Better LinkType support

CHANGELOG.md

@@ -10,7 +10,7 @@
 
 ### Enhancements
 
-* None.
+* Added `Tabe::get_link_type()` as a helper method for getting the link type from link columns.
 
 -----------
 

src/realm/data_type.hpp

@@ -19,6 +19,8 @@
 #ifndef REALM_DATA_TYPE_HPP
 #define REALM_DATA_TYPE_HPP
 
+#include <cstdint>
+
 namespace realm {
 
 class StringData;

src/realm/table.cpp

@@ -1841,6 +1841,18 @@ bool Table::is_nullable(size_t col_ndx) const
            m_spec->get_column_type(col_ndx) == col_type_Link;
 }
 
+LinkType Table::get_link_type(size_t col_ndx) const
+{
+    if (!is_attached()) {
+        throw LogicError{LogicError::detached_accessor};
+    }
+    if (!(m_spec->get_column_type(col_ndx) == col_type_Link) && !(m_spec->get_column_type(col_ndx) == col_type_LinkList)) {
+        throw LogicError{LogicError::illegal_type};
+    }
+    REALM_ASSERT_DEBUG(col_ndx < m_spec->get_column_count());
+    return (m_spec->get_column_attr(col_ndx) & col_attr_StrongLinks) ? LinkType::link_Strong : LinkType::link_Weak;
+}
+
 const ColumnBase& Table::get_column_base(size_t ndx) const noexcept
 {
     REALM_ASSERT_DEBUG(ndx < m_spec->get_column_count());

src/realm/table.hpp

@@ -164,6 +164,10 @@ class Table {
     // Whether or not elements can be null.
     bool is_nullable(size_t col_ndx) const;
 
+    // Returns the link type for the given column.
+    // Throws an LogicError if target column is not a link column.
+    LinkType get_link_type(size_t col_ndx) const;
+
     //@{
     /// Conventience functions for inspecting the dynamic table type.
     ///

test/test_table.cpp

@@ -8363,4 +8363,26 @@ TEST(Table_KeyRow)
     CHECK_EQUAL(i, 1);
 }
 
+TEST(Table_getLinkType)
+{
+    Group g;
+    TableRef table = g.add_table("table");
+
+    table->add_column(type_Int, "int");
+    table->add_column_link(type_Link, "weak_link", *table);
+    table->add_column_link(type_Link, "strong_link", *table, link_Strong);
+    table->add_column_link(type_LinkList, "weak_list", *table);
+    table->add_column_link(type_LinkList, "strong_list", *table, link_Strong);
+
+    CHECK(link_Weak == table->get_link_type(1));
+    CHECK(link_Strong == table->get_link_type(2));
+    CHECK(link_Weak == table->get_link_type(3));
+    CHECK(link_Strong == table->get_link_type(4));
+
+    CHECK_THROW(table->get_link_type(0), LogicError);
+
+    g.remove_table("table");
+    CHECK_THROW(table->get_link_type(1), LogicError);
+}
+
 #endif // TEST_TABLE