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// Example program showing signals with custom combiners.
//
// Copyright Douglas Gregor 2001-2004.
// Copyright Frank Mori Hess 2009.
//
// Use, modification and
// distribution is subject to the Boost Software License, Version
// 1.0. (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
// For more information, see http://www.boost.org
#include <iostream>
#include <boost/signals2/signal.hpp>
#include <vector>
float product(float x, float y) { return x * y; }
float quotient(float x, float y) { return x / y; }
float sum(float x, float y) { return x + y; }
float difference(float x, float y) { return x - y; }
//[ custom_combiners_maximum_def_code_snippet
// combiner which returns the maximum value returned by all slots
template<typename T>
struct maximum
{
typedef T result_type;
template<typename InputIterator>
T operator()(InputIterator first, InputIterator last) const
{
// If there are no slots to call, just return the
// default-constructed value
if(first == last ) return T();
T max_value = *first++;
while (first != last) {
if (max_value < *first)
max_value = *first;
++first;
}
return max_value;
}
};
//]
void maximum_combiner_example()
{
// signal which uses our custom "maximum" combiner
boost::signals2::signal<float (float x, float y), maximum<float> > sig;
//[ custom_combiners_maximum_usage_code_snippet
sig.connect(&product);
sig.connect("ient);
sig.connect(&sum);
sig.connect(&difference);
// Outputs the maximum value returned by the connected slots, in this case
// 15 from the product function.
std::cout << "maximum: " << sig(5, 3) << std::endl;
//]
}
//[ custom_combiners_aggregate_values_def_code_snippet
// aggregate_values is a combiner which places all the values returned
// from slots into a container
template<typename Container>
struct aggregate_values
{
typedef Container result_type;
template<typename InputIterator>
Container operator()(InputIterator first, InputIterator last) const
{
Container values;
while(first != last) {
values.push_back(*first);
++first;
}
return values;
}
};
//]
void aggregate_values_example()
{
// signal which uses aggregate_values as its combiner
boost::signals2::signal<float (float, float),
aggregate_values<std::vector<float> > > sig;
//[ custom_combiners_aggregate_values_usage_code_snippet
sig.connect("ient);
sig.connect(&product);
sig.connect(&sum);
sig.connect(&difference);
std::vector<float> results = sig(5, 3);
std::cout << "aggregate values: ";
std::copy(results.begin(), results.end(),
std::ostream_iterator<float>(std::cout, " "));
std::cout << "\n";
//]
}
int main()
{
maximum_combiner_example();
aggregate_values_example();
}
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