Make g - switch to the last used shell (#6249)

* Make `g -` switch to the last used shell

Related #6223

Signed-off-by: nibon7 <nibon7@163.com>

* simplify error handling

Signed-off-by: nibon7 <nibon7@163.com>

* update NUSHELL_LAST_SHELL environment

Signed-off-by: nibon7 <nibon7@163.com>

* add test

Signed-off-by: nibon7 <nibon7@163.com>

* fix description

Signed-off-by: nibon7 <nibon7@163.com>

crates/nu-cli/src/repl.rs

@@ -395,9 +395,23 @@ pub fn evaluate_repl(
                         0
                     };
 
+                    let last_shell = stack.get_env_var(engine_state, "NUSHELL_LAST_SHELL");
+                    let last_shell = if let Some(v) = last_shell {
+                        v.as_integer().unwrap_or_default() as usize
+                    } else {
+                        0
+                    };
+
                     shells[current_shell] = Value::String { val: path, span };
 
                     stack.add_env_var("NUSHELL_SHELLS".into(), Value::List { vals: shells, span });
+                    stack.add_env_var(
+                        "NUSHELL_LAST_SHELL".into(),
+                        Value::Int {
+                            val: last_shell as i64,
+                            span,
+                        },
+                    );
                 } else {
                     trace!("eval source: {}", s);
 

crates/nu-command/src/shells/enter.rs

@@ -66,6 +66,14 @@ impl Command for Enter {
         let mut shells = get_shells(engine_state, stack, cwd);
         let mut current_shell = get_current_shell(engine_state, stack);
 
+        stack.add_env_var(
+            "NUSHELL_LAST_SHELL".into(),
+            Value::Int {
+                val: current_shell as i64,
+                span: call.head,
+            },
+        );
+
         if current_shell + 1 > shells.len() {
             shells.push(new_path.clone());
             current_shell = shells.len();

crates/nu-command/src/shells/exit.rs

@@ -1,4 +1,4 @@
-use super::{get_current_shell, get_shells};
+use super::{get_current_shell, get_last_shell, get_shells};
 use nu_engine::{current_dir, CallExt};
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
@@ -60,9 +60,14 @@ impl Command for Exit {
 
         let mut shells = get_shells(engine_state, stack, cwd);
         let mut current_shell = get_current_shell(engine_state, stack);
+        let mut last_shell = get_last_shell(engine_state, stack);
 
         shells.remove(current_shell);
 
+        if current_shell <= last_shell {
+            last_shell = 0;
+        }
+
         if current_shell == shells.len() && !shells.is_empty() {
             current_shell -= 1;
         }
@@ -86,6 +91,13 @@ impl Command for Exit {
                     span: call.head,
                 },
             );
+            stack.add_env_var(
+                "NUSHELL_LAST_SHELL".into(),
+                Value::Int {
+                    val: last_shell as i64,
+                    span: call.head,
+                },
+            );
 
             stack.add_env_var("PWD".into(), new_path);
 

crates/nu-command/src/shells/g.rs

@@ -1,4 +1,4 @@
-use super::{get_current_shell, get_shells};
+use super::{get_current_shell, get_last_shell, get_shells};
 use nu_engine::{current_dir, CallExt};
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
@@ -20,7 +20,7 @@ impl Command for GotoShell {
         Signature::build("g")
             .optional(
                 "shell_number",
-                SyntaxShape::Int,
+                SyntaxShape::String,
                 "shell number to change to",
             )
             .category(Category::Shells)
@@ -38,7 +38,7 @@ impl Command for GotoShell {
         _input: PipelineData,
     ) -> Result<PipelineData, ShellError> {
         let span = call.head;
-        let new_shell: Option<Spanned<i64>> = call.opt(engine_state, stack, 0)?;
+        let new_shell: Option<Spanned<String>> = call.opt(engine_state, stack, 0)?;
 
         let cwd = current_dir(engine_state, stack)?;
         let cwd = Value::String {
@@ -50,12 +50,22 @@ impl Command for GotoShell {
 
         match new_shell {
             Some(shell_span) => {
-                let new_path = if let Some(v) = shells.get(shell_span.item as usize) {
+                let index = if shell_span.item == "-" {
-                    v.clone()
+                    get_last_shell(engine_state, stack)
                 } else {
-                    return Err(ShellError::NotFound(shell_span.span));
+                    shell_span
+                        .item
+                        .parse::<usize>()
+                        .map_err(|_| ShellError::NotFound(shell_span.span))?
                 };
 
+                let new_path = shells
+                    .get(index)
+                    .ok_or(ShellError::NotFound(shell_span.span))?
+                    .to_owned();
+
+                let current_shell = get_current_shell(engine_state, stack);
+
                 stack.add_env_var(
                     "NUSHELL_SHELLS".into(),
                     Value::List {
@@ -66,7 +76,14 @@ impl Command for GotoShell {
                 stack.add_env_var(
                     "NUSHELL_CURRENT_SHELL".into(),
                     Value::Int {
-                        val: shell_span.item,
+                        val: index as i64,
+                        span: call.head,
+                    },
+                );
+                stack.add_env_var(
+                    "NUSHELL_LAST_SHELL".into(),
+                    Value::Int {
+                        val: current_shell as i64,
                         span: call.head,
                     },
                 );
@@ -114,6 +131,11 @@ impl Command for GotoShell {
                 example: r#"shells; g 2"#,
                 result: None,
             },
+            Example {
+                description: "Make two directories and enter new shells for them, use `g -` to jump to the last used shell",
+                example: r#"mkdir foo bar; enter foo; enter ../bar; g -"#,
+                result: None,
+            },
         ]
     }
 }

crates/nu-command/src/shells/mod.rs

@@ -34,3 +34,12 @@ pub fn get_current_shell(engine_state: &EngineState, stack: &mut Stack) -> usize
         0
     }
 }
+
+fn get_last_shell(engine_state: &EngineState, stack: &mut Stack) -> usize {
+    let last_shell = stack.get_env_var(engine_state, "NUSHELL_LAST_SHELL");
+    if let Some(v) = last_shell {
+        v.as_integer().unwrap_or_default() as usize
+    } else {
+        0
+    }
+}

crates/nu-command/src/shells/n.rs

@@ -36,6 +36,13 @@ impl Command for NextShell {
 
         let shells = get_shells(engine_state, stack, cwd);
         let mut current_shell = get_current_shell(engine_state, stack);
+        stack.add_env_var(
+            "NUSHELL_LAST_SHELL".into(),
+            Value::Int {
+                val: current_shell as i64,
+                span: call.head,
+            },
+        );
 
         current_shell += 1;
 

crates/nu-command/src/shells/p.rs

@@ -36,6 +36,13 @@ impl Command for PrevShell {
 
         let shells = get_shells(engine_state, stack, cwd);
         let mut current_shell = get_current_shell(engine_state, stack);
+        stack.add_env_var(
+            "NUSHELL_LAST_SHELL".into(),
+            Value::Int {
+                val: current_shell as i64,
+                span: call.head,
+            },
+        );
 
         if current_shell == 0 {
             current_shell = shells.len() - 1;

crates/nu-command/tests/commands/g.rs

@@ -1,4 +1,4 @@
-use nu_test_support::{nu, pipeline};
+use nu_test_support::{nu, pipeline, playground::Playground};
 
 #[test]
 fn list_shells() {
@@ -29,3 +29,63 @@ fn enter_not_exist_shell() {
 
     assert!(actual.err.contains("Not found"));
 }
+
+#[test]
+fn switch_to_last_used_shell_1() {
+    Playground::setup("switch_last_used_shell_1", |dirs, sandbox| {
+        sandbox.mkdir("foo").mkdir("bar");
+
+        let actual = nu!(
+            cwd: dirs.test(),
+            pipeline(
+            r#"enter foo; enter ../bar; g 0; g -;g | get active.2"#
+        ));
+
+        assert_eq!(actual.out, "true");
+    })
+}
+
+#[test]
+fn switch_to_last_used_shell_2() {
+    Playground::setup("switch_last_used_shell_2", |dirs, sandbox| {
+        sandbox.mkdir("foo").mkdir("bar");
+
+        let actual = nu!(
+            cwd: dirs.test(),
+            pipeline(
+            r#"enter foo; enter ../bar; n; g -;g | get active.2"#
+        ));
+
+        assert_eq!(actual.out, "true");
+    })
+}
+
+#[test]
+fn switch_to_last_used_shell_3() {
+    Playground::setup("switch_last_used_shell_3", |dirs, sandbox| {
+        sandbox.mkdir("foo").mkdir("bar");
+
+        let actual = nu!(
+            cwd: dirs.test(),
+            pipeline(
+            r#"enter foo; enter ../bar; p; g -;g | get active.2"#
+        ));
+
+        assert_eq!(actual.out, "true");
+    })
+}
+
+#[test]
+fn switch_to_last_used_shell_4() {
+    Playground::setup("switch_last_used_shell_4", |dirs, sandbox| {
+        sandbox.mkdir("foo").mkdir("bar");
+
+        let actual = nu!(
+            cwd: dirs.test(),
+            pipeline(
+            r#"enter foo; enter ../bar; g 2; exit; g -;g | get active.0"#
+        ));
+
+        assert_eq!(actual.out, "true");
+    })
+}