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Access to the Neo4j graph database through Java
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/**
 * Copyright (c) 2002-2016 "Neo Technology,"
 * Network Engine for Objects in Lund AB [http://neotechnology.com]
 *
 * This file is part of Neo4j.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.neo4j.driver.v1;

import java.util.Collections;
import java.util.HashMap;
import java.util.Map;

import org.neo4j.driver.internal.ParameterSupport;

import static java.lang.String.format;

/**
 * An executable statement, i.e. the statements' text and its parameters.
 *
 * @see Session
 * @see Transaction
 * @see ResultCursor
 * @see ResultCursor#summarize()
 * @see ResultSummary
 */
@Immutable
public class Statement
{
    private final String template;
    private final Map parameters;

    public Statement( String template, Map parameters )
    {
        this.template = template;
        this.parameters = parameters == null || parameters.isEmpty()
            ? ParameterSupport.NO_PARAMETERS
            : Collections.unmodifiableMap( parameters );
    }

    public Statement( String template )
    {
        this( template, null );
    }

    /**
     * @return the statement's template
     */
    public String template()
    {
        return template;
    }

    /**
     * @return the statement's parameters
     */
    public Map parameters()
    {
        return parameters;
    }

    /**
     * @param newTemplate the new statement's template
     * @return a new statement with updated template
     */
    public Statement withTemplate( String newTemplate )
    {
        return new Statement( newTemplate, parameters );
    }

    /**
     * @param newParameters the new statement's parameters
     * @return a new statement with updated parameters
     */
    public Statement withParameters( Map newParameters )
    {
        return new Statement( template, newParameters );
    }

    /**
     * Create a new statement with new parameters derived by updating this'
     * statement's parameters using the given updates.
     *
     * Every update key that points to a null value will be removed from
     * the new statement's parameters. All other entries will just replace
     * any existing parameter in the new statement.
     *
     * @param updates describing how to update the parameters
     * @return a new statement with updated parameters
     */
    public Statement withUpdatedParameters( Map updates )
    {
        if ( updates == null || updates.isEmpty() )
        {
            return this;
        }
        else
        {
            Map newParameters = new HashMap<>( Math.max( parameters.size(), updates.size() ) );
            newParameters.putAll( parameters );
            for ( Map.Entry entry : updates.entrySet() )
            {
                Value value = entry.getValue();
                if ( value.isNull() )
                {
                    newParameters.remove( entry.getKey() );
                }
                else
                {
                    newParameters.put( entry.getKey(), value );
                }
            }
            return withParameters( newParameters );
        }
    }

    @Override
    public boolean equals( Object o )
    {
        if ( this == o )
        {
            return true;
        }
        if ( o == null || getClass() != o.getClass() )
        {
            return false;
        }

        Statement statement = (Statement) o;
        return template.equals( statement.template ) && parameters.equals( statement.parameters );

    }

    @Override
    public int hashCode()
    {
        int result = template.hashCode();
        result = 31 * result + parameters.hashCode();
        return result;
    }

    @Override
    public String toString()
    {
        return format( "Statement{template='%s', parameters=%s}", template, parameters );
    }
}