From 9735c3fceaf3962f31999ef84fb42a37afaecfaa Mon Sep 17 00:00:00 2001
From: Ramon Snir <r@mon.co.il>
Date: Sun, 25 Aug 2019 12:14:17 -0400
Subject: [PATCH] add reverse

---
 src/cli.rs              |  1 +
 src/commands.rs         |  2 ++
 src/commands/reverse.rs | 38 ++++++++++++++++++++++++++++++++++++++
 tests/filters_test.rs   | 11 +++++++++++
 4 files changed, 52 insertions(+)
 create mode 100644 src/commands/reverse.rs

diff --git a/src/cli.rs b/src/cli.rs
index a04a6211b9..ba795316a9 100644
--- a/src/cli.rs
+++ b/src/cli.rs
@@ -159,6 +159,7 @@ pub async fn cli() -> Result<(), Box<dyn Error>> {
             whole_stream_command(SplitRow),
             whole_stream_command(Lines),
             whole_stream_command(Reject),
+            whole_stream_command(Reverse),
             whole_stream_command(Trim),
             whole_stream_command(ToArray),
             whole_stream_command(ToCSV),
diff --git a/src/commands.rs b/src/commands.rs
index 3728474f22..f7e46b83ec 100644
--- a/src/commands.rs
+++ b/src/commands.rs
@@ -34,6 +34,7 @@ crate mod pick;
 crate mod plugin;
 crate mod prev;
 crate mod ps;
+crate mod reverse;
 crate mod reject;
 crate mod rm;
 crate mod save;
@@ -89,6 +90,7 @@ crate use pick::Pick;
 crate use prev::Previous;
 crate use ps::PS;
 crate use reject::Reject;
+crate use reverse::Reverse;
 crate use rm::Remove;
 crate use save::Save;
 crate use shells::Shells;
diff --git a/src/commands/reverse.rs b/src/commands/reverse.rs
new file mode 100644
index 0000000000..2b43f01470
--- /dev/null
+++ b/src/commands/reverse.rs
@@ -0,0 +1,38 @@
+use crate::commands::WholeStreamCommand;
+use crate::errors::ShellError;
+use crate::parser::CommandRegistry;
+use crate::prelude::*;
+
+pub struct Reverse;
+
+impl WholeStreamCommand for Reverse {
+    fn run(
+        &self,
+        args: CommandArgs,
+        registry: &CommandRegistry,
+    ) -> Result<OutputStream, ShellError> {
+        reverse(args, registry)
+    }
+
+    fn name(&self) -> &str {
+        "reverse"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("reverse")
+    }
+}
+
+fn reverse(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
+    let args = args.evaluate_once(registry)?;
+    let (input, _args) = args.parts();
+
+    let output = input.values.collect::<Vec<_>>();
+
+    let output = output.map(move |mut vec| {
+        vec.reverse();
+        vec.into_iter().collect::<VecDeque<_>>()
+    });
+
+    Ok(output.flatten_stream().from_input_stream())
+}
diff --git a/tests/filters_test.rs b/tests/filters_test.rs
index c2678b22be..0fbb5635be 100644
--- a/tests/filters_test.rs
+++ b/tests/filters_test.rs
@@ -111,3 +111,14 @@ fn can_get_last() {
 
     assert_eq!(output, "utf16.ini");
 }
+
+#[test]
+fn can_get_reverse_first() {
+    nu!(
+        output,
+        cwd("tests/fixtures/formats"),
+        "ls | sort-by name | reverse | first 1 | get name | trim | echo $it"
+    );
+
+    assert_eq!(output, "utf16.ini");
+}