管理员界面

本课属于 Coddy GDScript 学习旅程的“面向对象编程”单元。第 60 课，共 65 课。

挑战

中等

为图书管理员生成一份统计报告。保留你在前面步骤中编写的所有内容，只修改 library.gd。

在 Library 中编写 get_statistics() -> Dictionary。它会返回一个包含 5 个 int 值的字典：

"total_books"：图书数量
"available_books"：available 为 true 的图书
"borrowed_books"：已借出的图书
"total_users"：用户数量
"users_with_books"：至少借了一本书的用户

提供的代码添加了 stats 命令，用于打印这 5 个值。对于以下输入：

Community
book The Great Gatsby|F. Scott Fitzgerald|123456
book To Kill a Mockingbird|Harper Lee|789012
book 1984|George Orwell|345678
user U001|Alice
user U002|Bob
user U003|Charlie
borrow 123456|U001
borrow 789012|U001
borrow 345678|U002
stats

输出为：

Book borrowed successfully
Book borrowed successfully
Book borrowed successfully
Total Books: 3
Available Books: 0
Borrowed Books: 3
Total Users: 3
Users with Books: 2

你的代码应写在 book.gd、user.gd 和 library.gd 中。main.gd 存放提供的输入/输出代码，不能编辑。

亲手试试

extends Node

func _ready():
	# 已提供的输入/输出代码：保持原样。
	var library := Library.new(OS.read_string_from_stdin())
	var line := OS.read_string_from_stdin()
	while line != "":
		var parts := line.split(" ", true, 1)
		var fields: PackedStringArray = parts[1].split("|") if parts.size() > 1 else PackedStringArray()
		match parts[0]:
			"book":
				library.add_book(Book.new(fields[0], fields[1], fields[2]))
			"user":
				library.add_user(User.new(fields[0], fields[1]))
			"borrow":
				print(library.borrow_book(fields[0], fields[1]))
			"search":
				var term: String = parts[1] if parts.size() > 1 else ""
				var found: Array = library.search_by_title(term)
				print("Results for '%s': %d" % [term, found.size()])
				for book in found:
					print("- ", book.title, " by ", book.author)
			"stats":
				var stats: Dictionary = library.get_statistics()
				print("Total Books: ", stats["total_books"])
				print("Available Books: ", stats["available_books"])
				print("Borrowed Books: ", stats["borrowed_books"])
				print("Total Users: ", stats["total_users"])
				print("Users with Books: ", stats["users_with_books"])
			"loans":
				var reader: User = library.find_user(fields[0])
				print(reader.user_name, " has borrowed:")
				for isbn in reader.borrowed_isbns:
					print("- ", library.find_book(isbn).title)
			"holder":
				var book: Book = library.find_book(fields[0])
				if book.available:
					print(book.title, " is on the shelf")
				else:
					print(book.title, " is borrowed by ", library.find_user(book.borrower_id).user_name)
			"books":
				for book in library.books:
					print(book)
			"users":
				for user in library.users:
					print(user)
			"show":
				print(library)
		line = OS.read_string_from_stdin()