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82 lines
2.2 KiB
C++
82 lines
2.2 KiB
C++
/*
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* Licensed to the Apache Software Foundation (ASF) under one
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* or more contributor license agreements. See the NOTICE file
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* distributed with this work for additional information
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* regarding copyright ownership. The ASF licenses this file
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* to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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/*
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* Modified by Cloudius Systems
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*
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* Copyright 2014 Cloudius Systems
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*/
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#ifndef CQL3_FUNCTIONS_AGGREGATE_FUNCTION_HH_
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#define CQL3_FUNCTIONS_AGGREGATE_FUNCTION_HH_
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#include "function.hh"
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namespace cql3 {
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namespace functions {
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/**
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* Performs a calculation on a set of values and return a single value.
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*/
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class aggregate_function : public virtual function {
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public:
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class aggregate;
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/**
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* Creates a new <code>Aggregate</code> instance.
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*
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* @return a new <code>Aggregate</code> instance.
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*/
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virtual std::unique_ptr<aggregate> new_aggregate() = 0;
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/**
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* An aggregation operation.
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*/
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class aggregate {
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public:
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virtual ~aggregate() {}
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/**
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* Adds the specified input to this aggregate.
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*
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* @param protocol_version native protocol version
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* @param values the values to add to the aggregate.
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*/
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virtual void add_input(int protocol_version, const std::vector<bytes>& values) = 0;
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/**
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* Computes and returns the aggregate current value.
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*
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* @param protocol_version native protocol version
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* @return the aggregate current value.
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*/
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virtual bytes compute(int protocol_version) = 0;
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/**
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* Reset this aggregate.
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*/
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virtual void reset() = 0;
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};
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};
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}
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}
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#endif /* CQL3_FUNCTIONS_AGGREGATE_FUNCTION_HH_ */
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