fix: copy of buffered file iterator (#96)

Author: uncommon-nickname

include/rusty_iterators/file_iterator.hpp

@@ -21,8 +21,6 @@ template <FIterType type>
 class FileIterator : public IterInterface<std::string, FileIterator<type>>
 {};
 
-// TODO: Perf.
-// With the buffered iterator a lot of iterator functions could be optimized.
 template <>
 class FileIterator<FIterType::Buffered>
     : public IterInterface<std::string, FileIterator<FIterType::Buffered>>
@@ -31,38 +29,34 @@ class FileIterator<FIterType::Buffered>
     explicit FileIterator(const std::string& filePath)
     {
         std::ifstream is{filePath};
-
         if (!is.is_open())
         {
             throw std::runtime_error{"Could not open the file."};
         }
-
         std::string nextLine;
-
         while (std::getline(is, nextLine))
         {
             fileLines.push_back(std::move(nextLine));
         }
         is.close();
-        ptr = fileLines.begin();
     };
 
     auto next() -> std::optional<std::string>
     {
-        [[unlikely]] if (ptr == fileLines.end())
+        [[unlikely]] if (ptr == fileLines.size())
         {
             return std::nullopt;
         }
-        auto line = *ptr;
+        auto line = fileLines.at(ptr);
         ptr += 1;
         return std::move(line);
     }
 
-    [[nodiscard]] auto sizeHint() const -> std::optional<size_t> { return fileLines.end() - ptr; }
+    [[nodiscard]] auto sizeHint() const -> std::optional<size_t> { return fileLines.size() - ptr; }
 
   private:
     std::vector<std::string> fileLines{};
-    std::vector<std::string>::iterator ptr;
+    size_t ptr = 0;
 };
 
 template <>
@@ -81,7 +75,6 @@ class FileIterator<FIterType::Lazy>
     auto next() -> std::optional<std::string>
     {
         std::string nextLine;
-
         [[unlikely]] if (!std::getline(is, nextLine))
         {
             return std::nullopt;

tests/file_iterator.test.cpp

@@ -69,3 +69,24 @@ TEST(TestBufferedFileIterator, TestSizeHint)
 
     ASSERT_EQ(it.sizeHint(), 4);
 }
+
+TEST(TestBufferedFileIterator, TestSizeHintAfterConsumption)
+{
+    auto testFileName = std::string{"./tests/test_data.txt"};
+    auto it           = FileIterator<FIterType::Buffered>{testFileName}.advanceBy(2);
+
+    ASSERT_EQ(it.sizeHint(), 2);
+}
+
+TEST(TestBufferedFileIterator, TestCopyBufferedIterator)
+{
+    auto testFileName = std::string{"./tests/test_data.txt"};
+    auto it           = FileIterator<FIterType::Buffered>{testFileName};
+
+    it.next();
+    auto cp = it;
+    it.next();
+
+    EXPECT_THAT(it.collect(), ElementsAreArray({"3", "4"}));
+    EXPECT_THAT(cp.collect(), ElementsAreArray({"2", "3", "4"}));
+}

tests/iterator.test.cpp

@@ -22,13 +22,15 @@ TEST(TestIterator, TestCopySavesIteratorState)
     auto vec = std::vector{1, 2, 3, 4};
 
     auto it = LazyIterator{vec};
+
     it.next();
     auto cp = it;
+    it.next();
 
     auto x = it.collect();
     auto y = cp.collect();
 
-    EXPECT_THAT(x, ElementsAreArray(std::array{2, 3, 4}));
+    EXPECT_THAT(x, ElementsAreArray(std::array{3, 4}));
     EXPECT_THAT(y, ElementsAreArray(std::array{2, 3, 4}));
 }