From 19772f82aaecd21db87f4d14ac085130c3b7f01f Mon Sep 17 00:00:00 2001
From: Dmitry Starostin <incrop@gmail.com>
Date: Sat, 24 Aug 2019 23:31:45 +0300
Subject: [PATCH] Add --reverse option for sort-by

---
 README.md               |  2 +-
 src/commands/sort_by.rs | 14 +++++++++++---
 tests/filters_test.rs   | 11 +++++++++++
 3 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/README.md b/README.md
index 7d9e102347..317df72ed5 100644
--- a/README.md
+++ b/README.md
@@ -185,7 +185,7 @@ Nu adheres closely to a set of goals that make up its design philosophy. As feat
 | pick ...columns | Down-select table to only these columns |
 | reject ...columns | Remove the given columns from the table |
 | get column-or-column-path | Open given cells as text |
-| sort-by ...columns | Sort by the given columns |
+| sort-by ...columns (--reverse) | Sort by the given columns |
 | where condition | Filter table to match the condition |
 | inc (field) | Increment a value or version. Optional use the field of a table |
 | add field value | Add a new field to the table |
diff --git a/src/commands/sort_by.rs b/src/commands/sort_by.rs
index 52d97a5952..820e0a471d 100644
--- a/src/commands/sort_by.rs
+++ b/src/commands/sort_by.rs
@@ -18,7 +18,7 @@ impl WholeStreamCommand for SortBy {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("sort-by")
+        Signature::build("sort-by").switch("reverse")
     }
 }
 
@@ -37,13 +37,21 @@ fn sort_by(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream
 
     let output = input.values.collect::<Vec<_>>();
 
+    let reverse = args.has("reverse");
     let output = output.map(move |mut vec| {
-        vec.sort_by_key(|item| {
+        let calc_key = |item: &Tagged<Value>| {
             fields
                 .iter()
                 .map(|f| item.get_data_by_key(f).map(|i| i.clone()))
                 .collect::<Vec<Option<Tagged<Value>>>>()
-        });
+        };
+        if reverse {
+            vec.sort_by_cached_key(|item| {
+                std::cmp::Reverse(calc_key(item))
+            });
+        } else {
+            vec.sort_by_cached_key(calc_key);
+        }
 
         vec.into_iter().collect::<VecDeque<_>>()
     });
diff --git a/tests/filters_test.rs b/tests/filters_test.rs
index 8b0e40bef3..20eba8050c 100644
--- a/tests/filters_test.rs
+++ b/tests/filters_test.rs
@@ -57,6 +57,17 @@ fn can_sort_by_column() {
     assert_eq!(output, "description");
 }
 
+#[test]
+fn can_sort_by_column_reverse() {
+    nu!(
+        output,
+        cwd("tests/fixtures/formats"),
+        "open cargo_sample.toml --raw | lines | skip 1 | first 4 | split-column \"=\" | sort-by Column1 --reverse | skip 1 | first 1 | get Column1 | trim | echo $it"
+    );
+
+    assert_eq!(output, "name");
+}
+
 #[test]
 fn can_split_by_column() {
     nu!(