70 lines
2.3 KiB
C++
70 lines
2.3 KiB
C++
/**************************************************************************
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*
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* negator.cpp - Example program for reversing the sense of predicate
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* function objects by using function adaptors and function
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* objects.
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*
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* $Id: negator.cpp 550991 2007-06-26 23:58:07Z sebor $
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*
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***************************************************************************
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed
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* with this work for additional information regarding copyright
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* ownership. The ASF licenses this file to you under the Apache
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* License, Version 2.0 (the "License"); you may not use this file
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* except in compliance with the License. You may obtain a copy of
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* 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
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* implied. See the License for the specific language governing
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* permissions and limitations under the License.
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*
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* Copyright 1994-2006 Rogue Wave Software.
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*
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**************************************************************************/
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#include <functional> // for unary_function
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#include <ios> // for boolalpha
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#include <iostream> // for cout, endl
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#include <examples.h>
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// Create a new predicate from unary_function.
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template <class Arg>
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struct is_odd : public std::unary_function<Arg, bool>
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{
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bool operator() (const Arg &arg1) const {
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return arg1 % 2 != 0;
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}
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};
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int main ()
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{
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std::less<int> less_func;
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// Use not2 on less.
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std::cout << std::boolalpha
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<< less_func (1, 4) << '\n'
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<< less_func (4, 1) << '\n'
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<< std::not2 (std::less<int>())(1, 4) << '\n'
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<< std::not2 (std::less<int>())(4, 1) << '\n';
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// Create an instance of our predicate.
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is_odd<int> odd;
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// Use not1 on our user defined predicate.
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std::cout << odd (1) << '\n'
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<< odd (4) << '\n'
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<< std::not1 (odd)(1) << '\n'
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<< std::not1 (odd)(4) << std::endl;
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return 0;
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}
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