Add commands to scope variable (#3272)

* Add commands to scope variable

* List commands with signature on scope variables

Usage:

```shell
echo $scope.commands | pivot
```

* Run rust formater

* Update variables.rs

Co-authored-by: Jonathan Turner <jonathandturner@users.noreply.github.com>

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

@@ -229,7 +229,11 @@ fn evaluate_reference(name: &str, ctx: &EvaluationContext, tag: Tag) -> Result<V
     match name {
         "$nu" => crate::evaluate::variables::nu(&ctx.scope, tag, ctx),
 
-        "$scope" => crate::evaluate::variables::scope(&ctx.scope.get_aliases(), tag),
+        "$scope" => crate::evaluate::variables::scope(
+            &ctx.scope.get_aliases(),
+            &ctx.scope.get_commands(),
+            tag,
+        ),
 
         "$true" => Ok(Value {
             value: UntaggedValue::boolean(true),

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

@@ -2,7 +2,7 @@ use crate::whole_stream_command::{whole_stream_command, Command};
 use indexmap::IndexMap;
 use nu_errors::ShellError;
 use nu_parser::ParserScope;
-use nu_protocol::{hir::Block, Value};
+use nu_protocol::{hir::Block, Signature, Value};
 use nu_source::Spanned;
 use std::sync::Arc;
 
@@ -46,6 +46,18 @@ impl Scope {
         output
     }
 
+    pub fn get_commands(&self) -> IndexMap<String, Signature> {
+        let mut output = IndexMap::new();
+
+        for frame in self.frames.lock().iter().rev() {
+            for (name, command) in frame.commands.iter() {
+                output.insert(name.clone(), command.signature());
+            }
+        }
+
+        output
+    }
+
     pub fn get_aliases_with_name(&self, name: &str) -> Option<Vec<Vec<Spanned<String>>>> {
         let aliases: Vec<_> = self
             .frames

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

@@ -2,7 +2,7 @@ use crate::{evaluate::scope::Scope, EvaluationContext};
 use indexmap::IndexMap;
 use nu_data::config::path::{default_history_path, history_path};
 use nu_errors::ShellError;
-use nu_protocol::{TaggedDictBuilder, UntaggedValue, Value};
+use nu_protocol::{Signature, TaggedDictBuilder, UntaggedValue, Value};
 use nu_source::{Spanned, Tag};
 
 pub fn nu(
@@ -83,13 +83,14 @@ pub fn nu(
 
 pub fn scope(
     aliases: &IndexMap<String, Vec<Spanned<String>>>,
+    commands: &IndexMap<String, Signature>,
     tag: impl Into<Tag>,
 ) -> Result<Value, ShellError> {
     let tag = tag.into();
 
     let mut scope_dict = TaggedDictBuilder::new(&tag);
 
-    let mut dict = TaggedDictBuilder::new(&tag);
+    let mut aliases_dict = TaggedDictBuilder::new(&tag);
     for v in aliases.iter() {
         let values = v.1.clone();
         let mut vec = Vec::new();
@@ -99,9 +100,18 @@ pub fn scope(
         }
 
         let alias = vec.join(" ");
-        dict.insert_untagged(v.0, UntaggedValue::string(alias));
+
+        aliases_dict.insert_untagged(v.0, UntaggedValue::string(alias));
     }
 
-    scope_dict.insert_value("aliases", dict.into_value());
+    let mut commands_dict = TaggedDictBuilder::new(&tag);
+    for (name, signature) in commands.iter() {
+        commands_dict.insert_untagged(name, UntaggedValue::string(&signature.allowed().join(" ")))
+    }
+
+    scope_dict.insert_value("aliases", aliases_dict.into_value());
+
+    scope_dict.insert_value("commands", commands_dict.into_value());
+
     Ok(scope_dict.into_value())
 }

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

@@ -68,3 +68,21 @@ fn scope_variable_with_correct_number_of_aliases_present() {
         );
     })
 }
+
+#[test]
+fn scope_variable_with_command_present() {
+    Playground::setup("scope_commands_test_1", |dirs, nu| {
+        let file = AbsolutePath::new(dirs.test().join("config.toml"));
+
+        nu.with_config(&file);
+        nu.with_files(vec![FileWithContent(
+            "config.toml",
+            "skip_welcome_message = true",
+        )]);
+
+        assert_that!(
+            nu.pipeline("def meaning-of-life [--number: int] { echo $number }; echo $scope.commands | get meaning-of-life"),
+            says().to_stdout("-h --help --number")
+        );
+    })
+}