Add shells support (#671)

crates/nu-command/src/default_context.rs

@@ -181,7 +181,12 @@ pub fn create_default_context(cwd: impl AsRef<Path>) -> EngineState {
 
         // Shells
         bind_command! {
+            Enter,
             Exit,
+            GotoShell,
+            NextShell,
+            PrevShell,
+            Shells,
         };
 
         // Formats

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

@@ -0,0 +1,95 @@
+use nu_engine::{current_dir, CallExt};
+use nu_protocol::ast::Call;
+use nu_protocol::engine::{Command, EngineState, Stack};
+use nu_protocol::{Category, PipelineData, ShellError, Signature, SyntaxShape, Value};
+
+/// Source a file for environment variables.
+#[derive(Clone)]
+pub struct Enter;
+
+impl Command for Enter {
+    fn name(&self) -> &str {
+        "enter"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("enter")
+            .required(
+                "path",
+                SyntaxShape::Filepath,
+                "the path to enter as a new shell",
+            )
+            .category(Category::Shells)
+    }
+
+    fn usage(&self) -> &str {
+        "Enters a new shell at the given path."
+    }
+
+    fn run(
+        &self,
+        engine_state: &EngineState,
+        stack: &mut Stack,
+        call: &Call,
+        _input: PipelineData,
+    ) -> Result<PipelineData, ShellError> {
+        let new_path: Value = call.req(engine_state, stack, 0)?;
+
+        let cwd = current_dir(engine_state, stack)?;
+
+        if let Ok(s) = new_path.as_string() {
+            let path = nu_path::expand_path_with(s, &cwd);
+            if !path.exists() {
+                return Err(ShellError::DirectoryNotFound(new_path.span()?));
+            }
+        }
+
+        let cwd = Value::String {
+            val: cwd.to_string_lossy().to_string(),
+            span: call.head,
+        };
+
+        let shells = stack.get_env_var(engine_state, "NUSHELL_SHELLS");
+        let mut shells = if let Some(v) = shells {
+            v.as_list()
+                .map(|x| x.to_vec())
+                .unwrap_or_else(|_| vec![cwd])
+        } else {
+            vec![cwd]
+        };
+
+        let current_shell = stack.get_env_var(engine_state, "NUSHELL_CURRENT_SHELL");
+        let mut current_shell = if let Some(v) = current_shell {
+            v.as_integer().unwrap_or_default() as usize
+        } else {
+            0
+        };
+
+        if current_shell + 1 > shells.len() {
+            shells.push(new_path.clone());
+            current_shell = shells.len();
+        } else {
+            shells.insert(current_shell + 1, new_path.clone());
+            current_shell += 1;
+        }
+
+        stack.add_env_var(
+            "NUSHELL_SHELLS".into(),
+            Value::List {
+                vals: shells,
+                span: call.head,
+            },
+        );
+        stack.add_env_var(
+            "NUSHELL_CURRENT_SHELL".into(),
+            Value::Int {
+                val: current_shell as i64,
+                span: call.head,
+            },
+        );
+
+        stack.add_env_var("PWD".into(), new_path);
+
+        Ok(PipelineData::new(call.head))
+    }
+}

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

@@ -1,6 +1,7 @@
+use nu_engine::{current_dir, CallExt};
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, PipelineData, ShellError, Signature};
+use nu_protocol::{Category, PipelineData, ShellError, Signature, SyntaxShape, Value};
 
 /// Source a file for environment variables.
 #[derive(Clone)]
@@ -12,7 +13,14 @@ impl Command for Exit {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("exit").category(Category::Shells)
+        Signature::build("exit")
+            .optional(
+                "exit-code",
+                SyntaxShape::Int,
+                "Exit code to return immediately with",
+            )
+            .switch("now", "Exit out of the shell immediately", Some('n'))
+            .category(Category::Shells)
     }
 
     fn usage(&self) -> &str {
@@ -21,13 +29,72 @@ impl Command for Exit {
 
     fn run(
         &self,
-        _engine_state: &EngineState,
-        _stack: &mut Stack,
-        _call: &Call,
+        engine_state: &EngineState,
+        stack: &mut Stack,
+        call: &Call,
         _input: PipelineData,
     ) -> Result<PipelineData, ShellError> {
-        //TODO: add more shell support
+        let exit_code: Option<i64> = call.opt(engine_state, stack, 0)?;
 
+        if let Some(exit_code) = exit_code {
+            std::process::exit(exit_code as i32);
+        }
+
+        if call.has_flag("now") {
             std::process::exit(0);
         }
+
+        let cwd = current_dir(engine_state, stack)?;
+        let cwd = Value::String {
+            val: cwd.to_string_lossy().to_string(),
+            span: call.head,
+        };
+
+        let shells = stack.get_env_var(engine_state, "NUSHELL_SHELLS");
+        let mut shells = if let Some(v) = shells {
+            v.as_list()
+                .map(|x| x.to_vec())
+                .unwrap_or_else(|_| vec![cwd])
+        } else {
+            vec![cwd]
+        };
+
+        let current_shell = stack.get_env_var(engine_state, "NUSHELL_CURRENT_SHELL");
+        let mut current_shell = if let Some(v) = current_shell {
+            v.as_integer().unwrap_or_default() as usize
+        } else {
+            0
+        };
+
+        shells.remove(current_shell);
+
+        if current_shell == shells.len() && !shells.is_empty() {
+            current_shell -= 1;
+        }
+
+        if shells.is_empty() {
+            std::process::exit(0);
+        } else {
+            let new_path = shells[current_shell].clone();
+
+            stack.add_env_var(
+                "NUSHELL_SHELLS".into(),
+                Value::List {
+                    vals: shells,
+                    span: call.head,
+                },
+            );
+            stack.add_env_var(
+                "NUSHELL_CURRENT_SHELL".into(),
+                Value::Int {
+                    val: current_shell as i64,
+                    span: call.head,
+                },
+            );
+
+            stack.add_env_var("PWD".into(), new_path);
+
+            Ok(PipelineData::new(call.head))
+        }
+    }
 }

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

@@ -0,0 +1,78 @@
+use nu_engine::{current_dir, CallExt};
+use nu_protocol::ast::Call;
+use nu_protocol::engine::{Command, EngineState, Stack};
+use nu_protocol::{Category, PipelineData, ShellError, Signature, Spanned, SyntaxShape, Value};
+
+/// Source a file for environment variables.
+#[derive(Clone)]
+pub struct GotoShell;
+
+impl Command for GotoShell {
+    fn name(&self) -> &str {
+        "g"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("g")
+            .required(
+                "shell-number",
+                SyntaxShape::Int,
+                "shell number to change to",
+            )
+            .category(Category::Shells)
+    }
+
+    fn usage(&self) -> &str {
+        "Switch to a given shell."
+    }
+
+    fn run(
+        &self,
+        engine_state: &EngineState,
+        stack: &mut Stack,
+        call: &Call,
+        _input: PipelineData,
+    ) -> Result<PipelineData, ShellError> {
+        let new_shell: Spanned<i64> = call.req(engine_state, stack, 0)?;
+
+        let cwd = current_dir(engine_state, stack)?;
+        let cwd = Value::String {
+            val: cwd.to_string_lossy().to_string(),
+            span: call.head,
+        };
+
+        let shells = stack.get_env_var(engine_state, "NUSHELL_SHELLS");
+        let shells = if let Some(v) = shells {
+            v.as_list()
+                .map(|x| x.to_vec())
+                .unwrap_or_else(|_| vec![cwd])
+        } else {
+            vec![cwd]
+        };
+
+        let new_path = if let Some(v) = shells.get(new_shell.item as usize) {
+            v.clone()
+        } else {
+            return Err(ShellError::NotFound(new_shell.span));
+        };
+
+        stack.add_env_var(
+            "NUSHELL_SHELLS".into(),
+            Value::List {
+                vals: shells,
+                span: call.head,
+            },
+        );
+        stack.add_env_var(
+            "NUSHELL_CURRENT_SHELL".into(),
+            Value::Int {
+                val: new_shell.item,
+                span: call.head,
+            },
+        );
+
+        stack.add_env_var("PWD".into(), new_path);
+
+        Ok(PipelineData::new(call.head))
+    }
+}

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

@@ -1,3 +1,13 @@
+mod enter;
 mod exit;
+mod g;
+mod n;
+mod p;
+mod shells_;
 
+pub use enter::Enter;
 pub use exit::Exit;
+pub use g::GotoShell;
+pub use n::NextShell;
+pub use p::PrevShell;
+pub use shells_::Shells;

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

@@ -0,0 +1,79 @@
+use nu_engine::current_dir;
+use nu_protocol::ast::Call;
+use nu_protocol::engine::{Command, EngineState, Stack};
+use nu_protocol::{Category, PipelineData, ShellError, Signature, Value};
+
+/// Source a file for environment variables.
+#[derive(Clone)]
+pub struct NextShell;
+
+impl Command for NextShell {
+    fn name(&self) -> &str {
+        "n"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("n").category(Category::Shells)
+    }
+
+    fn usage(&self) -> &str {
+        "Switch to the next shell."
+    }
+
+    fn run(
+        &self,
+        engine_state: &EngineState,
+        stack: &mut Stack,
+        call: &Call,
+        _input: PipelineData,
+    ) -> Result<PipelineData, ShellError> {
+        let cwd = current_dir(engine_state, stack)?;
+        let cwd = Value::String {
+            val: cwd.to_string_lossy().to_string(),
+            span: call.head,
+        };
+
+        let shells = stack.get_env_var(engine_state, "NUSHELL_SHELLS");
+        let shells = if let Some(v) = shells {
+            v.as_list()
+                .map(|x| x.to_vec())
+                .unwrap_or_else(|_| vec![cwd])
+        } else {
+            vec![cwd]
+        };
+
+        let current_shell = stack.get_env_var(engine_state, "NUSHELL_CURRENT_SHELL");
+        let mut current_shell = if let Some(v) = current_shell {
+            v.as_integer().unwrap_or_default() as usize
+        } else {
+            0
+        };
+
+        current_shell += 1;
+
+        if current_shell == shells.len() {
+            current_shell = 0;
+        }
+
+        let new_path = shells[current_shell].clone();
+
+        stack.add_env_var(
+            "NUSHELL_SHELLS".into(),
+            Value::List {
+                vals: shells,
+                span: call.head,
+            },
+        );
+        stack.add_env_var(
+            "NUSHELL_CURRENT_SHELL".into(),
+            Value::Int {
+                val: current_shell as i64,
+                span: call.head,
+            },
+        );
+
+        stack.add_env_var("PWD".into(), new_path);
+
+        Ok(PipelineData::new(call.head))
+    }
+}

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

@@ -0,0 +1,79 @@
+use nu_engine::current_dir;
+use nu_protocol::ast::Call;
+use nu_protocol::engine::{Command, EngineState, Stack};
+use nu_protocol::{Category, PipelineData, ShellError, Signature, Value};
+
+/// Source a file for environment variables.
+#[derive(Clone)]
+pub struct PrevShell;
+
+impl Command for PrevShell {
+    fn name(&self) -> &str {
+        "p"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("p").category(Category::Shells)
+    }
+
+    fn usage(&self) -> &str {
+        "Switch to the previous shell."
+    }
+
+    fn run(
+        &self,
+        engine_state: &EngineState,
+        stack: &mut Stack,
+        call: &Call,
+        _input: PipelineData,
+    ) -> Result<PipelineData, ShellError> {
+        let cwd = current_dir(engine_state, stack)?;
+        let cwd = Value::String {
+            val: cwd.to_string_lossy().to_string(),
+            span: call.head,
+        };
+
+        let shells = stack.get_env_var(engine_state, "NUSHELL_SHELLS");
+        let shells = if let Some(v) = shells {
+            v.as_list()
+                .map(|x| x.to_vec())
+                .unwrap_or_else(|_| vec![cwd])
+        } else {
+            vec![cwd]
+        };
+
+        let current_shell = stack.get_env_var(engine_state, "NUSHELL_CURRENT_SHELL");
+        let mut current_shell = if let Some(v) = current_shell {
+            v.as_integer().unwrap_or_default() as usize
+        } else {
+            0
+        };
+
+        if current_shell == 0 {
+            current_shell = shells.len() - 1;
+        } else {
+            current_shell -= 1;
+        }
+
+        let new_path = shells[current_shell].clone();
+
+        stack.add_env_var(
+            "NUSHELL_SHELLS".into(),
+            Value::List {
+                vals: shells,
+                span: call.head,
+            },
+        );
+        stack.add_env_var(
+            "NUSHELL_CURRENT_SHELL".into(),
+            Value::Int {
+                val: current_shell as i64,
+                span: call.head,
+            },
+        );
+
+        stack.add_env_var("PWD".into(), new_path);
+
+        Ok(PipelineData::new(call.head))
+    }
+}

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

@@ -0,0 +1,72 @@
+use nu_engine::current_dir;
+use nu_protocol::ast::Call;
+use nu_protocol::engine::{Command, EngineState, Stack};
+use nu_protocol::{
+    Category, IntoInterruptiblePipelineData, PipelineData, ShellError, Signature, Value,
+};
+
+/// Source a file for environment variables.
+#[derive(Clone)]
+pub struct Shells;
+
+impl Command for Shells {
+    fn name(&self) -> &str {
+        "shells"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("shells").category(Category::Shells)
+    }
+
+    fn usage(&self) -> &str {
+        "Lists all open shells."
+    }
+
+    fn run(
+        &self,
+        engine_state: &EngineState,
+        stack: &mut Stack,
+        call: &Call,
+        _input: PipelineData,
+    ) -> Result<PipelineData, ShellError> {
+        let span = call.head;
+        let cwd = current_dir(engine_state, stack)?;
+        let cwd = Value::String {
+            val: cwd.to_string_lossy().to_string(),
+            span,
+        };
+
+        let shells = stack.get_env_var(engine_state, "NUSHELL_SHELLS");
+        let shells = if let Some(v) = shells {
+            v.as_list()
+                .map(|x| x.to_vec())
+                .unwrap_or_else(|_| vec![cwd])
+        } else {
+            vec![cwd]
+        };
+
+        let current_shell = stack.get_env_var(engine_state, "NUSHELL_CURRENT_SHELL");
+        let current_shell = if let Some(v) = current_shell {
+            v.as_integer().unwrap_or_default() as usize
+        } else {
+            0
+        };
+
+        let output = shells
+            .into_iter()
+            .enumerate()
+            .map(move |(idx, val)| Value::Record {
+                cols: vec!["active".to_string(), "path".to_string()],
+                vals: vec![
+                    Value::Bool {
+                        val: idx == current_shell,
+                        span,
+                    },
+                    val,
+                ],
+                span,
+            });
+
+        Ok(output.into_pipeline_data(None))
+    }
+}

src/main.rs

@@ -456,10 +456,7 @@ fn main() -> Result<()> {
                                 span: Span { start: 0, end: 0 },
                             },
                         );
-
-                        continue;
-                    }
-
+                    } else {
                         trace!("eval source: {}", s);
 
                         eval_source(
@@ -469,6 +466,11 @@ fn main() -> Result<()> {
                             &format!("entry #{}", entry_num),
                         );
                     }
+                    // FIXME: permanent state changes like this hopefully in time can be removed
+                    // and be replaced by just passing the cwd in where needed
+                    let cwd = nu_engine::env::current_dir_str(&engine_state, &stack)?;
+                    let _ = std::env::set_current_dir(cwd);
+                }
                 Ok(Signal::CtrlC) => {
                     // `Reedline` clears the line content. New prompt is shown
                 }