tpl: Template library for piping operations

Overview

Tpl is C++ header-only library designed to simplify basic collections/containers operations. It strongly relies on C++ templates allowing the compiler to do heavy-lifting and generate efficient code.

Using ideas from functional languages and some more modern imperative languages (like Kotlin) combined with power of C++ gives many benefits:

• value semantics
• type safety
• speed
• lazy evaluation - nothing is ever computed if you don't ask for result
• syntax simplification via operator overloads
• readability and elegance
• pure functions that are easy to reason about

Build statuses

Linux gcc 4.9+

gcc 4.9	gcc 5	gcc 6	gcc 7	gcc 8

Linux clang 3.9+

clang 3.9	clang 4	clang 5	clang 6	clang 7

Visual Studio 2015+

Visual Studio 2015/2017

Getting started

Requirements

For library:

• C++14 compliant compiler (compilers that work for sure are listed above)

Catch framework is shipped with the library so for building and running tests You need:

• cmake tool

Installation

tpl is a header only library. The only things You have to do are:

• clone this repository git clone https://github.com/bartop/tpl.git
• (optionally) setup additional include path in Your project to tpl/include/

If you want to build the tests You have to do the following:

• clone this repository git clone https://github.com/bartop/tpl.git
• enter main directory of the repository cd tpl
• make directory for build and enter it mkdir build && cd build
• generate files for desired build system using cmake .. -G <name_of_cmake_generator>
• (if using makefiles) to run all tests use ctest

Sample code

Filter collection

#include <tpl.hpp>
#include <iostream>

using namespace tpl;
using namespace std;

int main(){
  const auto collection = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
  const auto filtered = collection | filter([](const auto &i){ return i > 5 });
  for(const auto i : filtered)
    cout << i;
  //output will be 6, 7, 8, 9, 10
  return 0;
}

Transform collection

#include <tpl.hpp>
#include <iostream>

using namespace tpl;
using namespace std;

int main(){
  const auto collection = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
  const auto transformed = collection | transform([](const auto &i){ return i > 5; });//transform to booleans
  for(const auto i : transformed)
    cout << i;
  //output will be 0, 0, 0, 0, 0, 1, 1, 1, 1, 1
  return 0;
}

Pepare operations for further use

#include <tpl.hpp>
#include <iostream>

using namespace tpl;
using namespace std;

int main(){
  const auto collection1 = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
  const auto collection2 = { 1, 11 };
  const auto operation =
      filter([](const auto &i){ return i > 5 }) | 
      transform([](const auto &i){ return i + 1; });
  const auto result1 = collection1 | operation;
  const auto result2 = collection2 | operation;
  for(const auto i : result1)
    cout << i; //output will be 7, 8, 9, 10, 11
    
  for(const auto i : result2)
    cout << i; //output will be 12
    
  return 0;
}

Extract keys of the map

#include <tpl.hpp>
#include <iostream>
#include <map>

using namespace tpl;
using namespace std;

int main(){
  const map<int, int> map = { {1, 2}, {3, 4}, {5, 6}, {7, 8}, {9, 10} };
  const auto keys = map | keys;
  for(const auto i : keys)
    cout << i;
  //output will be 1, 3, 5, 7, 9
  return 0;
}

Flatten the collection of collections

#include <tpl.hpp>
#include <iostream>
#include <vector>

using namespace tpl;
using namespace std;

int main(){
  const vector<vector<int>> vec = { {1, 2, 3, 4}, {5, 6}, {7, 8, 9} , {10} };
  const auto flat = vec | flatten;
  for(const auto i : flat)
    cout << i;
  //output will be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10
  return 0;
}

Fold left the collection

#include <tpl.hpp>
#include <iostream>
#include <vector>

using namespace tpl;
using namespace std;

int main(){
  const auto collection = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
  const auto fold = vec | fold_left([](const auto &l, const auto &r) { return l + r; });
  cout << i;
  //output will be 55
  return 0;
}

Generate 10 items from cyclic generator

#include <tpl.hpp>
#include <iostream>
#include <vector>

using namespace tpl;
using namespace std;

int main(){
  const auto collection = cycle(vector<int>{ 1, 2, 3 }) | take(10);//initializer list is not accepted, sadly
  for(const auto &i : collection)
    cout << i;
  //output will be 1, 2, 3, 1, 2, 3, 1, 2, 3, 1
  return 0;
}

More complex example

The whole power of this solutin is ease of extension. For example, if you want to filter, sort and transform you can do it just like that:

const auto afterComplexOperation = map
  | keys
  | filter([](const auto &i){ /* your filter here */ }
  | sort([](const auto &i, const auto &j){ /* your sort predicate */}
  | transform([](const auto &i){ /* apply your transformation */})
  | flatten;