Creating an iterator library.

This library contains two smart iterator types, end_aware_iterator, and join_iterator.
end_aware_iterator acts to create an iterator that knows when its at end().
join_iterator is used to provide an iteration behavior for nested containers so that you can seamlessly iterate over all values.

There is also a short (possibly incomplete) test suite for each iterator.

end_aware_iterator.hpp

@@ -0,0 +1,57 @@
+//
+//  end_aware_iterator.hpp
+//  iterator
+//
+//  Created by Sam Jaffe on 2/7/17.
+//
+
+#pragma once
+
+#include <iterator>
+
+template <typename Iterator>
+class end_aware_iterator {
+public:
+  using iter_type = Iterator;
+  using value_type = typename std::iterator_traits<iter_type>::value_type;
+  using reference = typename std::iterator_traits<iter_type>::reference;
+  using pointer = typename std::iterator_traits<iter_type>::pointer;
+  using difference_type = typename std::iterator_traits<iter_type>::difference_type;
+  using iterator_category = std::forward_iterator_tag;
+public:
+  end_aware_iterator(iter_type it, iter_type end) : curr_(it), end_(end) {}
+  
+  template <typename I>
+  end_aware_iterator( end_aware_iterator<I> const & other )
+  : curr_(other.current()), end_(other.end()) {
+    
+  }
+  
+  end_aware_iterator & operator++() {
+    if ( !done() ) { ++curr_; }
+    return *this;
+  }
+  
+  end_aware_iterator operator++(int) {
+    end_aware_iterator tmp{*this};
+    operator++();
+    return tmp;
+  }
+
+  reference operator*() { return *curr_; }
+  pointer operator->() { return std::addressof(*curr_); }
+  
+  bool done() const { return curr_ == end_; }
+  bool operator==(end_aware_iterator const & other) const {
+    return curr_ == other.curr_ && end_ == other.end_;
+  }
+  
+  bool operator!=(end_aware_iterator const & other) {
+    return !(operator==(other));
+  }
+  
+  iter_type current() const { return curr_; }
+  iter_type end() const { return end_; }
+private:
+  iter_type curr_, end_;
+};

end_aware_iterator.t.h

@@ -0,0 +1,50 @@
+//
+//  end_aware_iterator.t.h
+//  iterator
+//
+//  Created by Sam Jaffe on 2/7/17.
+//
+
+#pragma once
+
+#include <cxxtest/TestSuite.h>
+
+#include <vector>
+
+#include "end_aware_iterator.hpp"
+
+class end_aware_TestSuite : public CxxTest::TestSuite {
+public:
+  using vec_t = std::vector<int>;
+  using ea_iter = end_aware_iterator<vec_t::iterator>;
+public:
+  void test_iterator_points_to_same() {
+    vec_t v{1, 2, 3, 4, 5};
+    TS_ASSERT_EQUALS(*v.begin(), *ea_iter(v.begin(), v.end()));
+  }
+
+  void test_iterator_edits_same() {
+    vec_t v{1, 2, 3, 4, 5};
+    *ea_iter(v.begin(), v.end()) = -1;
+    TS_ASSERT_EQUALS(v[0], -1);
+  }
+  
+  void test_not_done_until_end() {
+    vec_t v{1, 2, 3, 4, 5};
+    ea_iter it{v.end()-1, v.end()};
+    TS_ASSERT(!it.done());
+    ++it;
+    TS_ASSERT_EQUALS(it, ea_iter(v.end(),v.end()));
+    TS_ASSERT(it.done());
+  }
+
+  void test_cannot_go_past_end() {
+    vec_t v{1, 2, 3, 4, 5};
+    ea_iter it{v.end(), v.end()};
+    ea_iter const cp = it;
+    ++it;
+    TS_ASSERT_EQUALS(it, cp);
+    TS_ASSERT(it.done());
+  }
+  
+};

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@@ -0,0 +1,279 @@
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join_iterator.hpp

@@ -0,0 +1,88 @@
+//
+//  join_iterator.hpp
+//  iterator
+//
+//  Created by Sam Jaffe on 2/7/17.
+//
+
+#pragma once
+
+#include <iterator>
+
+#include "end_aware_iterator.hpp"
+
+template <typename MetaIterator>
+class joining_iterator {
+public:
+  using join_iter = MetaIterator;
+  using joinable_type = typename join_iter::value_type;
+  using iter_type = decltype(std::begin(*std::declval<MetaIterator>()));
+ 
+  using value_type = typename std::iterator_traits<iter_type>::value_type;
+  using reference = typename std::iterator_traits<iter_type>::reference;
+  using pointer = typename std::iterator_traits<iter_type>::pointer;
+  using difference_type = typename std::iterator_traits<iter_type>::difference_type;
+  using iterator_category = std::forward_iterator_tag;
+public:
+  explicit joining_iterator( )
+  : joiner_({}, {}), iterator_({}, {}) {
+    
+  }
+  
+  template <typename I>
+  joining_iterator( joining_iterator<I> const & other )
+  : joiner_(other.join_iterator()), iterator_(other.element_iterator()) {
+    
+  }
+  
+  joining_iterator( join_iter start, join_iter end )
+  : joiner_(start, end), iterator_({}, {}) {
+    update_iterator();
+  }
+
+  joining_iterator( join_iter start, join_iter end, iter_type lstart, iter_type lend, bool update = false )
+  : joiner_(start, end), iterator_(lstart, lend) {
+    if ( update ) { update_iterator(); }
+  }
+
+  joining_iterator & operator++() {
+    if ( (++iterator_).done() ) {
+      ++joiner_;
+      update_iterator();
+    }
+    return *this;
+  }
+  
+  joining_iterator operator++(int) {
+    joining_iterator tmp{*this};
+    operator++();
+    return tmp;
+  }
+  
+  reference operator*() { return iterator_.operator*(); }
+  pointer operator->() { return iterator_.operator->(); }
+  
+  bool operator==(joining_iterator const & other) const {
+    return joiner_ == other.joiner_ && ((joiner_.done() && other.joiner_.done()) ||
+                                        iterator_ == other.iterator_);
+  }
+  
+  bool operator!=(joining_iterator const & other) {
+    return !(operator==(other));
+  }
+  
+  end_aware_iterator<join_iter> join_iterator() const { return joiner_; }
+  end_aware_iterator<iter_type> element_iterator() const { return iterator_; }
+private:
+  void update_iterator() {
+    while ( !joiner_.done() && std::begin(*joiner_) == std::end(*joiner_) ) {
+      ++joiner_;
+    }
+    if ( !joiner_.done() ) {
+      iterator_ = { std::begin(*joiner_), std::end(*joiner_) };
+    }
+  }
+  
+  end_aware_iterator<join_iter> joiner_;
+  end_aware_iterator<iter_type> iterator_;
+};

join_iterator.t.h

@@ -0,0 +1,40 @@
+//
+//  iterator.t.h
+//  iterator
+//
+//  Created by Sam Jaffe on 2/7/17.
+//
+#pragma once
+
+#include <cxxtest/TestSuite.h>
+
+#include "join_iterator.hpp"
+
+class join_iterator_TestSuite : public CxxTest::TestSuite {
+public:
+  using vec_t = std::vector<int>;
+  using meta_vec_t = std::vector<vec_t>;
+  using jn_iter = joining_iterator<meta_vec_t::iterator>;
+  
+//  vec_t v{1,2,3,4,5,6};
+//  meta_vec_t mv{{1,2,3},{4,5,6}};
+public:
+  void test_points_to_beginning() {
+    meta_vec_t mv{{1,2,3},{4,5,6}};
+    TS_ASSERT_EQUALS(*jn_iter(mv.begin(), mv.end()), mv[0][0]);
+  }
+  
+  void test_steps_to_next_list() {
+    meta_vec_t mv{{1,2,3},{4,5,6}};
+    jn_iter it(mv.begin(), mv.end(), mv.front().end(), mv.front().end());
+    TS_ASSERT_EQUALS(*++it, mv[1][0]);
+  }
+  
+  void test_cannot_go_past_end() {
+    meta_vec_t mv{{1,2,3},{4,5,6}};
+    jn_iter it(mv.end(), mv.end(), mv.back().end(), mv.back().end());
+    jn_iter const cp = it;
+    ++it;
+    TS_ASSERT_EQUALS(it, cp);
+  }
+};