From f7a40005ec854131629acac8d03aed0e8a5da415 Mon Sep 17 00:00:00 2001
From: crupest <crupest@outlook.com>
Date: Sat, 30 Dec 2023 01:43:18 +0800
Subject: Refactor SelfResolvable.

---
 include/cru/common/SelfResolvable.h | 39 +++++++++++++++++++++++--------------
 1 file changed, 24 insertions(+), 15 deletions(-)

(limited to 'include/cru')

diff --git a/include/cru/common/SelfResolvable.h b/include/cru/common/SelfResolvable.h
index 0cbb35fb..5a609340 100644
--- a/include/cru/common/SelfResolvable.h
+++ b/include/cru/common/SelfResolvable.h
@@ -1,6 +1,6 @@
 #pragma once
-#include "PreConfig.h"
 
+#include <cassert>
 #include <memory>
 
 namespace cru {
@@ -12,7 +12,7 @@ class ObjectResolver {
   friend SelfResolvable<T>;
 
  private:
-  ObjectResolver(const std::shared_ptr<T*>& resolver) : resolver_(resolver) {}
+  explicit ObjectResolver(T* o) : shared_object_ptr_(new T*(o)) {}
 
  public:
   ObjectResolver(const ObjectResolver&) = default;
@@ -21,48 +21,57 @@ class ObjectResolver {
   ObjectResolver& operator=(ObjectResolver&&) = default;
   ~ObjectResolver() = default;
 
+  bool IsValid() const { return this->shared_object_ptr_ != nullptr; }
+
   T* Resolve() const {
-    // resolver_ is null only when this has been moved.
-    // You shouldn't resolve a moved resolver. So assert it.
-    Expects(resolver_);
-    return *resolver_;
+    assert(IsValid());
+    return *this->shared_object_ptr_;
+  }
+
+  explicit operator bool() const { return this->IsValid(); }
+
+ private:
+  void SetResolvedObject(T* o) {
+    assert(IsValid());
+    *this->shared_object_ptr_ = o;
   }
 
  private:
-  std::shared_ptr<T*> resolver_;
+  std::shared_ptr<T*> shared_object_ptr_;
 };
 
 template <typename T>
 class SelfResolvable {
  public:
-  SelfResolvable() : resolver_(new T*(static_cast<T*>(this))) {}
+  SelfResolvable() : resolver_(static_cast<T*>(this)) {}
   SelfResolvable(const SelfResolvable&) = delete;
   SelfResolvable& operator=(const SelfResolvable&) = delete;
 
   // Resolvers to old object will resolve to new object.
   SelfResolvable(SelfResolvable&& other)
       : resolver_(std::move(other.resolver_)) {
-    (*resolver_) = static_cast<T*>(this);
+    this->resolver_.SetResolvedObject(this);
   }
 
   // Old resolvers for this object will resolve to nullptr.
   // Other's resolvers will now resolve to this.
   SelfResolvable& operator=(SelfResolvable&& other) {
     if (this != &other) {
-      (*resolver_) = nullptr;
-      resolver_ = std::move(other.resolver_);
-      (*resolver_) = static_cast<T*>(this);
+      this->resolver_ = std::move(other.resolver_);
+      this->resolver_.SetResolvedObject(this);
     }
     return *this;
   }
 
   virtual ~SelfResolvable() {
-    if (resolver_ != nullptr) (*resolver_) = nullptr;
+    if (this->resolver_.IsValid()) {
+      this->resolver_.SetResolvedObject(nullptr);
+    }
   }
 
-  ObjectResolver<T> CreateResolver() { return ObjectResolver<T>(resolver_); }
+  ObjectResolver<T> CreateResolver() { return resolver_; }
 
  private:
-  std::shared_ptr<T*> resolver_;
+  ObjectResolver<T> resolver_;
 };
 }  // namespace cru
-- 
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