From 56f10e6104f407352ff1ab5e2743100bb7ece872 Mon Sep 17 00:00:00 2001
From: Alexander van Gessel <ai0867@gmail.com>
Date: Sat, 11 Nov 2017 00:14:51 +0100
Subject: [PATCH 1/2] Add emplace_{back,front} to circular_buffer

---
 include/boost/circular_buffer/base.hpp | 80 ++++++++++++++++++++++++++++++++++
 1 file changed, 80 insertions(+)

diff --git a/include/boost/circular_buffer/base.hpp b/include/boost/circular_buffer/base.hpp
index 4babd9f..fa73e81 100644
--- a/include/boost/circular_buffer/base.hpp
+++ b/include/boost/circular_buffer/base.hpp
@@ -1449,6 +1449,42 @@ private:
         BOOST_CATCH_END
     }
 
+    template <class ...Args>
+    void emplace_back_impl(BOOST_FWD_REF(Args) ...args) {
+        if (full()) {
+            if (empty())
+                return;
+            replace(m_last, value_type(::boost::forward<Args>(args)...));
+            increment(m_last);
+            m_first = m_last;
+        } else {
+            boost::container::allocator_traits<Alloc>::construct(m_alloc, cb_details::to_address(m_last), ::boost::forward<Args>(args)...);
+            increment(m_last);
+            ++m_size;
+        }
+    }
+
+    template <class ...Args>
+    void emplace_front_impl(BOOST_FWD_REF(Args) ...args) {
+        BOOST_TRY {
+            if (full()) {
+                if (empty())
+                    return;
+                decrement(m_first);
+                replace(m_first, value_type(::boost::forward<Args>(args)...));
+                m_last = m_first;
+            } else {
+                decrement(m_first);
+                boost::container::allocator_traits<Alloc>::construct(m_alloc, cb_details::to_address(m_first), ::boost::forward<Args>(args)...);
+                ++m_size;
+            }
+        } BOOST_CATCH(...) {
+            increment(m_first);
+            BOOST_RETHROW
+        }
+        BOOST_CATCH_END
+    }
+
 public:
     //! Insert a new element at the end of the <code>circular_buffer</code>.
     /*!
@@ -1578,6 +1614,50 @@ public:
         push_front(boost::move(temp));
     }
 
+    //! Construct a new element at the end of the <code>circular_buffer</code>.
+    /*!
+        \post if <code>capacity() > 0</code> then <code>back() == item</code><br>
+              If the <code>circular_buffer</code> is full, the first element will be removed. If the capacity is
+              <code>0</code>, nothing will be inserted.
+        \param item The element to be inserted.
+        \throws Whatever <code>T::T(Args...)</code> throws.
+                Whatever <code>T::operator = (T&&)</code> throws.
+        \par Exception Safety
+             Basic; no-throw if the operation in the <i>Throws</i> section does not throw anything.
+        \par Iterator Invalidation
+             Does not invalidate any iterators with the exception of iterators pointing to the overwritten element.
+        \par Complexity
+             Constant (in the size of the <code>circular_buffer</code>).
+        \sa <code>\link push_back() push_back(const_reference)\endlink</code>,
+            <code>pop_back()</code>, <code>emplace_front()</code>
+    */
+    template <class ...Args>
+    void emplace_back(BOOST_FWD_REF(Args) ...args) {
+        emplace_back_impl(::boost::forward<Args>(args)...);
+    }
+
+    //! Construct a new element at the beginning of the <code>circular_buffer</code>.
+    /*!
+        \post if <code>capacity() > 0</code> then <code>back() == item</code><br>
+              If the <code>circular_buffer</code> is full, the last element will be removed. If the capacity is
+              <code>0</code>, nothing will be inserted.
+        \param item The element to be inserted.
+        \throws Whatever <code>T::T(Args...)</code> throws.
+                Whatever <code>T::operator = (T&&)</code> throws.
+        \par Exception Safety
+             Basic; no-throw if the operation in the <i>Throws</i> section does not throw anything.
+        \par Iterator Invalidation
+             Does not invalidate any iterators with the exception of iterators pointing to the overwritten element.
+        \par Complexity
+             Constant (in the size of the <code>circular_buffer</code>).
+        \sa <code>\link push_front() push_front(const_reference)\endlink</code>,
+            <code>pop_front()</code>, <code>emplace_back()</code>
+    */
+    template <class ...Args>
+    void emplace_front(BOOST_FWD_REF(Args) ...args) {
+        emplace_front_impl(::boost::forward<Args>(args)...);
+    }
+
     //! Remove the last element from the <code>circular_buffer</code>.
     /*!
         \pre <code>!empty()</code>
-- 
2.11.0