String: Add operator=

libluna/include/luna/String.h

@@ -17,6 +17,9 @@ class String
     String(String&&);
     String(const String&) = delete;
 
+    String& operator=(String&&);
+    String& operator=(const String&) = delete;
+
     ~String();
 
     Result<String> clone() const;

libluna/src/String.cpp

@@ -23,6 +23,24 @@ String::String(String&& other)
     other.m_string = nullptr;
 }
 
+String& String::operator=(String&& other)
+{
+    if (&other == this) return *this;
+
+    if (!m_inline) free_impl(m_string);
+
+    m_inline = other.m_inline;
+
+    m_string = other.m_string;
+    m_length = other.m_length;
+
+    if (m_inline) memcpy(m_inline_storage, other.m_inline_storage, sizeof(m_inline_storage));
+
+    other.m_string = nullptr;
+
+    return *this;
+}
+
 String::String(char* c_str)
 {
     check(c_str);