Make reduce -n more sensible (#4791)

crates/nu-command/src/filters/reduce.rs

@@ -1,3 +1,5 @@
+use std::sync::atomic::Ordering;
+
 use nu_engine::{eval_block, CallExt};
 
 use nu_protocol::ast::Call;
@@ -69,19 +71,9 @@ impl Command for Reduce {
                     }
                 }"#,
                 description: "Find the longest string and its index",
-                result: Some(Value::Record {
-                    cols: vec!["index".to_string(), "item".to_string()],
-                    vals: vec![
-                        Value::Int {
-                            val: 3,
-                            span: Span::test_data(),
-                        },
-                        Value::String {
+                result: Some(Value::String {
                     val: "longest".to_string(),
                     span: Span::test_data(),
-                        },
-                    ],
-                    span: Span::test_data(),
                 }),
             },
         ]
@@ -94,10 +86,6 @@ impl Command for Reduce {
         call: &Call,
         input: PipelineData,
     ) -> Result<PipelineData, ShellError> {
-        // TODO: How to make this interruptible?
-        // TODO: Change the vars to $acc and $it instead of $it.acc and $it.item
-        //       (requires parser change)
-
         let span = call.head;
 
         let fold: Option<Value> = call.get_flag(engine_state, stack, "fold")?;
@@ -105,6 +93,7 @@ impl Command for Reduce {
         let capture_block: CaptureBlock = call.req(engine_state, stack, 0)?;
         let mut stack = stack.captures_to_stack(&capture_block.captures);
         let block = engine_state.get_block(capture_block.block_id);
+        let ctrlc = engine_state.ctrlc.clone();
 
         let orig_env_vars = stack.env_vars.clone();
         let orig_env_hidden = stack.env_hidden.clone();
@@ -126,13 +115,12 @@ impl Command for Reduce {
             ));
         };
 
-        Ok(input_iter
-            .enumerate()
-            .fold(start_val, move |acc, (idx, x)| {
-                stack.with_env(&orig_env_vars, &orig_env_hidden);
+        let mut acc = start_val;
 
+        for (idx, x) in input_iter.enumerate() {
+            stack.with_env(&orig_env_vars, &orig_env_hidden);
             // if the acc coming from previous iter is indexed, drop the index
-                let acc = if let Value::Record { cols, vals, .. } = &acc {
+            acc = if let Value::Record { cols, vals, .. } = &acc {
                 if cols.len() == 2 && vals.len() == 2 {
                     if cols[0].eq("index") && cols[1].eq("item") {
                         vals[1].clone()
@@ -173,37 +161,24 @@ impl Command for Reduce {
                 }
             }
 
-                let v = match eval_block(
+            acc = eval_block(
                 engine_state,
                 &mut stack,
                 block,
                 PipelineData::new(span),
                 redirect_stdout,
                 redirect_stderr,
-                ) {
-                    Ok(v) => v.into_value(span),
-                    Err(error) => Value::Error { error },
-                };
+            )?
+            .into_value(span);
 
-                if numbered {
-                    // make sure the output is indexed
-                    Value::Record {
-                        cols: vec!["index".to_string(), "item".to_string()],
-                        vals: vec![
-                            Value::Int {
-                                val: idx as i64 + off,
-                                span,
-                            },
-                            v,
-                        ],
-                        span,
+            if let Some(ctrlc) = &ctrlc {
+                if ctrlc.load(Ordering::SeqCst) {
+                    break;
                 }
-                } else {
-                    v
             }
-            })
-            .with_span(span)
-            .into_pipeline_data())
+        }
+
+        Ok(acc.with_span(span).into_pipeline_data())
     }
 }
 

crates/nu-command/tests/commands/reduce.rs

@@ -70,7 +70,6 @@ fn reduce_numbered_integer_addition_example() {
         r#"
         echo [1 2 3 4]
         | reduce -n { |it, acc| $acc + $it.item }
-        | get item
         "#
         )
     );