From 41a49aaf11ab44df824e957d4947d4c427163c16 Mon Sep 17 00:00:00 2001
From: Sayan Nandan <nandansayan@outlook.com>
Date: Tue, 7 Sep 2021 09:32:02 -0700
Subject: [PATCH] Add `POP` subaction to `lmod`

---
 server/src/actions/lists/mod.rs | 39 +++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/server/src/actions/lists/mod.rs b/server/src/actions/lists/mod.rs
index 0ad79efa..a3f7190e 100644
--- a/server/src/actions/lists/mod.rs
+++ b/server/src/actions/lists/mod.rs
@@ -39,6 +39,7 @@ const CLEAR: &[u8] = "CLEAR".as_bytes();
 const PUSH: &[u8] = "PUSH".as_bytes();
 const REMOVE: &[u8] = "REMOVE".as_bytes();
 const INSERT: &[u8] = "INSERT".as_bytes();
+const POP: &[u8] = "POP".as_bytes();
 
 macro_rules! listmap {
     ($tbl:expr, $con:expr) => {
@@ -285,6 +286,44 @@ action! {
                     conwrite!(con, groups::SERVER_ERR)?;
                 }
             }
+            POP => {
+                err_if_len_is!(act, con, gt 1);
+                let idx = if act.len() == 1 {
+                    // we have an idx
+                    Some(get_numeric_count!())
+                } else {
+                    // no idx
+                    None
+                };
+                if registry::state_okay() {
+                    let maybe_pop = listmap.get(listname).map(|list| {
+                        let mut wlock = list.write();
+                        if let Some(idx) = idx {
+                            if idx < wlock.len() {
+                                // so we can pop
+                                Some(wlock.remove(idx))
+                            } else {
+                                None
+                            }
+                        } else {
+                            wlock.pop()
+                        }
+                    });
+                    match maybe_pop {
+                        Some(Some(val)) => {
+                            unsafe {
+                                writer::write_raw_mono(con, listmap.get_payload_tsymbol(), &val).await?;
+                            }
+                        }
+                        Some(None) => {
+                            conwrite!(con, groups::LISTMAP_BAD_INDEX)?;
+                        }
+                        None => conwrite!(con, groups::NIL)?,
+                    }
+                } else {
+                    conwrite!(con, groups::SERVER_ERR)?;
+                }
+            }
             _ => conwrite!(con, groups::UNKNOWN_ACTION)?,
         }
         Ok(())