feat: add Post::clone() method for shallow copying a Post (#18)

This PR adds a new static method `Post::clone()` which takes a `Post` instance as an argument and creates a new shallow copy of that Post. The copied Post is then returned from this method.

Reviewed-on: https://codeberg.org/vlw/wp/pulls/18

src/Posts/Post.php

@@ -34,6 +34,27 @@
 			return $query->num_rows === 1 ? new static($query->fetch_assoc()[Posts::ID->value]) : null;
 		}
 
+		/**
+		 * Create and return a shallow copy of a Post
+		 *
+		 * @param Post $post
+		 * @return static
+		 */
+		public static function clone(Post $post): static {
+			$clone = Post::new($post->post_title);
+
+			foreach (Posts::cases() as $column) {
+				// ID column has to be unique, skip it
+				if ($column === Posts::ID) {
+					continue;
+				}
+
+				$clone->{$column->value} = $post->{$column->value};
+			}
+
+			return $clone;
+		}
+
 		/**
 		 * Create a new post
 		 *
@@ -166,9 +187,14 @@
 			set (DateTimeImmutable $post_modified_gmt) => $this->set(Posts::POST_MODIFIED_GMT->value, $post_modified_gmt->format(static::DATETIME_FORMAT), $post_modified_gmt);
 		}
 
-		public Post|false|null $post_parent {
+		public string $post_content_filtered {
+			get                                 => $this->get(Posts::POST_CONTENT_FILTERED->value);
+			set (string $post_content_filtered) => $this->set(Posts::POST_CONTENT_FILTERED->value, $post_content_filtered);
+		}
+
+		public ?Post $post_parent {
 			get                      => $this->get(Posts::POST_PARENT->value) !== 0 ? new self($this->get(Posts::POST_PARENT->value)) : null;
-			set (Post|false|null $post_parent) => $this->set(Posts::POST_PARENT->value, $post_parent ? $post_parent->id : 0, $post_parent);
+			set (?Post $post_parent) => $this->set(Posts::POST_PARENT->value, $post_parent ? $post_parent->id : 0, $post_parent);
 		}
 
 		public string $guid {