Allow creating modules from directories (#9066)

crates/nu-cmd-lang/src/core_commands/export_module.rs

@@ -0,0 +1,75 @@
+use nu_protocol::ast::Call;
+use nu_protocol::engine::{Command, EngineState, Stack};
+use nu_protocol::{
+    Category, Example, PipelineData, ShellError, Signature, SyntaxShape, Type, Value,
+};
+
+#[derive(Clone)]
+pub struct ExportModule;
+
+impl Command for ExportModule {
+    fn name(&self) -> &str {
+        "export module"
+    }
+
+    fn usage(&self) -> &str {
+        "Export a custom module from a module."
+    }
+
+    fn signature(&self) -> nu_protocol::Signature {
+        Signature::build("export module")
+            .input_output_types(vec![(Type::Nothing, Type::Nothing)])
+            .allow_variants_without_examples(true)
+            .required("module", SyntaxShape::String, "module name or module path")
+            .optional(
+                "block",
+                SyntaxShape::Block,
+                "body of the module if 'module' parameter is not a path",
+            )
+            .category(Category::Core)
+    }
+
+    fn extra_usage(&self) -> &str {
+        r#"This command is a parser keyword. For details, check:
+  https://www.nushell.sh/book/thinking_in_nu.html"#
+    }
+
+    fn is_parser_keyword(&self) -> bool {
+        true
+    }
+
+    fn run(
+        &self,
+        _engine_state: &EngineState,
+        _stack: &mut Stack,
+        _call: &Call,
+        _input: PipelineData,
+    ) -> Result<PipelineData, ShellError> {
+        Ok(PipelineData::empty())
+    }
+
+    fn examples(&self) -> Vec<Example> {
+        vec![Example {
+            description: "Define a custom command in a submodule of a module and call it",
+            example: r#"module spam {
+        export module eggs {
+            export def foo [] { "foo" }
+        }
+    }
+    use spam eggs
+    eggs foo"#,
+            result: Some(Value::test_string("foo")),
+        }]
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    #[test]
+    fn test_examples() {
+        use crate::test_examples;
+
+        test_examples(ExportModule {})
+    }
+}

crates/nu-cmd-lang/src/core_commands/mod.rs

@@ -14,6 +14,7 @@ mod export_alias;
 mod export_def;
 mod export_def_env;
 mod export_extern;
+mod export_module;
 mod export_use;
 mod extern_;
 mod for_;
@@ -55,6 +56,7 @@ pub use export_alias::ExportAlias;
 pub use export_def::ExportDef;
 pub use export_def_env::ExportDefEnv;
 pub use export_extern::ExportExtern;
+pub use export_module::ExportModule;
 pub use export_use::ExportUse;
 pub use extern_::Extern;
 pub use for_::For;

crates/nu-cmd-lang/src/core_commands/module.rs

@@ -19,8 +19,13 @@ impl Command for Module {
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("module")
             .input_output_types(vec![(Type::Nothing, Type::Nothing)])
-            .required("module_name", SyntaxShape::String, "module name")
-            .required("block", SyntaxShape::Block, "body of the module")
+            .allow_variants_without_examples(true)
+            .required("module", SyntaxShape::String, "module name or module path")
+            .optional(
+                "block",
+                SyntaxShape::Block,
+                "body of the module if 'module' parameter is not a module path",
+            )
             .category(Category::Core)
     }
 

crates/nu-cmd-lang/src/core_commands/use_.rs

@@ -21,7 +21,7 @@ impl Command for Use {
         Signature::build("use")
             .input_output_types(vec![(Type::Nothing, Type::Nothing)])
             .required("module", SyntaxShape::String, "Module or module file")
-            .optional(
+            .rest(
                 "members",
                 SyntaxShape::Any,
                 "Which members of the module to import",

crates/nu-cmd-lang/src/default_context.rs

@@ -33,6 +33,7 @@ pub fn create_default_context() -> EngineState {
             ExportDefEnv,
             ExportExtern,
             ExportUse,
+            ExportModule,
             Extern,
             For,
             Help,

crates/nu-cmd-lang/src/example_test.rs

@@ -13,11 +13,12 @@ mod test_examples {
         check_example_evaluates_to_expected_output,
         check_example_input_and_output_types_match_command_signature,
     };
-    use crate::{Break, Collect, Describe, Mut};
-    use crate::{Echo, If, Let};
+    use crate::{
+        Break, Collect, Def, Describe, Echo, ExportCommand, ExportDef, If, Let, Module, Mut, Use,
+    };
     use nu_protocol::{
         engine::{Command, EngineState, StateWorkingSet},
-        Type,
+        Type, Value,
     };
     use std::collections::HashSet;
 
@@ -55,18 +56,28 @@ mod test_examples {
 
     fn make_engine_state(cmd: Box<dyn Command>) -> Box<EngineState> {
         let mut engine_state = Box::new(EngineState::new());
+        let cwd = std::env::current_dir()
+            .expect("Could not get current working directory.")
+            .to_string_lossy()
+            .to_string();
+        engine_state.add_env_var("PWD".to_string(), Value::test_string(cwd));
 
         let delta = {
             // Base functions that are needed for testing
             // Try to keep this working set small to keep tests running as fast as possible
             let mut working_set = StateWorkingSet::new(&engine_state);
             working_set.add_decl(Box::new(Break));
+            working_set.add_decl(Box::new(Collect));
+            working_set.add_decl(Box::new(Def));
             working_set.add_decl(Box::new(Describe));
             working_set.add_decl(Box::new(Echo));
+            working_set.add_decl(Box::new(ExportCommand));
+            working_set.add_decl(Box::new(ExportDef));
             working_set.add_decl(Box::new(If));
             working_set.add_decl(Box::new(Let));
+            working_set.add_decl(Box::new(Module));
             working_set.add_decl(Box::new(Mut));
-            working_set.add_decl(Box::new(Collect));
+            working_set.add_decl(Box::new(Use));
 
             // Adding the command that is being tested to the working set
             working_set.add_decl(cmd);