Add 'split chars' command (#2101)

crates/nu-cli/src/cli.rs

@@ -288,6 +288,7 @@ pub fn create_default_context(
             whole_stream_command(Split),
             whole_stream_command(SplitColumn),
             whole_stream_command(SplitRow),
+            whole_stream_command(SplitChars),
             whole_stream_command(Lines),
             whole_stream_command(Trim),
             whole_stream_command(Echo),

crates/nu-cli/src/commands.rs

@@ -238,6 +238,7 @@ pub(crate) use skip_until::SkipUntil;
 pub(crate) use skip_while::SkipWhile;
 pub(crate) use sort_by::SortBy;
 pub(crate) use split::Split;
+pub(crate) use split::SplitChars;
 pub(crate) use split::SplitColumn;
 pub(crate) use split::SplitRow;
 pub(crate) use split_by::SplitBy;

crates/nu-cli/src/commands/split/chars.rs

@@ -0,0 +1,84 @@
+use crate::commands::WholeStreamCommand;
+use crate::prelude::*;
+use nu_errors::ShellError;
+use nu_protocol::{ReturnSuccess, Signature, Value};
+
+pub struct SubCommand;
+
+#[async_trait]
+impl WholeStreamCommand for SubCommand {
+    fn name(&self) -> &str {
+        "split chars"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("split chars")
+    }
+
+    fn usage(&self) -> &str {
+        "splits a string's characters into separate rows"
+    }
+
+    async fn run(
+        &self,
+        args: CommandArgs,
+        registry: &CommandRegistry,
+    ) -> Result<OutputStream, ShellError> {
+        split_chars(args, registry).await
+    }
+
+    fn examples(&self) -> Vec<Example> {
+        vec![Example {
+            description: "Split the string's characters into separate rows",
+            example: "echo 'hello' | split chars",
+            result: Some(vec![
+                Value::from("h"),
+                Value::from("e"),
+                Value::from("l"),
+                Value::from("l"),
+                Value::from("o"),
+            ]),
+        }]
+    }
+}
+
+async fn split_chars(
+    args: CommandArgs,
+    _registry: &CommandRegistry,
+) -> Result<OutputStream, ShellError> {
+    let name = args.call_info.name_tag.clone();
+    let input = args.input;
+    Ok(input
+        .flat_map(move |v| {
+            if let Ok(s) = v.as_string() {
+                futures::stream::iter(
+                    s.chars()
+                        .collect::<Vec<_>>()
+                        .into_iter()
+                        .map(move |x| ReturnSuccess::value(Value::from(x.to_string()))),
+                )
+                .to_output_stream()
+            } else {
+                OutputStream::one(Err(ShellError::labeled_error_with_secondary(
+                    "Expected a string from pipeline",
+                    "requires string input",
+                    name.span,
+                    "value originates from here",
+                    v.tag.span,
+                )))
+            }
+        })
+        .to_output_stream())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::SubCommand;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(SubCommand {})
+    }
+}

crates/nu-cli/src/commands/split/mod.rs

@@ -1,7 +1,9 @@
+pub mod chars;
 pub mod column;
 pub mod command;
 pub mod row;
 
+pub use chars::SubCommand as SplitChars;
 pub use column::SubCommand as SplitColumn;
 pub use command::Command as Split;
 pub use row::SubCommand as SplitRow;