generic: Add type command

src/cmd/generic.rs

@@ -8,6 +8,7 @@ use crate::cmd::parse::{ParseCommandError, Parser};
 #[derive(Debug, Clone)]
 pub enum GenericCommand {
     Delete(Vec<String>),
+    Type(String),
 }
 
 impl GenericCommand {
@@ -20,6 +21,10 @@ impl GenericCommand {
                 let keys = parser.remaining_strings()?;
                 Self::Delete(keys)
             }
+            "type" => {
+                let key = parser.next_string()?;
+                Self::Type(key)
+            }
             _ => return Ok(None),
         };
         Ok(Some(Command::Generic(generic_cmd)))

src/mem/generic/get_type.rs

@@ -0,0 +1,24 @@
+// Copyright (c) 2024 Xu Shaohua <[email protected]>. All rights reserved.
+// Use of this source is governed by GNU Affero General Public License
+// that can be found in the LICENSE file.
+
+use crate::cmd::reply_frame::ReplyFrame;
+use crate::mem::db::{Db, MemObject};
+
+/// Returns the string representation of the type of the value stored at key.
+///
+/// The different types that can be returned are:
+/// - string
+/// - list
+/// - set
+/// - zset
+/// - hash
+/// - stream
+pub fn get_type(db: &Db, key: &str) -> ReplyFrame {
+    let obj_type = match db.get(key) {
+        Some(MemObject::Str(_)) => "string",
+        Some(MemObject::List(_)) => "list",
+        None => "none",
+    };
+    ReplyFrame::ConstStatus(obj_type)
+}

src/mem/generic/mod.rs

@@ -7,12 +7,14 @@ use crate::cmd::reply_frame::ReplyFrame;
 use crate::mem::Mem;
 
 mod delete;
+mod get_type;
 
 
 impl Mem {
     pub fn handle_generic_command(&mut self, command: GenericCommand) -> ReplyFrame {
         match command {
             GenericCommand::Delete(keys) => delete::delete(&mut self.db, keys),
+            GenericCommand::Type(key) => get_type::get_type(&self.db, &key),
         }
     }
 }