From 77ccc13181868ab8660162f76a9ed6a175d4c0d6 Mon Sep 17 00:00:00 2001
From: levlam <levlam@telegram.org>
Date: Sun, 20 Feb 2022 23:03:34 +0300
Subject: [PATCH] Add Map/SetNode::copy_from.

---
 tdutils/td/utils/FlatHashMap.h       |  8 ++--
 tdutils/td/utils/FlatHashMapLinear.h | 60 +++++++++++++++++++---------
 tdutils/test/HashSet.cpp             | 14 +++++--
 3 files changed, 57 insertions(+), 25 deletions(-)

diff --git a/tdutils/td/utils/FlatHashMap.h b/tdutils/td/utils/FlatHashMap.h
index 097d02939..c1bd4ef47 100644
--- a/tdutils/td/utils/FlatHashMap.h
+++ b/tdutils/td/utils/FlatHashMap.h
@@ -14,13 +14,13 @@
 
 namespace td {
 template <class KeyT, class ValueT, class HashT = std::hash<KeyT>, class EqT = std::equal_to<KeyT>>
-//using FlatHashMap = FlatHashMapImpl<KeyT, ValueT, HashT, EqT>;
-using FlatHashMap = FlatHashMapChunks<KeyT, ValueT, HashT, EqT>;
+using FlatHashMap = FlatHashMapImpl<KeyT, ValueT, HashT, EqT>;
+//using FlatHashMap = FlatHashMapChunks<KeyT, ValueT, HashT, EqT>;
 //using FlatHashMap = std::unordered_map<KeyT, ValueT, HashT, EqT>;
 
 template <class KeyT, class HashT = std::hash<KeyT>, class EqT = std::equal_to<KeyT>>
-//using FlatHashSet = FlatHashSetImpl<KeyT, HashT, EqT>;
-using FlatHashSet = FlatHashSetChunks<KeyT, HashT, EqT>;
+using FlatHashSet = FlatHashSetImpl<KeyT, HashT, EqT>;
+//using FlatHashSet = FlatHashSetChunks<KeyT, HashT, EqT>;
 //using FlatHashSet = std::unordered_set<KeyT, HashT, EqT>;
 
 }  // namespace td
diff --git a/tdutils/td/utils/FlatHashMapLinear.h b/tdutils/td/utils/FlatHashMapLinear.h
index 8127b3005..4dcd6788b 100644
--- a/tdutils/td/utils/FlatHashMapLinear.h
+++ b/tdutils/td/utils/FlatHashMapLinear.h
@@ -71,6 +71,13 @@ struct MapNode {
     }
   }
 
+  void copy_from(const MapNode &other) {
+    DCHECK(empty());
+    DCHECK(!other.empty());
+    first = other.first;
+    new (&second) ValueT(other.second);
+  }
+
   bool empty() const {
     return is_key_empty(key());
   }
@@ -97,7 +104,9 @@ struct SetNode {
   using key_type = KeyT;
   using public_type = KeyT;
   using value_type = KeyT;
+
   KeyT first{};
+
   const auto &key() const {
     return first;
   }
@@ -125,6 +134,12 @@ struct SetNode {
   }
   ~SetNode() = default;
 
+  void copy_from(const SetNode &other) {
+    DCHECK(empty());
+    DCHECK(!other.empty());
+    first = other.first;
+  }
+
   bool empty() const {
     return is_key_empty(key());
   }
@@ -236,27 +251,33 @@ class FlatHashTable {
   using const_iterator = ConstIterator;
 
   FlatHashTable() = default;
-  FlatHashTable(const FlatHashTable &other) : FlatHashTable(other.begin(), other.end()) {
+  FlatHashTable(const FlatHashTable &other) {
+    assign(other);
   }
   FlatHashTable &operator=(const FlatHashTable &other) {
-    assign(other.begin(), other.end());
+    clear();
+    assign(other);
     return *this;
   }
 
   FlatHashTable(std::initializer_list<Node> nodes) {
+    if (nodes.size() == 0) {
+      return;
+    }
     reserve(nodes.size());
     for (auto &new_node : nodes) {
       CHECK(!new_node.empty());
-      auto bucket = calc_bucket(new_node.first);
+      auto bucket = calc_bucket(new_node.key());
       while (true) {
         auto &node = nodes_[bucket];
-        if (node.key() == new_node.first) {
-          node.second = new_node.second;
+        if (node.empty()) {
+          node.copy_from(new_node);
+          used_nodes_++;
           break;
         }
-        if (node.empty()) {
-          node.emplace(new_node.first, new_node.second);
-          used_nodes_++;
+        if (EqT()(node.key(), new_node.key())) {
+          node.clear();
+          node.copy_from(new_node);
           break;
         }
         next_bucket(bucket);
@@ -280,11 +301,6 @@ class FlatHashTable {
   }
   ~FlatHashTable() = default;
 
-  template <class ItT>
-  FlatHashTable(ItT begin, ItT end) {
-    assign(begin, end);
-  }
-
   size_t bucket_count() const {
     return nodes_.size();
   }
@@ -434,12 +450,20 @@ class FlatHashTable {
   fixed_vector<Node> nodes_;
   size_t used_nodes_{};
 
-  template <class ItT>
-  void assign(ItT begin, ItT end) {
-    resize(std::distance(begin, end));  // TODO: should be conditional
-    for (; begin != end; ++begin) {
-      emplace(begin->first, begin->second);
+  void assign(const FlatHashTable &other) {
+    resize(other.size());
+    for (const auto &new_node : other) {
+      auto bucket = calc_bucket(new_node.key());
+      while (true) {
+        auto &node = nodes_[bucket];
+        if (node.empty()) {
+          node.copy_from(new_node);
+          break;
+        }
+        next_bucket(bucket);
+      }
     }
+    used_nodes_ = other.size();
   }
 
   void try_grow() {
diff --git a/tdutils/test/HashSet.cpp b/tdutils/test/HashSet.cpp
index 029a90fa7..949918bb4 100644
--- a/tdutils/test/HashSet.cpp
+++ b/tdutils/test/HashSet.cpp
@@ -129,7 +129,10 @@ TEST(FlatHashMap, basic) {
   { ASSERT_EQ(Data{}, extract_kv(KV())); }
 
   {
-    KV kv(data.begin(), data.end());
+    KV kv;
+    for (auto &pair : data) {
+      kv.emplace(pair.first, pair.second);
+    }
     ASSERT_EQ(data, extract_kv(kv));
 
     KV copied_kv(kv);
@@ -153,7 +156,10 @@ TEST(FlatHashMap, basic) {
     ASSERT_TRUE(kv.empty());
     kv = std::move(assign_moved_kv);
 
-    KV it_copy_kv(kv.begin(), kv.end());
+    KV it_copy_kv;
+    for (auto &pair : kv) {
+      it_copy_kv.emplace(pair.first, pair.second);
+    }
     ASSERT_EQ(data, extract_kv(it_copy_kv));
   }
 
@@ -161,7 +167,9 @@ TEST(FlatHashMap, basic) {
     KV kv;
     ASSERT_TRUE(kv.empty());
     ASSERT_EQ(0u, kv.size());
-    kv = KV(data.begin(), data.end());
+    for (auto &pair : data) {
+      kv.emplace(pair.first, pair.second);
+    }
     ASSERT_TRUE(!kv.empty());
     ASSERT_EQ(2u, kv.size());