lc_memory/
base.rs

1// lc-memory/src/base.rs
2//! Memory base trait
3
4use async_trait::async_trait;
5use lc_schema::Message;
6use std::collections::HashMap;
7
8/// Memory error type
9#[derive(Debug, thiserror::Error)]
10#[non_exhaustive]
11pub enum MemoryError {
12    /// Load error
13    #[error("Failed to load memory: {0}")]
14    LoadError(String),
15
16    /// Save error
17    #[error("Failed to save memory: {0}")]
18    SaveError(String),
19
20    /// Clear error
21    #[error("Failed to clear memory: {0}")]
22    ClearError(String),
23
24    /// Other error
25    #[error("Memory error: {0}")]
26    Other(String),
27}
28
29/// Base Memory trait
30///
31/// The base interface for all Memory types.
32#[async_trait]
33pub trait BaseMemory: Send + Sync {
34    /// Get memory variable names
35    ///
36    /// Returns all variable keys stored in memory.
37    fn memory_variables(&self) -> Vec<&str>;
38
39    /// Load memory variables
40    ///
41    /// # Arguments
42    /// * `inputs` - Current input
43    ///
44    /// # Returns
45    /// Memory variable dictionary
46    async fn load_memory_variables(
47        &self,
48        inputs: &HashMap<String, String>,
49    ) -> Result<HashMap<String, serde_json::Value>, MemoryError>;
50
51    /// Save context
52    ///
53    /// # Arguments
54    /// * `inputs` - User input
55    /// * `outputs` - System output
56    ///
57    /// # Contract
58    /// 缺失 `input` / `output` key 时返回 [`MemoryError::SaveError`]。
59    /// 所有内置实现(Buffer / Window / Summary / SummaryBuffer)行为一致,
60    /// 不做静默空串兜底。
61    async fn save_context(
62        &mut self,
63        inputs: &HashMap<String, String>,
64        outputs: &HashMap<String, String>,
65    ) -> Result<(), MemoryError>;
66
67    /// Clear memory
68    async fn clear(&mut self) -> Result<(), MemoryError>;
69}
70
71/// Base Chat Memory trait
72///
73/// Memory specifically for chat scenarios.
74///
75/// P0-1: 让持有 `ChatMessageHistory` 的记忆类型可直接实现(内部仍用
76/// 具体 history,只加 impl 不改存储),从而支持泛型记忆代码
77/// `fn answer_with<T: BaseChatMemory>(m: &mut T)`。
78pub trait BaseChatMemory: BaseMemory {
79    /// Get chat message list
80    fn messages(&self) -> &[Message];
81
82    /// Add message
83    fn add_message(&mut self, message: Message);
84
85    /// Add user message
86    fn add_user_message(&mut self, content: &str) {
87        self.add_message(Message::human(content));
88    }
89
90    /// Add AI message
91    fn add_ai_message(&mut self, content: &str) {
92        self.add_message(Message::ai(content));
93    }
94}
95
96/// Chat message buffer
97///
98/// Simple message storage for ConversationBufferMemory.
99#[derive(Debug, Clone)]
100pub struct ChatMessageHistory {
101    /// Message list
102    messages: Vec<Message>,
103}
104
105impl ChatMessageHistory {
106    /// Create empty history
107    pub fn new() -> Self {
108        Self {
109            messages: Vec::new(),
110        }
111    }
112
113    /// Create from existing messages
114    pub fn from_messages(messages: Vec<Message>) -> Self {
115        Self { messages }
116    }
117
118    /// Add message
119    pub fn add_message(&mut self, message: Message) {
120        self.messages.push(message);
121    }
122
123    /// Add user message
124    pub fn add_user_message(&mut self, content: &str) {
125        self.add_message(Message::human(content));
126    }
127
128    /// Add AI message
129    pub fn add_ai_message(&mut self, content: &str) {
130        self.add_message(Message::ai(content));
131    }
132
133    /// Add system message
134    pub fn add_system_message(&mut self, content: &str) {
135        self.add_message(Message::system(content));
136    }
137
138    /// Get all messages
139    pub fn messages(&self) -> &[Message] {
140        &self.messages
141    }
142
143    /// Clear messages
144    pub fn clear(&mut self) {
145        self.messages.clear();
146    }
147
148    /// Message count
149    pub fn len(&self) -> usize {
150        self.messages.len()
151    }
152
153    /// Is empty
154    pub fn is_empty(&self) -> bool {
155        self.messages.is_empty()
156    }
157}
158
159impl std::fmt::Display for ChatMessageHistory {
160    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
161        let formatted: String = self
162            .messages
163            .iter()
164            .map(|msg| {
165                let role = match msg.message_type {
166                    lc_schema::MessageType::Human => "Human",
167                    lc_schema::MessageType::AI => "AI",
168                    lc_schema::MessageType::System => "System",
169                    lc_schema::MessageType::Tool { .. } => "Tool",
170                };
171                format!("{}: {}", role, msg.content)
172            })
173            .collect::<Vec<_>>()
174            .join("\n");
175        write!(f, "{}", formatted)
176    }
177}
178
179impl Default for ChatMessageHistory {
180    fn default() -> Self {
181        Self::new()
182    }
183}
184
185/// Convert `load_memory_variables` output into a message list for LLM consumption.
186///
187/// 记忆组件按变量产出两种形状:
188/// - `Value::Array`(`return_messages = true`):数组元素是序列化的 [`Message`],
189///   逐个反序列化;非 `Message` 的字符串元素包装为 `System` 消息;
190/// - `Value::String`(`return_messages = false` / summary / vectorstore):整段历史
191///   文本,包装为 `System` 消息。
192///
193/// 供 `lc-sessions` 桥接、`lc-chains` 等把记忆变量灌进 LLM 上下文时复用。
194pub fn memory_variables_to_messages(vars: &HashMap<String, serde_json::Value>) -> Vec<Message> {
195    let mut messages = Vec::new();
196    for value in vars.values() {
197        match value {
198            serde_json::Value::Array(items) => {
199                for item in items {
200                    if let Ok(msg) = serde_json::from_value::<Message>(item.clone()) {
201                        messages.push(msg);
202                    } else if let Some(s) = item.as_str() {
203                        messages.push(Message::system(s));
204                    }
205                }
206            }
207            serde_json::Value::String(s) => messages.push(Message::system(s)),
208            _ => {}
209        }
210    }
211    messages
212}
213
214#[cfg(test)]
215mod tests {
216    use super::*;
217
218    #[test]
219    fn test_chat_message_history() {
220        let mut history = ChatMessageHistory::new();
221
222        history.add_user_message("hello");
223        history.add_ai_message("Hello! How can I help you?");
224        history.add_user_message("introduce yourself");
225
226        assert_eq!(history.len(), 3);
227        assert!(!history.is_empty());
228    }
229
230    #[test]
231    fn test_chat_message_history_to_string() {
232        let mut history = ChatMessageHistory::new();
233
234        history.add_user_message("hello");
235        history.add_ai_message("Hello!");
236
237        let str = history.to_string();
238        assert!(str.contains("Human: hello"));
239        assert!(str.contains("AI: Hello!"));
240    }
241
242    #[test]
243    fn test_chat_message_history_clear() {
244        let mut history = ChatMessageHistory::new();
245
246        history.add_user_message("test");
247        assert_eq!(history.len(), 1);
248
249        history.clear();
250        assert_eq!(history.len(), 0);
251        assert!(history.is_empty());
252    }
253
254    /// P2-1: `memory_variables_to_messages` 转换两种记忆变量形状。
255    #[test]
256    fn test_memory_variables_to_messages() {
257        // 形状一:Value::Array(return_messages = true) -> 反序列化为 Message
258        let msg = Message::ai("你好");
259        let mut vars = HashMap::new();
260        vars.insert(
261            "history".to_string(),
262            serde_json::json!([serde_json::to_value(&msg).unwrap()]),
263        );
264        let messages = memory_variables_to_messages(&vars);
265        assert_eq!(messages.len(), 1);
266        assert_eq!(messages[0].content, "你好");
267
268        // 形状二:Value::String(return_messages = false / summary) -> 包装为 System
269        let mut vars = HashMap::new();
270        vars.insert(
271            "history".to_string(),
272            serde_json::Value::String("Human: 在吗\nAI: 在".to_string()),
273        );
274        let messages = memory_variables_to_messages(&vars);
275        assert_eq!(messages.len(), 1);
276        assert_eq!(messages[0].message_type, lc_schema::MessageType::System);
277    }
278}
lc_memory/base.rs

lc_memory/
base.rs
