Add export-env command (#6355)

* WIP Start export-env

* Add missing file

* Do not modify the parser

Let's leave that for later

* Enable tests for export-env; Fmt

crates/nu-command/src/core_commands/export_env.rs

@@ -3,9 +3,9 @@ use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{Category, Example, PipelineData, Signature, Span, SyntaxShape, Value};
 
 #[derive(Clone)]
-pub struct ExportEnv;
+pub struct ExportEnvModule;
 
-impl Command for ExportEnv {
+impl Command for ExportEnvModule {
     fn name(&self) -> &str {
         "export env"
     }

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

@@ -40,7 +40,7 @@ pub use export::ExportCommand;
 pub use export_alias::ExportAlias;
 pub use export_def::ExportDef;
 pub use export_def_env::ExportDefEnv;
-pub use export_env::ExportEnv;
+pub use export_env::ExportEnvModule;
 pub use export_extern::ExportExtern;
 pub use export_use::ExportUse;
 pub use extern_::Extern;

crates/nu-command/src/default_context.rs

@@ -40,7 +40,7 @@ pub fn create_default_context() -> EngineState {
             ExportCommand,
             ExportDef,
             ExportDefEnv,
-            ExportEnv,
+            ExportEnvModule,
             ExportExtern,
             ExportUse,
             Extern,
@@ -352,6 +352,7 @@ pub fn create_default_context() -> EngineState {
         // Env
         bind_command! {
             Env,
+            ExportEnv,
             LetEnv,
             LoadEnv,
             WithEnv,

crates/nu-command/src/env/export_env.rs

@@ -0,0 +1,74 @@
+use nu_engine::{eval_block, redirect_env, CallExt};
+use nu_protocol::{
+    ast::Call,
+    engine::{CaptureBlock, Command, EngineState, Stack},
+    Category, Example, PipelineData, Signature, Span, SyntaxShape, Value,
+};
+
+#[derive(Clone)]
+pub struct ExportEnv;
+
+impl Command for ExportEnv {
+    fn name(&self) -> &str {
+        "export-env"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("export-env")
+            .required(
+                "block",
+                SyntaxShape::Block(Some(vec![])),
+                "the block to run to set the environment",
+            )
+            .category(Category::Env)
+    }
+
+    fn usage(&self) -> &str {
+        "Run a block and preserve its environment in a current scope."
+    }
+
+    fn run(
+        &self,
+        engine_state: &EngineState,
+        caller_stack: &mut Stack,
+        call: &Call,
+        input: PipelineData,
+    ) -> Result<nu_protocol::PipelineData, nu_protocol::ShellError> {
+        let capture_block: CaptureBlock = call.req(engine_state, caller_stack, 0)?;
+        let block = engine_state.get_block(capture_block.block_id);
+        let mut callee_stack = caller_stack.captures_to_stack(&capture_block.captures);
+
+        let _ = eval_block(
+            engine_state,
+            &mut callee_stack,
+            block,
+            input,
+            call.redirect_stdout,
+            call.redirect_stderr,
+        );
+
+        redirect_env(engine_state, caller_stack, &callee_stack);
+
+        Ok(PipelineData::new(call.head))
+    }
+
+    fn examples(&self) -> Vec<Example> {
+        vec![Example {
+            description: "Set an environment",
+            example: r#"export-env { let-env SPAM = 'eggs' }; $env.SPAM"#,
+            result: Some(Value::string("eggs", Span::test_data())),
+        }]
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn test_examples() {
+        use crate::test_examples;
+
+        test_examples(ExportEnv {})
+    }
+}

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

@@ -1,5 +1,6 @@
 mod config;
 mod env_command;
+mod export_env;
 mod let_env;
 mod load_env;
 mod with_env;
@@ -9,6 +10,7 @@ pub use config::ConfigMeta;
 pub use config::ConfigNu;
 pub use config::ConfigReset;
 pub use env_command::Env;
+pub use export_env::ExportEnv;
 pub use let_env::LetEnv;
 pub use load_env::LoadEnv;
 pub use with_env::WithEnv;

crates/nu-command/src/example_test.rs

@@ -13,8 +13,8 @@ use crate::To;
 
 #[cfg(test)]
 use super::{
-    Ansi, Date, From, If, Into, Math, Path, Random, Split, SplitColumn, SplitRow, Str, StrCollect,
-    StrLength, StrReplace, Url, Wrap,
+    Ansi, Date, From, If, Into, LetEnv, Math, Path, Random, Split, SplitColumn, SplitRow, Str,
+    StrCollect, StrLength, StrReplace, Url, Wrap,
 };
 
 #[cfg(test)]
@@ -47,6 +47,7 @@ pub fn test_examples(cmd: impl Command + 'static) {
         working_set.add_decl(Box::new(Url));
         working_set.add_decl(Box::new(Ansi));
         working_set.add_decl(Box::new(Wrap));
+        working_set.add_decl(Box::new(LetEnv));
 
         use super::Echo;
         working_set.add_decl(Box::new(Echo));

crates/nu-engine/src/eval.rs

@@ -159,20 +159,7 @@ pub fn eval_call(
         );
 
         if block.redirect_env {
-            let caller_env_vars = caller_stack.get_env_var_names(engine_state);
-
-            // remove env vars that are present in the caller but not in the callee
-            // (the callee hid them)
-            for var in caller_env_vars.iter() {
-                if !callee_stack.has_env_var(engine_state, var) {
-                    caller_stack.remove_env_var(engine_state, var);
-                }
-            }
-
-            // add new env vars from callee to caller
-            for (var, value) in callee_stack.get_stack_env_vars() {
-                caller_stack.add_env_var(var, value);
-            }
+            redirect_env(engine_state, caller_stack, &callee_stack);
         }
 
         result
@@ -184,6 +171,24 @@ pub fn eval_call(
     }
 }
 
+/// Redirect the environment from callee to the caller.
+pub fn redirect_env(engine_state: &EngineState, caller_stack: &mut Stack, callee_stack: &Stack) {
+    let caller_env_vars = caller_stack.get_env_var_names(engine_state);
+
+    // remove env vars that are present in the caller but not in the callee
+    // (the callee hid them)
+    for var in caller_env_vars.iter() {
+        if !callee_stack.has_env_var(engine_state, var) {
+            caller_stack.remove_env_var(engine_state, var);
+        }
+    }
+
+    // add new env vars from callee to caller
+    for (var, value) in callee_stack.get_stack_env_vars() {
+        caller_stack.add_env_var(var, value);
+    }
+}
+
 /// Eval extarnal expression
 ///
 /// It returns PipelineData with a boolean flag, indicate that if the external runs to failed.

crates/nu-engine/src/lib.rs

@@ -11,6 +11,6 @@ pub use documentation::get_full_help;
 pub use env::*;
 pub use eval::{
     eval_block, eval_call, eval_expression, eval_expression_with_input, eval_operator,
-    eval_subexpression, eval_variable,
+    eval_subexpression, eval_variable, redirect_env,
 };
 pub use glob_from::glob_from;