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

lc_memory/
base.rs
