/* * *Author: Paul Caron *Date: August 1rst 2019 *License: Give me all credits *Inspiration: java.util.stream * */ /* *This container wrapper class called Streamer is a *class that adds few higher order functions to *existing standard library containers (eg list, *vector, deque). *Those methods, frequently used in functional *programming style, are namely: map, filter, reduce *and forEach. These methods have for goal to add *clarity to any code and overcome the need for *traditional for-loops. *The Streamer container also keeps the methods *of the given container it inherits from. * *-map: iterates through all the Streamer's contained *elements, then returns a new Streamer container *containing the results of a given function for each *original element. * *-filter: iterates through all the Streamer's *contained values and returns a new Streamer container *containing only elements that satisfies a predicate *function. * *-reduce: iterates through all the Streamer's *contained values and returns a single element or * value based on an accumulator operation function. * *-forEach: iterates through all the Streamer's *contained elements and returns nothing. It only *executes the given function for each element. * *This Streamer container wrapper class would work on *any containers, as long as the following methods are *implemented for the given container: *-size() *-resize() *-begin() *-end() */ #include #include #include #include using namespace std; template class Streamer: public Collection{ public: Streamer (){} Streamer (const Collection& col){ this->resize(col.size()); for(auto a=this->begin(),b=col.begin();b!=col.end();++a,++b) *a=*b; } void operator = (const Collection & col){ this->resize(col.size()); for(auto a=this->begin(),b=col.begin();b!=col.end();++a,++b) *a=*b; } template void forEach(const Func& func){ for_each(this->begin(),this->end(),func); } template Streamer map(const Func& func){ Collection col=Collection(this->size()); transform(this->begin(),this->end(), col.begin(), func); return Streamer(col); } template Streamer filter(const Func& func){ Collection col(this->size()); auto it=copy_if(this->begin(),this->end(), col.begin(), func); const size_t len=distance(col.begin(),it); col.resize(len); return Streamer(col); } template T reduce(const Func& func,T accumulator){ for(auto it=this->begin();it!=this->end();it++) accumulator=func(accumulator,*it); return accumulator; } }; int main() { vector vec{1,2,3,4,5}; auto printVal=[](int x)->void{cout<int{return x+1;}; auto isOddNumber=[](int x)->bool{return x%2;}; auto summing=[](int a, int b)->int{return a+b;}; Streamer> s=vec; cout<<"Vector now turned into a Streamer, printed with forEach method"<

Streamer - functional programming - map filter reduce forEach