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The Apache Cassandra Project develops a highly scalable second-generation distributed database, bringing together Dynamo's fully distributed design and Bigtable's ColumnFamily-based data model.
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/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.apache.cassandra.cql3;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import org.apache.cassandra.cql3.functions.Function;
import org.apache.cassandra.cql3.statements.StatementType;

import com.google.common.collect.Iterators;

/**
 * A set of Operations.
 *
 */
public final class Operations implements Iterable
{
    /**
     * The type of statement.
     */
    private final StatementType type;

    /**
     * The operations on regular columns.
     */
    private final List regularOperations = new ArrayList<>();

    /**
     * The operations on static columns.
     */
    private final List staticOperations = new ArrayList<>();

    public Operations(StatementType type)
    {
        this.type = type;
    }

    /**
     * Checks if some of the operations apply to static columns.
     *
     * @return true if some of the operations apply to static columns, false otherwise.
     */
    public boolean appliesToStaticColumns()
    {
        return !staticOperations.isEmpty();
    }

    /**
     * Checks if some of the operations apply to regular columns.
     *
     * @return true if some of the operations apply to regular columns, false otherwise.
     */
    public boolean appliesToRegularColumns()
    {
     // If we have regular operations, this applies to regular columns.
        // Otherwise, if the statement is a DELETE and staticOperations is also empty, this means we have no operations,
        // which for a DELETE means a full row deletion. Which means the operation applies to all columns and regular ones in particular.
        return !regularOperations.isEmpty() || (type.isDelete() && staticOperations.isEmpty());
    }

    /**
     * Returns the operation on regular columns.
     * @return the operation on regular columns
     */
    public List regularOperations()
    {
        return regularOperations;
    }

    /**
     * Returns the operation on static columns.
     * @return the operation on static columns
     */
    public List staticOperations()
    {
        return staticOperations;
    }

    /**
     * Adds the specified Operation to this set of operations.
     * @param operation the operation to add
     */
    public void add(Operation operation)
    {
        if (operation.column.isStatic())
            staticOperations.add(operation);
        else
            regularOperations.add(operation);
    }

    /**
     * Checks if one of the operations requires a read.
     *
     * @return true if one of the operations requires a read, false otherwise.
     */
    public boolean requiresRead()
    {
        // Lists SET operation incurs a read.
        for (Operation operation : this)
            if (operation.requiresRead())
                return true;

        return false;
    }

    /**
     * Checks if this Operations is empty.
     * @return true if this Operations is empty, false otherwise.
     */
    public boolean isEmpty()
    {
        return staticOperations.isEmpty() && regularOperations.isEmpty();
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public Iterator iterator()
    {
        return Iterators.concat(staticOperations.iterator(), regularOperations.iterator());
    }

    public void addFunctionsTo(List functions)
    {
        regularOperations.forEach(p -> p.addFunctionsTo(functions));
        staticOperations.forEach(p -> p.addFunctionsTo(functions));
    }
}