feat: Entity의 상태를 관리한다

README.md

@@ -4,7 +4,7 @@
 
 ### 요구 사항
 
-- [ ] 엔티티의 관리 상태를 추가한다
+- [X] 엔티티 관리 상태를 추가한다
 
 ## 3단계 - Persistence Context, Dirty Check
 

src/main/java/persistence/entity/EntityEntry.java

@@ -0,0 +1,17 @@
+package persistence.entity;
+
+public class EntityEntry {
+    private Status status;
+
+    private EntityEntry(Status status) {
+        this.status = status;
+    }
+
+    public static EntityEntry createManaged() {
+        return new EntityEntry(Status.MANAGED);
+    }
+
+    public void setDeleted() {
+        this.status = Status.DELETED;
+    }
+}

src/main/java/persistence/entity/EntityManagerImpl.java

@@ -3,7 +3,6 @@
 import jdbc.JdbcTemplate;
 
 import java.util.HashMap;
-import java.util.List;
 import java.util.Map;
 
 public class EntityManagerImpl implements EntityManager {

src/main/java/persistence/entity/PersistenceContextImpl.java

@@ -5,29 +5,32 @@
 
 public class PersistenceContextImpl implements PersistenceContext {
 
-    private final Map<EntityKey, Object> entityMap = new HashMap<>();
+    private final Map<EntityKey, Object> managedEntities = new HashMap<>();
     private final Map<EntityKey, EntitySnapshot> entitySnapshots = new HashMap<>();
+    private final Map<EntityKey, EntityEntry> entityEntries = new HashMap<>();
 
     @Override
     public void put(EntityKey entityKey, Object entity) {
-        entityMap.put(entityKey, entity);
+        managedEntities.put(entityKey, entity);
         entitySnapshots.put(entityKey, EntitySnapshot.from(entity));
+        entityEntries.put(entityKey, EntityEntry.createManaged());
     }
 
     @Override
     public boolean contains(EntityKey entityKey) {
-        return entityMap.containsKey(entityKey);
+        return managedEntities.containsKey(entityKey);
     }
 
     @Override
     public Object get(EntityKey entityKey) {
-        return entityMap.get(entityKey);
+        return managedEntities.get(entityKey);
     }
 
     @Override
     public void remove(EntityKey entityKey) {
-        entityMap.remove(entityKey);
+        managedEntities.remove(entityKey);
         entitySnapshots.remove(entityKey);
+        entityEntries.get(entityKey).setDeleted();
     }
 
     @Override

src/main/java/persistence/entity/Status.java

@@ -0,0 +1,10 @@
+package persistence.entity;
+
+public enum Status {
+    MANAGED,
+    READ_ONLY,
+    DELETED,
+    GONE,
+    LOADING,
+    SAVING
+}