From 9c779b071b4f24fe34e67602292c7afeb0cdbbc2 Mon Sep 17 00:00:00 2001
From: Jae-Heon Ji <32578710+jaeheonji@users.noreply.github.com>
Date: Wed, 18 May 2022 23:49:34 +0900
Subject: [PATCH] feat: apply the `--numbered` option to acc in `reduce`
 command. (#5575)

* feat: apply the `-n` option to acc

* feat: update tests and examples
---
 crates/nu-command/src/filters/reduce.rs    | 82 ++++++++++++++--------
 crates/nu-command/tests/commands/reduce.rs |  6 +-
 2 files changed, 54 insertions(+), 34 deletions(-)

diff --git a/crates/nu-command/src/filters/reduce.rs b/crates/nu-command/src/filters/reduce.rs
index 772fe9f331..902f3ff7f7 100644
--- a/crates/nu-command/src/filters/reduce.rs
+++ b/crates/nu-command/src/filters/reduce.rs
@@ -51,7 +51,7 @@ impl Command for Reduce {
                 }),
             },
             Example {
-                example: "[ 1 2 3 ] | reduce -n {|it, acc| $acc + $it.item }",
+                example: "[ 1 2 3 ] | reduce -n {|it, acc| $acc.item + $it.item }",
                 description: "Sum values of a list (same as 'math sum')",
                 result: Some(Value::Int {
                     val: 6,
@@ -76,10 +76,10 @@ impl Command for Reduce {
             },
             Example {
                 example: r#"[ one longest three bar ] | reduce -n { |it, acc|
-                    if ($it.item | str length) > ($acc | str length) {
+                    if ($it.item | str length) > ($acc.item | str length) {
                         $it.item
                     } else {
-                        $acc
+                        $acc.item
                     }
                 }"#,
                 description: "Find the longest string and its index",
@@ -129,29 +129,22 @@ impl Command for Reduce {
             ));
         };
 
-        let mut acc = start_val;
+        let mut acc = if numbered {
+            Value::Record {
+                cols: vec!["index".to_string(), "item".to_string()],
+                vals: vec![Value::Int { val: 0, span }, start_val],
+                span,
+            }
+        } else {
+            start_val
+        };
 
-        let mut input_iter = input_iter.enumerate().peekable();
-        while let Some((idx, x)) = input_iter.next() {
-            stack.with_env(&orig_env_vars, &orig_env_hidden);
-            // if the acc coming from previous iter is indexed, drop the index
-            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()
-                    } else {
-                        acc
-                    }
-                } else {
-                    acc
-                }
-            } else {
-                acc
-            };
-
-            if let Some(var) = block.signature.get_positional(0) {
-                if let Some(var_id) = &var.var_id {
-                    let it = if numbered {
+        let mut input_iter = input_iter
+            .enumerate()
+            .map(|(idx, x)| {
+                if numbered {
+                    (
+                        idx,
                         Value::Record {
                             cols: vec!["index".to_string(), "item".to_string()],
                             vals: vec![
@@ -162,16 +155,45 @@ impl Command for Reduce {
                                 x,
                             ],
                             span,
-                        }
-                    } else {
-                        x
-                    };
+                        },
+                    )
+                } else {
+                    (idx, x)
+                }
+            })
+            .peekable();
 
-                    stack.add_var(*var_id, it);
+        while let Some((idx, x)) = input_iter.next() {
+            stack.with_env(&orig_env_vars, &orig_env_hidden);
+
+            if let Some(var) = block.signature.get_positional(0) {
+                if let Some(var_id) = &var.var_id {
+                    stack.add_var(*var_id, x);
                 }
             }
+
             if let Some(var) = block.signature.get_positional(1) {
                 if let Some(var_id) = &var.var_id {
+                    acc = if numbered {
+                        if let Value::Record { .. } = &acc {
+                            acc
+                        } else {
+                            Value::Record {
+                                cols: vec!["index".to_string(), "item".to_string()],
+                                vals: vec![
+                                    Value::Int {
+                                        val: idx as i64 + off,
+                                        span,
+                                    },
+                                    acc,
+                                ],
+                                span,
+                            }
+                        }
+                    } else {
+                        acc
+                    };
+
                     stack.add_var(*var_id, acc);
                 }
             }
diff --git a/crates/nu-command/tests/commands/reduce.rs b/crates/nu-command/tests/commands/reduce.rs
index 37555012db..fb496e8106 100644
--- a/crates/nu-command/tests/commands/reduce.rs
+++ b/crates/nu-command/tests/commands/reduce.rs
@@ -46,15 +46,13 @@ fn reduce_rows_example() {
     assert_eq!(actual.out, "14.8");
 }
 
-// FIXME: jt: needs more work
-#[ignore]
 #[test]
 fn reduce_numbered_example() {
     let actual = nu!(
         cwd: ".", pipeline(
         r#"
         echo one longest three bar
-        | reduce -n { |it, acc| if ($it.item | str length) > ($acc | str length) {echo $it.item} else {echo $acc}}
+        | reduce -n { |it, acc| if ($it.item | str length) > ($acc.item | str length) {echo $it} else {echo $acc}}
         | get index
         "#
         )
@@ -69,7 +67,7 @@ fn reduce_numbered_integer_addition_example() {
         cwd: ".", pipeline(
         r#"
         echo [1 2 3 4]
-        | reduce -n { |it, acc| $acc + $it.item }
+        | reduce -n { |it, acc| $acc.item + $it.item }
         "#
         )
     );