.SchemaDescriptorSupplier;

/**
 * This class holds functionality to match {@link SchemaDescriptor} to entities.
 */
public class SchemaMatcher
{
    private SchemaMatcher()
    {
        throw new AssertionError( "no instance" );
    }

    /**
     * Iterate over some schema suppliers, and invoke a callback for every supplier that matches the entity. To match the
     * entity E the supplier must supply a {@link SchemaDescriptor} D, such that E has values for all the properties of D.
     * The supplied schemas are all assumed to match E on token (label or relationship).
     * 
     * To avoid unnecessary store lookups, this implementation only gets propertyKeyIds for the entity if some
     * descriptor has a valid token.
     *
     * @param  the type to match. Must implement SchemaDescriptorSupplier
     * @param  The type of exception that can be thrown when taking the action
     * @param schemaSuppliers The suppliers to match
     * @param specialPropertyId This property id will always count as a match for the descriptor, regardless of
     * whether the entity has this property or not
     * @param callback The action to take on match
     * @throws EXCEPTION This exception is propagated from the action
     */
    static  void onMatchingSchema(
            Iterator schemaSuppliers,
            int specialPropertyId,
            int[] existingPropertyIds,
            ThrowingConsumer callback
    ) throws EXCEPTION
    {
        while ( schemaSuppliers.hasNext() )
        {
            SUPPLIER schemaSupplier = schemaSuppliers.next();
            SchemaDescriptor schema = schemaSupplier.schema();

            if ( entityHasSchemaProperties( existingPropertyIds, schema.getPropertyIds(), specialPropertyId ) )
            {
                callback.accept( schemaSupplier );
            }
        }
    }

    private static boolean entityHasSchemaProperties(
            int[] existingPropertyIds, int[] indexPropertyIds, int changedPropertyId )
    {
        for ( int indexPropertyId : indexPropertyIds )
        {
            if ( indexPropertyId != changedPropertyId && !contains( existingPropertyIds, indexPropertyId ) )
            {
                return false;
            }
        }
        return true;
    }

    private static boolean contains( int[] existingPropertyIds, int indexPropertyId )
    {
        return Arrays.binarySearch( existingPropertyIds, indexPropertyId ) >= 0;
    }
}