headers plugin

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

@@ -0,0 +1,39 @@
+use crate::commands::WholeStreamCommand;
+use crate::context::CommandRegistry;
+use crate::prelude::*;
+use futures::stream::StreamExt;
+use nu_errors::ShellError;
+use nu_protocol::{ReturnSuccess, Signature, UntaggedValue, Value};
+
+pub struct Headers;
+
+impl WholeStreamCommand for Headers {
+    fn name(&self) -> &str {
+        "headers"
+    }
+    fn signature(&self) -> Signature {
+        Signature::build("headers")
+    }
+    fn usage(&self) -> &str {
+        "Use the first row of the table as headers"
+    }
+    fn run(
+        &self,
+        args: CommandArgs,
+        registry: &CommandRegistry,
+    ) -> Result<OutputStream, ShellError> {
+        args.process(registry, count)?.run()
+    }
+}
+pub fn count(
+    CountArgs {}: CountArgs,
+    RunnableContext { input, name, .. }: RunnableContext,
+) -> Result<OutputStream, ShellError> {
+    let stream = async_stream! {
+        let rows: Vec<Value> = input.values.collect().await;
+
+        yield ReturnSuccess::value(UntaggedValue::int(rows.len()).into_value(name))
+    };
+
+    Ok(stream.to_output_stream())
+}