Implement copy assignment operator for hvec_map (#4388)

Implement copy constructor for hvec_map. We cannot use a default one since it would involved copying of std::pair<const KEY, VAL> that had its copy ctor explicitly disabled.

Instead, go the standard "way" for maps via clear() and reinsert().

Fixes #4331

lib/hvec_map.h

@@ -17,6 +17,7 @@ limitations under the License.
 #ifndef LIB_HVEC_MAP_H_
 #define LIB_HVEC_MAP_H_
 
+#include <initializer_list>
 #include <tuple>
 #include <vector>
 
@@ -52,7 +53,18 @@ class hvec_map : hash_vector_base {
     }
     hvec_map(const hvec_map &) = default;
     hvec_map(hvec_map &&) = default;
-    hvec_map &operator=(const hvec_map &) = default;
+    hvec_map &operator=(const hvec_map &that) {
+        if (this != std::addressof(that)) {
+            clear();
+            hf = that.hf;
+            eql = that.eql;
+
+            data.reserve(that.size());
+            insert(that.begin(), that.end());
+        }
+
+        return *this;
+    }
     hvec_map &operator=(hvec_map &&) = default;
     ~hvec_map() = default;
     template <class ITER>
@@ -247,6 +259,11 @@ class hvec_map : hash_vector_base {
         }
         return std::make_pair(iterator(*this, idx), new_key);
     }
+    template <typename InputIterator>
+    void insert(InputIterator first, InputIterator last) {
+        for (; first != last; ++first) insert(*first);
+    }
+    void insert(std::initializer_list<value_type> vl) { return insert(vl.begin(), vl.end()); }
     template <class HVM, class VT>
     _iter<HVM, VT> erase(_iter<HVM, VT> it) {
         BUG_CHECK(this == it.self, "incorrect iterator for hvec_map::erase");

test/gtest/hvec_map.cpp

@@ -150,20 +150,24 @@ TEST(hvec_map, insert_emplace_erase) {
 }
 
 TEST(hvec_map, string_map) {
-    hvec_map<std::string, std::string> m;
+    hvec_map<std::string, std::string> m, m1;
 
     for (int i = 1; i <= 100; ++i) {
         m[std::to_string(i)] = "test";
         m[std::to_string(i)] += std::to_string(i);
     }
-    EXPECT_EQ(m.size(), 100);
-    for (int i = 1; i <= 100; i += 2) m.erase(std::to_string(i));
-    EXPECT_EQ(m.size(), 50);
-    for (int i = 102; i <= 200; i += 2) m[std::to_string(i)] = "foobar";
-    EXPECT_EQ(m.size(), 100);
+    m1 = m;
+
+    hvec_map<std::string, std::string> m2(m);
+
+    EXPECT_EQ(m1.size(), 100);
+    for (int i = 1; i <= 100; i += 2) m1.erase(std::to_string(i));
+    EXPECT_EQ(m1.size(), 50);
+    for (int i = 102; i <= 200; i += 2) m1[std::to_string(i)] = "foobar";
+    EXPECT_EQ(m1.size(), 100);
 
     int idx = 2;
-    for (auto &el : m) {
+    for (auto &el : m1) {
         EXPECT_TRUE(el.first == std::to_string(idx));
         if (idx <= 100)
             EXPECT_TRUE(el.second.c_str() + 4 == std::to_string(idx));