Add env shorthand

crates/nu-command/src/default_context.rs

@@ -91,6 +91,7 @@ pub fn create_default_context() -> EngineState {
             Touch,
             Use,
             Where,
+            WithEnv,
             Wrap,
             Zip
         );

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

@@ -1,3 +1,5 @@
 mod let_env;
+mod with_env;
 
 pub use let_env::LetEnv;
+pub use with_env::WithEnv;

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

@@ -0,0 +1,180 @@
+use std::{
+    collections::HashMap,
+    convert::{TryFrom, TryInto},
+};
+
+use nu_engine::{eval_block, CallExt};
+use nu_protocol::{
+    ast::Call,
+    engine::{Command, EngineState, Stack},
+    Example, PipelineData, ShellError, Signature, SyntaxShape, Value,
+};
+
+#[derive(Clone)]
+pub struct WithEnv;
+
+impl Command for WithEnv {
+    fn name(&self) -> &str {
+        "with-env"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("with-env")
+            .required(
+                "variable",
+                SyntaxShape::Any,
+                "the environment variable to temporarily set",
+            )
+            .required(
+                "block",
+                SyntaxShape::Block(Some(vec![SyntaxShape::Any])),
+                "the block to run once the variable is set",
+            )
+    }
+
+    fn usage(&self) -> &str {
+        "Runs a block with an environment variable set."
+    }
+
+    fn run(
+        &self,
+        engine_state: &EngineState,
+        stack: &mut Stack,
+        call: &Call,
+        input: PipelineData,
+    ) -> Result<nu_protocol::PipelineData, nu_protocol::ShellError> {
+        with_env(engine_state, stack, call, input)
+    }
+
+    fn examples(&self) -> Vec<Example> {
+        vec![
+            Example {
+                description: "Set the MYENV environment variable",
+                example: r#"with-env [MYENV "my env value"] { $nu.env.MYENV }"#,
+                result: Some(Value::test_string("my env value")),
+            },
+            Example {
+                description: "Set by primitive value list",
+                example: r#"with-env [X Y W Z] { $nu.env.X }"#,
+                result: Some(Value::test_string("Y")),
+            },
+            Example {
+                description: "Set by single row table",
+                example: r#"with-env [[X W]; [Y Z]] { $nu.env.W }"#,
+                result: Some(Value::test_string("Z")),
+            },
+            Example {
+                description: "Set by row(e.g. `open x.json` or `from json`)",
+                example: r#"echo '{"X":"Y","W":"Z"}'|from json|with-env $it { echo $nu.env.X $nu.env.W }"#,
+                result: None,
+            },
+        ]
+    }
+}
+
+#[derive(Debug, Clone)]
+pub enum EnvVar {
+    Proper(String),
+    Nothing,
+}
+
+impl TryFrom<&Value> for EnvVar {
+    type Error = ShellError;
+
+    fn try_from(value: &Value) -> Result<Self, Self::Error> {
+        if matches!(value, Value::Nothing { .. }) {
+            Ok(EnvVar::Nothing)
+        } else if let Ok(s) = value.as_string() {
+            if s.is_empty() {
+                Ok(EnvVar::Nothing)
+            } else {
+                Ok(EnvVar::Proper(s))
+            }
+        } else {
+            Err(ShellError::CantConvert("string".into(), value.span()?))
+        }
+    }
+}
+
+fn with_env(
+    engine_state: &EngineState,
+    stack: &mut Stack,
+    call: &Call,
+    input: PipelineData,
+) -> Result<PipelineData, ShellError> {
+    // let external_redirection = args.call_info.args.external_redirection;
+    let variable: Value = call.req(engine_state, stack, 0)?;
+
+    let block_id = call.positional[1]
+        .as_block()
+        .expect("internal error: expected block");
+    let block = engine_state.get_block(block_id).clone();
+    let mut stack = stack.collect_captures(&block.captures);
+
+    let mut env: HashMap<String, EnvVar> = HashMap::new();
+
+    match &variable {
+        Value::List { vals: table, .. } => {
+            if table.len() == 1 {
+                // single row([[X W]; [Y Z]])
+                match &table[0] {
+                    Value::Record { cols, vals, .. } => {
+                        for (k, v) in cols.iter().zip(vals.iter()) {
+                            env.insert(k.to_string(), v.try_into()?);
+                        }
+                    }
+                    _ => {
+                        return Err(ShellError::CantConvert(
+                            "string list or single row".into(),
+                            call.positional[1].span,
+                        ));
+                    }
+                }
+            } else {
+                // primitive values([X Y W Z])
+                for row in table.chunks(2) {
+                    if row.len() == 2 {
+                        env.insert(row[0].as_string()?, (&row[1]).try_into()?);
+                    }
+                }
+            }
+        }
+        // when get object by `open x.json` or `from json`
+        Value::Record { cols, vals, .. } => {
+            for (k, v) in cols.iter().zip(vals) {
+                env.insert(k.clone(), v.try_into()?);
+            }
+        }
+        _ => {
+            return Err(ShellError::CantConvert(
+                "string list or single row".into(),
+                call.positional[1].span,
+            ));
+        }
+    };
+
+    for (k, v) in env {
+        match v {
+            EnvVar::Nothing => {
+                stack.env_vars.remove(&k);
+            }
+            EnvVar::Proper(s) => {
+                stack.env_vars.insert(k, s);
+            }
+        }
+    }
+
+    eval_block(engine_state, &mut stack, &block, input)
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn test_examples() {
+        use crate::test_examples;
+
+        test_examples(WithEnv {})
+    }
+}

crates/nu-command/src/system/benchmark.rs

@@ -3,7 +3,7 @@ use std::time::Instant;
 use nu_engine::eval_block;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{PipelineData, Signature, SyntaxShape};
+use nu_protocol::{IntoPipelineData, PipelineData, Signature, SyntaxShape, Value};
 
 #[derive(Clone)]
 pub struct Benchmark;
@@ -42,7 +42,12 @@ impl Command for Benchmark {
         eval_block(engine_state, &mut stack, block, PipelineData::new())?.into_value();
 
         let end_time = Instant::now();
-        println!("{} ms", (end_time - start_time).as_millis());
-        Ok(PipelineData::new())
+
+        let output = Value::Duration {
+            val: (end_time - start_time).as_nanos() as i64,
+            span: call.head,
+        };
+
+        Ok(output.into_pipeline_data())
     }
 }