Solved: 52 - Monadic Expected

modules/14_cpp26/src/monadic_expected.cpp

@@ -3,18 +3,23 @@
 namespace cpp26 {
 
 auto parse_id(const std::string& text) -> std::expected<int, ErrorCode> {
-    (void)text;
-    return std::unexpected(ErrorCode::Invalid);
+    int id = 0;
+    if (auto [ptr, ec] = std::from_chars(text.data(), text.data() + text.size(), id);
+        ec != std::errc{} || ptr != text.data() + text.size()) {
+        return std::unexpected(ErrorCode::Invalid);
+    }
+    return id;
 }
 
-auto load_user(int id) -> std::expected<std::string, ErrorCode> {
-    (void)id;
-    return std::unexpected(ErrorCode::NotFound);
+auto load_user(const int id) -> std::expected<std::string, ErrorCode> {
+    if (id == 999) {
+        return std::unexpected(ErrorCode::NotFound);
+    }
+    return "User-" + std::to_string(id);
 }
 
 auto load_user_name(const std::string& text) -> std::expected<std::string, ErrorCode> {
-    (void)text;
-    return std::unexpected(ErrorCode::Invalid);
+    return parse_id(text).and_then(load_user);
 }
 
 }  // namespace cpp26