Merge shuffle nu plugin as core command. (#1475)

crates/nu-cli/src/commands/shuffle.rs

@@ -0,0 +1,69 @@
+use crate::commands::WholeStreamCommand;
+use crate::context::CommandRegistry;
+use crate::prelude::*;
+use nu_errors::ShellError;
+use nu_protocol::{ReturnSuccess, ReturnValue, Signature, SyntaxShape, Value};
+use nu_source::Tagged;
+
+use rand::seq::SliceRandom;
+use rand::thread_rng;
+
+pub struct Shuffle;
+
+#[derive(Deserialize)]
+pub struct Arguments {
+    #[serde(rename = "num")]
+    limit: Option<Tagged<u64>>,
+}
+
+impl WholeStreamCommand for Shuffle {
+    fn name(&self) -> &str {
+        "shuffle"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("shuffle").named(
+            "num",
+            SyntaxShape::Int,
+            "Limit `num` number of rows",
+            Some('n'),
+        )
+    }
+
+    fn usage(&self) -> &str {
+        "Shuffle rows randomly."
+    }
+
+    fn run(
+        &self,
+        args: CommandArgs,
+        registry: &CommandRegistry,
+    ) -> Result<OutputStream, ShellError> {
+        args.process(registry, shuffle)?.run()
+    }
+}
+
+fn shuffle(
+    Arguments { limit }: Arguments,
+    RunnableContext { input, .. }: RunnableContext,
+) -> Result<OutputStream, ShellError> {
+    let stream = async_stream! {
+        let mut values: Vec<Value> = input.values.collect().await;
+
+        let out = if let Some(n) = limit {
+            let (shuffled, _) = values.partial_shuffle(&mut thread_rng(), *n as usize);
+            shuffled.to_vec()
+        } else {
+            values.shuffle(&mut thread_rng());
+            values.clone()
+        };
+
+        for val in out.into_iter() {
+            yield ReturnSuccess::value(val);
+        }
+    };
+
+    let stream: BoxStream<'static, ReturnValue> = stream.boxed();
+
+    Ok(stream.to_output_stream())
+}