Add shuffle plugin (#1443)

* Add shuffle plugin

see #1437

* Change plugin to integrate into nu structure and build system

crates/nu_plugin_shuffle/Cargo.toml

@@ -0,0 +1,22 @@
+[package]
+name = "nu_plugin_shuffle"
+description = "Nushell plugin to shuffle input"
+version = "0.10.0"
+license = "MIT"
+authors = ["Falco Hirschenberger <falco.hirschenberger@gmail.com>"]
+edition = "2018"
+
+[lib]
+doctest = false
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+nu-plugin = { path = "../nu-plugin", version = "0.10.0" }
+nu-protocol = { path = "../nu-protocol", version = "0.10.0" }
+nu-source = { path = "../nu-source", version = "0.10.0" }
+nu-errors = { path = "../nu-errors", version = "0.10.0" }
+rand = "0.7"
+
+[build-dependencies]
+nu-build = { version = "0.10.0", path = "../nu-build" }

crates/nu_plugin_shuffle/build.rs

@@ -0,0 +1,3 @@
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+    nu_build::build()
+}

crates/nu_plugin_shuffle/src/lib.rs

@@ -0,0 +1,3 @@
+mod nu;
+
+pub use nu::Shuffle;

crates/nu_plugin_shuffle/src/main.rs

@@ -0,0 +1,6 @@
+use nu_plugin::serve_plugin;
+use nu_plugin_shuffle::Shuffle;
+
+fn main() {
+    serve_plugin(&mut Shuffle::new());
+}

crates/nu_plugin_shuffle/src/nu/mod.rs

@@ -0,0 +1,36 @@
+use nu_errors::ShellError;
+use nu_plugin::Plugin;
+use nu_protocol::{ReturnValue, Signature, Value};
+
+use rand::seq::SliceRandom;
+use rand::thread_rng;
+
+#[derive(Default)]
+pub struct Shuffle {
+    values: Vec<ReturnValue>,
+}
+
+impl Shuffle {
+    pub fn new() -> Self {
+        Self::default()
+    }
+}
+
+impl Plugin for Shuffle {
+    fn config(&mut self) -> Result<Signature, ShellError> {
+        Ok(Signature::build("shuffle")
+            .desc("Shuffle input randomly")
+            .filter())
+    }
+
+    fn filter(&mut self, input: Value) -> Result<Vec<ReturnValue>, ShellError> {
+        self.values.push(input.into());
+        Ok(vec![])
+    }
+
+    fn end_filter(&mut self) -> Result<Vec<ReturnValue>, ShellError> {
+        let mut rng = thread_rng();
+        self.values.shuffle(&mut rng);
+        Ok(self.values.clone())
+    }
+}