Corrected level merging issue within radix_tree

Author: Thermadiag

CMakeLists.txt

@@ -1,7 +1,7 @@
 cmake_minimum_required(VERSION 3.16)
 
 project(seq
-    VERSION 2.0
+    VERSION 2.1
     DESCRIPTION "Collection of C++17 original containers"
     HOMEPAGE_URL "https://github.com/Thermadiag/seq"
     LANGUAGES CXX

docs/algorithm.md

@@ -16,12 +16,12 @@
 -	`seq::unique`: removed duplicates from a range in a stable way. This is very similar to `std::unique` except that the range does not need to be sorted. It uses a hash table under the hood to find duplicate values. A custom hash function and comparison function can be passed for custom types.
 
 -	`seq::net_sort` and `seq::net_sort_size`: "new" generic stable sorting algorithm that is used everywhere within the seq library.  `seq::net_sort` is a merge sort algorithm with the following specificities:
-		-	Bottom-up merging instead of the more traditional top-down approach,
-		-	Small blocks of 8 elements are sorted using a sorting network,
-		-	Bidirectional merging is used for relocatable types,
-		-	Ping-pong merge is used to merge 4 sorted ranges,
-		-	Can work without allocating memory through a (potentially null) user provided buffer,
-		-	Also works on bidirectional iterators.
+	-	Bottom-up merging instead of the more traditional top-down approach,
+	-	Small blocks of 8 elements are sorted using a sorting network,
+	-	Bidirectional merging is used for relocatable types,
+	-	Ping-pong merge is used to merge 4 sorted ranges,
+	-	Can work without allocating memory through a (potentially null) user provided buffer,
+	-	Also works on bidirectional iterators.
 
 	If provided buffer is one of `seq::default_buffer`, `seq::medium_buffer`, `seq::small_buffer` or `seq::tiny_buffer`, this function will try to allocate memory.
 

seq/internal/radix_tree.hpp

@@ -2128,15 +2128,19 @@ namespace seq
 				directory* new_dir = directory::make(d_data->base, new_hash_len);
 				// copy prefix length
 				new_dir->prefix_len = dir->prefix_len;
+				// set parent, used by iterator::get_bit_pos
+				new_dir->parent = parent_dir;
 
 				try {
 					for (unsigned i = 0; i < size; ++i) {
 						directory* child = static_cast<directory*>(dir->children()[i].ptr());
 						unsigned child_count = child->size();
 
 						if (prefix_search && child->prefix_len >= start_arity) {
-							// keep this directory and remove max_hash_len to the prefix.
-							unsigned loc = (i << start_arity) | (get_prefix_first_bits(child, start_arity, bit_pos));
+							// keep this directory and remove start_arity to the prefix.
+							size_t dir_pos = iterator::get_bit_pos(new_dir);
+							unsigned loc = hash_key(child->any_child()).n_bits(dir_pos, new_hash_len);
+
 							child->prefix_len -= start_arity;
 							new_dir->child(loc) = dir->const_child(i);
 							new_dir->child_count++;
@@ -2148,7 +2152,7 @@ namespace seq
 						}
 
 						if (child->hash_len != start_arity) {
-							// if child has more than min_hash_len bits
+							// if child has more than start_arity bits
 							unsigned rem_bits = child->hash_len - start_arity;
 							unsigned mask = ((1U << rem_bits) - 1U);
 
@@ -2211,6 +2215,9 @@ namespace seq
 					throw;
 				}
 
+				// reset parent
+				new_dir->parent = nullptr;
+
 				// destroy old directory
 				directory::destroy(d_data->base, dir, false);
 
@@ -2973,7 +2980,7 @@ namespace seq
 			}
 
 			/// @brief Check if given hash value share the same prefix as d
-			//SEQ_ALWAYS_INLINE bool check_prefix(const hash_type& hash, const directory* d) const noexcept { return check_prefix(hash, hash_key(d->any_child()), d->prefix_len); }
+			// SEQ_ALWAYS_INLINE bool check_prefix(const hash_type& hash, const directory* d) const noexcept { return check_prefix(hash, hash_key(d->any_child()), d->prefix_len); }
 
 			/// @brief Find key in vector node
 			template<class U>
@@ -3062,7 +3069,7 @@ namespace seq
 
 							// check directory prefix
 							if (prefix_search && d->prefix_len) {
-								if (!check_prefix(hash, bit_pos, d)) 
+								if (!check_prefix(hash, bit_pos, d))
 									return nullptr;
 								else
 									bit_pos += d->prefix_len;