From d12eca638c8741ad2f00d5a1492b0d8999b6bc42 Mon Sep 17 00:00:00 2001
From: winner245 <winner245@hotmail.com>
Date: Sat, 19 Oct 2024 18:46:25 -0400
Subject: [PATCH] Implement vector constructor to support single-pass input
 iterator range

---
 MyTinySTL/iterator.h        |  4 ++
 MyTinySTL/stream_iterator.h | 81 +++++++++++++++++++++++++++++++++++++
 MyTinySTL/vector.h          | 12 +++++-
 Test/vector_test.h          | 10 ++++-
 4 files changed, 104 insertions(+), 3 deletions(-)
 create mode 100644 MyTinySTL/stream_iterator.h

diff --git a/MyTinySTL/iterator.h b/MyTinySTL/iterator.h
index 28a9a69..a3e5cfa 100644
--- a/MyTinySTL/iterator.h
+++ b/MyTinySTL/iterator.h
@@ -103,6 +103,10 @@ struct has_iterator_cat_of
 template <class T, class U>
 struct has_iterator_cat_of<T, U, false> : public m_false_type {};
 
+template <class Iter>
+struct is_exactly_input_iterator : public m_bool_constant<has_iterator_cat_of<Iter, input_iterator_tag>::value && 
+    !has_iterator_cat_of<Iter, forward_iterator_tag>::value> {};
+
 template <class Iter>
 struct is_input_iterator : public has_iterator_cat_of<Iter, input_iterator_tag> {};
 
diff --git a/MyTinySTL/stream_iterator.h b/MyTinySTL/stream_iterator.h
new file mode 100644
index 0000000..3762f03
--- /dev/null
+++ b/MyTinySTL/stream_iterator.h
@@ -0,0 +1,81 @@
+#ifndef MYTINYSTL_STREAM_ITERATOR_H_
+#define MYTINYSTL_STREAM_ITERATOR_H_
+
+#include "basic_string.h"
+
+namespace mystl
+{
+
+template<typename T, typename CharT = char,
+        typename Traits = std::char_traits<CharT>, typename Dist = ptrdiff_t>
+class istream_iterator
+: public iterator<input_iterator_tag, T, Dist, const T*, const T&>
+{
+public:
+    using char_type = CharT;
+    using traits_type = Traits;
+    using istream_type = std::basic_istream<CharT, Traits>;  
+
+    istream_iterator() /* noexcept(std::is_nothrow_default_constructible<T>::value) */
+        : m_stream{nullptr}, m_value{} {}
+
+    istream_iterator(istream_type& is)
+        : m_stream{std::addressof(is)}
+    { read(); }
+
+    istream_iterator(const istream_iterator& other) /* noexcept(std::is_nothrow_copy_constructible<T>::value) */
+        = default;   // memberwise copy
+
+    istream_iterator& operator=(const istream_iterator&) = default;   // memberwise copy-asgn
+    
+    ~istream_iterator() = default;
+
+    const T& operator*() const noexcept {
+        MYSTL_DEBUG(m_stream != nullptr);
+        return m_value;
+    }
+
+    const T* operator->() const noexcept {
+        return std::addressof(*this);
+    }
+
+    istream_iterator& operator++() {
+        MYSTL_DEBUG(m_stream != nullptr);
+        read();
+        return *this;
+    }
+
+     istream_iterator operator++(int) {
+        auto tmp = *this;
+        ++*this;
+        return tmp;
+    }
+
+private:
+    istream_type* m_stream;
+    T m_value; 
+
+    void read() {
+        if (m_stream && !(*m_stream >> m_value)) {  // m_stream 有效且读到 EOS
+            m_stream = nullptr;  
+        }
+    }  
+
+    friend bool operator==(const istream_iterator& lhs, const istream_iterator& rhs) {
+        return lhs.m_stream == rhs.m_stream;
+    }  
+
+    friend bool operator!=(const istream_iterator& lhs, const istream_iterator& rhs) {
+        return lhs.m_stream != rhs.m_stream;
+    }  
+};
+
+
+// TODO 
+// template<typename T, typename CharT = char,
+//          typename Traits = char_traits<CharT> >
+// class ostream_iterator : public iterator<output_iterator_tag, void, void, void, void> {};
+}
+
+
+#endif
\ No newline at end of file
diff --git a/MyTinySTL/vector.h b/MyTinySTL/vector.h
index 5192761..c906930 100644
--- a/MyTinySTL/vector.h
+++ b/MyTinySTL/vector.h
@@ -80,7 +80,17 @@ class vector
   { fill_init(n, value); }
 
   template <class Iter, typename std::enable_if<
-    mystl::is_input_iterator<Iter>::value, int>::type = 0>
+    mystl::is_exactly_input_iterator<Iter>::value, int>::type = 0>
+  vector(Iter first, Iter last) 
+  {
+    try_init();
+    for (; first != last; ++first) {
+        emplace_back(*first);
+    }
+  }
+
+  template <class Iter, typename std::enable_if<
+    mystl::is_forward_iterator<Iter>::value, int>::type = 0>
   vector(Iter first, Iter last)
   {
     MYSTL_DEBUG(!(last < first));
diff --git a/Test/vector_test.h b/Test/vector_test.h
index 8b79ef6..b5ddb57 100644
--- a/Test/vector_test.h
+++ b/Test/vector_test.h
@@ -3,10 +3,11 @@
 
 // vector test : 测试 vector 的接口与 push_back 的性能
 
-#include <vector>
+#include <vector> 
 
 #include "../MyTinySTL/vector.h"
 #include "test.h"
+#include "stream_iterator.h"  // 用于测试 input_iterator 迭代器版构造函数
 
 namespace mystl
 {
@@ -32,7 +33,6 @@ void vector_test()
   v8 = v3;
   v9 = std::move(v3);
   v10 = { 1,2,3,4,5,6,7,8,9 };
-
   FUN_AFTER(v1, v1.assign(8, 8));
   FUN_AFTER(v1, v1.assign(a, a + 5));
   FUN_AFTER(v1, v1.emplace(v1.begin(), 0));
@@ -90,6 +90,12 @@ void vector_test()
   FUN_AFTER(v1, v1.shrink_to_fit());
   FUN_VALUE(v1.size());
   FUN_VALUE(v1.capacity());
+
+  std::istringstream is("1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9");
+  mystl::istream_iterator<int> beg{is}, end; 
+  mystl::vector<int> v11{beg, end};
+  COUT(v11);
+
   PASSED;
 #if PERFORMANCE_TEST_ON
   std::cout << "[--------------------- Performance Testing ---------------------]\n";