fix from_copy() and select_many()

CppLinq/cpplinq.hpp

@@ -544,28 +544,31 @@ namespace cpplinq
                     container_type&&        container
                 )
                 :   container   (std::move (container))
-                ,   current     (container.begin ())
-                ,   upcoming    (container.begin ())
-                ,   end         (container.end ())
             {
+                upcoming  = current = this->container.begin();
+                end       = this->container.end();
             }
 
             CPPLINQ_INLINEMETHOD from_copy_range (
                     container_type const &  container
                 )
                 :   container   (container)
-                ,   current     (container.begin ())
-                ,   upcoming    (container.begin ())
-                ,   end         (container.end ())
             {
+                upcoming  = current = this->container.begin();
+                end       = this->container.end();
             }
 
             CPPLINQ_INLINEMETHOD from_copy_range (from_copy_range const & v)
                 :   container   (v.container)
-                ,   current     (v.current)
-                ,   upcoming    (v.upcoming)
-                ,   end         (v.end)
             {
+                iterator_type s_b = v.container.begin();
+                auto d_c = std::distance(s_b, v.current);
+                auto d_u = std::distance(v.current, v.upcoming); // upcoming is never before current.
+                current = container.begin();
+                std::advance(current,  d_c);
+                upcoming = current;
+                std::advance(upcoming, d_u);
+                end = container.end(); // end must re-create from new container.
             }
 
             CPPLINQ_INLINEMETHOD from_copy_range (from_copy_range && v) CPPLINQ_NOEXCEPT
@@ -2113,10 +2116,13 @@ namespace cpplinq
                     return true;
                 }
 
-                if (range.next ())
+                while(range.next ())
                 {
                     inner_range = predicate (range.front ());
-                    return inner_range && inner_range->next ();
+                    if(inner_range && inner_range->next ())
+                    {
+                        return true;
+                    }
                 }
 
                 inner_range.clear ();

Test/CppLinqTests.hpp

@@ -32,6 +32,7 @@
 // ----------------------------------------------------------------------------------------------
 #include <limits.h>
 #include <stdio.h>
+#include <cmath>
 // ----------------------------------------------------------------------------------------------
 #include "../CppLinq/cpplinq.hpp"
 // ----------------------------------------------------------------------------------------------
@@ -1775,7 +1776,41 @@ namespace
                 }
             }
         }
+        {
+            std::vector<int> seed;
+            seed.push_back(1);
+            seed.push_back(2);
+            std::vector<int> select_many_result =
+                from (seed)
+                >>  select_many ([&seed](int n){
+                    if(n == 1)
+                        return from(std::vector<int>());
+                    else
+                        return from(seed);
+                })
+                >>  to_vector ()
+            ;
+
+            TEST_ASSERT (2U, select_many_result.size ());
+        }
+        {
+            std::vector<int> seed;
+            seed.push_back(1);
+            std::vector<int> select_many_result =
+                from (seed)
+                    >>  select_many ([](int n){
+                        std::vector<int> seq;
+                        seq.push_back(n);
+                        seq.push_back(n);
+                        return from_copy(std::move(seq));
+                    })
+                    >>  to_vector ()
+            ;
 
+            TEST_ASSERT (2U, select_many_result.size ());
+            TEST_ASSERT (1, select_many_result[0]);
+            TEST_ASSERT (1, select_many_result[1]);
+        }
     }
 
     void test_orderby ()