...

src/cmd.rs

@@ -39,13 +39,20 @@ pub enum Cmd {
     // List commands
     LPush(String, Vec<String>),
     RPush(String, Vec<String>),
+    LPop(String, Option<u64>),
+    RPop(String, Option<u64>),
+    LLen(String),
+    LRem(String, i64, String),
+    LTrim(String, i64, i64),
+    LIndex(String, i64),
+    LRange(String, i64, i64),
     Unknow(String),
 }
 
 impl Cmd {
-    pub fn from(s: &str) -> Result<(Self, Protocol), DBError> {
-        let protocol = Protocol::from(s)?;
-        match protocol.clone().0 {
+    pub fn from(s: &str) -> Result<(Self, Protocol, &str), DBError> {
+        let (protocol, remaining) = Protocol::from(s)?;
+        match protocol.clone() {
             Protocol::Array(p) => {
                 let cmd = p.into_iter().map(|x| x.decode()).collect::<Vec<_>>();
                 if cmd.is_empty() {
@@ -303,14 +310,85 @@ impl Cmd {
                                 Cmd::Client(vec![])
                             }
                         }
+                        "lpush" => {
+                            if cmd.len() < 3 {
+                                return Err(DBError(format!("wrong number of arguments for LPUSH command")));
+                            }
+                            Cmd::LPush(cmd[1].clone(), cmd[2..].to_vec())
+                        }
+                        "rpush" => {
+                            if cmd.len() < 3 {
+                                return Err(DBError(format!("wrong number of arguments for RPUSH command")));
+                            }
+                            Cmd::RPush(cmd[1].clone(), cmd[2..].to_vec())
+                        }
+                        "lpop" => {
+                            if cmd.len() < 2 || cmd.len() > 3 {
+                                return Err(DBError(format!("wrong number of arguments for LPOP command")));
+                            }
+                            let count = if cmd.len() == 3 {
+                                Some(cmd[2].parse::<u64>().map_err(|_| DBError("ERR value is not an integer or out of range".to_string()))?)
+                            } else {
+                                None
+                            };
+                            Cmd::LPop(cmd[1].clone(), count)
+                        }
+                        "rpop" => {
+                            if cmd.len() < 2 || cmd.len() > 3 {
+                                return Err(DBError(format!("wrong number of arguments for RPOP command")));
+                            }
+                            let count = if cmd.len() == 3 {
+                                Some(cmd[2].parse::<u64>().map_err(|_| DBError("ERR value is not an integer or out of range".to_string()))?)
+                            } else {
+                                None
+                            };
+                            Cmd::RPop(cmd[1].clone(), count)
+                        }
+                        "llen" => {
+                            if cmd.len() != 2 {
+                                return Err(DBError(format!("wrong number of arguments for LLEN command")));
+                            }
+                            Cmd::LLen(cmd[1].clone())
+                        }
+                        "lrem" => {
+                            if cmd.len() != 4 {
+                                return Err(DBError(format!("wrong number of arguments for LREM command")));
+                            }
+                            let count = cmd[2].parse::<i64>().map_err(|_| DBError("ERR value is not an integer or out of range".to_string()))?;
+                            Cmd::LRem(cmd[1].clone(), count, cmd[3].clone())
+                        }
+                        "ltrim" => {
+                            if cmd.len() != 4 {
+                                return Err(DBError(format!("wrong number of arguments for LTRIM command")));
+                            }
+                            let start = cmd[2].parse::<i64>().map_err(|_| DBError("ERR value is not an integer or out of range".to_string()))?;
+                            let stop = cmd[3].parse::<i64>().map_err(|_| DBError("ERR value is not an integer or out of range".to_string()))?;
+                            Cmd::LTrim(cmd[1].clone(), start, stop)
+                        }
+                        "lindex" => {
+                            if cmd.len() != 3 {
+                                return Err(DBError(format!("wrong number of arguments for LINDEX command")));
+                            }
+                            let index = cmd[2].parse::<i64>().map_err(|_| DBError("ERR value is not an integer or out of range".to_string()))?;
+                            Cmd::LIndex(cmd[1].clone(), index)
+                        }
+                        "lrange" => {
+                            if cmd.len() != 4 {
+                                return Err(DBError(format!("wrong number of arguments for LRANGE command")));
+                            }
+                            let start = cmd[2].parse::<i64>().map_err(|_| DBError("ERR value is not an integer or out of range".to_string()))?;
+                            let stop = cmd[3].parse::<i64>().map_err(|_| DBError("ERR value is not an integer or out of range".to_string()))?;
+                            Cmd::LRange(cmd[1].clone(), start, stop)
+                        }
                         _ => Cmd::Unknow(cmd[0].clone()),
                     },
-                    protocol.0,
+                    protocol,
+                    remaining
                 ))
             }
             _ => Err(DBError(format!(
                 "fail to parse as cmd for {:?}",
-                protocol.0
+                protocol
             ))),
         }
     }
@@ -379,6 +457,16 @@ impl Cmd {
             Cmd::Client(_) => Ok(Protocol::SimpleString("OK".to_string())),
             Cmd::ClientSetName(name) => client_setname_cmd(server, name).await,
             Cmd::ClientGetName => client_getname_cmd(server).await,
+            // List commands
+            Cmd::LPush(key, elements) => lpush_cmd(server, key, elements).await,
+            Cmd::RPush(key, elements) => rpush_cmd(server, key, elements).await,
+            Cmd::LPop(key, count) => lpop_cmd(server, key, count).await,
+            Cmd::RPop(key, count) => rpop_cmd(server, key, count).await,
+            Cmd::LLen(key) => llen_cmd(server, key).await,
+            Cmd::LRem(key, count, element) => lrem_cmd(server, key, *count, element).await,
+            Cmd::LTrim(key, start, stop) => ltrim_cmd(server, key, *start, *stop).await,
+            Cmd::LIndex(key, index) => lindex_cmd(server, key, *index).await,
+            Cmd::LRange(key, start, stop) => lrange_cmd(server, key, *start, *stop).await,
             Cmd::Unknow(s) => {
                 println!("\x1b[31;1munknown command: {}\x1b[0m", s);
                 Ok(Protocol::err(&format!("ERR unknown command '{}'", s)))
@@ -387,6 +475,96 @@ impl Cmd {
     }
 }
 
+async fn lindex_cmd(server: &Server, key: &str, index: i64) -> Result<Protocol, DBError> {
+    match server.storage.lindex(key, index) {
+        Ok(Some(element)) => Ok(Protocol::BulkString(element)),
+        Ok(None) => Ok(Protocol::Null),
+        Err(e) => Ok(Protocol::err(&e.0)),
+    }
+}
+
+async fn lrange_cmd(server: &Server, key: &str, start: i64, stop: i64) -> Result<Protocol, DBError> {
+    match server.storage.lrange(key, start, stop) {
+        Ok(elements) => Ok(Protocol::Array(elements.into_iter().map(Protocol::BulkString).collect())),
+        Err(e) => Ok(Protocol::err(&e.0)),
+    }
+}
+
+async fn ltrim_cmd(server: &Server, key: &str, start: i64, stop: i64) -> Result<Protocol, DBError> {
+    match server.storage.ltrim(key, start, stop) {
+        Ok(_) => Ok(Protocol::SimpleString("OK".to_string())),
+        Err(e) => Ok(Protocol::err(&e.0)),
+    }
+}
+
+async fn lrem_cmd(server: &Server, key: &str, count: i64, element: &str) -> Result<Protocol, DBError> {
+    match server.storage.lrem(key, count, element) {
+        Ok(removed_count) => Ok(Protocol::SimpleString(removed_count.to_string())),
+        Err(e) => Ok(Protocol::err(&e.0)),
+    }
+}
+
+async fn llen_cmd(server: &Server, key: &str) -> Result<Protocol, DBError> {
+    match server.storage.llen(key) {
+        Ok(len) => Ok(Protocol::SimpleString(len.to_string())),
+        Err(e) => Ok(Protocol::err(&e.0)),
+    }
+}
+
+async fn lpop_cmd(server: &Server, key: &str, count: &Option<u64>) -> Result<Protocol, DBError> {
+    match server.storage.lpop(key, *count) {
+        Ok(Some(elements)) => {
+            if count.is_some() {
+                Ok(Protocol::Array(elements.into_iter().map(Protocol::BulkString).collect()))
+            } else {
+                Ok(Protocol::BulkString(elements[0].clone()))
+            }
+        },
+        Ok(None) => {
+            if count.is_some() {
+                Ok(Protocol::Array(vec![]))
+            } else {
+                Ok(Protocol::Null)
+            }
+        },
+        Err(e) => Ok(Protocol::err(&e.0)),
+    }
+}
+
+async fn rpop_cmd(server: &Server, key: &str, count: &Option<u64>) -> Result<Protocol, DBError> {
+    match server.storage.rpop(key, *count) {
+        Ok(Some(elements)) => {
+            if count.is_some() {
+                Ok(Protocol::Array(elements.into_iter().map(Protocol::BulkString).collect()))
+            } else {
+                Ok(Protocol::BulkString(elements[0].clone()))
+            }
+        },
+        Ok(None) => {
+            if count.is_some() {
+                Ok(Protocol::Array(vec![]))
+            } else {
+                Ok(Protocol::Null)
+            }
+        },
+        Err(e) => Ok(Protocol::err(&e.0)),
+    }
+}
+
+async fn lpush_cmd(server: &Server, key: &str, elements: &[String]) -> Result<Protocol, DBError> {
+    match server.storage.lpush(key, elements.to_vec()) {
+        Ok(len) => Ok(Protocol::SimpleString(len.to_string())),
+        Err(e) => Ok(Protocol::err(&e.0)),
+    }
+}
+
+async fn rpush_cmd(server: &Server, key: &str, elements: &[String]) -> Result<Protocol, DBError> {
+    match server.storage.rpush(key, elements.to_vec()) {
+        Ok(len) => Ok(Protocol::SimpleString(len.to_string())),
+        Err(e) => Ok(Protocol::err(&e.0)),
+    }
+}
+
 async fn exec_cmd(
     queued_cmd: &mut Option<Vec<(Cmd, Protocol)>>,
     server: &mut Server,

src/protocol.rs

@@ -17,7 +17,7 @@ impl fmt::Display for Protocol {
 }
 
 impl Protocol {
-    pub fn from(protocol: &str) -> Result<(Self, usize), DBError> {
+    pub fn from(protocol: &str) -> Result<(Self, &str), DBError> {
         let ret = match protocol.chars().nth(0) {
             Some('+') => Self::parse_simple_string_sfx(&protocol[1..]),
             Some('$') => Self::parse_bulk_string_sfx(&protocol[1..]),
@@ -27,10 +27,7 @@ impl Protocol {
                 protocol
             ))),
         };
-        match ret {
-            Ok((p, s)) => Ok((p, s + 1)),
-            Err(e) => Err(e),
-        }
+        ret
     }
 
     pub fn from_vec(array: Vec<&str>) -> Self {
@@ -91,9 +88,9 @@ impl Protocol {
         }
     }
 
-    fn parse_simple_string_sfx(protocol: &str) -> Result<(Self, usize), DBError> {
+    fn parse_simple_string_sfx(protocol: &str) -> Result<(Self, &str), DBError> {
         match protocol.find("\r\n") {
-            Some(x) => Ok((Self::SimpleString(protocol[..x].to_string()), x + 2)),
+            Some(x) => Ok((Self::SimpleString(protocol[..x].to_string()), &protocol[x + 2..])),
             _ => Err(DBError(format!(
                 "[new simple string] unsupported protocol: {:?}",
                 protocol
@@ -101,27 +98,20 @@ impl Protocol {
         }
     }
 
-    fn parse_bulk_string_sfx(protocol: &str) -> Result<(Self, usize), DBError> {
-        if let Some(len) = protocol.find("\r\n") {
-            let size = Self::parse_usize(&protocol[..len])?;
-            if let Some(data_len) = protocol[len + 2..].find("\r\n") {
-                let s = Self::parse_string(&protocol[len + 2..len + 2 + data_len])?;
-                if size != s.len() {
-                    Err(DBError(format!(
-                        "[new bulk string] unmatched string length in prototocl {:?}",
-                        protocol,
-                    )))
-                } else {
-                    Ok((
-                        Protocol::BulkString(s.to_lowercase()),
-                        len + 2 + data_len + 2,
-                    ))
-                }
-            } else {
-                Err(DBError(format!(
-                    "[new bulk string] unsupported protocol: {:?}",
-                    protocol
+    fn parse_bulk_string_sfx(protocol: &str) -> Result<(Self, &str), DBError> {
+        if let Some(len_end) = protocol.find("\r\n") {
+            let size = Self::parse_usize(&protocol[..len_end])?;
+            let data_start = len_end + 2;
+            let data_end = data_start + size;
+            let s = Self::parse_string(&protocol[data_start..data_end])?;
+
+            if protocol.len() < data_end + 2 || &protocol[data_end..data_end+2] != "\r\n" {
+                 Err(DBError(format!(
+                    "[new bulk string] unmatched string length in prototocl {:?}",
+                    protocol,
                 )))
+            } else {
+                Ok((Protocol::BulkString(s), &protocol[data_end + 2..]))
             }
         } else {
             Err(DBError(format!(
@@ -131,30 +121,22 @@ impl Protocol {
         }
     }
 
-    fn parse_array_sfx(s: &str) -> Result<(Self, usize), DBError> {
-        let mut offset = 0;
-        match s.find("\r\n") {
-            Some(x) => {
-                let array_len = s[..x].parse::<usize>()?;
-                offset += x + 2;
-                let mut vec = vec![];
-                for _ in 0..array_len {
-                    match Protocol::from(&s[offset..]) {
-                        Ok((p, len)) => {
-                            offset += len;
-                            vec.push(p);
-                        }
-                        Err(e) => {
-                            return Err(e);
-                        }
-                    }
-                }
-                Ok((Protocol::Array(vec), offset))
+    fn parse_array_sfx(s: &str) -> Result<(Self, &str), DBError> {
+        if let Some(len_end) = s.find("\r\n") {
+            let array_len = s[..len_end].parse::<usize>()?;
+            let mut remaining = &s[len_end + 2..];
+            let mut vec = vec![];
+            for _ in 0..array_len {
+                let (p, rem) = Protocol::from(remaining)?;
+                vec.push(p);
+                remaining = rem;
             }
-            _ => Err(DBError(format!(
+            Ok((Protocol::Array(vec), remaining))
+        } else {
+            Err(DBError(format!(
                 "[new array] unsupported protocol: {:?}",
                 s
-            ))),
+            )))
         }
     }
 

src/server.rs

@@ -41,20 +41,29 @@ impl Server {
         let mut queued_cmd: Option<Vec<(Cmd, Protocol)>> = None;
         
         loop {
-            if let Ok(len) = stream.read(&mut buf).await {
-                if len == 0 {
+            let len = match stream.read(&mut buf).await {
+                Ok(0) => {
                     println!("[handle] connection closed");
                     return Ok(());
                 }
-                
-                let s = str::from_utf8(&buf[..len])?;
-                let (cmd, protocol) = match Cmd::from(s) {
-                    Ok((cmd, protocol)) => (cmd, protocol),
+                Ok(len) => len,
+                Err(e) => {
+                    println!("[handle] read error: {:?}", e);
+                    return Err(e.into());
+                }
+            };
+
+            let mut s = str::from_utf8(&buf[..len])?;
+            while !s.is_empty() {
+                let (cmd, protocol, remaining) = match Cmd::from(s) {
+                    Ok((cmd, protocol, remaining)) => (cmd, protocol, remaining),
                     Err(e) => {
                         println!("\x1b[31;1mprotocol error: {:?}\x1b[0m", e);
-                        (Cmd::Unknow("protocol_error".to_string()), Protocol::err(&format!("protocol error: {}", e.0)))
+                        (Cmd::Unknow("protocol_error".to_string()), Protocol::err(&format!("protocol error: {}", e.0)), "")
                     }
                 };
+                s = remaining;
+
                 if self.option.debug {
                     println!("\x1b[34;1mgot command: {:?}, protocol: {:?}\x1b[0m", cmd, protocol);
                 } else {
@@ -68,27 +77,22 @@ impl Server {
                     .run(&mut self.clone(), protocol.clone(), &mut queued_cmd)
                     .await
                     .unwrap_or(Protocol::err("unknown cmd from server"));
+                
                 if self.option.debug {
                     println!("\x1b[34;1mqueued cmd {:?}\x1b[0m", queued_cmd);
-                } else {
-                    print!("queued cmd {:?}", queued_cmd);
-                }
-
-                if self.option.debug {
                     println!("\x1b[32;1mgoing to send response {}\x1b[0m", res.encode());
                 } else {
+                    print!("queued cmd {:?}", queued_cmd);
                     println!("going to send response {}", res.encode());
                 }
+
                 _ = stream.write(res.encode().as_bytes()).await?;
-                
+
                 // If this was a QUIT command, close the connection
                 if is_quit {
                     println!("[handle] QUIT command received, closing connection");
                     return Ok(());
                 }
-            } else {
-                println!("[handle] going to break");
-                break;
             }
         }
         Ok(())

src/storage.rs

@@ -12,6 +12,7 @@ use crate::error::DBError;
 const TYPES_TABLE: TableDefinition<&str, &str> = TableDefinition::new("types");
 const STRINGS_TABLE: TableDefinition<&str, &[u8]> = TableDefinition::new("strings");
 const HASHES_TABLE: TableDefinition<(&str, &str), &str> = TableDefinition::new("hashes");
+const LISTS_TABLE: TableDefinition<&str, &[u8]> = TableDefinition::new("lists");
 const STREAMS_META_TABLE: TableDefinition<&str, &[u8]> = TableDefinition::new("streams_meta");
 const STREAMS_DATA_TABLE: TableDefinition<(&str, &str), &[u8]> = TableDefinition::new("streams_data");
 
@@ -26,6 +27,12 @@ pub struct StreamEntry {
     pub fields: Vec<(String, String)>,
 }
 
+#[derive(Serialize, Deserialize, Debug, Clone)]
+pub struct ListValue {
+    pub elements: Vec<String>,
+}
+
+
 #[inline]
 pub fn now_in_millis() -> u128 {
     let start = SystemTime::now();
@@ -47,6 +54,7 @@ impl Storage {
             let _ = write_txn.open_table(TYPES_TABLE)?;
             let _ = write_txn.open_table(STRINGS_TABLE)?;
             let _ = write_txn.open_table(HASHES_TABLE)?;
+            let _ = write_txn.open_table(LISTS_TABLE)?;
             let _ = write_txn.open_table(STREAMS_META_TABLE)?;
             let _ = write_txn.open_table(STREAMS_DATA_TABLE)?;
         }
@@ -143,6 +151,7 @@ impl Storage {
             let mut types_table = write_txn.open_table(TYPES_TABLE)?;
             let mut strings_table = write_txn.open_table(STRINGS_TABLE)?;
             let mut hashes_table = write_txn.open_table(HASHES_TABLE)?;
+            let mut lists_table = write_txn.open_table(LISTS_TABLE)?;
             
             // Remove from type table
             types_table.remove(key.as_str())?;
@@ -165,6 +174,9 @@ impl Storage {
             for (hash_key, field) in to_remove {
                 hashes_table.remove((hash_key.as_str(), field.as_str()))?;
             }
+
+            // Remove from lists table
+            lists_table.remove(key.as_str())?;
         }
         
         write_txn.commit()?;
@@ -633,4 +645,414 @@ impl Storage {
             None => Ok(false),
         }
     }
-}
+    
+    // List operations
+    pub fn lpush(&self, key: &str, elements: Vec<String>) -> Result<u64, DBError> {
+        let write_txn = self.db.begin_write()?;
+        let mut new_len = 0u64;
+
+        {
+            let mut types_table = write_txn.open_table(TYPES_TABLE)?;
+            let mut lists_table = write_txn.open_table(LISTS_TABLE)?;
+
+            let existing_type = match types_table.get(key)? {
+                Some(type_val) => Some(type_val.value().to_string()),
+                None => None,
+            };
+
+            match existing_type {
+                Some(ref type_str) if type_str != "list" => {
+                    return Err(DBError("WRONGTYPE Operation against a key holding the wrong kind of value".to_string()));
+                }
+                None => {
+                    types_table.insert(key, "list")?;
+                }
+                _ => {}
+            }
+
+            let mut list_value: ListValue = match lists_table.get(key)? {
+                Some(data) => bincode::deserialize(data.value())?,
+                None => ListValue { elements: Vec::new() },
+            };
+
+            for element in elements.into_iter().rev() {
+                list_value.elements.insert(0, element);
+            }
+            new_len = list_value.elements.len() as u64;
+
+            let serialized = bincode::serialize(&list_value)?;
+            lists_table.insert(key, serialized.as_slice())?;
+        }
+
+        write_txn.commit()?;
+        Ok(new_len)
+    }
+
+    pub fn rpush(&self, key: &str, elements: Vec<String>) -> Result<u64, DBError> {
+        let write_txn = self.db.begin_write()?;
+        let mut new_len = 0u64;
+
+        {
+            let mut types_table = write_txn.open_table(TYPES_TABLE)?;
+            let mut lists_table = write_txn.open_table(LISTS_TABLE)?;
+
+            let existing_type = match types_table.get(key)? {
+                Some(type_val) => Some(type_val.value().to_string()),
+                None => None,
+            };
+
+            match existing_type {
+                Some(ref type_str) if type_str != "list" => {
+                    return Err(DBError("WRONGTYPE Operation against a key holding the wrong kind of value".to_string()));
+                }
+                None => {
+                    types_table.insert(key, "list")?;
+                }
+                _ => {}
+            }
+
+            let mut list_value: ListValue = match lists_table.get(key)? {
+                Some(data) => bincode::deserialize(data.value())?,
+                None => ListValue { elements: Vec::new() },
+            };
+
+            for element in elements {
+                list_value.elements.push(element);
+            }
+            new_len = list_value.elements.len() as u64;
+
+            let serialized = bincode::serialize(&list_value)?;
+            lists_table.insert(key, serialized.as_slice())?;
+        }
+
+        write_txn.commit()?;
+        Ok(new_len)
+    }
+
+    pub fn lpop(&self, key: &str, count: Option<u64>) -> Result<Option<Vec<String>>, DBError> {
+        let write_txn = self.db.begin_write()?;
+        let mut result_elements = Vec::new();
+
+        {
+            let mut types_table = write_txn.open_table(TYPES_TABLE)?;
+            let mut lists_table = write_txn.open_table(LISTS_TABLE)?;
+
+            let existing_type = match types_table.get(key)? {
+                Some(type_val) => Some(type_val.value().to_string()),
+                None => None,
+            };
+
+            match existing_type {
+                Some(ref type_str) if type_str != "list" => {
+                    return Err(DBError("WRONGTYPE Operation against a key holding the wrong kind of value".to_string()));
+                }
+                Some(_) => {
+                    let mut list_value: ListValue = match lists_table.get(key)? {
+                        Some(data) => bincode::deserialize(data.value())?,
+                        None => return Ok(None), // Key exists but list is empty (shouldn't happen if type is "list")
+                    };
+
+                    let num_to_pop = count.unwrap_or(1) as usize;
+                    for _ in 0..num_to_pop {
+                        if !list_value.elements.is_empty() {
+                            result_elements.push(list_value.elements.remove(0));
+                        } else {
+                            break;
+                        }
+                    }
+
+                    if list_value.elements.is_empty() {
+                        lists_table.remove(key)?;
+                        types_table.remove(key)?;
+                    } else {
+                        let serialized = bincode::serialize(&list_value)?;
+                        lists_table.insert(key, serialized.as_slice())?;
+                    }
+                }
+                None => return Ok(None),
+            }
+        }
+
+        write_txn.commit()?;
+        if result_elements.is_empty() {
+            Ok(None)
+        } else {
+            Ok(Some(result_elements))
+        }
+    }
+
+    pub fn rpop(&self, key: &str, count: Option<u64>) -> Result<Option<Vec<String>>, DBError> {
+        let write_txn = self.db.begin_write()?;
+        let mut result_elements = Vec::new();
+
+        {
+            let mut types_table = write_txn.open_table(TYPES_TABLE)?;
+            let mut lists_table = write_txn.open_table(LISTS_TABLE)?;
+
+            let existing_type = match types_table.get(key)? {
+                Some(type_val) => Some(type_val.value().to_string()),
+                None => None,
+            };
+
+            match existing_type {
+                Some(ref type_str) if type_str != "list" => {
+                    return Err(DBError("WRONGTYPE Operation against a key holding the wrong kind of value".to_string()));
+                }
+                Some(_) => {
+                    let mut list_value: ListValue = match lists_table.get(key)? {
+                        Some(data) => bincode::deserialize(data.value())?,
+                        None => return Ok(None),
+                    };
+
+                    let num_to_pop = count.unwrap_or(1) as usize;
+                    for _ in 0..num_to_pop {
+                        if let Some(element) = list_value.elements.pop() {
+                            result_elements.push(element);
+                        } else {
+                            break;
+                        }
+                    }
+
+                    if list_value.elements.is_empty() {
+                        lists_table.remove(key)?;
+                        types_table.remove(key)?;
+                    } else {
+                        let serialized = bincode::serialize(&list_value)?;
+                        lists_table.insert(key, serialized.as_slice())?;
+                    }
+                }
+                None => return Ok(None),
+            }
+        }
+
+        write_txn.commit()?;
+        if result_elements.is_empty() {
+            Ok(None)
+        } else {
+            Ok(Some(result_elements))
+        }
+    }
+
+    pub fn llen(&self, key: &str) -> Result<u64, DBError> {
+        let read_txn = self.db.begin_read()?;
+        
+        let types_table = read_txn.open_table(TYPES_TABLE)?;
+        match types_table.get(key)? {
+            Some(type_val) if type_val.value() == "list" => {
+                let lists_table = read_txn.open_table(LISTS_TABLE)?;
+                match lists_table.get(key)? {
+                    Some(data) => {
+                        let list_value: ListValue = bincode::deserialize(data.value())?;
+                        Ok(list_value.elements.len() as u64)
+                    }
+                    None => Ok(0), // Key exists but list is empty
+                }
+            }
+            Some(_) => Err(DBError("WRONGTYPE Operation against a key holding the wrong kind of value".to_string())),
+            None => Ok(0), // Key does not exist
+        }
+    }
+    
+    pub fn lrem(&self, key: &str, count: i64, element: &str) -> Result<u64, DBError> {
+        let write_txn = self.db.begin_write()?;
+        let mut removed_count = 0u64;
+
+        {
+            let mut types_table = write_txn.open_table(TYPES_TABLE)?;
+            let mut lists_table = write_txn.open_table(LISTS_TABLE)?;
+
+            let existing_type = match types_table.get(key)? {
+                Some(type_val) => Some(type_val.value().to_string()),
+                None => None,
+            };
+
+            match existing_type {
+                Some(ref type_str) if type_str != "list" => {
+                    return Err(DBError("WRONGTYPE Operation against a key holding the wrong kind of value".to_string()));
+                }
+                Some(_) => {
+                    let mut list_value: ListValue = match lists_table.get(key)? {
+                        Some(data) => bincode::deserialize(data.value())?,
+                        None => return Ok(0),
+                    };
+
+                    let initial_len = list_value.elements.len();
+                    
+                    if count > 0 {
+                        let mut i = 0;
+                        let mut removed = 0;
+                        while i < list_value.elements.len() && removed < count {
+                            if list_value.elements[i] == element {
+                                list_value.elements.remove(i);
+                                removed += 1;
+                            } else {
+                                i += 1;
+                            }
+                        }
+                    } else if count < 0 {
+                        let mut i = list_value.elements.len() as i32 - 1;
+                        let mut removed = 0;
+                        while i >= 0 && removed < -count {
+                            if list_value.elements[i as usize] == element {
+                                list_value.elements.remove(i as usize);
+                                removed += 1;
+                            }
+                            i -= 1;
+                        }
+                    } else { // count == 0
+                        list_value.elements.retain(|el| el != element);
+                    }
+
+                    removed_count = (initial_len - list_value.elements.len()) as u64;
+
+                    if list_value.elements.is_empty() {
+                        lists_table.remove(key)?;
+                        types_table.remove(key)?;
+                    } else {
+                        let serialized = bincode::serialize(&list_value)?;
+                        lists_table.insert(key, serialized.as_slice())?;
+                    }
+                }
+                None => return Ok(0),
+            }
+        }
+
+        write_txn.commit()?;
+        Ok(removed_count)
+    }
+
+    pub fn ltrim(&self, key: &str, start: i64, stop: i64) -> Result<(), DBError> {
+        let write_txn = self.db.begin_write()?;
+        
+        {
+            let mut types_table = write_txn.open_table(TYPES_TABLE)?;
+            let mut lists_table = write_txn.open_table(LISTS_TABLE)?;
+
+            let existing_type = match types_table.get(key)? {
+                Some(type_val) => Some(type_val.value().to_string()),
+                None => None,
+            };
+            
+            match existing_type {
+                Some(ref type_str) if type_str != "list" => {
+                    return Err(DBError("WRONGTYPE Operation against a key holding the wrong kind of value".to_string()));
+                }
+                Some(_) => {
+                    let mut list_value: ListValue = match lists_table.get(key)? {
+                        Some(data) => bincode::deserialize(data.value())?,
+                        None => return Ok(()),
+                    };
+
+                    let len = list_value.elements.len() as i64;
+                    let mut start = start;
+                    let mut stop = stop;
+
+                    if start < 0 {
+                        start += len;
+                    }
+                    if stop < 0 {
+                        stop += len;
+                    }
+
+                    if start < 0 {
+                        start = 0;
+                    }
+
+                    if start > stop || start >= len {
+                        list_value.elements.clear();
+                    } else {
+                        if stop >= len {
+                            stop = len - 1;
+                        }
+                        let start = start as usize;
+                        let stop = stop as usize;
+                        list_value.elements = list_value.elements.drain(start..=stop).collect();
+                    }
+
+                    if list_value.elements.is_empty() {
+                        lists_table.remove(key)?;
+                        types_table.remove(key)?;
+                    } else {
+                        let serialized = bincode::serialize(&list_value)?;
+                        lists_table.insert(key, serialized.as_slice())?;
+                    }
+                }
+                None => {}
+            }
+        }
+        
+        write_txn.commit()?;
+        Ok(())
+    }
+
+    pub fn lindex(&self, key: &str, index: i64) -> Result<Option<String>, DBError> {
+        let read_txn = self.db.begin_read()?;
+        
+        let types_table = read_txn.open_table(TYPES_TABLE)?;
+        match types_table.get(key)? {
+            Some(type_val) if type_val.value() == "list" => {
+                let lists_table = read_txn.open_table(LISTS_TABLE)?;
+                match lists_table.get(key)? {
+                    Some(data) => {
+                        let list_value: ListValue = bincode::deserialize(data.value())?;
+                        let len = list_value.elements.len() as i64;
+                        let mut index = index;
+                        if index < 0 {
+                            index += len;
+                        }
+                        if index < 0 || index >= len {
+                            Ok(None)
+                        } else {
+                            Ok(list_value.elements.get(index as usize).cloned())
+                        }
+                    }
+                    None => Ok(None),
+                }
+            }
+            Some(_) => Err(DBError("WRONGTYPE Operation against a key holding the wrong kind of value".to_string())),
+            None => Ok(None),
+        }
+    }
+
+    pub fn lrange(&self, key: &str, start: i64, stop: i64) -> Result<Vec<String>, DBError> {
+        let read_txn = self.db.begin_read()?;
+        
+        let types_table = read_txn.open_table(TYPES_TABLE)?;
+        match types_table.get(key)? {
+            Some(type_val) if type_val.value() == "list" => {
+                let lists_table = read_txn.open_table(LISTS_TABLE)?;
+                match lists_table.get(key)? {
+                    Some(data) => {
+                        let list_value: ListValue = bincode::deserialize(data.value())?;
+                        let len = list_value.elements.len() as i64;
+                        let mut start = start;
+                        let mut stop = stop;
+
+                        if start < 0 {
+                            start += len;
+                        }
+                        if stop < 0 {
+                            stop += len;
+                        }
+
+                        if start < 0 {
+                            start = 0;
+                        }
+                        
+                        if start > stop || start >= len {
+                            Ok(Vec::new())
+                        } else {
+                            if stop >= len {
+                                stop = len - 1;
+                            }
+                            Ok(list_value.elements[start as usize..=stop as usize].to_vec())
+                        }
+                    }
+                    None => Ok(Vec::new()),
+                }
+            }
+            Some(_) => Err(DBError("WRONGTYPE Operation against a key holding the wrong kind of value".to_string())),
+            None => Ok(Vec::new()),
+        }
+    }
+}