Handle mixed LF+CRLF in lines (#7316)

This closes #4989. Previously `lines` was unable to handle text input
with CRLF line breaks _and_ LF line breaks.

### Before:

![image](https://user-images.githubusercontent.com/26268125/205207685-b25da9e1-19fa-4abb-8ab2-0dd216c63fc0.png)

### After:


![image](https://user-images.githubusercontent.com/26268125/205207808-9f687242-a8c2-4b79-a12c-38b0583d8d52.png)

Cargo.lock

@@ -2638,6 +2638,7 @@ dependencies = [
  "rand 0.8.5",
  "rayon",
  "reedline",
+ "regex",
  "reqwest",
  "roxmltree",
  "rstest",

crates/nu-command/Cargo.toml

@@ -68,6 +68,7 @@ powierza-coefficient = "1.0.1"
 quick-xml = "0.25"
 rand = "0.8"
 rayon = "1.5.1"
+regex = "1.6.0"
 reqwest = {version = "0.11", features = ["blocking", "json"] }
 roxmltree = "0.16.0"
 rust-embed = "6.3.0"

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

@@ -4,6 +4,10 @@ use nu_protocol::{
     Category, Example, IntoInterruptiblePipelineData, PipelineData, RawStream, ShellError,
     Signature, Span, Type, Value,
 };
+use once_cell::sync::Lazy;
+// regex can be replaced with fancy-regex once it suppports `split()`
+// https://github.com/fancy-regex/fancy-regex/issues/104
+use regex::Regex;
 
 #[derive(Clone)]
 pub struct Lines;
@@ -34,16 +38,18 @@ impl Command for Lines {
         let head = call.head;
         let ctrlc = engine_state.ctrlc.clone();
         let skip_empty = call.has_flag("skip-empty");
+
+        // match \r\n or \n
+        static LINE_BREAK_REGEX: Lazy<Regex> =
+            Lazy::new(|| Regex::new(r"\r\n|\n").expect("unable to compile regex"));
         match input {
             #[allow(clippy::needless_collect)]
             // Collect is needed because the string may not live long enough for
             // the Rc structure to continue using it. If split could take ownership
             // of the split values, then this wouldn't be needed
             PipelineData::Value(Value::String { val, span }, ..) => {
-                let split_char = if val.contains("\r\n") { "\r\n" } else { "\n" };
-
-                let mut lines = val
-                    .split(split_char)
+                let mut lines = LINE_BREAK_REGEX
+                    .split(&val)
                     .map(|s| s.to_string())
                     .collect::<Vec<String>>();
 
@@ -66,18 +72,12 @@ impl Command for Lines {
                 Ok(iter.into_pipeline_data(engine_state.ctrlc.clone()))
             }
             PipelineData::ListStream(stream, ..) => {
-                let mut split_char = "\n";
-
                 let iter = stream
                     .into_iter()
                     .filter_map(move |value| {
                         if let Value::String { val, span } = value {
-                            if split_char != "\r\n" && val.contains("\r\n") {
-                                split_char = "\r\n";
-                            }
-
-                            let mut lines = val
-                                .split(split_char)
+                            let mut lines = LINE_BREAK_REGEX
+                                .split(&val)
                                 .filter_map(|s| {
                                     if skip_empty && s.trim().is_empty() {
                                         None
@@ -153,6 +153,9 @@ impl Iterator for RawStreamLinesAdapter {
     type Item = Result<Value, ShellError>;
 
     fn next(&mut self) -> Option<Self::Item> {
+        static LINE_BREAK_REGEX: Lazy<Regex> =
+            Lazy::new(|| Regex::new(r"\r\n|\n").expect("unable to compile regex"));
+
         loop {
             if !self.queue.is_empty() {
                 let s = self.queue.remove(0usize);
@@ -188,11 +191,8 @@ impl Iterator for RawStreamLinesAdapter {
                                 Value::String { val, span } => {
                                     self.span = span;
 
-                                    let split_char =
-                                        if val.contains("\r\n") { "\r\n" } else { "\n" };
-
-                                    let mut lines = val
-                                        .split(split_char)
+                                    let mut lines = LINE_BREAK_REGEX
+                                        .split(&val)
                                         .map(|s| s.to_string())
                                         .collect::<Vec<_>>();
 

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

@@ -48,3 +48,16 @@ fn lines_multi_value_split() {
 
     assert_eq!(actual.out, "6");
 }
+
+/// test whether this handles CRLF and LF in the same input
+#[test]
+fn lines_mixed_line_endings() {
+    let actual = nu!(
+        cwd: "tests/fixtures/formats", pipeline(
+        r#"
+            "foo\nbar\r\nquux" | lines | length
+        "#
+    ));
+
+    assert_eq!(actual.out, "3");
+}