add reverse

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())
+}