Lines no longer treats a text buffer as a line (#3153)

crates/nu-command/src/commands/lines.rs

@@ -56,9 +56,9 @@ async fn lines(args: CommandArgs) -> Result<OutputStream, ShellError> {
     Ok(args
         .input
         .chain(eos)
-        .map(move |item| {
+        .filter_map(move |item| {
             let leftover_string = leftover_string.clone();
-
+            async move {
                 match item {
                     Value {
                         value: UntaggedValue::Primitive(Primitive::String(st)),
@@ -66,9 +66,11 @@ async fn lines(args: CommandArgs) -> Result<OutputStream, ShellError> {
                     } => {
                         let mut leftover_string = leftover_string.lock();
 
-                    let lo_lines = (&*leftover_string).lines().map(|x| x.to_string());
-                    let st_lines = st.lines().map(|x| x.to_string());
-                    let mut lines: Vec<String> = lo_lines.chain(st_lines).collect();
+                        let mut buffer = leftover_string.clone();
+                        buffer.push_str(&st);
+
+                        let mut lines: Vec<String> =
+                            buffer.lines().map(|x| x.to_string()).collect();
 
                         leftover_string.clear();
 
@@ -78,14 +80,20 @@ async fn lines(args: CommandArgs) -> Result<OutputStream, ShellError> {
                             }
                         }
 
+                        if !lines.is_empty() {
                             let success_lines: Vec<_> = lines
                                 .iter()
                                 .map(|x| {
-                            ReturnSuccess::value(UntaggedValue::string(x).into_untagged_value())
+                                    ReturnSuccess::value(
+                                        UntaggedValue::string(x).into_untagged_value(),
+                                    )
                                 })
                                 .collect();
 
-                    futures::stream::iter(success_lines)
+                            Some(futures::stream::iter(success_lines))
+                        } else {
+                            None
+                        }
                     }
                     Value {
                         value: UntaggedValue::Primitive(Primitive::EndOfStream),
@@ -93,22 +101,25 @@ async fn lines(args: CommandArgs) -> Result<OutputStream, ShellError> {
                     } => {
                         let st = (&*leftover_string).lock().clone();
                         if !st.is_empty() {
-                        futures::stream::iter(vec![ReturnSuccess::value(
+                            Some(futures::stream::iter(vec![ReturnSuccess::value(
                                 UntaggedValue::string(st).into_untagged_value(),
-                        )])
+                            )]))
                         } else {
-                        futures::stream::iter(vec![])
+                            None
                         }
                     }
                     Value {
                         tag: value_span, ..
-                } => futures::stream::iter(vec![Err(ShellError::labeled_error_with_secondary(
+                    } => Some(futures::stream::iter(vec![Err(
+                        ShellError::labeled_error_with_secondary(
                             "Expected a string from pipeline",
                             "requires string input",
                             name_span,
                             "value originates from here",
                             value_span,
-                ))]),
+                        ),
+                    )])),
+                }
             }
         })
         .flatten()

crates/nu-command/src/utils/test_bins.rs

@@ -17,6 +17,21 @@ pub fn nonu() {
     args().iter().skip(1).for_each(|arg| print!("{}", arg));
 }
 
+pub fn repeater() {
+    let mut stdout = io::stdout();
+    let args = args();
+    let mut args = args.iter().skip(1);
+    let letter = args.next().expect("needs a character to iterate");
+    let count = args.next().expect("need the number of times to iterate");
+
+    let count: u64 = count.parse().expect("can't convert count to number");
+
+    for _ in 0..count {
+        let _ = write!(stdout, "{}", letter);
+    }
+    let _ = stdout.flush();
+}
+
 pub fn iecho() {
     // println! panics if stdout gets closed, whereas writeln gives us an error
     let mut stdout = io::stdout();

crates/nu-command/tests/commands/lines.rs

@@ -46,5 +46,5 @@ fn lines_multi_value_split() {
         "#
     ));
 
-    assert_eq!(actual.out, "6");
+    assert_eq!(actual.out, "5");
 }

src/main.rs

@@ -29,7 +29,7 @@ fn main() -> Result<(), Box<dyn Error>> {
                 .hidden(true)
                 .long("testbin")
                 .value_name("TESTBIN")
-                .possible_values(&["cococo", "iecho", "fail", "nonu", "chop"])
+                .possible_values(&["cococo", "iecho", "fail", "nonu", "chop", "repeater"])
                 .takes_value(true),
         )
         .arg(
@@ -77,6 +77,7 @@ fn main() -> Result<(), Box<dyn Error>> {
             "fail" => binaries::fail(),
             "nonu" => binaries::nonu(),
             "chop" => binaries::chop(),
+            "repeater" => binaries::repeater(),
             _ => unreachable!(),
         }
 

tests/shell/pipeline/commands/external.rs

@@ -121,6 +121,17 @@ mod it_evaluation {
         })
     }
 
+    #[test]
+    fn can_properly_buffer_lines_externally() {
+        let actual = nu!(
+            cwd: ".",
+            r#"
+                nu --testbin repeater c 8197 | lines | count
+            "#
+        );
+
+        assert_eq!(actual.out, "1");
+    }
     #[test]
     fn supports_fetching_given_a_column_path_to_it() {
         Playground::setup("it_argument_test_3", |dirs, sandbox| {