From b677713a7caf179b144674ff4c6e6b7171ad1337 Mon Sep 17 00:00:00 2001
From: Jonas Maier <>
Date: Fri, 17 Apr 2026 17:56:58 +0200
Subject: aliases

---
 src/run/mod.rs | 60 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 60 insertions(+)

(limited to 'src/run/mod.rs')

diff --git a/src/run/mod.rs b/src/run/mod.rs
index 091c662..d52c4e7 100644
--- a/src/run/mod.rs
+++ b/src/run/mod.rs
@@ -18,6 +18,7 @@ pub enum ExecError {
     IO(std::io::Error),
     ErrorStack(Vec<ExecError>),
     Panic,
+    AliasDepthExceeded,
 }
 
 impl ExecError {
@@ -59,6 +60,7 @@ impl ExecError {
                 }
                 out
             }
+            ExecError::AliasDepthExceeded => "alias depth exceeded".to_string(),
         }
     }
 }
@@ -404,6 +406,62 @@ impl parse::Expander for Executor {
         }
         Ok(buf)
     }
+
+    type AliasAge = AliasAge;
+
+    fn expand_alias(
+        &mut self,
+        cmd: &bstr,
+        older_than: Option<AliasAge>,
+    ) -> Result<Option<(AliasAge, Vec<ExpString>)>, Self::Error> {
+        Ok(self
+            .se
+            .lock()
+            .unwrap()
+            .aliases
+            .get(cmd, older_than.unwrap_or(AliasAge::MAX)))
+    }
+}
+
+type AliasAge = u32;
+type AliasBody = Vec<ExpString>;
+type AliasSet = Vec<(AliasAge, AliasBody)>;
+
+pub struct Aliases {
+    age: u32,
+    aliases: HashMap<BString, AliasSet>,
+}
+
+impl Aliases {
+    pub fn new() -> Self {
+        Self {
+            age: 0,
+            aliases: HashMap::new(),
+        }
+    }
+
+    fn insert(&mut self, name: BString, body: AliasBody) {
+        let age = self.age;
+        self.age += 1;
+        let new = (age, body);
+        if let Some(entry) = self.aliases.get_mut(&name) {
+            entry.push(new);
+        } else {
+            self.aliases.insert(name, vec![new]);
+        }
+    }
+
+    fn get(&mut self, name: &bstr, older_than: AliasAge) -> Option<(AliasAge, AliasBody)> {
+        let Some(alias_set) = self.aliases.get(name) else {
+            return None;
+        };
+
+        alias_set.iter().rev().find(|e| e.0 < older_than).cloned()
+    }
+
+    fn remove(&mut self, name: &bstr) {
+        self.aliases.remove(name);
+    }
 }
 
 fn exec(se: Arc<Mutex<Session>>, ast: Ast<PreExpansion>) -> Result<(), ExecError> {
@@ -479,6 +537,8 @@ const BUILTINS: &[&'static dyn Builtin] = &[
     &builtin::null,
     &builtin::var,
     &builtin::completion,
+    &builtin::alias,
+    &builtin::unalias,
 ];
 
 pub fn builtin_map() -> HashMap<BString, &'static dyn Builtin> {
-- 
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