Added stream-related aggregators

Author: jay-tux

README.md

@@ -1,6 +1,6 @@
 # fpgen
 *Functional programming in C++ using C++20 coroutines*  
-![](https://img.shields.io/badge/test_coverage-96.5%25-brightgreen)
+![](https://img.shields.io/badge/test_coverage-96.9%25-brightgreen)
 
 
 ## Aim

inc/aggregators.hpp

@@ -3,6 +3,7 @@
 
 #include "generator.hpp"
 #include <forward_list>
+#include <ostream>
 #include <tuple>
 #include <type_traits>
 
@@ -200,6 +201,44 @@ template <typename T, typename Fun> void foreach (generator<T> gen, Fun func) {
     func(gen());
   }
 }
+
+template <typename T>
+std::ostream &to_stream(generator<T> gen, std::ostream &stream) {
+  while (gen) {
+    stream << gen();
+  }
+  return stream;
+}
+
+template <typename T, typename T2>
+std::ostream &to_stream(generator<T> gen, std::ostream &stream, T2 separator) {
+  if (gen) {
+    stream << gen();
+  }
+  while (gen) {
+    stream << separator << gen();
+  }
+  return stream;
+}
+
+template <typename T>
+std::ostream &to_lines(generator<T> gen, std::ostream &stream) {
+  while (gen) {
+    stream << gen() << std::endl;
+  }
+  return stream;
+}
+
+template <typename T>
+std::ostream &to_lines_no_trail(generator<T> gen, std::ostream &stream) {
+  if (gen) {
+    stream << gen();
+  }
+  while (gen) {
+    stream << std::endl << gen();
+  }
+  return stream;
+}
 } // namespace fpgen
 
 #endif

test/src/test_aggreg.cpp

@@ -6,6 +6,7 @@
 #include "gtest/gtest.h"
 
 #include <map>
+#include <sstream>
 #include <vector>
 
 fpgen::generator<size_t> a_empty() { co_return; }
@@ -170,3 +171,40 @@ TEST(foreach, normal) {
   fpgen::foreach (gen, [&res](size_t val) { res += val; });
   EXPECT_EQ(res, fpgen::sum(gen2));
 }
+
+TEST(stream, nosep) {
+  std::vector<int> vals = {1, 2, 3, 4, 5, 6};
+  auto gen = fpgen::from(vals);
+  std::stringstream strm;
+  fpgen::to_stream(gen, strm);
+  EXPECT_EQ(strm.str(), "123456");
+}
+
+TEST(stream, sep) {
+  std::vector<int> vals = {1, 2, 3, 4, 5, 6, 7};
+  auto gen = fpgen::from(vals);
+  std::stringstream strm;
+  fpgen::to_stream(gen, strm, " ");
+  EXPECT_EQ(strm.str(), "1 2 3 4 5 6 7");
+}
+
+TEST(stream, lines_trail) {
+  std::vector<int> vals = {1, 2, 3, 4};
+  auto gen = fpgen::from(vals);
+  std::stringstream strm;
+  std::stringstream expect;
+  for (auto v : vals)
+    expect << v << std::endl;
+  fpgen::to_lines(gen, strm);
+  EXPECT_EQ(strm.str(), expect.str());
+}
+
+TEST(stream, lines_no_trail) {
+  std::vector<int> vals = {1, 2, 3, 4};
+  auto gen = fpgen::from(vals);
+  std::stringstream strm;
+  std::stringstream expect;
+  expect << 1 << std::endl << 2 << std::endl << 3 << std::endl << 4;
+  fpgen::to_lines_no_trail(gen, strm);
+  EXPECT_EQ(strm.str(), expect.str());
+}