use reference_wrapper instead of raw pointer

Author: HuaHuaY

src/iceberg/schema.cc

@@ -90,16 +90,16 @@ bool Schema::Equals(const Schema& other) const {
 Result<std::optional<std::reference_wrapper<const SchemaField>>> Schema::FindFieldByName(
     std::string_view name, bool case_sensitive) const {
   if (case_sensitive) {
-    ICEBERG_ASSIGN_OR_RAISE(auto* name_to_id, name_to_id_.Get(*this));
-    auto it = name_to_id->find(name);
-    if (it == name_to_id->end()) {
+    ICEBERG_ASSIGN_OR_RAISE(auto name_to_id, name_to_id_.Get(*this));
+    auto it = name_to_id.get().find(name);
+    if (it == name_to_id.get().end()) {
       return std::nullopt;
     };
     return FindFieldById(it->second);
   }
-  ICEBERG_ASSIGN_OR_RAISE(auto* lowercase_name_to_id, lowercase_name_to_id_.Get(*this));
-  auto it = lowercase_name_to_id->find(StringUtils::ToLower(name));
-  if (it == lowercase_name_to_id->end()) {
+  ICEBERG_ASSIGN_OR_RAISE(auto lowercase_name_to_id, lowercase_name_to_id_.Get(*this));
+  auto it = lowercase_name_to_id.get().find(StringUtils::ToLower(name));
+  if (it == lowercase_name_to_id.get().end()) {
     return std::nullopt;
   }
   return FindFieldById(it->second);
@@ -136,9 +136,9 @@ Schema::InitLowerCaseNameToIdMap(const Schema& self) {
 
 Result<std::optional<std::reference_wrapper<const SchemaField>>> Schema::FindFieldById(
     int32_t field_id) const {
-  ICEBERG_ASSIGN_OR_RAISE(auto* id_to_field, id_to_field_.Get(*this));
-  auto it = id_to_field->find(field_id);
-  if (it == id_to_field->end()) {
+  ICEBERG_ASSIGN_OR_RAISE(auto id_to_field, id_to_field_.Get(*this));
+  auto it = id_to_field.get().find(field_id);
+  if (it == id_to_field.get().end()) {
     return std::nullopt;
   }
   return it->second;

src/iceberg/type.cc

@@ -51,9 +51,9 @@ std::string StructType::ToString() const {
 std::span<const SchemaField> StructType::fields() const { return fields_; }
 Result<std::optional<NestedType::SchemaFieldConstRef>> StructType::GetFieldById(
     int32_t field_id) const {
-  ICEBERG_ASSIGN_OR_RAISE(auto* field_by_id, field_by_id_.Get(*this));
-  auto it = field_by_id->find(field_id);
-  if (it == field_by_id->end()) return std::nullopt;
+  ICEBERG_ASSIGN_OR_RAISE(auto field_by_id, field_by_id_.Get(*this));
+  auto it = field_by_id.get().find(field_id);
+  if (it == field_by_id.get().end()) return std::nullopt;
   return it->second;
 }
 Result<std::optional<NestedType::SchemaFieldConstRef>> StructType::GetFieldByIndex(
@@ -66,17 +66,17 @@ Result<std::optional<NestedType::SchemaFieldConstRef>> StructType::GetFieldByInd
 Result<std::optional<NestedType::SchemaFieldConstRef>> StructType::GetFieldByName(
     std::string_view name, bool case_sensitive) const {
   if (case_sensitive) {
-    ICEBERG_ASSIGN_OR_RAISE(auto* field_by_name, field_by_name_.Get(*this));
-    auto it = field_by_name->find(name);
-    if (it != field_by_name->end()) {
+    ICEBERG_ASSIGN_OR_RAISE(auto field_by_name, field_by_name_.Get(*this));
+    auto it = field_by_name.get().find(name);
+    if (it != field_by_name.get().end()) {
       return it->second;
     }
     return std::nullopt;
   }
-  ICEBERG_ASSIGN_OR_RAISE(auto* field_by_lowercase_name,
+  ICEBERG_ASSIGN_OR_RAISE(auto field_by_lowercase_name,
                           field_by_lowercase_name_.Get(*this));
-  auto it = field_by_lowercase_name->find(StringUtils::ToLower(name));
-  if (it != field_by_lowercase_name->end()) {
+  auto it = field_by_lowercase_name.get().find(StringUtils::ToLower(name));
+  if (it != field_by_lowercase_name.get().end()) {
     return it->second;
   }
   return std::nullopt;

src/iceberg/util/lazy.h

@@ -23,6 +23,7 @@
 /// Transparent lazy initialization utility.
 
 #include <concepts>
+#include <functional>
 #include <mutex>
 
 #include "iceberg/result.h"
@@ -46,7 +47,7 @@ class Lazy {
   template <typename... Args>
     requires std::invocable<decltype(InitFunc), Args...> &&
              std::same_as<std::invoke_result_t<decltype(InitFunc), Args...>, Result<T>>
-  Result<T*> Get(Args&&... args) const {
+  Result<std::reference_wrapper<T>> Get(Args&&... args) const {
     Result<T> result;
     std::call_once(flag_, [&result, this, &args...]() {
       result = InitFunc(std::forward<Args>(args)...);
@@ -55,7 +56,7 @@ class Lazy {
       }
     });
     ICEBERG_RETURN_UNEXPECTED(result);
-    return &value_;
+    return std::ref(value_);
   }
 
  private: