move lang command to $nu (#3720)

crates/nu-command/src/commands/platform/mod.rs

@@ -6,7 +6,6 @@ mod clip;
 mod du;
 mod exec;
 mod kill;
-mod lang;
 #[cfg(feature = "clipboard-cli")]
 mod paste;
 mod pwd;
@@ -23,7 +22,6 @@ pub use clip::Clip;
 pub use du::Du;
 pub use exec::Exec;
 pub use kill::Kill;
-pub use lang::Lang;
 #[cfg(feature = "clipboard-cli")]
 pub use paste::Paste;
 pub use pwd::Pwd;

crates/nu-command/src/default_context.rs

@@ -69,7 +69,6 @@ pub fn create_default_context(interactive: bool) -> Result<EvaluationContext, Bo
             whole_stream_command(Benchmark),
             // Metadata
             whole_stream_command(Tags),
-            whole_stream_command(Lang),
             // Shells
             whole_stream_command(Next),
             whole_stream_command(Previous),

crates/nu-engine/src/evaluate/lang.rs

@@ -1,28 +1,16 @@
-use crate::prelude::*;
+use crate::Scope;
 use indexmap::IndexMap;
-use nu_engine::WholeStreamCommand;
 use nu_errors::ShellError;
 use nu_protocol::{Dictionary, Signature, UntaggedValue, Value};
+use nu_source::Tag;
 
 pub struct Lang;
 
-impl WholeStreamCommand for Lang {
-    fn name(&self) -> &str {
-        "lang"
-    }
-
-    fn signature(&self) -> Signature {
-        Signature::build("lang")
-    }
-
-    fn usage(&self) -> &str {
-        "Returns the nushell-lang information"
-    }
-
-    fn run(&self, args: CommandArgs) -> Result<OutputStream, ShellError> {
-        let tag = args.call_info.name_tag.clone();
-        let full_commands = args.context.scope.get_commands_info();
-        let mut cmd_vec_deque = VecDeque::new();
+impl Lang {
+    pub fn query_commands(scope: &Scope) -> Result<Vec<Value>, ShellError> {
+        let tag = Tag::unknown();
+        let full_commands = scope.get_commands_info();
+        let mut cmd_vec = Vec::new();
         for (key, cmd) in full_commands {
             let mut indexmap = IndexMap::new();
             let mut sig = cmd.signature();
@@ -78,18 +66,10 @@ impl WholeStreamCommand for Lang {
                 UntaggedValue::string(cmd.extra_usage().to_string()).into_value(&tag),
             );
 
-            cmd_vec_deque
-                .push_back(UntaggedValue::Row(Dictionary::from(indexmap)).into_value(&tag));
-        }
-        Ok(cmd_vec_deque.into_iter().into_output_stream())
+            cmd_vec.push(UntaggedValue::Row(Dictionary::from(indexmap)).into_value(&tag));
         }
 
-    fn examples(&self) -> Vec<Example> {
-        vec![Example {
-            description: "Query command information from Nushell",
-            example: "lang",
-            result: None,
-        }]
+        Ok(cmd_vec)
     }
 }
 

crates/nu-engine/src/evaluate/mod.rs

@@ -3,6 +3,7 @@ pub(crate) mod evaluate_args;
 pub mod evaluator;
 pub(crate) mod expr;
 pub mod internal;
+pub(crate) mod lang;
 pub(crate) mod operator;
 pub(crate) mod scope;
 pub(crate) mod variables;

crates/nu-engine/src/evaluate/variables.rs

@@ -1,4 +1,7 @@
-use crate::{evaluate::scope::Scope, EvaluationContext};
+use crate::{
+    evaluate::{lang, scope::Scope},
+    EvaluationContext,
+};
 use indexmap::IndexMap;
 use nu_data::config::path::{default_history_path, history_path};
 use nu_errors::ShellError;
@@ -88,6 +91,12 @@ pub fn nu(scope: &Scope, ctx: &EvaluationContext) -> Result<Value, ShellError> {
         );
     }
 
+    let cmd_info = lang::Lang::query_commands(scope);
+    match cmd_info {
+        Ok(cmds) => nu_dict.insert_value("lang", UntaggedValue::table(&cmds).into_value(&tag)),
+        Err(_) => nu_dict.insert_value("lang", UntaggedValue::string("no commands found")),
+    }
+
     Ok(nu_dict.into_value())
 }