{"record":{"id":"b33f461c2dcde8a8","repo":"krahets/hello-algo","slug":"error-b33f46","errorCode":null,"errorMessage":"キューが空です","messagePattern":"キューが空です","errorType":"panic","errorClass":null,"httpStatus":null,"severity":"error","filePath":"ja/codes/zig/chapter_stack_and_queue/linkedlist_queue.zig","lineNumber":48,"sourceCode":"        // デストラクタ（メモリを解放する）\n        pub fn deinit(self: *Self) void {\n            if (self.mem_arena == null) return;\n            self.mem_arena.?.deinit();\n        }\n\n        // キューの長さを取得\n        pub fn size(self: *Self) usize {\n            return self.que_size;\n        }\n\n        // キューが空かどうかを判定\n        pub fn isEmpty(self: *Self) bool {\n            return self.size() == 0;\n        }\n\n        // キュー先頭の要素にアクセス\n        pub fn peek(self: *Self) T {\n            if (self.size() == 0) @panic(\"キューが空です\");\n            return self.front.?.val;\n        }  \n\n        // エンキュー\n        pub fn push(self: *Self, num: T) !void {\n            // 末尾ノードの後ろに num を追加\n            var node = try self.mem_allocator.create(inc.ListNode(T));\n            node.init(num);\n            // キューが空なら、先頭・末尾ノードをともにそのノードに設定\n            if (self.front == null) {\n                self.front = node;\n                self.rear = node;\n            // キューが空でなければ、そのノードを末尾ノードの後ろに追加\n            } else {\n                self.rear.?.next = node;\n                self.rear = node;\n            }\n            self.que_size += 1;","sourceCodeStart":30,"sourceCodeEnd":66,"githubUrl":"https://github.com/krahets/hello-algo/blob/69932aed1891a7b7f6a0de88cd116d3fe13e7032/ja/codes/zig/chapter_stack_and_queue/linkedlist_queue.zig#L30-L66","documentation":"This panic is raised by peek() in a singly-linked-list queue (Japanese localization). It fires when reading the front element while que_size == 0. The guard prevents a null front dereference. @panic aborts and is uncatchable.","triggerScenarios":"Calling queue.peek() on a new queue, or after the last element has been dequeued.","commonSituations":"BFS frontier peek after draining; producer/consumer where consumer reads ahead; porting catchable-exception queue code from another language.","solutions":["Check queue.isEmpty() (or size()==0) before peek().","Drive the consumer with while (!queue.isEmpty()).","Cache size locally and branch before reading front.","Wrap peek in a helper returning ?T for recoverable use."],"exampleFix":"// before\nvar head = queue.peek(); // @panics when empty\n\n// after\nwhile (!queue.isEmpty()) {\n    var head = queue.peek();\n}","handlingStrategy":"validation","validationCode":"// Validate non-empty before reading the front\nif (!queue.isEmpty()) {\n    var head = queue.peek();\n}","typeGuard":null,"tryCatchPattern":null,"preventionTips":["Use while (!queue.isEmpty()) and peek inside.","Never assume a default value is returned on empty — it aborts.","Cache size() when conditionally reading the front."],"tags":["zig","queue","panic","precondition","data-structure","i18n-ja"],"backgroundTag":null,"analyzedSha":"69932aed1891a7b7f6a0de88cd116d3fe13e7032","analyzedAt":"2026-08-13T23:02:37.581Z","schemaVersion":2},"datasetVersion":"2026-08-14T00:17:13.853Z"}