Merge pull request #11 from jay-tux/feat/filestream

Feat/filestream

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-97%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 +201,94 @@ template <typename T, typename Fun> void foreach (generator<T> gen, Fun func) {
     func(gen());
   }
 }
+
+/**
+ *  \brief Sends each value to the stream.
+ *
+ *  Calls `stream << value` for each value in the generator, then returns the
+ * resulting (modified) stream.
+ *
+ *  \tparam T The type of values in the stream.
+ *  \param[in,out] gen The generator supplying the values.
+ *  \param[in,out] stream The stream to output to.
+ *  \returns The resulting stream.
+ */
+template <typename T>
+std::ostream &to_stream(generator<T> gen, std::ostream &stream) {
+  while (gen) {
+    stream << gen();
+  }
+  return stream;
+}
+
+/**
+ *  \brief Sends each value to the stream. Values are separated by the given
+ * separator.
+ *
+ *  Calls `stream << value` for each value in the generator, then returns the
+ * resulting (modified) stream. Between each pair of values in the generator,
+ * the separator is added.
+ *
+ *  \tparam T The type of values in the stream.
+ *  \tparam T2 The type of the separator.
+ *  \param[in,out] gen The generator supplying the values.
+ *  \param[in,out] stream The stream to output to.
+ *  \param[in] separator The separator to use.
+ *  \returns The resulting 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;
+}
+
+/**
+ *  \brief Sends each value to the stream on a separate line.
+ *
+ *  Calls `stream << value << std::endl` for each value in the generator, then
+ * returns the resulting (modified) stream. To avoid a trailing newline, see
+ * `fpgen::to_lines_no_trail`
+ *
+ *  \tparam T The type of values in the stream.
+ *  \param[in,out] gen The generator supplying the values.
+ *  \param[in,out] stream The stream to output to.
+ *  \returns The resulting stream.
+ */
+template <typename T>
+std::ostream &to_lines(generator<T> gen, std::ostream &stream) {
+  while (gen) {
+    stream << gen() << std::endl;
+  }
+  return stream;
+}
+
+/**
+ *  \brief Sends each value to the stream on a separate line, without trailing
+ * newline.
+ *
+ *  Calls `stream << std::endl << value` for each value in the generator (except
+ * the first), then returns the resulting (modified) stream.
+ *
+ *  \tparam T The type of values in the stream.
+ *  \param[in,out] gen The generator supplying the values.
+ *  \param[in,out] stream The stream to output to.
+ *  \returns The resulting 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

inc/sources.hpp

@@ -2,7 +2,9 @@
 #define _FPGEN_SOURCES
 
 #include "generator.hpp"
+#include <istream>
 #include <iterator>
+#include <type_traits>
 
 /**
  *  \brief The namespace containing all of fpgen's code.
@@ -103,6 +105,49 @@ template <typename T> generator<T> inc(T start) {
   }
 }
 
+/**
+ *  \brief Creates a generator from an input stream.
+ *
+ *  The generator will apply the given function on the stream each time the
+ * generator is invoked. The function should return a value of the type you want
+ * in the generator. Once the stream fails (`!stream.good()`) or the stream
+ * reaches EOF, the generator stops. Trailing whitespace may result in
+ * unpredictable behaviour. Since the stream isn't copied, using the generator
+ * after the stream goes out of scope is undefined behaviour.
+ *
+ *  \tparam Fun The type of the function. Should have the signature
+ * (std::istream &) -> T.
+ *  \param[in,out] stream The input stream.
+ *  \param[in] func The function to extract data from the stream.
+ *  \returns A new generator which will iterate over the given stream, each time
+ * applying the given function to retrieve the next value.
+ */
+template <typename Fun>
+generator<typename std::invoke_result<Fun, std::istream &>::type>
+from_stream(std::istream &stream, Fun func) {
+  while (stream.good() && !stream.eof()) {
+    co_yield func(stream);
+  }
+  co_return;
+}
+
+/**
+ *  \brief Creates a generator supplying each line from a file.
+ *
+ *  This generator is formed by combining `fpgen::from_stream<>` with
+ * `std::getline` on the stream.
+ *
+ *  \param[in,out] stream The stream to extract lines from.
+ *  \returns A new generator which yields each line in the stream.
+ */
+inline generator<std::string> from_lines(std::istream &stream) {
+  return from_stream(stream, [](std::istream &stream) {
+    std::string value;
+    std::getline(stream, value);
+    return value;
+  });
+}
+
 } // namespace fpgen
 
 #endif

test/Makefile

@@ -1,6 +1,6 @@
 SOURCES=$(shell find $(SRCD) -name '*.cpp')
 DEPS=$(SOURCES:$(SRCD)/%.cpp=$(OBJD)/%.d)
-TESTS=generator sources manip aggreg stream chain
+TESTS=generator sources manip aggreg chain
 TESTOBJ=$(TESTS:%=$(OBJD)/test_%.o)
 
 CONAN_PKG_OVERRIDE=gtest

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());
+}

test/src/test_sources.cpp

@@ -5,6 +5,7 @@
 
 #include <map>
 #include <set>
+#include <sstream>
 #include <string>
 #include <vector>
 
@@ -79,3 +80,74 @@ TEST(sources, incrementable_struct) {
     EXPECT_EQ(gen().value, i);
   }
 }
+
+TEST(sources, instream) {
+  std::vector<int> numbers = {1, 2, 3, 4, 5};
+  std::stringstream str;
+  for (auto v : numbers)
+    str << " " << v;
+  auto func = [](std::istream &strm) {
+    int i;
+    strm >> i;
+    return i;
+  };
+
+  auto gen = fpgen::from_stream(str, func);
+  for (int i = 0; i < 5; i++) {
+    bool genstate = gen;
+    EXPECT_TRUE(genstate);
+    auto tmp = gen();
+    EXPECT_EQ(tmp, numbers[i]);
+    std::cout << i << "," << tmp << std::endl;
+  }
+
+  bool genstate = gen;
+  EXPECT_FALSE(genstate);
+}
+
+TEST(sources, lipsum_lines) {
+  std::string lipsum = R"(
+Lorem ipsum dolor sit amet, consectetur adipiscing elit. Quisque diam magna,
+laoreet non dictum eget, scelerisque eu nibh. Cras luctus purus sit amet
+sodales aliquet. Proin vulputate risus quam. Curabitur ultricies, elit nec
+pharetra accumsan, leo eros mollis nibh, pulvinar lobortis dolor diam non quam.
+Vivamus odio arcu, aliquet ornare leo quis, mollis porta nisl. Mauris malesuada
+semper efficitur. Vestibulum nulla diam, hendrerit in diam a, tempor dignissim
+turpis. Maecenas eleifend laoreet velit id semper. Aliquam quis mattis enim.
+Cras gravida, felis vitae porta auctor, magna purus aliquet lorem, ut maximus
+tortor tortor sit amet mauris. Mauris eleifend enim eget arcu blandit auctor.
+Etiam vel porta augue. Maecenas volutpat odio in lacus sagittis fermentum.
+)";
+  std::string lines[] = {"Lorem ipsum dolor sit amet, consectetur adipiscing "
+                         "elit. Quisque diam magna,",
+                         "laoreet non dictum eget, scelerisque eu nibh. Cras "
+                         "luctus purus sit amet",
+                         "sodales aliquet. Proin vulputate risus quam. "
+                         "Curabitur ultricies, elit nec",
+                         "pharetra accumsan, leo eros mollis nibh, pulvinar "
+                         "lobortis dolor diam non quam.",
+                         "Vivamus odio arcu, aliquet ornare leo quis, mollis "
+                         "porta nisl. Mauris malesuada",
+                         "semper efficitur. Vestibulum nulla diam, hendrerit "
+                         "in diam a, tempor dignissim",
+                         "turpis. Maecenas eleifend laoreet velit id semper. "
+                         "Aliquam quis mattis enim.",
+                         "Cras gravida, felis vitae porta auctor, magna purus "
+                         "aliquet lorem, ut maximus",
+                         "tortor tortor sit amet mauris. Mauris eleifend enim "
+                         "eget arcu blandit auctor.",
+                         "Etiam vel porta augue. Maecenas volutpat odio in "
+                         "lacus sagittis fermentum."};
+  std::stringstream strm;
+  strm << lipsum;
+  auto gen = fpgen::from_lines(strm);
+  EXPECT_EQ("", gen());
+  for (size_t i = 0; i < 10; i++) {
+    bool gens = gen;
+    EXPECT_TRUE(gens);
+    EXPECT_EQ(gen(), lines[i]);
+  }
+  EXPECT_EQ(gen(), "");
+  bool gens = gen;
+  EXPECT_FALSE(gens);
+}