这段代码为 NaiveTime 结构体实现了 Serde 序列化和反序列化功能。
核心实现
1. 序列化 (Serialize)
rust
impl ser::Serialize for NaiveTime {
fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
where
S: ser::Serializer,
{
serializer.collect_str(&self)
}
}特点：
- 将时间转换为字符串格式进行序列化
- 利用
NaiveTime已有的Displaytrait 实现 - 输出格式如：
"00:00:00","23:59:60.999999999"
2. 反序列化 (Deserialize)
rust
impl<'de> de::Deserialize<'de> for NaiveTime {
fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
where
D: de::Deserializer<'de>,
{
deserializer.deserialize_str(NaiveTimeVisitor)
}
}使用访问者模式：
rust
struct NaiveTimeVisitor;
impl de::Visitor<'_> for NaiveTimeVisitor {
type Value = NaiveTime;
fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
formatter.write_str("a formatted time string")
}
fn visit_str<E>(self, value: &str) -> Result<Self::Value, E>
where
E: de::Error,
{
value.parse().map_err(E::custom)
}
}特点：
- 期望接收格式化的时间字符串
- 利用
NaiveTime的FromStrtrait 进行解析 - 自动处理错误转换
测试用例分析
序列化测试
rust
// 基本时间
"00:00:00" → NaiveTime::from_hms_opt(0, 0, 0)
"00:01:02" → NaiveTime::from_hms_opt(0, 1, 2)
// 含毫秒
"00:00:00.950" → NaiveTime::from_hms_milli_opt(0, 0, 0, 950)
// 闰秒处理
"00:00:60" → NaiveTime::from_hms_milli_opt(0, 0, 59, 1_000)
"23:59:60.999999999" → 闰秒表示反序列化测试
支持的格式：
- 标准格式：
"00:00:00" - 简写格式：
"0:0:0" - 小数秒：
"00:00:00.950","0:0:0.95" - 闰秒：
"00:00:60"
错误情况：
- 空字符串：
"" - 无效时间：
"00:00:61","00:60:00","24:00:00" - 错误分隔符：
"23:59:59,1" - 非时间格式：
"hh:mm:ss","012:34:56" - 错误类型：数字
0,86399或对象{}
Bincode 测试
rust
// 测试二进制序列化
let t = NaiveTime::from_hms_nano_opt(3, 5, 7, 98765432).unwrap();
let encoded = serialize(&t).unwrap();
let decoded: NaiveTime = deserialize(&encoded).unwrap();
assert_eq!(t, decoded);设计特点
- 字符串格式：使用人类可读的字符串格式而非二进制
- 格式兼容：支持多种时间格式（带/不带前导零）
- 闰秒支持：正确处理闰秒的序列化和反序列化
- 错误处理：提供清晰的错误信息
- 格式宽松 ：允许简写格式（如
"0:0:0"）
注意事项
代码中的 TODO 注释指出：
- 空间优化不足：字符串格式对二进制格式不够高效
- 闰秒往返 ：对一般闰秒的往返支持不完整（仅支持
second = 60的情况）
这种实现适合文本格式（如 JSON），但对于二进制格式可能需要更优化的方案。
源码
rust
use super::NaiveTime;
use core::fmt;
use serde::{de, ser};
// TODO not very optimized for space (binary formats would want something better)
// TODO round-trip for general leap seconds (not just those with second = 60)
impl ser::Serialize for NaiveTime {
fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
where
S: ser::Serializer,
{
serializer.collect_str(&self)
}
}
struct NaiveTimeVisitor;
impl de::Visitor<'_> for NaiveTimeVisitor {
type Value = NaiveTime;
fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
formatter.write_str("a formatted time string")
}
fn visit_str<E>(self, value: &str) -> Result<Self::Value, E>
where
E: de::Error,
{
value.parse().map_err(E::custom)
}
}
impl<'de> de::Deserialize<'de> for NaiveTime {
fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
where
D: de::Deserializer<'de>,
{
deserializer.deserialize_str(NaiveTimeVisitor)
}
}
#[cfg(test)]
mod tests {
use crate::NaiveTime;
#[test]
fn test_serde_serialize() {
assert_eq!(
serde_json::to_string(&NaiveTime::from_hms_opt(0, 0, 0).unwrap()).ok(),
Some(r#""00:00:00""#.into())
);
assert_eq!(
serde_json::to_string(&NaiveTime::from_hms_milli_opt(0, 0, 0, 950).unwrap()).ok(),
Some(r#""00:00:00.950""#.into())
);
assert_eq!(
serde_json::to_string(&NaiveTime::from_hms_milli_opt(0, 0, 59, 1_000).unwrap()).ok(),
Some(r#""00:00:60""#.into())
);
assert_eq!(
serde_json::to_string(&NaiveTime::from_hms_opt(0, 1, 2).unwrap()).ok(),
Some(r#""00:01:02""#.into())
);
assert_eq!(
serde_json::to_string(&NaiveTime::from_hms_nano_opt(3, 5, 7, 98765432).unwrap()).ok(),
Some(r#""03:05:07.098765432""#.into())
);
assert_eq!(
serde_json::to_string(&NaiveTime::from_hms_opt(7, 8, 9).unwrap()).ok(),
Some(r#""07:08:09""#.into())
);
assert_eq!(
serde_json::to_string(&NaiveTime::from_hms_micro_opt(12, 34, 56, 789).unwrap()).ok(),
Some(r#""12:34:56.000789""#.into())
);
let leap = NaiveTime::from_hms_nano_opt(23, 59, 59, 1_999_999_999).unwrap();
assert_eq!(serde_json::to_string(&leap).ok(), Some(r#""23:59:60.999999999""#.into()));
}
#[test]
fn test_serde_deserialize() {
let from_str = serde_json::from_str::<NaiveTime>;
assert_eq!(from_str(r#""00:00:00""#).ok(), Some(NaiveTime::from_hms_opt(0, 0, 0).unwrap()));
assert_eq!(from_str(r#""0:0:0""#).ok(), Some(NaiveTime::from_hms_opt(0, 0, 0).unwrap()));
assert_eq!(
from_str(r#""00:00:00.950""#).ok(),
Some(NaiveTime::from_hms_milli_opt(0, 0, 0, 950).unwrap())
);
assert_eq!(
from_str(r#""0:0:0.95""#).ok(),
Some(NaiveTime::from_hms_milli_opt(0, 0, 0, 950).unwrap())
);
assert_eq!(
from_str(r#""00:00:60""#).ok(),
Some(NaiveTime::from_hms_milli_opt(0, 0, 59, 1_000).unwrap())
);
assert_eq!(from_str(r#""00:01:02""#).ok(), Some(NaiveTime::from_hms_opt(0, 1, 2).unwrap()));
assert_eq!(
from_str(r#""03:05:07.098765432""#).ok(),
Some(NaiveTime::from_hms_nano_opt(3, 5, 7, 98765432).unwrap())
);
assert_eq!(from_str(r#""07:08:09""#).ok(), Some(NaiveTime::from_hms_opt(7, 8, 9).unwrap()));
assert_eq!(
from_str(r#""12:34:56.000789""#).ok(),
Some(NaiveTime::from_hms_micro_opt(12, 34, 56, 789).unwrap())
);
assert_eq!(
from_str(r#""23:59:60.999999999""#).ok(),
Some(NaiveTime::from_hms_nano_opt(23, 59, 59, 1_999_999_999).unwrap())
);
assert_eq!(
from_str(r#""23:59:60.9999999999997""#).ok(), // excess digits are ignored
Some(NaiveTime::from_hms_nano_opt(23, 59, 59, 1_999_999_999).unwrap())
);
// bad formats
assert!(from_str(r#""""#).is_err());
assert!(from_str(r#""000000""#).is_err());
assert!(from_str(r#""00:00:61""#).is_err());
assert!(from_str(r#""00:60:00""#).is_err());
assert!(from_str(r#""24:00:00""#).is_err());
assert!(from_str(r#""23:59:59,1""#).is_err());
assert!(from_str(r#""012:34:56""#).is_err());
assert!(from_str(r#""hh:mm:ss""#).is_err());
assert!(from_str(r#"0"#).is_err());
assert!(from_str(r#"86399"#).is_err());
assert!(from_str(r#"{}"#).is_err());
}
#[test]
fn test_serde_bincode() {
// Bincode is relevant to test separately from JSON because
// it is not self-describing.
use bincode::{deserialize, serialize};
let t = NaiveTime::from_hms_nano_opt(3, 5, 7, 98765432).unwrap();
let encoded = serialize(&t).unwrap();
let decoded: NaiveTime = deserialize(&encoded).unwrap();
assert_eq!(t, decoded);
}
}